WO2021192394A1

WO2021192394A1 - Secondary battery device, and control method for secondary battery

Info

Publication number: WO2021192394A1
Application number: PCT/JP2020/041684
Authority: WO
Inventors: 栄二關; 耕平本蔵; 杉政　昌俊; 渉太伊藤; 誠之廣岡; 井上　健士
Original assignee: 株式会社日立製作所
Priority date: 2020-03-23
Filing date: 2020-11-09
Publication date: 2021-09-30
Also published as: JP2021151169A

Abstract

Provided is a secondary battery device in which a third electrode for measuring potential of positive/negative electrodes also serves as a lithium ion supply source to the positive/negative electrodes, wherein loss of potential measurement function of the third electrode can be prevented. Also provided is a method for controlling a secondary battery. A control unit 11 controls a control circuit 10 on the basis of at least one from among: a positive-negative interelectrode voltage between a positive electrode 211 and a negative electrode 212; a third-positive interelectrode voltage between a third electrode 213 and the positive electrode 211; and a third-negative interelectrode voltage between the third electrode 213 and the negative electrode 212. The control unit 11 controls the control circuit 10 to switch from/to: a first mode in which no current is caused to flow between the positive electrode 211, the negative electrode 212, and the third electrode 213; a second mode in which current is caused to flow from the negative electrode 212 to the third electrode 213; a third mode in which current is caused to flow from the positive electrode 211 to the third electrode 213; or a fourth mode in which current is caused to flow from the third electrode 213 to the positive electrode 211 or the negative electrode 212.

Description

Secondary battery device and secondary battery control method

The present disclosure relates to a secondary battery device and a control method for the secondary battery.

Inventions related to power storage systems have been known conventionally (see Patent Document 1 below). The power storage system of Patent Document 1 includes a plurality of power storage devices (the same document, abstract, paragraph 0020, claim 1, etc.). One or more power storage devices of the plurality of power storage devices include a cell, positive and negative electrode potential measuring means, and a dynamic life controller. The cell is a secondary battery including a positive electrode and a negative electrode.

The positive / negative electrode potential measuring means measures the positive electrode potential and the negative electrode potential of the cell, and the potential information of the positive electrode potential and the negative electrode potential of the cell is transmitted to the database server. In the database server, a cell life prediction relationship corresponding to changes in cell operating conditions is constructed based on the cell potential information. The dynamic life controller controls a plurality of power storage devices according to the estimated life of the cell based on the cell life prediction relationship.

INDUSTRIAL APPLICABILITY According to the present invention, in a power storage system using a secondary battery, it is possible to accurately grasp the deterioration state of the secondary battery and bring the expected life of the power storage system closer to the life of the secondary battery (the same document, the same document). 0021).

Further, this power storage system includes a configuration in which a Li ion supply control means is provided inside the cell (the same document, Example 3, FIG. 5, claim 5, etc.). In this case, the power storage device includes a controller transmission means. The controller transmission means transmits a signal for supplying Li ions to the positive electrode or the negative electrode of the cell to the Li ion supply control means based on the signal from the dynamic life controller, and Li ions are supplied to the positive electrode or the negative electrode based on the signal. Will be done.

More specifically, a third electrode that also serves as a Li ion supply source for supplying Li ions to the positive electrode or the negative electrode of the cell is provided (the same document, paragraph 0054, FIG. 5). The third electrode, which also serves as a Li ion supply source, usually acts as a third electrode and is used as a means for measuring the potential of the positive and negative electrodes (paragraph 0055 of the same document).

With such a configuration, even if the capacity retention rate is lower than expected, the life due to the characteristics of the cell and the assumed replacement life can be brought close to each other, and preferably they can be matched. In addition, even if the cell is operated harder than expected and the deterioration of the cell progresses more than expected, the capacity retention rate can be recovered and the life can be recovered to the expected life (paragraph 0059 of the same document). , Fig. 9 etc.).

International Publication No. 2015/037068

In the conventional power storage system, the supply of lithium ions from the third electrode, which also serves as the lithium ion supply source, to the positive electrode or the negative electrode becomes excessive, and the potential measurement function of the positive electrode and the negative electrode by the third electrode may be lost. ..

In the present disclosure, in a secondary battery in which the third electrode for measuring the potentials of the positive electrode and the negative electrode also serves as a supply source of lithium ions to the positive electrode and the negative electrode, the loss of the potential measurement function by the third electrode is eliminated. A secondary battery device that can be prevented and a method for controlling the secondary battery are provided.

One aspect of the present disclosure includes a secondary battery having a positive electrode, a negative electrode, and a third electrode, a control circuit connected to the secondary battery, and a control unit for controlling the control circuit. In the next battery device, the control unit includes a positive / negative electrode voltage between the positive electrode and the negative electrode, a third positive electrode voltage between the third electrode and the positive electrode, and the third electrode. A first mode in which no current flows between the positive electrode, the negative electrode, and the third electrode in the control circuit based on at least one of the voltage between the positive electrode and the third negative electrode. A second mode in which a current is passed from the negative electrode to the third electrode, a third mode in which a current is passed from the positive electrode to the third electrode, and a current is passed from the third electrode to the positive electrode or the negative electrode. It is a secondary battery device characterized by switching between a fourth mode of flowing.

According to the above aspect of the present disclosure, in a secondary battery in which the third electrode for measuring the potentials of the positive electrode and the negative electrode also serves as a supply source of lithium ions to the positive electrode and the negative electrode, the third electrode is used. It is possible to provide a secondary battery device capable of preventing loss of the potential measurement function.

The block diagram which shows one Embodiment of the secondary battery apparatus of this disclosure. The block diagram which shows an example of the cell | cell which comprises the secondary battery device of FIG. The circuit diagram which shows an example of the control circuit connected to the secondary battery of FIG. The flow diagram explaining an example of the operation of the control part connected to the control circuit of FIG. The graph which shows an example of the discharge characteristic of the secondary battery of FIG. The graph which shows an example of the discharge characteristic of the secondary battery of FIG.

Hereinafter, embodiments of the secondary battery device and the control method for the secondary battery of the present disclosure will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the secondary battery device of the present disclosure. The secondary battery device 1 of the present embodiment includes, for example, a cell group 2, a pair of

external terminals

3P, 3N, a current sensor 4, a temperature sensor 5, a battery management unit 6, a state calculation unit 7, and the like. It includes an information input terminal 8 and an information output terminal 9.

The cell group 2 is composed of, for example, a plurality of cell cells 21 connected in series. The cell 21 is not particularly limited, but is, for example, a square lithium ion secondary battery. Although not shown, the secondary battery device 1 may include, for example, a plurality of cell groups 2. The plurality of cell groups 2 are connected in series or in parallel, for example. Further, a plurality of cell groups 2 connected in series may be connected in parallel.

In the pair of

external terminals

3P and 3N, one external terminal 3P is connected to the positive electrode terminal of the cell group 2 via the power wiring, and the other external terminal 3N is connected to the negative electrode terminal of the cell group 2 via the power wiring. It is connected. Although not shown, the pair of

external terminals

3P and 3N are connected to an external load such as a motor via, for example, power wiring.

The current sensor 4 is connected to, for example, the power wiring between the cell group 2 and the external terminal 3P, and measures the current flowing through the cell group 2. The temperature sensor 5 is attached to at least one of a plurality of cell cells 21 constituting the cell group 2, for example, and measures the temperature of the cell group 2.

The battery management unit 6 and the state calculation unit 7 are, for example, a microcontroller or firmware including a processing device such as a CPU, a storage device such as a RAM or ROM, a timer, and a signal input / output unit. The battery management unit 6 and the state calculation unit 7 realize various functions described below by, for example, executing a program stored in the storage device by the processing device.

The battery management unit 6 has, for example, a function as a voltage sensor for measuring the voltage of each cell 21 constituting the cell group 2 and a function for equalizing the voltage between the individual cells 21. doing. The state calculation unit 7 is connected to the current sensor 4, the temperature sensor 5, and the battery management unit 6 via, for example, a signal input / output unit. The state calculation unit 7 has, for example, a function of calculating the state of the cell group 2, that is, the battery state.

The battery state of the cell group 2 calculated by the state calculation unit 7 is, for example, the charge state (SOC), the deterioration state (SOH) of the cell group 2, the maximum power or current that can be input / output, the presence / absence of abnormality, and the characteristics. Includes parameters, history information, etc. Further, the state calculation unit 7 multiplies, for example, the current value acquired from the current sensor 4 and the voltage of each cell 21 acquired from the battery management unit 6, so that the output power and input power of the cell group 2 are multiplied. Has a function to calculate.

The state calculation unit 7 outputs, for example, the calculated information including the battery state of the cell group 2 to an external control device (not shown) via the information output terminal 9. Further, the state calculation unit 7 acquires, for example, information used for various calculations from an external control device (not shown) via the information input terminal 8.

FIG. 2 is a block diagram showing an example of a cell 21 constituting the secondary battery device 1 of FIG. More specifically, the cell 21 shown in FIG. 2 is one of a plurality of cell 21s constituting the cell group 2 of the secondary battery device 1 of FIG. The cell 21 is, for example, a lithium ion secondary battery as described above. That is, the secondary battery device 1 includes, for example, a plurality of cell cells 21 as a secondary battery.

The cell 21 includes, for example, a positive electrode 211, a negative electrode 212, and a third electrode 213. The positive electrode 211, the negative electrode 212, and the third electrode 213 are housed inside, for example, a sealed battery container 214 while being immersed in an electrolytic solution, and an insulating sheet (not shown) is not shown between the positive electrode 211 and the negative electrode 212. Is arranged and electrically insulated from the battery container 214. The cell 21 may be a wound electrode type or a laminated electrode type.

The positive electrode 211 includes, for example, a current collector and a mixture layer formed on the surface of the current collector. As the current collector of the positive electrode 211, for example, a metal foil of aluminum or an aluminum alloy can be used. The mixture layer of the positive electrode 211 contains, for example, a positive electrode material represented by the _{composition formula: LiMO 2, with a transition metal containing Ni, Co, and Mn as M.} Further, as the positive electrode material, for example, lithium manganese composite oxide partially substituted or doped with a metal element, lithium cobaltate or lithium titanate having a layered crystal structure, and lithium partially substituted or doped with a metal element. -A metal composite oxide or the like can be used.

The negative electrode 212 includes, for example, a current collector and a mixture layer formed on the surface of the current collector. As the current collector of the negative electrode 212, for example, a metal foil of copper or a copper alloy can be used. The mixture layer of the negative electrode 212 is, for example, natural graphite capable of inserting and removing lithium ions, various artificial graphite materials, carbonaceous materials such as coke, and compounds such as Si and Sn (for example, SiO, TiSi _{2 and the} like). , Or a composite material of these.

The third electrode 213 includes, for example, a current collector and a mixture layer formed on the surface of the current collector. The third electrode 213 can have the same configuration as the positive electrode 211, for example. That is, the third electrode 213 includes, for example, a current collector and a mixture layer formed on the surface of the current collector. As the current collector of the third electrode 213, for example, a metal foil of aluminum or an aluminum alloy can be used. Further, the mixture layer of the third electrode 213 contains, for example, a positive electrode material represented by the _{composition formula: LiMO 2, with a transition metal containing Ni, Co, and Mn as M.} The positive electrode material contained in the mixture layer of the third electrode 213 can contain, for example, 80% or more of Ni.

The third electrode 213 can be used as a reference electrode for measuring the potential of the positive electrode 211 and the potential of the third electrode 213, for example. That is, the potential of the positive electrode 211 can be measured by measuring the voltage Vtp between the third positive electrodes, which is the voltage between the third electrode 213 and the positive electrode 211. Further, the potential of the negative electrode 212 can be measured by measuring the voltage Vtn between the third negative electrodes, which is the voltage between the third electrode 213 and the negative electrode 212. Further, as will be described in detail later, the third electrode 213 can be used as a lithium ion supply source for supplying lithium ions to the positive electrode 211 or the negative electrode 212.

The wound electrode type cell 21 includes, for example, a group of wound electrodes in which a long strip-shaped positive electrode 211 and a long strip-shaped negative electrode 212 are wound via a long strip-shaped separator. .. The separator is, for example, a porous sheet having electrical insulation. In the wound electrode type cell 21, the third electrode 213 may be arranged in the hollow portion inside the wound electrode group, for example, and the wound electrode group and the battery container 214 are located outside the wound electrode group. It may be placed between.

The laminated electrode type cell 21 has, for example, a structure in which a sheet-shaped positive electrode 211 and a sheet-shaped negative electrode 212 are alternately laminated over a plurality of layers via a sheet-shaped separator. In the laminated electrode type cell 21, the third electrode 213 is arranged, for example, between the positive electrode 211 and the negative electrode 212, or outside the laminated body of the positive electrode 211 and the negative electrode 212 via a separator. Can be done.

As the electrolytic solution impregnated in the positive electrode 211, the negative electrode 212 and the third electrode 213, for example, a lithium salt such as lithium _{hexafluorophosphate (LiPF 6) is dissolved in a carbonic acid ester-based organic solvent such as ethylene carbonate.} A non-aqueous electrolyte solution can be used.

As shown in FIG. 2, each cell 21 is connected to the control circuit 10. More specifically, the current collector of the positive electrode 211 is connected to the positive electrode external terminal of the cell 21 via the positive electrode current collector plate or the positive electrode lead, and the control circuit 10 is connected to the positive electrode external terminal of the cell 21. As a result, the positive electrode 211 is connected to the control circuit 10. Further, the current collector of the negative electrode 212 is connected to the negative electrode external terminal of the cell 21 via the negative electrode current collector plate or the negative electrode lead, and the control circuit 10 is connected to the negative electrode external terminal of the cell 21 to be negative. The electrode 212 is connected to the control circuit 10.

Similarly, the current collector of the third electrode 213 is connected to the third external terminal of the cell 21 via the third current collector plate or the third lead, and the control circuit 10 is connected to the third external terminal of the cell 21. By doing so, the third electrode 213 is connected to the control circuit 10. That is, the cell 21 includes three external terminals, a positive electrode external terminal, a negative electrode external terminal, and a third external terminal, and each external terminal is connected to the control circuit 10. The control circuit 10 is, for example, a part of the battery management unit 6 shown in FIG.

FIG. 3 is a circuit diagram showing an example of the control circuit 10 connected to the cell 21 of FIG. The control circuit 10 is connected to the positive electrode 211, the negative electrode 212, and the third electrode 213 via wiring connected to each of the positive electrode external terminal, the negative electrode external terminal, and the third external terminal of the cell 21, for example. NS. Further, the control circuit 10 is connected to the control unit 11 via signal wiring.

The control circuit 10 is, for example, an electronic circuit provided for each cell 21 on a circuit board constituting the battery management unit 6. The control circuit 10 includes, for example,

voltmeters

101 and 102, a power supply unit 103,

switches

104 and 105, and an ammeter 106.

The voltmeter 101 measures, for example, the voltage Vpn between the positive and negative electrodes, which is the voltage between the positive electrode 211 and the negative electrode 212 of the cell 21, and outputs the measurement result to the control unit 11. The voltmeter 102 measures, for example, the voltage Vtp between the third positive electrodes, which is the voltage between the third electrode 213 and the positive electrode 211, and outputs the measurement result to the control unit 11. Further, the voltmeter 102 measures, for example, the voltage Vtn between the third negative electrodes, which is the voltage between the third electrode 213 and the negative electrode 212, and outputs the measurement result to the control unit 11.

The power supply unit 103 is connected to, for example, an external power source, and switches the direction in which the current flows according to the control signal input from the control unit 11. The current meter 106 measures and controls the current value It of the current flowing from the third electrode 213 to the positive electrode 211 or the negative electrode 212 and the current value It of the current flowing from the positive electrode 211 or the negative electrode 212 to the third electrode 213. Output to unit 11.

The switch 104, for example, disconnects the connection between the third electrode 213 and the power supply unit 103 and the connection between the third electrode 213 and the power supply unit 103 in response to the control signal input from the control unit 11. Switch between states. The switch 105 switches between a state in which the positive electrode 211 and the third electrode 213 are connected and a state in which the negative electrode 212 and the third electrode 213 are connected, for example, according to a control signal input from the control unit 11. ..

The control unit 11 is, for example, a part of the battery management unit 6 or the state calculation unit 7 shown in FIG. The control unit 11 is connected to, for example, a plurality of control circuits 10. A control unit 11 may be provided for each control circuit 10. The control unit 11 includes, for example, a processing device 111, a storage device 112, a timer 113, and an input / output unit 114.

The processing device 111 includes, for example, a central processing unit (CPU). The storage device 112 includes, for example, a RAM or a ROM, and stores a control program executed by the processing device 111. The timer 113 measures, for example, the time and the elapsed time. The input / output unit 114 is connected to, for example, a processing device 111, a storage device 112, and a timer 113. As a result, the processing device 111, the storage device 112, and the timer 113 are connected to each other via the input / output unit 114 so that information can be communicated.

Further, the input / output unit 114 is connected to each unit of the control circuit 10 including, for example, the

voltmeters

101 and 102, the power supply unit 103, the

switches

104 and 105, and the ammeter 106 via signal wiring. .. With such a configuration, the control unit 11 executes, for example, the control program stored in the storage device 112 by the processing device 111, and controls each part of the control circuit 10 based on the information acquired from each part of the control circuit 10. be able to.

More specifically, the control unit 11 is a power supply unit of the control circuit 10 based on, for example, the positive / negative electrode voltage Vpn, the third positive electrode voltage Vtp, and the third negative electrode voltage Vtn obtained from the control circuit 10. 103,

switches

104 and 105 are controlled. Further, the control unit 11 is, for example, a power supply unit of the control circuit 10 based on the positive / negative electrode voltage Vpn, the third positive electrode voltage Vtp, the third negative electrode voltage Vtn, and the current value It acquired from the control circuit 10. 103,

switches

104 and 105 may be controlled.

FIG. 4 is a flow chart illustrating an example of the operation of the control unit 11 of FIG. 5A and 5B are graphs showing an example of the discharge characteristics of the cell 21 of FIG. In each of the graphs of FIGS. 5A and 5B, the horizontal axis is the discharge capacity [Ah] and the vertical axis is the potential [V]. The graph of FIG. 5A shows the discharge characteristics of the cell 21 before the lithium ions of the negative electrode 212 are deactivated. The graph of FIG. 5B shows the discharge characteristics of the cell 21 after a part of the lithium ions of the negative electrode 212 is deactivated.

At the start of use of the secondary battery device 1, the cell 21 exhibits, for example, the discharge characteristics as shown in FIG. 5A. In the cell 21, for example, the voltage Vpn between the positive and negative electrodes is used in a range from the end-of-charge voltage Vc to the end-of-discharge voltage Vd.

The end-of-charge voltage Vc of the cell 21 is determined, for example, based on the end-of-charge voltage Vpc of the positive electrode 211, which is lower than the maximum chargeable voltage of the positive electrode 211. The capacity of the positive electrode 211 having the charge termination voltage Vpc is smaller than the capacity of the positive electrode 211 having the maximum chargeable voltage by a predetermined capacity δp. Further, the discharge capacity of the negative electrode 212 having the end-of-charge voltage Vnc corresponding to the end-of-charge voltage Vpc of the positive electrode 211 is smaller than the capacity of the negative electrode 212 having the maximum chargeable voltage by a predetermined capacity δn. ..

Further, the discharge end voltage Vd of the cell 21 is determined based on, for example, the discharge end voltage Vnd before the potential of the negative electrode 212 suddenly increases. As described above, by setting the range of the voltage Vpn between the positive and negative electrodes of the cell 21 from the charge termination voltage Vc to the discharge termination voltage Vd, the cell 21 can be safely used for a long period of time. At the start of use of the secondary battery device 1, the control unit 11 first executes a process P1 for switching the control mode M of the control circuit 10 to the first mode, as shown in FIG.

In process P1, the control unit 11 outputs a control signal to, for example, the switch 104 of the control circuit 10, disconnects the third electrode 213 and the power supply unit 103, and disconnects the third electrode 213 and the voltmeter 102. The switch 104 is switched so as to connect with. Further, the control unit 11 outputs a control signal to the switch 105 of the control circuit 10, for example, and switches the switch 105 so as to connect the negative electrode 212 and the voltmeter 102.

In the first mode of the control circuit 10, no current flows between the positive electrode 211, the negative electrode 212, and the third electrode 213 in the control circuit 10. Therefore, in the secondary battery device 1 shown in FIG. 1, the cell 21 performs a normal operation. That is, the plurality of cell cells 21 constituting the cell cell group 2 are charged and discharged under the control of the battery management unit 6 and the state calculation unit 7.

Next, the control unit 11 executes a process P2 for determining whether or not the third negative electrode voltage Vtn is lower than the threshold value Vtn1 based on the third negative electrode voltage Vtn input from the voltmeter 102. The threshold value Vtn1 of the third negative electrode voltage Vtn, which is the voltage between the third electrode 213 and the negative electrode 212, is set in advance based on, for example, the discharge end voltage Vnd of the negative electrode 212 described above, and is stored in the control unit 11. It is stored in the device 112.

In this process P2, when the control unit 11 determines that the voltage Vtn between the third negative electrodes is not lower than the threshold value Vtn1 (NO), for example, it outputs a control signal to the switch 105 of the control circuit 10 to output the next Process P3 is executed. Based on the control signal input from the control unit 11, the switch 105 disconnects, for example, the connection between the negative electrode 212 and the voltmeter 102, and switches to a state in which the positive electrode 211 and the voltmeter 102 are connected. ..

In the process P3, the control unit 11 sets the third positive electrode voltage Vtp to the threshold Vtp1 based on the third positive electrode voltage Vtp which is the voltage between the third electrode 213 and the positive electrode 211 input from the voltmeter 102. It is judged whether or not it is lower than. This threshold value Vtp1 is set in advance based on, for example, in the discharge characteristics of the cell 21 shown in FIG. 5A, based on the voltage at which the voltage Vtp between the third positive electrodes sharply drops, and is stored in the storage device 112 of the control unit 11. ..

In the process P3, when the control unit 11 determines that the voltage Vtp between the third positive electrodes is not lower than the threshold value Vtp1 (NO), the above-mentioned processes P1 and P2 are repeated. When the secondary battery device 1 repeatedly charges and discharges the cell group 2 while repeating the process P1 to the process P3, for example, lithium due to a side reaction on the surface of the negative electrode 212 of the cell 21 with the passage of time. Ion deactivation occurs.

As a result, the discharge capacity of the negative electrode 212 decreases as shown by arrow A1 in FIG. 5A, and the voltage Vtn between the third negative electrodes showing the discharge characteristics of the negative electrode 212 as shown by arrows A2 and A3 in FIG. 5B. The curve shifts to the left. Therefore, the voltage Vpn between the positive and negative electrodes of the cell 21 also shifts to the left side in the same manner.

As a result, the discharge capacity of the cell 21 is reduced even if the voltage Vpn between the positive and negative electrodes is used in the range from the end-of-charge voltage Vc to the end-of-discharge voltage Vd. Further, as shown in FIG. 5B, the capacity which is the difference between the discharge capacity of the negative electrode 212 of the charge termination voltage Vnc corresponding to the charge end voltage Vpc of the positive electrode 211 and the capacity of the negative electrode 212 of the maximum chargeable voltage. δn is further enlarged as compared with the start of use of the cell 21 shown in FIG. 5A.

Before such a state occurs, in the process P2 shown in FIG. 4, the control unit 11 determines that the third negative electrode voltage Vtn is lower than the threshold value Vtn1 (YES). Then, the control unit 11 executes the process P4 of switching the control mode M of the control circuit 10 to the second mode in which the current flows from the negative electrode 212 to the third electrode 213.

In process P4, for example, the control unit 11 outputs a control signal to the switch 104 of the control circuit 10, connects the third electrode 213 and the power supply unit 103, and connects the third electrode 213 and the voltmeter 102. Toggle switch 104 to disconnect. Further, the control unit 11 outputs a control signal to the switch 105 of the control circuit 10, for example, and switches the switch 105 so as to connect the negative electrode 212 and the power supply unit 103. Further, the control unit 11 outputs a control signal to the power supply unit 103, and the power supply unit 103 causes a current to flow from the negative electrode 212 to the third electrode 213.

By this process P4, lithium ions move from the third electrode 213 to the negative electrode 212, and the lithium ions deactivated on the surface of the negative electrode 212 are supplemented. Next, the control unit 11 executes, for example, a process P5 for determining whether or not the third negative electrode voltage Vtn is equal to or higher than the threshold value Vtn2. The threshold value Vtn2 is set in advance based on, for example, the discharge end voltage Vnd of the negative electrode 212 described above, and is stored in the storage device 112 of the control unit 11.

In this process P5, the control unit 11 switches the control circuit 10 from the second mode to the first mode, connects the negative electrode 212 to the voltmeter 102, and acquires the voltage Vtn between the third negative electrodes from the voltmeter 102. In this process P5, when the control unit 11 determines that the third negative electrode voltage Vtn is not equal to or higher than the threshold value Vtn2 (NO), the control mode M of the control circuit 10 is switched from the first mode to the second mode.

Next, the control unit 11 executes the process P6 for calculating and estimating the capacitance Qt of the third electrode 213. In the process P6, the control unit 11 calculates the integrated value of the capacitance Qt of the third electrode 213 based on, for example, the current value It output from the ammeter 106 and the elapsed time measured by the timer 113.

Next, the control unit 11 executes the process P7 for determining whether or not the capacitance Qt of the third electrode 213 is greater than the threshold value Qt1. The threshold value Qt1 is determined in advance by experiments or the like with a capacitance within a range in which the third electrode 213 can supply lithium ions and can maintain the function as an electrode for measuring the potentials of the positive electrode 211 and the negative electrode 212. It can be calculated and set based on the capacity. Further, the threshold value Qt1 can be stored in advance in the storage device 112 of the control unit 11.

In the process P7, when the control unit 11 determines that the capacitance Qt of the third electrode 213 is not greater than the threshold value Qt1 (NO), the control mode M of the control circuit 10 is switched from the second mode to the first mode, and the above-mentioned Process P5 is executed. In this way, while the control unit 11 repeats the process from the process P5 to the process P7, a current flows from the negative electrode 212 to the third electrode 213, lithium ions move from the third electrode 213 to the negative electrode 212, and the negative electrode is negative. The deactivated lithium ion is supplemented on the surface of the electrode 212.

As a result, the discharge characteristic of the negative electrode 212 shifts from the state shown in FIG. 5B to the right side, and becomes, for example, the state shown in FIG. 5A. As a result, the capacity retention rate of the cell 21 can be restored. Then, in the above-mentioned process P5, the control unit 11 determines that the third negative electrode voltage Vtn is equal to or higher than the threshold value Vtn2 (YES), and ends the process shown in FIG. After that, the control unit 11 restarts the process shown in FIG.

Further, if the amount of lithium ions transferred from the third electrode 213 to the negative electrode 212 becomes excessive, the function of the third electrode 213 as a reference electrode for measuring the potentials of the positive electrode 211 and the negative electrode 212 may be lost. Therefore, when the control unit 11 determines in the above-mentioned process P7 that the capacitance Qt of the third electrode 213 is larger than the threshold value Qt1 (YES), the control mode M of the control circuit 10 is changed from the third electrode 213 to the positive electrode 211. Alternatively, the process P8 for switching to the fourth mode in which a current is passed through the negative electrode 212 is executed.

More specifically, in the process P8, the control unit 11 outputs a control signal to, for example, the power supply unit 103, and causes a current to flow from the third electrode 213 to the negative electrode 212. Alternatively, in the process P8, the control unit 11 outputs a control signal to the switch 105, for example, disconnects the connection between the negative electrode 212 and the power supply unit 103, and connects the positive electrode 211 and the power supply unit 103. The switch 105 is switched so as to be connected, and a control signal is output to the power supply unit 103 to allow a current to flow from the third electrode 213 to the positive electrode 211.

As a result, lithium ions move from the negative electrode 212 or the positive electrode 211 to the third electrode 213, and the function of the third electrode 213 as a reference electrode for measuring the potentials of the positive electrode 211 and the negative electrode 212 can be maintained. become. After the end of the process P8, the control unit 11 ends the process shown in FIG. After that, the control unit 11 restarts the process shown in FIG.

Further, in the above-described process P3, when the control unit 11 determines that the voltage Vtp between the third positive electrodes is lower than the threshold value Vtp1 (YES), the control unit 11 sets the control mode M of the control circuit 10 to positive. The process P9 for switching to the third mode in which a current flows from the electrode 211 to the third electrode 213 is executed.

In process P9, the control unit 11 outputs a control signal to, for example, the switch 104 of the control circuit 10, connects the third electrode 213 and the power supply unit 103, and connects the third electrode 213 and the voltmeter 102. Toggle switch 104 to disconnect. Further, the control unit 11 outputs a control signal to the switch 105 of the control circuit 10, for example, and switches the switch 105 so as to connect the positive electrode 211 and the power supply unit 103. Further, the control unit 11 outputs a control signal to the power supply unit 103, and the power supply unit 103 causes a current to flow from the positive electrode 211 to the third electrode 213.

By this process P9, lithium ions move from the third electrode 213 to the positive electrode 211, and the positive electrode 211 is replenished with lithium ions. Next, the control unit 11 executes, for example, a process P10 for determining whether or not the third positive electrode voltage Vtp is equal to or higher than the threshold value Vtp2. The threshold value Vtp2 is set in advance based on, for example, the discharge end voltage Vpd of the positive electrode 211 described above, and is stored in the storage device 112 of the control unit 11.

In this process P10, the control unit 11 switches the control circuit 10 from the third mode to the first mode, connects the positive electrode 211 to the voltmeter 102, and acquires the voltage Vtp between the third positive electrodes from the voltmeter 102. In this process P10, when the control unit 11 determines that the third positive electrode voltage Vtp is not equal to or higher than the threshold value Vtn2 (NO), the control mode M of the control circuit 10 is switched from the first mode to the third mode.

Next, the control unit 11 executes the process P11 for calculating and estimating the capacitance Qt of the third electrode 213. In the process P11, the control unit 11 calculates the integrated value of the capacitance Qt of the third electrode 213 based on, for example, the current value It output from the ammeter 106 and the elapsed time measured by the timer 113.

Next, the control unit 11 executes the process P12 for determining whether or not the capacitance Qt of the third electrode 213 is greater than the threshold value Qt1. This threshold value Qt1 is, for example, the same as the threshold value Qt1 in the above-mentioned processing P7.

In the process P12, when the control unit 11 determines that the capacitance Qt of the third electrode 213 is not greater than the threshold value Qt1 (NO), the control unit 11 executes the above-mentioned process P10. In this way, while the control unit 11 repeats the process from the process P10 to the process P12, a current flows from the positive electrode 211 to the third electrode 213, lithium ions move from the third electrode 213 to the positive electrode 211, and the positive electrode is positive. The electrode 211 is replenished with lithium ions.

Further, if the amount of lithium ions transferred from the third electrode 213 to the positive electrode 211 becomes excessive, the function of the third electrode 213 as a reference electrode for measuring the potentials of the positive electrode 211 and the negative electrode 212 may be lost. Therefore, when the control unit 11 determines in the above-mentioned process P12 that the capacitance Qt of the third electrode 213 is larger than the threshold value Qt1 (YES), the control mode M of the control circuit 10 is changed from the third electrode 213 to the positive electrode 211. Alternatively, the process P13 for switching to the fourth mode in which a current is passed through the negative electrode 212 is executed.

More specifically, in the process P13, the control unit 11 outputs a control signal to, for example, the power supply unit 103, and causes a current to flow from the third electrode 213 to the positive electrode 211. Alternatively, in the process P13, the control unit 11 outputs a control signal to the switch 105, for example, disconnects the connection between the positive electrode 211 and the power supply unit 103, and connects the negative electrode 212 and the power supply unit 103. The switch 105 is switched so as to be connected, and a control signal is output to the power supply unit 103 to allow a current to flow from the third electrode 213 to the negative electrode 212.

As a result, lithium ions move from the positive electrode 211 or the negative electrode 212 to the third electrode 213, and the function of the third electrode 213 as a reference electrode for measuring the potentials of the positive electrode 211 and the negative electrode 212 can be maintained. become. After the end of the process P13, the control unit 11 ends the process shown in FIG. After that, the control unit 11 restarts the process shown in FIG.

As described above, the secondary battery device 1 of the present embodiment includes a cell 21 which is a secondary battery having a positive electrode 211, a negative electrode 212, and a third electrode 213, and a control connected to the cell 21. It includes a circuit 10 and a control unit 11 that controls the control circuit 10. The control unit 11 includes a voltage Vpn between the positive and negative electrodes between the positive electrode 211 and the negative electrode 212, a voltage Vtp between the third positive electrode between the third electrode 213 and the positive electrode 211, and the third electrode 213 and the negative electrode 212. The control circuit 10 switches between the first mode, the second mode, the third mode, and the fourth mode based on at least one of the third negative electrode voltage Vtn between the two. The first mode is a mode in which no current flows between the positive electrode 211, the negative electrode 212, and the third electrode. The second mode is a mode in which a current flows from the negative electrode 212 to the third electrode 213. The third mode is a mode in which a current flows from the positive electrode 211 to the third electrode 213. The fourth mode is a mode in which a current is passed from the third electrode 213 to the positive electrode 211 or the negative electrode 212.

With such a configuration, in the secondary battery device 1 of the present embodiment, the third electrode 213 for measuring the potentials of the positive electrode 211 and the negative electrode 212 is a source of lithium ions to the positive electrode 211 and the negative electrode 212. In the cell 21 which also serves as the above, it is possible to prevent the loss of the potential measurement function by the third electrode 213. That is, the secondary battery device 1 of the present embodiment supplies lithium ions from the third electrode 213 to the negative electrode 212 or the positive electrode 211 by switching the control circuit 10 to the second mode or the third mode by the control circuit 10. can do. Further, when the supply of lithium ions from the third electrode 213 to the negative electrode 212 or the positive electrode 211 becomes larger than expected, the control unit 11 switches the control circuit 10 to the fourth mode, so that the negative electrode 212 or Lithium ions can be returned from the positive electrode 211 to the third electrode 213.

That is, the method for controlling the secondary battery of the present embodiment is a method for controlling the cell 21 as a secondary battery having a positive electrode 211, a negative electrode 212, and a third electrode 213. The secondary battery control method of the present embodiment includes a positive and negative electrode voltage Vpn between the positive electrode 211 and the negative electrode 212, a third positive electrode voltage Vtp between the third electrode 213 and the positive electrode 211, and a third. The first mode, the second mode, the third mode, and the fourth mode are switched based on at least one of the third negative electrode voltage Vtn between the electrode 213 and the negative electrode 212. The first mode is a mode in which no current flows between the positive electrode 211, the negative electrode 212, and the third electrode. The second mode is a mode in which a current flows from the negative electrode 212 to the third electrode 213. The third mode is a mode in which a current flows from the positive electrode 211 to the third electrode 213. The fourth mode is a mode in which a current is passed from the third electrode 213 to the positive electrode 211 or the negative electrode 212.

With such a configuration, the method for controlling the secondary battery of the present embodiment can achieve the same effect as that of the above-mentioned secondary battery device 1. Therefore, according to the present embodiment, in the cell battery 21 in which the third electrode 213 also serves as a supply source of lithium ions to the positive electrode 211 and the negative electrode 212, it is possible to prevent the loss of the potential measurement function by the third electrode 213. It is possible to provide a possible secondary battery device 1 and a method for controlling the secondary battery.

Further, in the secondary battery device 1 of the present embodiment, when the control unit 11 lowers the third negative electrode voltage Vtun from the threshold value Vtn1 in the first mode of the control circuit 10 when the cell 21 which is the secondary battery is discharged. In addition, the control circuit 10 is switched from the first mode to the second mode.

With such a configuration, as shown in FIG. 5B, the secondary battery device 1 of the present embodiment has a third negative electrode when the curve of the third negative electrode voltage Vtun showing the discharge characteristic of the negative electrode 212 is shifted to the left side. Lithium ions can be transferred from the electrode 213 to the negative electrode 212 to supplement the lithium ions deactivated on the surface of the negative electrode 212. As a result, the discharge characteristic of the negative electrode 212 shifted to the left as shown in FIG. 5B can be shifted to the right and restored to the state shown in FIG. 5A or a state close to it.

Further, as shown in FIG. 1, the secondary battery device 1 of the present embodiment further includes a current sensor 4 as an ammeter for measuring the current value at the time of discharging the cell 21 which is a secondary battery. In this case, the control unit 11 may execute the following processing instead of the above-mentioned processing P2. The control unit 11 estimates the capacity of the negative electrode 212 based on the current value at the time of discharging the cell 21 in the first mode of the control circuit 10. Then, the control unit 11 executes the process P4 of switching the control circuit 10 from the first mode to the second mode when the ratio of the change in the voltage Vtn between the third negative electrodes to the capacitance of the negative electrode 212 exceeds the threshold value.

With such a configuration, the secondary battery device 1 sets the control circuit 10 from the first mode to the second mode when the slope of the voltage Vtn between the third negative electrodes shown in FIGS. 5A and 5B exceeds a predetermined threshold value. The process P4 for switching to can be executed. As a result, not only can the same effect as that of the secondary battery device 1 in the above-described embodiment be obtained, but also the state of the negative electrode 212 can be grasped more accurately.

Further, in the secondary battery device 1 of the present embodiment, the control unit 11 determines that the voltage Vtp between the third positive electrodes drops below the threshold value in the first mode of the control circuit 10 when the cell 21 which is the secondary battery is discharged. , The control circuit 10 is switched from the first mode to the third mode.

With such a configuration, in the secondary battery device 1 of the present embodiment, as shown in FIGS. 5A and 5B, when the curve of the third positive electrode voltage Vtp showing the discharge characteristics of the positive electrode 211 is shifted to the left side. , Lithium ions can be moved from the third electrode 213 to the positive electrode 211, and the positive electrode 211 can be replenished with lithium ions. As a result, the discharge characteristic of the positive electrode 211 shifted to the left side can be shifted to the right side and restored to the state shown in FIG. 5A or a state close to it.

Further, as described above, the secondary battery device 1 of the present embodiment further includes a current sensor 4 as an ammeter for measuring the current value at the time of discharging the single battery 21 which is a secondary battery. In this case, the control unit 11 may execute the following process instead of the above-mentioned process P3. The control unit 11 estimates the capacity of the positive electrode 211 based on the current value at the time of discharging the cell 21 in the first mode of the control circuit 10. Then, the control unit 11 executes a process P9 for switching the control circuit 10 from the first mode to the third mode when the ratio of the change in the voltage Vtp between the third positive electrodes to the capacitance of the positive electrode 211 exceeds the threshold value.

With such a configuration, the secondary battery device 1 of the present embodiment sets the control circuit 10 in the first mode when the slope of the voltage Vtp between the third positive electrodes shown in FIGS. 5A and 5B exceeds a predetermined threshold value. The process P9 for switching to the third mode can be executed. As a result, not only can the same effect as that of the secondary battery device 1 in the above-described embodiment be obtained, but also the state of the positive electrode 211 can be grasped more accurately.

Further, in the secondary battery device 1 of the present embodiment, the control circuit 10 outputs the measurement result of the current value It of the current flowing through the third electrode 213 to the control unit 11. The control unit 11 calculates the capacitance Qt of the third electrode 213 based on the current value It in the second mode or the third mode of the control circuit 10, and when the capacitance Qt exceeds the threshold value Qt1, the control circuit 10 is set to the third. Switch to 4 mode.

With such a configuration, the secondary battery device 1 of the present embodiment prevents excessive movement of lithium ions from the third electrode 213 to the positive electrode 211 or the negative electrode 212. Therefore, it is possible to prevent the third electrode 213 from losing the potential measurement function of the positive electrode 211 and the negative electrode 212.

Further, in the secondary battery device 1 of the present embodiment, the cell 21 as the secondary battery is a lithium ion secondary battery. Further, the third electrode 213 includes a current collector and a mixture layer formed on the current collector. The mixture layer of the third electrode 213 contains a positive electrode material represented by the _{composition formula: LiMO 2} , with the transition metal containing Ni, Co, and Mn as M.

With such a configuration, the secondary battery device 1 of the present embodiment can not only supply lithium ions from the third electrode 213 to the positive electrode 211 and the negative electrode 212, but also supply lithium ions from the positive electrode 211 and the negative electrode 212. It becomes possible to return lithium ions to the three electrodes 213.

Further, in the secondary battery device 1 of the present embodiment, the positive electrode material contained in the mixture layer of the third electrode 213 can contain 80% or more of Ni.

With such a configuration, in the secondary battery device 1 of the present embodiment, the positive electrode 211 or the negative electrode 211 or the negative electrode 213 is compared with the case where the Ni contained in the positive electrode material of the third electrode 213 is less than 80%. The lithium ions that can be supplied to the electrode 212 can be increased.

Although the embodiments of the secondary battery device and the control method for the secondary battery according to the present disclosure have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the present disclosure is not limited to this embodiment. Any design changes, etc. that do not deviate from the gist are included in this disclosure.

1 Secondary battery device 4 Current sensor (ammeter)
10 Control circuit 11 Control unit 21 Single battery (secondary battery)
211 Positive electrode 212 Negative electrode 213 Third electrode It Current value Qt Capacity Qt1 Threshold Vpn Positive / negative electrode voltage Vtn Third negative electrode voltage Vtn1 Threshold Vtp Third positive electrode voltage Vtp1 Threshold

Claims

A secondary battery device including a secondary battery having a positive electrode, a negative electrode, and a third electrode, a control circuit connected to the secondary battery, and a control unit for controlling the control circuit.
The control unit includes a voltage between the positive and negative electrodes between the positive electrode and the negative electrode, a voltage between the third positive electrode between the third electrode and the positive electrode, and a voltage between the third electrode and the negative electrode. In the control circuit, a first mode in which no current flows between the positive electrode, the negative electrode, and the third electrode, and the first mode from the negative electrode to the third electrode, based on at least one of the third negative electrode voltages of the above. The second mode in which a current is passed through the three electrodes, the third mode in which a current is passed from the positive electrode to the third electrode, and the fourth mode in which a current is passed from the third electrode to the positive electrode or the negative electrode are switched. A secondary battery device characterized by the fact that.
The control unit switches the control circuit from the first mode to the second mode when the voltage between the third negative electrodes drops below the threshold value in the first mode of the control circuit when the secondary battery is discharged. The secondary battery device according to claim 1, wherein the secondary battery device is characterized by the above.
An ammeter for measuring the current value at the time of discharging the secondary battery is further provided.
The control unit estimates the capacitance of the negative electrode based on the current value in the first mode, and when the ratio of the change in the voltage between the third negative electrodes to the capacitance exceeds the threshold value, the control circuit is used. The secondary battery device according to claim 1, wherein the mode is switched from the first mode to the second mode.
The control unit switches the control circuit from the first mode to the third mode when the voltage between the third positive electrodes drops below the threshold value in the first mode of the control circuit when the secondary battery is discharged. The secondary battery device according to claim 1, wherein the secondary battery device is characterized by the above.
An ammeter for measuring the current value at the time of discharging the secondary battery is further provided.
The control unit estimates the capacitance of the positive electrode based on the current value in the first mode, and when the ratio of the change in the voltage between the third positive electrodes to the capacitance exceeds the threshold value, the control circuit is used. The secondary battery device according to claim 1, wherein the mode is switched from the first mode to the third mode.
The control circuit outputs the measurement result of the current value of the current flowing through the third electrode to the control unit.
The control unit calculates the capacitance of the third electrode based on the current value in the second mode or the third mode of the control circuit, and when the capacitance exceeds the threshold value, the control circuit is used. The secondary battery device according to claim 1, wherein the secondary battery device is switched to the fourth mode.
The secondary battery is a lithium ion secondary battery.
The third electrode includes a current collector and a mixture layer formed on the current collector.
The secondary battery device according to claim 1, wherein the mixture layer contains a positive electrode material represented by a composition formula: LiMO 2 , with a transition metal containing Ni, Co, and Mn as M.
The secondary battery device according to claim 7, wherein the positive electrode material contains 80% or more of the Ni.
A method for controlling a secondary battery having a positive electrode, a negative electrode, and a third electrode.
The voltage between the positive and negative electrodes between the positive electrode and the negative electrode, the voltage between the third positive electrode between the third electrode and the positive electrode, and the third negative electrode between the third electrode and the negative electrode. A first mode in which no current flows between the positive electrode, the negative electrode, and the third electrode based on at least one of the voltages, and a second mode in which a current flows from the negative electrode to the third electrode. Control of the secondary battery, which comprises switching between a third mode in which a current flows from the positive electrode to the third electrode and a fourth mode in which a current flows from the third electrode to the positive electrode or the negative electrode. Method.