WO2019017183A1 - Estimation device, power storage device, estimation method, and computer program - Google Patents

Abstract

Power storage elements 3 each have a single pole including an active material in which a first characteristic that is a power storage amount-potential charging characteristic and a second characteristic that is a power storage amount-potential discharging characteristic are changed by repetition of charging/discharging. An estimation device 6 is provided with: a storage unit 63 that stores V - dQ/dV, the first characteristic, or the second characteristic of the single pole in association with a feature value changed by repetition of charging/discharging, so as to store plural values of the V - dQ/dV, the first characteristic, or the second characteristic in accordance with the change of the feature value, or to store the V - dQ/dV, the first characteristic, or the second characteristic as a function of the feature value; an acquisition unit 62 that acquires the feature value of each power storage element 3; and a first estimation unit 62 that estimates the V - dQ/dV, the first characteristic, or the second characteristic of the single pole by referring to the V - dQ/dV, the first characteristic, or the second characteristic of the single pole or by referring to the function on the basis of the feature value acquired by the acquisition unit 62.

Description

Estimation device, power storage device, estimation method, and computer program

The present invention relates to an estimation device, a power storage device including the estimation device, an estimation method, and a computer program.

In the secondary battery for vehicles used for an electric vehicle, a hybrid vehicle, etc., and the secondary battery for industrial use used for an electric power storage apparatus, a solar power generation system, etc., high-capacity-ization is calculated | required. Until now, various studies and improvements have been made, and it is difficult to realize a further increase in capacity only by improving the electrode structure and the like. Therefore, development of a positive electrode material having a higher capacity than current materials is in progress.

Conventionally, a lithium transition metal complex oxide having an α-NaFeO ₂ type crystal structure has been studied as a positive electrode active material for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and a non-aqueous electrolyte ₂ using LiCoO ₂ The secondary battery has been widely put to practical use. The discharge capacity of LiCoO ₂ was about 120 to 130 mAh / g.
When the lithium transition metal complex oxide is represented by LiMeO ₂ (Me is a transition metal), it has been desired to use Mn as Me. When Mn is contained as Me, when the molar ratio of Mn in Me exceeds 0.5, structural change occurs to the spinel type upon charging, and the crystal structure can not be maintained, so charge and discharge The cycle performance is extremely poor.
Various LiMeO ₂ -type active materials have been proposed and put to practical use, in which the molar ratio Mn / Me of Mn in Me is 0.5 or less and the molar ratio Li / Me relative to Me is approximately 1. The positive electrode active material containing LiNi _1/2 Mn _1/2 O ₂ and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ which are lithium transition metal composite oxides has a discharge capacity of 150 to 180 mAh / g. Have.

A lithium transition metal complex oxide in which the molar ratio Mn / Me of Mn in Me to LiMeO _{2 type} active material exceeds 0.5, and the composition ratio Li / Me of Li to the ratio of transition metal (Me) is more than 1 So-called excessive lithium type active materials are also known.

As the above-mentioned high-capacity positive electrode material, an Li ₂ MnO ₃ -based active material which is a lithium excess type is being studied. This material has the property of hysteresis which causes a difference in voltage and electrochemical characteristics between SOC-OCV (Open Circuit Voltage) at the time of charge and discharge for the same SOC (State Of Charge). .
In the case of having hysteresis, since the voltage can not be uniquely determined with respect to the SOC, it is difficult to estimate the SOC by the OCV method that estimates the SOC based on the SOC-OCV. Since the SOC-OCV curve can not be uniquely determined, it is also difficult to predict the dischargeable energy at a certain point.

The material of the lithium excess type has a property of voltage drop (Voltage Fade) in which the SOC-OCP (Open Circuit Potential) curve of the positive electrode changes almost over the entire area by repetition of charge and discharge. Since the value of the average discharge potential decreases, it is necessary to estimate not only the dischargeable capacity but also the dischargeable power amount as the current state of health (SOH). Since the SOC-OCV curve shape of the battery cell based on the unipolar SOC-OCP curve (hereinafter, also simply referred to as "cell") changes significantly due to deterioration even if the latest charge / discharge history is the same, OCV The law can not be adopted. The conditions under which the latest charge and discharge history is the same include, for example, charge after passing through a complete discharge state. In charging after passing through the full discharge state, the SOC-OCV curve shape of the cell is significantly changed because the unipolar SOC-OCP curve changes according to the deterioration.

When estimating SOC by the current integration method which integrates the charging / discharging current of a secondary battery, when current integration is continued for a long period, the measurement error of a current sensor will accumulate. In addition, the battery capacity decreases with time. Therefore, in the SOC estimated by the current integration method, the estimation error increases with time. Conventionally, when current integration is continued for a long period, an OCV reset is performed to estimate the SOC by the OCV method and reset the accumulation of errors.

Even in a storage element using an electrode material having a potential drop and hysteresis, errors continue to accumulate when current integration is continued. However, since the voltage can not be determined uniquely with respect to the SOC, it is difficult to estimate the SOC by the OCV method (to perform the OCV reset).

In controlling a storage element including such an active material, it is necessary to estimate the SOC-OCP characteristics of the positive electrode from the full charge state to the full discharge state, from the full discharge state to the full charge state.
Current SOH and SOC estimation techniques for non-aqueous electrolyte secondary batteries are difficult to apply to storage devices using active materials having VF and hysteresis properties.

BACKGROUND ART Storage devices such as lithium ion secondary batteries are often used repeatedly in a state in which the SOC is 40% or more in vehicles and the like. When charging, the voltage is often raised to near full charge, and when the degradation state can be grasped in a high voltage region (high SOC region) where the voltage is high, that is, the SOC is high after charging, dischargeable capacity and dischargeable Since the amount of power can be estimated and control can be performed to suppress deterioration at an appropriate timing, convenience is high.
Even in the high SOC region, it is required to simply, quickly, and accurately estimate the degraded state.

The determination unit of the storage battery evaluation device disclosed in Patent Document 1 determines the charge / discharge tendency of the storage battery based on measurement data including voltage data of the storage battery. The correction unit corrects the voltage data based on the correction parameter according to the charge / discharge tendency and / or the deterioration state of the storage battery. The QV curve generation unit generates a storage battery QV curve based on the voltage data. The evaluation unit evaluates the deterioration state based on the QV curve.

JP, 2016-85166, A

The storage battery evaluation device of Patent Document 1 requires complicated steps to evaluate the storage battery. The voltage data is acquired by acquiring the voltage data and removing the voltage component caused by the internal resistance. In the active material of Patent Document 1, the unipolar SOC-OCP does not change over substantially the entire region due to the repetition of charge and discharge. In the case of an active material that causes a potential drop, the storage battery evaluation device and evaluation method of Patent Document 1 can not be adopted.

The present invention can be applied to a storage element having a single pole in which the storage capacity-potential characteristic changes due to repetition of charge and discharge, an estimation apparatus for estimating the storage capacity characteristic, etc., a storage apparatus including the estimation apparatus, an estimation method, and a computer The purpose is to provide a program.
Here, the storage amount means a charging rate such as SOC, an amount of power that can be released, and the like.

An estimation device according to one aspect of the present invention is a single electrode including an active material in which a first characteristic, which is a storage amount-potential charge characteristic, and a second characteristic, which is a storage amount-potential discharge characteristic, change by repetition of charge and discharge. The first and second characteristics of the single pole of the storage element having at least one of V-dQ / dV, which is the relationship between the potential V and dQ / dV, are estimated. The estimation apparatus responds to the change in the feature value, at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole corresponding to the feature value that changes due to the repetition of charge and discharge. Storage unit for storing the plurality of storage units as a function of the feature value, an acquisition unit for acquiring the feature value of the storage element, and the first characteristic based on the characteristic value acquired by the acquisition unit. Two characteristics, and at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole with reference to at least one of the V-dQ / dV or with reference to the function. And a first estimation unit that estimates

According to the above configuration, based on the characteristic value, the storage amount characteristic of the storage element having a single electrode including the active material in which the first characteristic and the second characteristic change due to repetition of charge and discharge can be favorably estimated. .

It is a graph which shows an example of SOC-OCP of a positive electrode. FIG. 6 is a conceptual diagram showing a relationship between a unipolar potential range corresponding to a predetermined voltage range and a range of charge amount corresponding to each deterioration state in each potential range. FIG. 3A is a graph showing the relationship between the potential of the positive electrode and the dQ / dV of the initial product including the active material whose first and second characteristics change due to repetition of charge and discharge, and FIG. 3B is the potential of the positive electrode of the deteriorated product. It is a graph which shows the relationship between and dQ / dV. It is a graph which shows transition of K absorption edge energy of Ni of the above-mentioned active material computed by X-ray absorption spectrometry (XAFS measurement) to a charge potential. FIG. 2 is a perspective view showing an example of a power storage device. It is a perspective view which shows the other example of an electrical storage apparatus. It is an exploded perspective view of a battery module. It is a block diagram of a battery module. It is a flowchart which shows the procedure of the estimation process of the electrical storage amount characteristic by CPU. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a graph which shows the result of having calculated the error to the SOC-OCP data based on an actual measurement value of the calculated SOC-OCP data. It is a flowchart which shows the procedure of the SOC estimation process by CPU. It is a flowchart which shows the procedure of the SOC estimation process by CPU. It is a flowchart which shows the procedure of the estimation process of the degradation state by CPU62. It is a graph which shows the result of having asked V-dQ / dV at the time of charge corresponding to a plurality of cycle numbers. It is a graph which shows the result of having asked V-dQ / dV at the time of discharge corresponding to a plurality of cycles. It is a graph which shows the result of having calculated | required the relationship between the number of cycles of a battery, and dQ / dV in 4.55V at the time of charge. It is a graph which shows the result of having asked for the relation between the number of cycles of a battery, and the time Δt from 4.50 V to 4.55 V at the time of charge. It is a graph which shows the result of having obtained the number of cycles of the battery and the slope [Δ (dQ / dV) / ΔV] of the curve of V-dQ / dV between 4.50 V and 4.55 V when charging. . It is a graph which shows the result of having calculated | required the number of cycles of a battery, and | dQ / dV | in 4.45V at the time of discharge. It is a graph which shows the result of having calculated | required the relationship between the cycle number of a battery, and time (DELTA) t from the voltage at the time of discharge to 4.45V to 4.40V. It is a graph which shows the result of having calculated | required the inclination [(DELTA) (dQ / dV) / (DELTA) V] of the V-dQ / dV curve between 4.45V and 4.40V at the time of discharge, and the cycle number of a battery.

Hereinafter, the present invention will be specifically described based on the drawings showing the embodiments thereof.
[Overview of the embodiment]

The estimation device according to the embodiment has an electric storage having a single electrode including an active material in which a first characteristic, which is a storage amount-potential charge characteristic, and a second characteristic, which is a storage amount-potential discharge characteristic, change with repeated charging and discharging. At least one of a first characteristic and a second characteristic of the single pole of the element and V−dQ / dV which is a relation between the potential V and dQ / dV is estimated. The estimation apparatus responds to the change in the feature value, at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole corresponding to the feature value that changes due to the repetition of charge and discharge. Storage unit for storing the plurality of storage units as a function of the feature value, an acquisition unit for acquiring the feature value of the storage element, and the first characteristic based on the characteristic value acquired by the acquisition unit. Two characteristics, and at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole with reference to at least one of the V-dQ / dV or with reference to the function. And a first estimation unit that estimates
Here, dQ / dV is a charge value or a differential value obtained by differentiating the discharge capacity Q by the potential V.

According to the above configuration, a plurality of first characteristics, second characteristics, or V-dQ / dV corresponding to the feature value are stored according to the deterioration of the storage element. When the current feature value is obtained, the current first property, second property or dQ / dV-V is estimated with reference to the stored first property, second property or V-dQ / dV. Be done. Alternatively, data relating to the first characteristic, the second characteristic, or V-dQ / dV is stored as a function of the feature value, and by substituting the current feature value, the first characteristic, the second feature, or the second characteristic is stored. dQ / dV-V is calculated.
In the case of using an active material having the property of potential drop, in which the charge amount-potential characteristic of a single pole changes by repetition of charge and discharge, current single pole charge storage easily and accurately using feature values The quantity-potential characteristic or V-dQ / dV can be determined.
The current single pole first characteristic, second characteristic, or V-dQ / dV is an index indicating the current deterioration state. Therefore, even in a complicated use environment, it is possible to monitor the deterioration state of the single pole with high accuracy.

In the above-described estimation device, the characteristic value may be at least one of a charge amount or a discharge capacity in a predetermined voltage range and an average discharge potential.

There is a linear relationship between the amount of charge or discharge capacity and the average discharge potential, and the voltage range of the cell corresponding to the potential range where the potential difference (cell voltage) with the counter electrode does not change before and after deterioration is the predetermined voltage. It is considered a range. In the case where a plurality of first characteristics, second characteristics, or V-dQ / dV are stored in association with a feature value according to the degree of deterioration using a charge quantity of charge or discharge capacity in a predetermined voltage range as a feature value The first characteristic, the second characteristic, or V-dQ / dV at the present time can be accurately estimated. Also when the average discharge potential is used, the first characteristic, the second characteristic, or V-dQ / dV can be estimated with high accuracy as well.

In the above-described estimation device, the storage unit stores a plurality of V-dQ / dV or stores the function according to the charge quantity or the discharge capacity, or the magnitude of the average discharge potential. The first estimation unit may estimate the unipolar V-dQ / dV with reference to the relationship between the feature value and the V-dQ / dV.

A plurality of V-dQ / dV or the function is stored according to the size of the feature value, and by referring to the relationship between the feature value and the V-dQ / dV, the unipolar V-dQ / dV has high accuracy It can be estimated.

In the above-described estimation device, the amount of charge or the discharge capacity may be corrected according to the degree of deterioration of the active material.

Since the charge quantity or discharge capacity changes with the deterioration, the storage amount-potential characteristic or V-dQ / dV can be estimated more accurately by correcting according to the degree of deterioration.

In the above-described estimation apparatus, the feature value is dQ / dV at a predetermined voltage, a time from a first voltage to a second voltage, and between the first voltage and a second voltage within a high voltage range. It may be any of the slope of V−dQ / dV (Δ (dQ / dV) / ΔV).

The dQ / dV, the time, and the [Δ (dQ / dV) / ΔV] change in response to changes in V−dQ / dV due to repeated charge and discharge. Therefore, when a plurality of first characteristics, second characteristics, or V-dQ / dV are stored in association with these feature values, the first characteristics, second characteristics, or V-dQ at the current time can be accurately obtained. / DV can be estimated.

The estimation device according to the embodiment has an electric storage having a single electrode including an active material in which a first characteristic, which is a storage amount-potential charge characteristic, and a second characteristic, which is a storage amount-potential discharge characteristic, change with repeated charging and discharging. Estimate the degradation state of the element. The estimation device is configured to calculate the dQ / dV at a predetermined voltage, the time from the first voltage to the second voltage, and the slope of V−dQ / dV between the first voltage and the second voltage within the high voltage range. An acquisition unit that acquires a feature value of [Δ (dQ / dV) / ΔV], and an estimation unit that estimates a deterioration state of the storage element based on the feature value.

When an active material having a potential drop is used, the reaction proceeds even in a high voltage range due to a compound generated by degradation. Therefore, dQ / dV increases with deterioration.
Since the above reaction occurs in the high voltage range, the time Δt from the first voltage to the second voltage in the high voltage range is increased.
[Δ (dQ / dV) / ΔV] also changes according to the deterioration.
It is possible to obtain dQ / dV, Δt, or Δ (dQ / dV) / ΔV as a feature value, and use this feature value to properly estimate the state of deterioration of the storage element.

In the above-described estimation device, the estimation unit may estimate the deterioration state of the storage element based on a threshold value of the feature value.

The deterioration state of the storage element can be easily estimated by the threshold value.

In the above-described estimation device, the active material exhibits a hysteresis between a first characteristic and a second characteristic, and the first characteristic and / or the second characteristic estimated by the first estimation unit, and the charging of the storage element. In the third characteristic which is the charge amount-voltage charge characteristic for reference when estimating the charge amount based on the voltage of the storage element based on the history of discharge, and / or the charge amount-voltage discharge characteristic for reference You may provide the 2nd estimation part which estimates a certain 4th characteristic.

When the active material has hysteresis, the third characteristic and / or the fourth characteristic are accurately based on the first characteristic and / or the second characteristic according to the current deterioration state of the single pole and the charge / discharge history of the storage element. Properties can be estimated.

The above-described estimation device may include a third estimation unit configured to estimate the storage amount based on the charge / discharge history, the third characteristic and / or the fourth characteristic, and the acquired voltage.

In the above configuration, the storage amount of the storage element having the active material having the property of potential drop and exhibiting the storage amount-voltage characteristic exhibiting hysteresis can be easily estimated.
Since the voltage is used, the storage amount is not limited to the SOC, and the amount of current energy stored in the storage element, such as the amount of power, can be estimated. Based on the charge / discharge characteristics, dischargeable energy up to SOC 0% and charge energy required up to SOC 100% can be predicted. It is possible to estimate the current remaining power and the storable power.
Therefore, it is possible to accurately perform balancing in the case of using a plurality of storage elements, control of regeneration reception, estimation of a traveling distance in the case of mounting the storage elements, and the like.

A power storage device according to an embodiment includes a power storage element and the above-described estimation device.

In the above configuration, the storage amount of the storage element can be accurately estimated even in a complicated use environment.

According to an estimation method of an embodiment, a storage element having a single electrode including an active material in which a first characteristic which is a storage amount-potential charge characteristic and a second characteristic which is a storage amount-potential discharge characteristic change with repetition of charge and discharge. The first and second characteristics of the single pole and / or V-dQ / dV, which is the relationship between the potential V and dQ / dV, are estimated. According to the change of the feature value, at least one of the first characteristic, the second characteristic and the V-dQ / dV of the single pole corresponding to the feature value which changes due to the repetition of charge and discharge. , Or stored as a function of the feature value, and based on the obtained feature value, at least one of the first characteristic, the second characteristic, and the V-dQ / dV is referred to Or, referring to the function, at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole is estimated.

According to the above configuration, when an active material having a property of potential drop is used, the charge amount-potential characteristic or V-dQ / dV of a single electrode can be easily and accurately determined using the feature value. be able to.

Another estimation method of the embodiment estimates the deterioration state of the storage element having a single electrode including an active material, in which the storage amount-potential charge characteristic and the storage amount-potential discharge characteristic change due to repetition of charge and discharge. The estimation method is dQ / dV at a predetermined voltage, the time from the first voltage to the second voltage, and the slope of V-dQ / dV between the first voltage and the second voltage within the high voltage range. A feature value of [Δ (dQ / dV) / ΔV] is acquired, and the degradation state of the storage element is estimated based on the feature value.

According to the above configuration, dQ / dV, Δt, or Δ (dQ / dV) / ΔV is acquired as a feature value, and the degradation state of the storage element can be favorably estimated using this feature value.

The computer program according to the embodiment has a storage having a single electrode including an active material in which a first characteristic that is a storage amount-potential charge characteristic and a second characteristic that is a storage amount-potential discharge characteristic change with repeated charging and discharging. In a computer for estimating at least one of the first characteristic and the second characteristic of the single pole of the element, and V-dQ / dV which is the relationship between the potential V and dQ / dV, the charge / discharge of the storage element A feature value that changes due to repetition of at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole corresponding to the feature value changes in the feature value Accordingly, the first characteristic, the second characteristic, and the second characteristic of the single pole are referred to based on the acquired feature value with reference to the plurality of stored tables or the function stored with the function value. , V-dQ / dV, To execute a process of estimating at least one.

Another computer program according to the embodiment is a computer for estimating a deterioration state of a storage element having a single electrode including an active material whose storage amount-potential charge characteristic and storage amount-potential discharge characteristic change due to repetition of charge and discharge. , DQ / dV at a predetermined voltage, the time from the first voltage to the second voltage, and the slope of V-dQ / dV between the first voltage and the second voltage, [(Δ (Δ ( A feature value of any of dQ / dV) / ΔV)] is acquired, and a process of estimating the degradation state of the storage element is executed based on the feature value.

The embodiment will be specifically described below.
The single electrode of the electrode body of the storage element according to the embodiment includes an active material having a property of potential drop and having a storage amount-potential characteristic of hysteresis.
When the active material has the property of potential drop, the shapes of the unipolar SOC-OCP curve (first characteristic, second characteristic) and the SOC-OCV curve of the cell change due to repetition of charge and discharge. A cell containing this active material flows a minute current, and when charged from a fully discharged state to a fully charged state, and when discharged from a fully charged state to a fully discharged state, the maximum potential difference between SOC-OCV curves is 100 mV. It has the hysteresis which is the above.

FIG. 1 is a graph showing an example of the SOC-OCP of the positive electrode. The horizontal axis is SOC (%), and the vertical axis is the potential E as OCP (VvsLi / Li ⁺ : Li / Li ⁺ potential based on the equilibrium potential). The charge / discharge curve before deterioration is shown by a broken line, and the charge / discharge curve after deterioration is shown by a solid line.
As shown in FIG. 1, the potential drop occurs due to the deterioration, and the charge / discharge curve shifts downward.

In the case of an active material not having the property of potential drop, the hysteresis is not provided, and the unipolar SOC-OCP curve does not change by repetition of charge and discharge. The shape of the SOC-OCV curve of the cell changes due to the repetition of charge and discharge due to the deterioration of the single pole (the reduction of the curve) or the increase of the displacement of the capacity balance.

In the present embodiment, the current storage amount characteristic is estimated. The storage amount characteristics include at least one of unipolar charge SOC-OCP characteristics, discharge SOC-OCP characteristics, charge V-dQ / dV, and discharge V-dQ / dV.
There is a correlation between the feature value that changes due to the repetition of charge and discharge and the above-mentioned storage amount characteristic.

When using the charge quantity and the discharge capacity as the characteristic values, correction may be made based on the charge state and the positive electrode effectiveness.
An example of the calculation formula for correction | amendment of charge amount of charge and discharge capacity is shown.
Q (x), dis = n × Q (x)
Q (x), cha = n × (100 + ΔQox, max × Rcha) / 100 × Q (x)
However, Q (x), dis: Correction value of discharge capacity Q (x): Measured value of discharge capacity Q (x), cha: Correction value of charge amount n: Effectiveness of positive electrode, 0 ≦ n ≦ 1, A value indicating the degree of contraction of the SOC-OCP curve in the x direction Rcha: Ratio of charging SOC-OCP of positive electrode,
Rcha = (ΔQox, max-ΔQox) / ΔQox, max, 0 ≦ Rcha ≦ 1
ΔQox = ΔSOCmax−ΔSOC
ΔQox, max: maximum value of ΔQox ΔSOC: difference of SOC between the discharge SOC-OCP and the charge SOC-OCP at the potential at which Q (x) was acquired ΔSOCmax: maximum value of ΔSOC

In the case of the active material having the property of potential drop, it is considered that the charge and discharge curve shape changes continuously and uniquely according to the change (deterioration) of the characteristic value. LiMeO ₂ -Li respect ₂ MnO ₃ system of the active material, along with the repetition of charge and discharge, the crystal structures have been reported to vary (Journal of Power Sources, vol.229 ( 2013), pp239-248). It is considered that the shape of the charge / discharge curve changes with the change of the crystal structure. It is suggested from the results of the paper that changes in crystal structure occur continuously in the short-term one temperature level charge / discharge cycle. And, from the report that the crystal structure has changed from layered to spinel-like crystals, it is presumed that the way of change is one way. That is, in the case of an active material having the property of potential drop at a single temperature level in the short term, the crystal structure changes continuously and uniquely. From this report, the inventor considered that the charge-discharge curve shape changes continuously and uniquely according to the change of the crystal structure in a long-term and any use history. From the experimental results described later, it was confirmed that the charge / discharge curve shape changes continuously and uniquely in the long run even if the usage history is different.

In the case of an active material not having the property of potential drop, the charge and discharge curve shape of a single electrode does not change by repetition of charge and discharge. As described above, due to the deterioration of the single electrode or the expansion of the displacement amount of the capacity balance, the charge / discharge curve shape of the cell changes individually, that is, unambiguously, due to the repetition of charge / discharge.

In the present embodiment, the storage characteristic of the single pole changes continuously and uniquely with respect to the change of the feature value, so that the transition of the change of the storage characteristic with respect to the change of the feature value is partially stored. Thus, it is possible to accurately estimate the storage amount characteristic at the present time.
That is, a plurality of at least one of the storage capacity characteristics described above are stored in a table in response to the change in the feature value. Alternatively, the storage amount characteristic is stored as a function of the feature value.

The CPU 62 described later acquires the current feature value.
The CPU 62 acquires the feature value in the predetermined voltage range when the feature value is the charge amount of electricity or the discharge capacity. However, if it is possible to estimate the potential of the counter electrode (the charge amount characteristic of the counter electrode and the capacity balance deviation) with respect to each storage amount at this time, the battery voltage is converted to a unipolar potential and the potential converted for feature value extraction. Ranges may be used.
As a unipolar potential range corresponding to the voltage range, there is a linear relationship between the charge quantity or discharge capacity and the average discharge potential of the unipolar, and the potential difference (cell voltage) with the counter electrode changes before and after deterioration. It is preferable to select a range that does not exist.

FIG. 2 is a conceptual diagram showing the relationship between the potential range of the positive electrode corresponding to the predetermined voltage range and the range of the charge amount corresponding to each deterioration state in each potential range. The potential range becomes narrower in the order of a, b and c. When the potential range narrows, the range of the charge amount of electricity narrows. That is, the error increases with the reduction of the potential range to be used. On the other hand, when the potential range is wide, it takes time and effort to acquire the amount of charge electricity. Therefore, it is preferable to set an appropriate potential range in consideration of the balance between the estimation accuracy and the ease of measurement.

The CPU 62 estimates the current storage amount characteristic based on the acquired feature value with reference to the stored storage amount characteristic. Alternatively, the CPU 62 substitutes the acquired feature value into the function of the stored feature value to calculate the current storage amount characteristic.

FIG. 3A is a graph showing the relationship between the potential of the positive electrode of the initial product containing the active material and dQ / dV, and FIG. 3B is a graph showing the relationship between the potential of the positive electrode of the deteriorated product and dQ / dV. The horizontal axis is the potential (VvsLi / Li ⁺ : potential based on the Li / Li ⁺ equilibrium potential), and the vertical axis is dQ / dV.

FIG. 4 is a graph showing transition of K absorption edge energy of Ni of the active material calculated by X-ray absorption spectrometry (XAFS measurement) with respect to charging potential. The horizontal axis is the charge potential E (VvsLi / Li ⁺ ), and the vertical axis is the K absorption edge energy E ₀ (eV) of Ni. In FIG. 4, the initial product is shown by ● and the degraded product is shown by ■.

In FIG. 3B, it can be seen that the potential is about 4.7 V and dQ / dV bulges upward, and a reaction occurs. In FIG. 4, in the case of the initial product, E ₀ is constant in the region, whereas in the case of the deteriorated product, E and E ₀ show a proportional relationship.
From the above, it can be seen that in the case of the initial product, the oxidation reaction of Ni does not occur in the region of 4.5 V or more, but as the deterioration progresses, the oxidation reaction of Ni occurs in the region.
It is believed that the deterioration caused the formation of a phase such as 5 V spinel LiNi _0.5 Mn _1.5 O ₄ . LiNi _0.5 Mn _1.5 O ₄ is stably present in the region of approximately 5V. In the case of LiNi _0.5 Mn _1.5 O ₄ , a redox reaction caused by Ni occurs near 4.9 V.
As shown in FIG. 4, in the case of the initial product, the curve is flattened in the high potential region and the reaction converges, whereas in the case of the deteriorated product, the reaction proceeds also in the high potential region.

Accordingly, the time of charge or discharge of the power storage device, by obtaining a dQ / dV of predetermined voltages V ₁ in the high voltage range, it is possible to estimate the state of deterioration of the power storage device.
In a high-potential range, the reaction described above occurs, the time Δt from the first voltages V ₁ in the high voltage range of the storage element up to the second voltage V ₂ becomes longer. By obtaining Δt, the state of deterioration of the storage element can be estimated.
Since changes in accordance with the V-dQ / dV slope (Δ (dQ / dV) / ΔV) deterioration from the first voltages V ₁ up to the second voltage _{V 2, [Δ (dQ /} dV) / ΔV The state of deterioration of the storage element can be estimated by acquiring.
Even in the high SOC region, the degradation state can be estimated easily, quickly, and with high accuracy.

Embodiment 1
Hereinafter, as the first embodiment, a power storage device mounted on a vehicle is exemplified.
FIG. 5 shows an example of a power storage device. Power storage device 50 includes a plurality of power storage elements 200, monitoring device 100, and a storage case 300 for storing them. Power storage device 50 may be used as a power source of an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV).
The storage element 200 is not limited to a square cell, and may be a cylindrical cell or a pouch cell. The monitoring device 100 may be a circuit board disposed to face the plurality of storage elements 200. Monitoring device 100 monitors the state of storage element 200. The monitoring device 100 may be an estimation device. Alternatively, a computer or server wired or wirelessly connected to the monitoring apparatus 100 may execute an estimation method of estimating the storage capacity characteristic or the storage capacity based on the information output from the monitoring apparatus 100.

FIG. 6 shows another example of the power storage device. The power storage device (hereinafter referred to as a battery module) 1 may be a 12 volt power source or a 48 volt power source suitably mounted on an engine vehicle. 6 is a perspective view of the battery module 1 for 12V power, FIG. 7 is an exploded perspective view of the battery module 1, and FIG. 8 is a block diagram of the battery module 1. As shown in FIG.
The battery module 1 has a rectangular parallelepiped case 2. In case 2, a plurality of lithium ion secondary batteries (hereinafter referred to as batteries) 3, a plurality of bus bars 4, a BMU (Battery Management Unit) 6, and a current sensor 7 are accommodated.

The battery 3 includes a rectangular parallelepiped case 31 and a pair of terminals 32 and 32 provided on one side of the case 31 and having different polarities. The case 31 accommodates an electrode body 33 in which a positive electrode plate, a separator, and a negative electrode plate are stacked.

At least one of the positive electrode active material of the positive electrode plate of the electrode body 33 and the negative electrode active material of the negative electrode plate has properties of potential drop and hysteresis.
As the positive electrode active _material, LiMeO ₂ -Li ₂ MnO ₃ solid solution, Li ₂ O-LiMeO ₂ solid solution, Li ₃ NbO ₄ -LiMeO ₂ solid solution, Li ₄ WO ₅ -LiMeO ₂ solid solution, Li ₄ TeO ₅ -LiMeO ₂ solid solution, Li ₃ SbO ₄ -LiFeO ₂ solid solution, Li ₂ RuO ₃ -LiMeO ₂ solid solution, and a Li-excess active material such as Li ₂ RuO ₃ -Li ₂ MeO ₃ solid solution. Examples of the negative electrode active material include hard carbon, metals such as hard carbon, Si, Sn, Cd, Zn, Al, Bi, Pb, Ge, Ag, or alloys thereof, chalcogenides containing these, and the like. One example of the chalcogenide is SiO. The technology of the present invention is applicable as long as at least one of the positive electrode active material and the negative electrode active material is included.

Case 2 is made of synthetic resin. The case 2 includes a case body 21, a lid 22 closing the opening of the case body 21, a BMU accommodating portion 23 provided on the outer surface of the lid 22, a cover 24 covering the BMU accommodating portion 23, and an inner lid 25 and a partition plate 26. The inner lid 25 and the partition plate 26 may not be provided.
The battery 3 is inserted between the partition plates 26 of the case main body 21.

A plurality of metal bus bars 4 are mounted on the inner lid 25. The inner cover 25 is disposed on the terminal surface on which the terminals 32 of the battery 3 are provided, and the adjacent terminals 32 of the adjacent batteries 3 are connected by the bus bar 4 and the batteries 3 are connected in series.

The BMU accommodating portion 23 has a box shape, and has a rectangular projecting portion 23 a at the center of one long side. A pair of external terminals 5 and 5 made of a metal such as a lead alloy and having different polarities is provided on both sides of the protrusion 23 a in the lid 22. The BMU 6 is formed by mounting an information processing unit 60, a voltage measurement unit 8, and a current measurement unit 9 on a substrate. The BMU 6 is accommodated in the BMU accommodating portion 23 and the BMU accommodating portion 23 is covered with the cover 24, whereby the battery 3 and the BMU 6 are connected.

As shown in FIG. 8, the information processing unit 60 includes a CPU 62 and a memory 63.
The memory 63 stores, in the memory 63, a program for estimating the storage capacity characteristic according to the present embodiment, various programs 63a including a storage capacity estimation program, and a table 63b in which the storage capacity characteristic is stored. . The program 63a is provided in the state of being stored in a computer readable recording medium 70 such as a CD-ROM, a DVD-ROM, a USB memory, etc., and is stored in the memory 63 by being installed in the BMU 6. Alternatively, the program 63a may be obtained from an external computer (not shown) connected to a communication network and stored in the memory 63. The memory 63 and the first estimation unit, the second estimation unit, or the third estimation unit as the processing unit of the CPU 62 are not limited to the case where they are mounted in the BMU 6. When these are mounted on an external device and the characteristic value is acquired, the storage amount-potential characteristic of single pole, the storage amount for voltage reference, the voltage characteristic, or the storage amount is estimated, and the result is passed to BMU6. Good.

The storage amount characteristic stored in the table 63b will be described by taking a specific example.
For each cell, each No. 1 cell was tested under the conditions of voltage range, cycle number, and test temperature shown in Table 1 below. Cycle test was conducted.

The conditions of charge and discharge are as follows.
-Negative electrode: Graphite-Test rate: Charge 0.5 CA, Discharge 1.0 CA

The conditions of the confirmation test for determining SOC-OCP are as follows.
・ Anode: Li metal
・ Test rate: charge 0.1CA, discharge 0.1CA
・ Test temperature: 25 ° C
Thereby, each No. The SOC-OCP characteristic of the positive electrode or the V-dQ / dV characteristic is determined as the storage capacity characteristic for the test of (1). The storage amount characteristic is stored in the table 63 b in association with the charge amount or discharge capacity of the predetermined voltage range, or the average discharge potential. A single pole storage capacity characteristic in a degraded state is acquired by each test, and this is arranged in the order of the feature value to associate the characteristic value with the storage capacity characteristic. It is confirmed that the storage capacity characteristic changes continuously and uniquely in the long run even if the usage history is different.
The CPU 62 executes storage amount characteristic estimation processing and storage amount estimation processing described later according to the program read from the memory 63.

The voltage measurement unit 8 is connected to both ends of the battery 3 via a voltage detection line, and measures the voltage of each battery 3 at predetermined time intervals.
The current measuring unit 9 measures the current flowing through the battery 3 via the current sensor 7 at predetermined time intervals.
The external terminals 5 and 5 of the battery module 1 are connected to a load 11 such as a starter motor for starting the engine and electrical components.
The ECU (Electronic Control Unit) 10 is connected to the BMU 6 and the load 11.

Hereinafter, the method of estimating the storage capacity characteristic according to the present embodiment will be described.
FIG. 9 is a flowchart showing the procedure of the process of estimating the storage capacity characteristic by the CPU 62.
The CPU 62 repeats the processing from S1 at predetermined intervals.
The CPU 62 acquires a feature value (S1).
The CPU 62 calculates a storage amount characteristic corresponding to the acquired feature value. The CPU 62 calculates the target storage capacity characteristic from the storage capacity characteristic corresponding to, for example, two reference feature values by interpolation calculation (S2). Alternatively, the obtained characteristic value is substituted into the above-described function of the characteristic value to calculate the target storage amount characteristic.
The CPU 62 stores the calculated storage capacity characteristic in the table 63b (S3).
The CPU 62 estimates the deterioration state of the battery 3 based on the calculated storage capacity characteristic (S4), and ends the process. The storage capacity characteristic is an indicator of deterioration. Note that the process of S4 may not be performed, and the process may end after the process of S3.

The details will be described below.
The CPU 62 obtains, as the characteristic value, a charge quantity with a unipolar potential range of P1V to P2V and a cell voltage range of C1V to C2V. This charge quantity of electricity is defined as QinP1-P2V.
In Table 63b, the numbers in Table 1 No. It is assumed that V-dQ / dV data is stored in association with QinP1-P2V for 1 to 15.
The CPU 62 determines that the acquired feature value is No. 2 and No. If it is between three respective QinP1-P2V, No. 2 and No. Interpolation calculation is performed using each of the three V-dQ / dV data to obtain V-dQ / dV data corresponding to the feature value.
The acquired V-dQ / dV data can be converted to SOC-OCP data.

FIGS. 10 to 20 are graphs showing the results of determining the error with respect to the SOC-OCP data based on the actual measurement value of the SOC-OCP data calculated as described above. The horizontal axis represents the potential E during charging or discharging (VvsLi / Li ⁺ : potential based on the Li / Li ⁺ equilibrium potential), and the vertical axis is the error (%). In the figure, e represents data of charge and f represents data of discharge.
FIG. 1 and No. 1 No. 3 from the data of No. It is a graph which shows the said error at the time of calculating | requiring 2 data.
FIG. 2 and No. From the data of No. It is a graph which shows the said error at the time of calculating | requiring 3 data.
FIG. 3 and No. No. 7 from the data of No. It is a graph which shows the said error at the time of calculating | requiring 4 data.
FIG. 4 and No. 4 No. 5 from the data of No. It is a graph which shows the said error at the time of calculating | requiring 7 data.

FIG. 5 and No. 5 From the data of No. It is a graph which shows the said error at the time of calculating | requiring 13 data.
FIG. 6 and No. No. 13 from the data. It is a graph which shows the said error at the time of calculating | requiring 5 data.
FIG. 12 and No. No. 13 from the data. It is a graph which shows the said error at the time of calculating | requiring 6 data.
FIG. 6 and No. No. 14 from the data. It is a graph which shows the said error at the time of calculating | requiring 12 data.

FIG. 11 and No. No. 14 from the data. It is a graph which shows the said error at the time of calculating | requiring 8 data.
In FIG. 8 and No. No. 10 data to No. It is a graph which shows the said error at the time of calculating | requiring 11 data.
In FIG. 9 and No. No. 11 from the data. It is a graph which shows the said error at the time of calculating | requiring 10 data.

From FIG. 10 to FIG. 20, it can be understood that the error of the calculation is small, particularly when the potential is in the range of 3.5 V to 4.5 V, the error is smaller. Even if data with different test conditions are selected in various combinations, the calculation error is small.
Therefore, it was confirmed that the V-dQ / dV data at the time of acquiring the feature value can be accurately calculated based on the V-dQ / dV data corresponding to the feature value and the acquired feature value. Since the shape of V-dQ / dV changes continuously and uniquely in the positive electrode containing the active material having the property of potential drop, the V at the time of full charge / discharge at this point can be accurately even using data with different test conditions -DQ / dV can be calculated. The transition of the change of V-dQ / dV with respect to the change of the feature value may be partially stored. The number of V-dQ / dV data stored in the table 63b may be small.

Hereinafter, the case of estimating the SOC using the V-dQ / dV data calculated most recently will be described.
21 and 22 are flowcharts showing the procedure of the SOC estimation process by the CPU 62. The CPU 62 repeats the processing from S11 at predetermined intervals.
The voltage with which the oxidation amount and the reduction amount of the reaction generating the hysteresis are small is previously determined by experiments and is set as the threshold value V1. The voltage acquired after the voltage becomes nobler than V1 is set to the upper reference voltage (Vup). Vup is updated when the acquired voltage is greater than the previously acquired voltage. The acquired voltage is set to the lower reference voltage (Vlow) after the voltage goes below V1. Vlow is updated when the acquired voltage is smaller than the previously acquired voltage.

The CPU 62 acquires the voltage and current between the terminals of the battery 3 (S11). Since the threshold V1 and the upper reference voltage Vup are OCV, when the current amount of the battery 3 is large, it is necessary to correct the acquired voltage to the OCV. The correction value to the OCV can be obtained by estimating the voltage when the current is zero using a regression line from a plurality of voltage and current data. If the amount of current flowing through the battery 3 is as small as the dark current (small current), the acquired voltage is regarded as OCV.

The CPU 62 determines whether the absolute value of the current is equal to or more than the pause threshold (S12). The rest threshold is set to determine whether the state of the battery 3 is in a charged state, a discharged state, or a rest state. When the CPU 62 determines that the absolute value of the current is not equal to or more than the pause threshold (S12: NO), the process proceeds to S22.

When the CPU 62 determines that the absolute value of the current is equal to or more than the pause threshold (S12: YES), the CPU 62 determines whether the current is larger than 0 (S13). If the current is greater than zero, the state of the battery 3 is determined to be in the charged state. When the CPU 62 determines that the current is not larger than 0 (S13: NO), the process proceeds to S18.

When the CPU 62 determines that the current is greater than 0 (S13: YES), it determines whether the voltage is V1 or more (S14). When the CPU 62 determines that the voltage is not V1 or more (S14: NO), the process proceeds to S17.

When the CPU 62 determines that the voltage is V1 or more (S14: YES), the CPU 62 determines whether the acquired voltage is larger than Vup stored in the memory 63 last time (S15). When the CPU 62 determines that the voltage is not larger than the previous Vup (S15: NO), the process proceeds to S17.

When the CPU 62 determines that the voltage is larger than the previous Vup (S15: YES), the memory 63 updates the voltage to Vup (S16).
The CPU 62 estimates the SOC by current integration (S17), and ends the process.

When the CPU 62 determines that the current is smaller than 0 and the battery 3 is in the discharged state (S13: NO), the CPU 62 determines whether the voltage is less than V1 (S18). When the CPU 62 determines that the voltage is not less than V1 (S18: NO), the process proceeds to S21.
When the CPU 62 determines that the voltage is less than V1 (S18: YES), it determines whether the acquired voltage is smaller than the lower reference voltage Vlow stored in the memory 63 last time (S19).
When the CPU 62 determines that the voltage is not smaller than the previous Vlow (S19: NO), the process proceeds to S21.
When the CPU 62 determines that the voltage is smaller than the previous Vup (S19: YES), the memory 63 updates the voltage to Vlow (S20)
The CPU 62 estimates the SOC by current integration (S21), and ends the process.

When the CPU 62 determines that the absolute value of the current is less than the pause threshold and the state of the battery 3 is in the pause state (S12: NO), the CPU 62 determines whether the set time has elapsed (S22). The set time is an experimentally determined time sufficient to regard the acquired voltage as an OCV. The CPU 62 determines whether or not the time has been exceeded, based on the number of acquisition times and the acquisition interval of the current after determining that the apparatus is in the pause state. Thus, the SOC can be estimated more accurately in the resting state.
When it is determined that the set time has not elapsed (S22: NO), the CPU 62 estimates the SOC by current integration (S23), and ends the process.

When the CPU 62 determines that the set time has elapsed (S22: YES), the acquired voltage can be regarded as an OCV.

The CPU 62 acquires the latest stored electricity amount characteristic from the table 63b (S24). In addition, when a period becomes vacant from the day when the feature value was finally acquired, the estimated storage capacity characteristic is corrected or the storage capacity characteristic is newly obtained and updated in consideration of the history from the acquisition to the present time. Is preferred.
The CPU 62 calculates the storage amount characteristic for voltage reference based on the acquired storage amount characteristic (S25). For example, when the storage amount characteristic is V-dQ / dV of the positive electrode, the CPU 62 converts it into V-dQ / dV of the cell. The CPU 62 calculates the charge SOC-OCV or the discharge SOC-OCV of the cell based on the V-dQ / dV of the cell. The CPU 62 calculates a charge SOC-OCV (third characteristic) for voltage reference or a discharge SOC-OCV (fourth characteristic) for voltage reference based on the charge SOC-OCV or the discharge SOC-OCV and Vup. The CPU 62 calculates the charge SOC-OCV or the discharge SOC-OCV for voltage reference, using, for example, the charge SOC-OCV or the discharge SOC-OCV in consideration of the oxidation amount and the reduction amount of the reaction that causes the hysteresis.

The CPU 62 reads the SOC corresponding to the voltage acquired in S1 in the charge SOC-OCV or the discharge SOC-OCV for voltage reference, estimates the SOC (S26), and ends the processing.

Note that the voltage obtained by the CPU 62 from the voltage measurement unit 8 slightly fluctuates due to the current, so that the voltage can be corrected by obtaining a correction coefficient by experiment.

As described above, in the present embodiment, the stored value-voltage characteristic or V-dQ / dV stored at the current characteristic value and stored, or the current stored amount-potential characteristic or V with reference to the function thereof. Estimate dQ / dV.
When using a storage element having an active material in which the charge amount-potential characteristic of the single pole changes by repetition of charge and discharge, the charge amount of the current charge of the single pole can be obtained with high accuracy from a feature value only Potential characteristics or V-dQ / dV can be estimated. The number of V-dQ / dV data stored in the table 63b may be small.

The current monopolar storage capacity-potential characteristic or V-dQ / dV is an index indicating the current deterioration state. Therefore, even in a complicated use environment, the deterioration state of the single pole can be monitored with high accuracy.

In the case where multiple charge amounts / potential characteristics or V-dQ / dV are stored in association with the characteristic value according to the degree of deterioration using the charge quantity in the predetermined voltage range and the discharge capacity as the feature value, it is accurate The current storage amount-potential characteristic or V-dQ / dV can be estimated. The same applies to the case of the average discharge potential.

When the active material has a hysteresis, the storage amount-voltage characteristics for voltage reference are accurately estimated based on the storage amount-potential characteristic according to the current deterioration state of the single pole and the charge / discharge history of the storage element. it can. The storage amount of the storage element including the active material having the property of potential drop can be easily and easily estimated by using knowledge of the behavior of the hysteresis in combination.
Since the voltage is used, the storage amount is not limited to the SOC, and the amount of current energy stored in the storage element, such as the amount of power, can be estimated. Based on the charge / discharge characteristics, dischargeable energy up to SOC 0% and charge energy required up to SOC 100% can be predicted. It is possible to estimate the current remaining power and storable power.
Therefore, it is possible to accurately perform balancing in the case of using a plurality of storage elements, control of regeneration reception, estimation of a traveling distance in the case of mounting the storage elements, and the like.

Second Embodiment
CPU62 of the information processing unit 60 of the battery module according to the second embodiment, in the high voltage range, dQ at a predetermined voltage V ₀ / dV, time Δt from the first voltages V ₁ up to the second voltage V _2, and obtaining first voltages V ₁ and the feature value of either of the slope of the V-dQ / dV [Δ ( dQ / dV) / ΔV] between the second voltage V _2. The CPU 62 estimates the deterioration state of the battery 3 based on the feature value.
As shown in FIG. 4, in the case of the initial product, the curve is flattened in the high potential region and the reaction converges, whereas in the case of the deteriorated product, the reaction proceeds also in the high potential region. Since dQ / dV at V ₀ in the high voltage range of the battery 3 changes due to deterioration, the state of deterioration of the battery 3 is estimated by acquiring the dQ / dV during charging or discharging of the battery 3 it can.
In a high-potential range, the reaction described above occurs, the time Δt from the first voltages V ₁ in the high voltage range of the storage element up to the second voltage V ₂ becomes longer. By acquiring Δt, the state of deterioration of the storage element can be estimated.
Since changes in accordance with the V-dQ / dV slope [Δ (dQ / dV) / ΔV] deterioration between the first voltages V ₁ and the second voltage V _2, delta and (dQ / dV) / ΔV By acquiring, it is possible to estimate the state of deterioration of the storage element.
The high voltage range is preferably in the range of 4.4 V to 5.0 V. For voltages V ₀ , V ₁ and V ₂ , refer to FIG. 4 and FIG. 24 and FIG. 25 described later, and select a voltage at which the change in the feature value increases according to deterioration during charging and discharging. Do.

In the table 63b of the memory 63, the relationship between the number of cycles and the dQ / dV, the relationship between the number of cycles and the Δt, and the relationship between the number of cycles and Δ (dQ / dV) / ΔV obtained in advance by experiment One is stored. The memory 63 may store these relationships as functions. The relationships or functions described above may be stored by rate. The memory 63 may also store the relationship between the feature value and the SOH.

FIG. 23 is a flowchart showing the procedure of the degradation state estimation process by the CPU 62.
The CPU 62 acquires one of dQ / dV, Δt, and Δ (dQ / dV) / ΔV feature values based on the charge / discharge history (S31).
The CPU 62 reads the relationship between the cycle number and dQ / dV, Δt, or Δ (dQ / dV) / ΔV from the table 63 b in accordance with the feature value. The CPU 62 refers to the read relationship, estimates whether or not the battery 3 at the current time is in the deteriorated state based on the acquired feature value (S32), and ends the process.
The CPU 62 estimates the deterioration state in consideration of the use condition of the user of the battery 3, the use condition, the judgment standard of deterioration input from the user, and the like. The CPU 62 may estimate the deterioration state based on the relationship between the feature value and the SOH. The CPU 62 may estimate the deterioration state based on the function described above.

(Modification 1)
In the table 63b of the memory 63 of the first modification, the threshold value of the feature value set to estimate the deterioration state based on the relationship between the cycle number and dQ / dV, Δt, or Δ (dQ / dV) / ΔV. Remember.
In this case, in S32, the CPU 62 reads the threshold value corresponding to the feature value acquired in S31 from the table 63b, and estimates the deterioration state of the battery 3 based on the threshold value.
When dQ / dV, Δt, or Δ (dQ / dV) / ΔV is acquired when the battery 3 is charged, the CPU 62 estimates that the battery 3 is in a deteriorated state when the feature value is equal to or greater than the threshold.
When dQ / dV or Δt is acquired as the feature value when the battery 3 is discharged, the CPU 62 estimates that the battery 3 is in the deteriorated state when | dQ / dV | or Δt is equal to or greater than the threshold. When dQ / dV is used as a negative number, if dQ / dV is equal to or less than the threshold, the CPU 62 estimates that the battery 3 is in a deteriorated state.
When Δ (dQ / dV) / ΔV is acquired as the feature value, the CPU 62 estimates that the battery 3 is in the deteriorated state when the feature value is equal to or less than the threshold value.

(Modification 2)
In the table 63b of the memory 63 of the second modification, a plurality of V-dQ / dV corresponding to temporal deterioration are stored in association with feature values.
The CPU 62 estimates the deterioration state according to the procedure shown in FIG. 9 as in the first embodiment.
The CPU 62 acquires feature values of dQ / dV, Δt, and Δ (dQ / dV) / ΔV (S1).
The CPU 62 calculates a target storage capacity characteristic (V−dQ / dV) corresponding to the acquired feature value. The CPU 62 calculates the target storage capacity characteristic from the storage capacity characteristic corresponding to, for example, two reference feature values by interpolation calculation (S2). Alternatively, the acquired characteristic value is substituted into the function of the characteristic value to calculate the target storage capacity characteristic.
The CPU 62 stores the calculated storage capacity characteristic in the table 63b (S3).
The CPU 62 estimates the deterioration state of the battery 3 based on the calculated storage capacity characteristic (S4), and ends the process. The obtained storage capacity characteristic is an indicator of deterioration.
The SOC-OCV was determined based on the obtained V-dQ / dV, the SOC-OCV for voltage reference was determined based on the SOC-OCV and the charge / discharge history, and the feature value was obtained by the OCV method. It is also possible to calculate the SOC of the time point.

(Example)
Hereinafter, although the example of Embodiment 2 is concretely described, it is not limited to this example.
The battery 3 of Example was produced using the above-mentioned Li excess type active material as a positive electrode active material, and graphite as a negative electrode active material. A charge / discharge cycle test was performed using this battery 3 to determine V-dQ / dV at the time of charge, corresponding to the number of cycles from 10 times to 480 times. The results are shown in FIG. The horizontal axis is voltage (V), and the vertical axis is dQ / dV.
In the charge and discharge cycle test, CC charging is performed until the voltage reaches 4.6 V at 0.5 C under conditions of 25 ° C., and CV charging is performed until the current reaches 0.1 C at 4.6 V, Rested for 10 minutes. Thereafter, CC discharge was performed at 1.0 C until the voltage reached 2.0 V and rested for 10 minutes. Charge and discharge were repeated by making this one cycle.
FIG. 24 is a graph showing the results of determination of V-dQ / dV during discharge, corresponding to the above-described plurality of cycles. The horizontal axis is voltage (V), and the vertical axis is dQ / dV.
In FIG. 24, the upper curve has a larger number of cycles than the lower curve. As shown in FIG. 24, it can be seen that the dQ / dV at 4.55 V of (1) increases as the number of cycles increases.
In the range of 4.50 V to 4.55 V of (2), the curve of V-dQ / dV is convex upward as the number of cycles increases, and more oxidation reaction occurs, so from 4.50 V to The time Δt to reach 4.55 V becomes long. The slope Δ (dQ / dV) / ΔV in the range of (2) increases as the number of cycles increases.

FIG. 25 is a graph showing the results of determination of V-dQ / dV at the time of discharge, corresponding to the above-described plurality of cycles. The horizontal axis is voltage (V), and the vertical axis is dQ / dV.
In FIG. 25, the lower curve has a larger number of cycles than the upper curve. As shown in FIG. 25, it can be seen that the absolute value of dQ / dV at 4.45 V in (3) increases as the number of cycles increases.
In the range of 4.40 V to 4.45 V in (4), the curve of V-dQ / dV is convex downward as the number of cycles increases, and more reduction reaction occurs, so from 4.45 V The time Δt to reach 4.40 V becomes long. The slope [Δ (dQ / dV) / ΔV] in the range of (4) decreases as the number of cycles increases.

FIG. 26 is a graph showing the relationship between the number of cycles of the battery 3 and dQ / dV at 4.55 V during charging. The horizontal axis is the number of cycles, and the vertical axis is dQ / dV.
As shown in FIG. 26, as the number of cycles increases, dQ / dV increases.

FIG. 27 is a graph showing the relationship between the cycle number of the battery 3 and the time Δt from 4.50 V to 4.55 V at the time of charge. The horizontal axis is the number of cycles, and the vertical axis is Δt.
As shown in FIG. 27, Δt increases as the number of cycles increases.

FIG. 28 shows the results of determination of the number of cycles of the battery 3 and the slope [Δ (dQ / dV) / ΔV] of the V-dQ / dV curve between the voltages of 4.50 V and 4.55 V during charging. Is a graph showing The horizontal axis is the cycle number, and the vertical axis is Δ (dQ / dV) / ΔV.
As shown in FIG. 28, Δ (dQ / dV) / ΔV increases as the number of cycles increases.

FIG. 29 is a graph showing the number of cycles of the battery 3 and | dQ / dV | at 4.45 V during discharge. The horizontal axis is the cycle number, and the vertical axis is | dQ / dV |.
As shown in FIG. 29, | dQ / dV | increases as the number of cycles increases.

FIG. 30 is a graph showing the relationship between the cycle number of the battery 3 and the time Δt from 4.45 V to 4.40 V at the time of discharge. The horizontal axis is the number of cycles, and the vertical axis is Δt.
As shown in FIG. 30, Δt increases as the number of cycles increases.

FIG. 31 is a graph showing the number of cycles of battery 3 and the slope [Δ (dQ / dV) / ΔV] of the V-dQ / dV curve between 4.45 V and 4.40 V during discharge. It is. The horizontal axis is the cycle number, and the vertical axis is Δ (dQ / dV) / ΔV.
As shown in FIG. 31, as the number of cycles increases, Δ (dQ / dV) / ΔV decreases.

As described above, when an active material having a potential drop is used, dQ / dV, Δt, and (Δ (dQ / dV) / ΔV) characteristically change in the high voltage range.
The relationship between the number of cycles and dQ / dV, Δt, or Δ (dQ / dV) / ΔV is stored in the table 63b, and the feature value is correlated by the amount of change in the feature value with the increase in the number of cycles and SOH. The degradation state at the time of acquisition can be estimated well. The deterioration state can also be favorably determined by the threshold value of the feature value.

When charging in an unused period at night after use of the vehicle, the deterioration state can be easily and quickly estimated at the start of use based on the feature values in the high voltage range, and the convenience is high.
Since the deterioration state can be accurately estimated, control for suppressing the deterioration can be performed at an appropriate timing, and the life of the battery 3 can be extended.
The deterioration state can be estimated within the range of normal use conditions, and the battery 3 is not deteriorated when the deterioration state is estimated.

The present invention is not limited to the contents of the embodiments described above, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

In the first and second embodiments, the case where the positive electrode includes the active material having the potential drop and the hysteresis has been described, but the charge amount-voltage characteristic or the charge capacity or the voltage characteristic may be similarly applied to the case where the negative electrode includes the active material having the potential drop and the hysteresis. V-dQ / dV can be estimated.

The estimation of the storage amount by voltage reference according to the present invention is not limited to the case of stopping, but may be performed in real time during charging or discharging. In this case, the current OCV is calculated from the acquired voltage and current. The calculation of the OCV can be obtained by, for example, estimating the voltage when the current is zero using regression lines from data of a plurality of voltages and currents. Also, when the current is small as dark current, the acquired voltage can be read as OCV.

The estimation device according to the present invention is not limited to the case of being applied to an on-vehicle lithium ion secondary battery, and can be applied to other power storage devices such as a railway regenerative power storage device and a solar power generation system. The estimation device according to the present invention can also be applied to mobile devices such as notebook computers, mobile phones, and shavers. In a power storage device in which a minute current flows, the voltage between the positive electrode terminal and the negative electrode terminal of the power storage element can be regarded as OCV.

The case where the monitoring apparatus 100 or BMU 6 is an estimation apparatus was illustrated. Alternatively, a CMU (Cell Monitoring Unit) may be an estimation device. The estimation device may be part of a battery module in which the monitoring device 100 or the like is incorporated. The estimation device may be configured separately from the storage element and the battery module, and connected to the battery module including the storage element for which the degradation state is to be estimated at the time of estimation of the degradation state. The estimation device may remotely monitor the storage element or the battery module.
The storage element is not limited to a lithium ion secondary battery, and may be another secondary battery or an electrochemical cell having potential drop and hysteresis characteristics.

The present invention can be applied to estimation of the deterioration state of a storage element such as a lithium ion secondary battery.

1, 50 battery module (power storage device)
DESCRIPTION OF SYMBOLS 2 case 21 case main body 22 lid part 23 BMU accommodating part 24 cover 25 middle lid 26 partition plate 3, 200 battery (electric storage element)
31 case 32 terminal 33 electrode body 4 bus bar 5 external terminal 6 BMU (estimation device)
60 information processing unit 62 CPU (acquisition unit, first estimation unit, second estimation unit, third estimation unit)
63 Memory (storage unit)
63a Program 63b Table 7 Current Sensor 8 Voltage Measurement Unit 9 Current Measurement Unit 10 ECU
100 Monitoring device (estimation device)
300 storage case

Claims (14)

1. The first characteristic of the storage element having a single electrode including an active material whose first characteristic, which is a storage amount-potential charge characteristic, and the second characteristic, which is a storage amount-potential discharge characteristic, change with repetition of charging and discharging An estimation apparatus for estimating at least one of a characteristic, a second characteristic, and V-dQ / dV that is a relationship between an electric potential V and dQ / dV,
   A plurality of at least one of the first characteristic, the second characteristic and the V-dQ / dV of the single pole corresponding to the characteristic value which changes due to repetition of charge and discharge is stored according to the change of the characteristic value. Or a storage unit which stores the data as a function of the feature value;
   An acquisition unit configured to acquire the feature value of the storage element;
   With reference to at least one of the first characteristic, the second characteristic, and the V-dQ / dV based on the feature value acquired by the acquisition unit, or with reference to the function, A first estimation unit configured to estimate at least one of the first characteristic, the second characteristic, and V-dQ / dV.
2. The estimation device according to claim 1, wherein the characteristic value is a charge quantity or a discharge capacity in a predetermined voltage range, or an average discharge potential.
3. The storage unit stores a plurality of V-dQ / dV or stores the function according to the charge quantity or the discharge capacity, or the magnitude of the average discharge potential.
   The estimation device according to claim 2, wherein the first estimation unit estimates the unipolar V-dQ / dV with reference to the relationship between the feature value and the V-dQ / dV.
4. The estimation device according to claim 2, wherein the amount of charge or the discharge capacity is corrected according to the degree of deterioration of the active material.
5. The characteristic values are dQ / dV at a predetermined voltage, the time from the first voltage to the second voltage, and V-dQ / dV between the first voltage and the second voltage within the high voltage range. The estimation device according to claim 1, which has one of a slope [Δ (dQ / dV) / ΔV].
6. It is estimated that the first characteristic, which is a storage amount-potential charge characteristic, and the second characteristic, which is a storage amount-potential discharge characteristic, estimate the degradation state of a storage element having a single electrode containing an active material that changes with repeated charging and discharging. A device,
   DQ / dV at a predetermined voltage, the time from the first voltage to the second voltage, and the slope of V-dQ / dV between the first voltage and the second voltage within the high voltage range [Δ (dQ An acquisition unit for acquiring any feature value of / dV) / ΔV];
   An estimation unit configured to estimate a deterioration state of the storage element based on the feature value.
7. The estimation device according to claim 6, wherein the estimation unit estimates a deterioration state of the storage element based on a threshold of the feature value.
8. The active material exhibits hysteresis between the first and second characteristics,
   For reference when estimating the storage amount by the voltage of the storage element based on the first characteristic and / or the second characteristic estimated by the first estimation unit and the charge / discharge history of the storage element The second estimation unit according to any one of claims 1 to 5, further comprising a second estimation unit that estimates a third characteristic that is a storage amount-voltage charge characteristic and / or a fourth characteristic that is a storage amount-voltage discharge characteristic for reference. The estimation device described in the item.
9. The estimation device according to claim 8, further comprising: a third estimation unit configured to estimate a storage amount based on the history of charge and discharge, the third characteristic and / or the fourth characteristic, and the acquired voltage.
10. A storage element,
    A storage device comprising: the estimation device according to any one of claims 1 to 9.
11. The first characteristic of a storage element having a single electrode including an active material whose first characteristic, which is a storage amount-potential charge characteristic, and the second characteristic, which is a storage amount-potential discharge characteristic, change with repetition of charge and discharge A second characteristic, and / or V-dQ / dV, which is a relationship between the potential V and dQ / dV,
    A plurality of at least one of the first characteristic, the second characteristic and the V-dQ / dV of the single pole corresponding to the characteristic value which changes due to repetition of charge and discharge is stored according to the change of the characteristic value. Or stored as a function of the feature value,
    The first characteristic of the single pole, referring to at least one of the first characteristic, the second characteristic, and the V-dQ / dV, or referring to the function, based on the acquired characteristic value. An estimation method for estimating at least one of a second characteristic and V-dQ / dV.
12. A storage amount-potential charge characteristic and a storage amount-potential discharge characteristic are estimation methods for estimating the degradation state of a storage element having a single electrode containing an active material that changes due to repetition of charge and discharge,
    DQ / dV at a predetermined voltage, the time from the first voltage to the second voltage, and the slope of V-dQ / dV between the first voltage and the second voltage within the high voltage range [Δ (dQ Get any feature value of / dV) / ΔV],
    The estimation method which estimates the deterioration state of the said electrical storage element based on the said characteristic value.
13. The first characteristic of the storage element having a single electrode including an active material whose first characteristic, which is a storage amount-potential charge characteristic, and the second characteristic, which is a storage amount-potential discharge characteristic, change with repetition of charging and discharging A computer for estimating at least one of a characteristic, a second characteristic, and V−dQ / dV, which is a relationship between the potential V and dQ / dV,
    Acquiring a feature value of the storage element that changes due to repeated charging and discharging;
    Referring to a table in which a plurality of at least one of the single pole first characteristic, second characteristic, and V-dQ / dV corresponding to the feature value is stored according to the change of the feature value, Or at least one of the first characteristic, the second characteristic, and V-dQ / dV of the single pole based on the acquired feature value with reference to the function stored as a function of the feature value A computer program that causes the process to be performed.
14. A computer for estimating the state of deterioration of a storage element having a single electrode containing an active material whose storage amount-potential charge characteristic and storage amount-potential discharge characteristic change due to repetition of charge / discharge,
    DQ / dV at a predetermined voltage, time from the first voltage to the second voltage, and V-dQ / dV slope between the first voltage and the second voltage [Δ (dQ / dV) in the high voltage range. Get any feature value of dV) / ΔV],
    A computer program that executes a process of estimating a deterioration state of the storage element based on the feature value.

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