KR101750600B1 - Apparatus For Measuring State Of Charging Of Flow Battery - Google Patents

Abstract

[0001] The present invention relates to an apparatus for measuring the remaining capacity of a flow battery, and more particularly to an apparatus for measuring the remaining capacity of a flow battery by connecting a bypass tube to an electrolyte tube of a flow battery to bypass the electrolyte, And estimating the composition ratio of the electrolytic solution and calculating the remaining capacity of the flow battery based on the estimated composition ratio.

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus for measuring remaining capacity of a flow battery,

[0001] The present invention relates to an apparatus for measuring the remaining capacity of a flow battery, and more particularly to an apparatus for measuring the remaining capacity of a flow battery by connecting a bypass tube to an electrolyte tube of a flow battery to bypass the electrolyte, And estimating the composition ratio of the electrolytic solution and calculating the remaining capacity of the flow battery based on the estimated composition ratio.

Power storage technology is an important technology for efficient use of energy, such as efficient use of power, improvement of power supply system's ability and reliability, expansion of new and renewable energy with a large fluctuation over time, energy recovery of mobile body, There is a growing demand for possibilities and social contributions.

The supply and demand balances of semi-autonomous regional electricity supply systems such as micro grid and the uneven output of renewable energy such as wind power and solar power are appropriately distributed and voltage and frequency fluctuations Researches on secondary batteries have been actively conducted to control the influence of secondary batteries, and expectations for utilization of secondary batteries are increasing in these fields.

Particularly, the characteristics required for a secondary battery to be used for a large-capacity power storage have to be high in energy storage density, and a redox flow battery (RFB) as a secondary battery with high capacity and high efficiency suitable for such characteristics has recently been attracting attention It is true.

The redox flow battery converts the electrical energy input through the charging process into chemical energy and stores it, and converts the stored chemical energy into electric energy through the discharging process. However, such a redox flow battery is different from a general secondary battery in that a tank or a storage container for storing an electrode active material is required because an electrode active material having energy is present in a liquid state rather than a solid state.

Such a redox flow battery can be designed to have a large capacity, operate at room temperature, and can independently design the capacity and output, and the remaining capacity of the battery is proportional or inversely proportional to the composition ratio of a specific electrode active material Many studies have been conducted recently.

In particular, the vanadium redox flow battery, which is made up of vanadium ions in the electrode active material, is more expensive than the redox flow battery in which other metal ions are used as the electrode active material, and has a longer cycle life, And it is advantageous as a next generation energy storage device because it has an advantage of returning to an electrode active material suitable for each electrode during charging and discharging even if different electrode active materials are mixed because vanadium ions are used only.

In order to utilize the vanadium redox flow battery as an energy storage device, it is necessary to accurately measure the remaining capacity of the vanadium redox flow battery in real time and provide it to the user, and to control charging and discharging efficiently based on the measured remaining capacity.

However, in the case of the vanadium redox flow battery, the electrode active material before the redox reaction and the electrode active material after the redox reaction are stored in the same container by charging / discharging electric power by using a large amount of electrolytic solution, There is a problem that it is impossible to accurately measure the remaining capacity of the battery in proportion to the composition ratio of the specific electrode active material while mixing with each other.

Korean Patent Publication No. 10-2013-0038234

It is an object of the present invention to provide a method of measuring the absorbance of an electrolytic solution through a measuring unit and correspondingly measuring the composition ratio of an electrolyte solution mixed with an electrode active material before and after the redox reaction, It is desirable to provide an apparatus for measuring remaining capacity of a flow battery capable of accurately calculating a remaining capacity of a battery proportional to a specific electrode active material.

It is another object of the present invention to provide a method and an apparatus for measuring a flow rate of an electrolytic solution flowing in a bypass tube by connecting a bypass tube to an electrolyte tube of a flow battery to bypass an electrolyte to a measuring unit, Which is capable of measuring the remaining capacity of a flow battery using a large-capacity electrolytic solution in real time by adjusting the capacity of the flow battery.

An apparatus for measuring remaining capacity of a flow battery according to the present invention includes: a measuring unit for measuring an absorbance by irradiating an electrolyte solution of a flow battery with light; An estimating unit that estimates a composition ratio of the electrolytic solution corresponding to the measured absorbance of the electrolytic solution; And a calculation unit for calculating a remaining capacity of the flow battery based on the estimated composition ratio of the electrolytic solution.

Preferably, the measurement unit includes an absorption cell for receiving the electrolyte solution for measuring the absorbance.

Preferably, the apparatus further comprises a bypass tube connected to the electrolyte tube of the flow battery and bypassing the electrolyte with the measurement unit.

Preferably, the bypass tube includes a first valve that adjusts a flow rate of the electrolytic solution flowing into the bypass tube.

Preferably, the bypass tube further includes a second valve for controlling a flow rate of the electrolyte discharged from the bypass tube.

Preferably, when the remaining capacity of the flow battery is measured, the first and second valves are closed.

Preferably, the measuring unit is an ultraviolet-visible light spectrophotometer.

Preferably, the flow battery is a vanadium redox flow battery.

Preferably, the calculating unit calculates the remaining capacity of the flow battery based on a composition ratio of vanadium divalent or trivalent ions contained in the electrolytic solution.

The present invention relates to a flow battery for storing an electrode active material before and after a redox reaction in a single electrolyte container by estimating a composition ratio of an electrolytic solution in which an electrode active material before and after a redox reaction is mixed to calculate a remaining capacity of the battery, Can be accurately measured.

The present invention also provides first and second valves at both ends of a bypass tube for bypassing the electrolyte solution in the electrolyte tube to the measurement section to control the flow rate of the electrolyte solution flowing in the bypass tube, The remaining capacity of the battery can be measured in real time.

1 is a schematic view showing a general structure of a redox flow battery.
FIG. 2 is a schematic view showing a state in which an apparatus for measuring remaining capacity of a flow battery according to an embodiment of the present invention is applied to a flow battery. FIG.
3A is a graph showing measurement data obtained by measuring the absorbance of an electrolyte solution of a flow battery according to the wavelength of light irradiated by the electrolyte solution.
FIG. 3B is a graph showing the absorbance of the electrolyte according to the composition ratio of the divalent vanadium ions, based on the measurement data of the graph shown in FIG. 3A, by the wavelength of the light irradiated to the electrolyte.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

Further, the term "part" in the description means a unit for processing one or more functions or operations, which may be implemented by hardware, software, or a combination of hardware and software.

FIG. 1 is a view schematically showing a general structure of a redox flow battery, FIG. 2 is a view schematically showing a state where an apparatus for measuring remaining capacity of a flow battery according to an embodiment of the present invention is applied to a flow battery 3A is a graph showing measurement data obtained by measuring the absorbance of an electrolyte solution of a flow battery according to the wavelength of light irradiated by an electrolyte solution, and FIG. 3B is a graph showing the measurement data of the electrolytic solution of a divalent vanadium ion The absorption of the electrolyte according to the composition ratio of the electrolyte solution is shown by the wavelength of light irradiated to the electrolyte solution.

< Flow  Battery>

Referring to FIG. 1, a redox flow battery generally includes a separator 10 and an electrode assembly including a cathode 11 and a cathode 12 located on both sides of the separator 10, And a positive electrode electrolyte reservoir 22 for receiving and storing the positive electrode electrolyte supplied to the positive electrode 12.

The negative electrode electrolyte stored in the negative electrode electrolyte reservoir 21 flows into the negative electrode electrolyte inflow port 51 provided in the negative electrode 11 through the negative electrode inlet tube 41 through the pump 31 Causing a redox reaction within the cathode (21). The cathodic electrolytic solution having undergone the redox reaction flows out to the negative electrode electrolyte outlet 61 and flows into the negative electrode electrolyte reservoir 21 through the negative electrode outlet tube 71 and stored.

Similarly, the positive electrode electrolyte stored in the positive electrode electrolyte reservoir 22 flows into the positive electrode electrolyte inlet 52 provided in the positive electrode 22 through the positive electrode inlet electrolyte tube 42 through the pump 32, (22). &Lt; / RTI &gt; The positive electrode electrolyte solution having undergone the redox reaction flows out to the positive electrode electrolyte outlet 62, flows into the positive electrode electrolyte reservoir 22 through the positive electrode outlet tube 72, and is stored.

That is, when the redox flow battery is a vanadium redox flow battery, the tetravalent vanadium ions are oxidized in the anode 12 and converted into pentavalent vanadium ions during the charging reaction, the electrons are consumed, and the hydrogen ions are separated from the separation membrane 10 An oxidation reaction is caused to move from the anode 12 to the cathode 11 and the reduction reaction in which the trivalent vanadium ion accepts electrons and converts to the divalent vanadium ion occurs in the cathode 11. On the other hand, during the discharge reaction, the oxidation / reduction reaction (that is, the redox reaction) in which the oxidation number of the vanadium ion is changed as opposed to the above-described reaction occurs, thereby effectively performing charging and discharging.

Here, the separator 10 serves to transfer hydrogen ions and to block the movement of the negative electrode and the positive electrode of the positive electrode electrolyte to the counter electrode, and the negative electrode electrolyte reservoir 21 and the positive electrode electrolyte reservoir 22 As described above, the cathode and the anode electrolyte are respectively stored and designed to evenly distribute the internal pressures of the respective storage units or to discharge gas that may occur during operation.

< Flow  Battery remaining capacity measuring device>

2, an apparatus 100 for measuring the remaining capacity of a flow battery according to an embodiment of the present invention includes a bypass tube 110, a measuring unit 120, an estimating unit 130, and a calculating unit 140 . In addition, the bypass tube 110 may further include a first valve 111 and a second valve 112, and the measurement unit 120 may further include an absorption cell 121.

Here, the bypass tube 110 includes at least one of the anode inlet electrolyte tube 41, the cathode outlet electrolyte tube 71, the anode inlet electrolytic tube 42, and the anode outlet electrolytic tube 72 shown in FIG. 1 2, the bypass tube 110 according to an embodiment of the present invention is shown connected to the negative inlet-electrolyte tube 41, but it is not limited to the negative-inlet-electrolyte tube 41 It should be noted that the present invention can be applied to any of the electrolyte tubes 41, 42, 71, and 72 connecting the electrodes 11 and 12 of the redox flow battery and the electrolyte reservoirs 21 and 22.

The bypass tube 110 is connected in the form of a bridge in the middle of the negative electrode inlet electrolytic solution tube 41 so that a part of the negative electrode electrolytic solution flowing into the negative electrode inlet electrolytic solution tube 41 flows into the measurement unit 110, .

In one embodiment, both ends of the bypass tube 110 are connected to the cathode inlet electrolyte tube 41, and a measurement unit 110, which will be described later, is connected to the center of the bypass tube 110.

Since the bypass tube 110 must be stable without causing a chemical reaction with the negative electrode electrolyte, the bypass tube 110 must be made of a metal material coated with an acid-resistant material, polyvinyl chloride (PVC), polypropylene (PP) polyethylene (PE)).

The first and second valves 111 and 112 are located at one side and the other side of the bypass tube 110 and are respectively bypassed from the negative inlet tube 41 to reduce the flow rate of the negative electrode electrolyte flowing into the bypass tube 110 .

More specifically, the first valve 111 is located at a position where the negative electrode electrolyte flows into the bypass tube 110, and controls the flow rate of the negative electrode electrolyte flowing into the bypass tube 110 from the negative electrode inlet electrolyte tube 41 do. Similarly, the second valve 112 is located at a position where the negative electrode electrolyte flows out of the bypass tube 110 to regulate the flow rate of the negative electrode electrolyte discharged from the bypass tube 110 to the negative inlet cell 41 .

The first and second valves 111 and 112 are disposed in the bypass tube 110 and the measurement unit 120 to prevent the negative electrode electrolyte from flowing into the bypass tube 110 and the measurement unit 120 when measuring the absorbance of the negative electrode electrolyte through the measurement unit 120, Is closed. Conversely, in order to measure the absorbance of the cathode electrolyte continuously changing the ionic state of the electrode active material due to the charging / discharging process of the flow battery, the first and second valves 111 and 112 are opened, And moves to the measurement unit 120 via the tube 110. [

Since the first and second valves 111 and 112 must be stable without causing a chemical reaction with the negative electrode electrolyte, the first and second valves 111 and 112 may be formed of a metal material coated with an acid-resistant material, polyvinyl chloride (PVC), polypropylene PP), and polyethylene (PE).

The measuring unit 120 is located in the middle of the bypass tube 110 and irradiates light of a predetermined wavelength to the negative electrode electrolyte flowing into the bypass tube 110 to obtain the light transmittance for the negative electrode electrolyte, It plays a role of measuring.

The predetermined wavelength may be a wavelength corresponding to an ultraviolet ray (UV) ray and a visible ray (Vis), and may be 100 nm to 800 nm.

That is, when the flow battery is a vanadium redox flow battery, the measuring unit 120 irradiates ultraviolet rays or visible rays having a wavelength of 100 nm to 800 nm to a negative electrode electrolyte in which divalent vanadium ions and trivalent vanadium ions are mixed, After obtaining the transmittance of the irradiated ultraviolet ray or visible ray, the absorbance is measured. At this time, it can be seen that the absorbance of the negative electrode electrolyte varies depending on the composition of the electrode active material contained in the negative electrode electrolyte, that is, the bivalent vanadium ion and the trivalent vanadium ion.

FIG. 3A is a graph showing the relationship between the amount of divalent vanadium ions and the amount of trivalent vanadium ion mixed in a mixture of 1.5 M and a sulfuric acid aqueous solution (H ₂ SO ₄ ) 3M mixed with a negative electrode electrolyte solution is irradiated with ultraviolet rays or visible light having a wavelength of 100 nm to 800 nm And the absorbance of the negative electrode electrolyte is measured.

3A, when the absorbance of a negative electrode electrolyte is measured by irradiating light having a wavelength of 400 nm, 600 nm and 800 nm, the absorbance varies depending on the composition ratio of the divalent vanadium ion and the trivalent vanadium ion. .

In one embodiment, the measurement unit 120 may be an ultraviolet-visible light spectrophotometer that measures the absorbance of the sample using ultraviolet-visible light spectrophotometry.

2, the absorption cell 121 has a function of preventing the liquid electrolyte in the liquid state from flowing in the process of measuring the absorbance of the cathode electrolyte by the measuring unit 120, As shown in FIG.

When measuring the absorbance of the negative electrode electrolyte through the absorption cell 121, the absorbance of the negative electrode electrolyte can be accurately measured using only the negative electrode electrolyte solution having the correct capacity without being influenced by the flow rate of the negative electrode electrolyte solution.

In one embodiment, the material of the absorption cell 121 differs depending on the wavelength of the light irradiated to the negative electrode electrolyte. When the ultraviolet rays are irradiated with ultraviolet rays to measure the absorbance of the negative electrode electrolyte, the material of the absorption cell 121 is quartz Fused Silica). When absorbance is measured by irradiating visible light to a negative electrode electrolyte, the material of the absorption cell 121 may be glass.

The estimator 130 estimates the composition ratio of the divalent vanadium ions and the trivalent vanadium ions participating in the redox reaction in the negative electrode electrolyte corresponding to the absorbance of the negative electrode electrolyte measured through the measurement unit 120.

In order to perform the role of the estimating unit 130, the estimating unit 130 may include previously measured absorbance data.

Herein, the measured absorbance data was obtained by measuring the absorbance of the negative electrode electrolyte by varying the wavelength of light irradiated to the negative electrode electrolyte and the composition of the electrode active material, that is, bivalent vanadium ion and trivalent vanadium ion, as shown in the graphs of FIGS. 3A and 3B And may be stored in the estimation unit 130 or added, deleted, and modified by a user.

3A and 3B, when the measurement unit 120 irradiates the negative electrode with a light having a wavelength of 400 nm, the absorbance of the negative electrode electrolyte solution is 0.5. When the absorbance of the negative electrode electrolyte is 0.5, 3A, a curve passing through a point A having a wavelength of 400 nm and an absorbance of 0.5 is estimated as a composition ratio of a negative electrode electrolyte, or a curve having a wavelength of 400 nm in the absorbance data shown in FIG. The composition ratio of the divalent vanadium ions corresponding to the point (B) where the absorbance is 0.5 on the straight line is estimated as the composition ratio of the negative electrode electrolytic solution. As a result, the estimator 130 estimates the composition ratios of the divalent vanadium ions and the trivalent vanadium ions to 75% and 25%, respectively.

2, the calculating unit 140 may calculate an electrode active material, that is, a divalent vanadium ion or a divalent vanadium ion, which participates in the redox reaction, based on the composition ratio of the negative electrode electrolyte and the capacity of the negative electrode electrolyte estimated through the estimator 130 Calculates the content of trivalent vanadium ions, and calculates the remaining capacity of the flow battery proportional to or in inverse proportion to the capacity of the divalent vanadium ions or trivalent vanadium ions.

More specifically, the remaining capacity of the flow battery is inversely proportional to the content of the trivalent vanadium ions, which are the ions for obtaining the electrons, in proportion to the content of the vanadium ions, which are the ions losing electrons. Conversely, The remaining capacity of the flow battery is calculated from the content of vanadium ions or trivalent vanadium ions.

3A and 3B, the measuring unit 120 irradiates the negative electrode with light having a wavelength of 400 nm to measure the absorbance. When the absorbance of the negative electrode electrolyte is 0.5 As described above, the estimator 130 estimates the composition ratios of the divalent vanadium ions and the trivalent vanadium ions to 75% and 25%, respectively.

When the capacity of the cathode electrolyte is 500 L, the calculating unit 140 calculates the content of the divalent vanadium ions and the trivalent vanadium ions from the composition ratios of the vanadium ions of the valence of vanadium and the vanadium ions of the trivalent ions estimated through the estimator 130 375L and 125L, respectively, and based on this, the remaining capacity of the flow battery is calculated to be 75% of the fully discharged state.

2, the measuring unit 120, the estimating unit 130, and the calculating unit 140 according to an embodiment of the present invention use a negative electrode electrolyte flowing in the negative electrode inlet electrolyte tube 41 of the vanadium redox flow battery The absorbance is measured, the composition ratio of the negative electrode electrolyte is estimated, and the remaining capacity is calculated. However, it is noted that the present invention can be applied to any of the electrolyte tubes of redox flow batteries using metal ions other than vanadium ions.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

10: Membrane
11: cathode 12: anode
21: cathode electrolyte storage part 22: anode electrolyte storage part
31, 32: pump
41: anode inlet electrolyte tube 42: anode inlet electrolyte tube
51: cathode electrolyte inlet 52: anode electrolyte inlet
61: cathode electrolyte outlet 62: anode electrolyte outlet
71: cathode outlet electrolyte tube 72: anode outlet electrolyte tube
100: Device for measuring the remaining capacity of the flow battery
110: bypass tube
111: first valve 112: second valve
120:
121: Absorbing cell
130:
140:

Claims (9)

A measuring unit for measuring the absorbance of the flow battery by irradiating the electrolyte solution with light;
An estimating unit that estimates a composition ratio of the electrolytic solution corresponding to the measured absorbance of the electrolytic solution;
A calculating unit for calculating a remaining capacity of the flow battery based on the estimated composition ratio of the electrolytic solution; And
And a bypass tube connected to at least one of the anode inlet electrolytic tube, the cathode outlet electrolytic tube, the anode inlet electrolytic tube and the anode outlet electrolytic tube of the flow battery to bypass the electrolytic solution to the measuring unit As a result,
Flow capacity of the battery.
The method according to claim 1,
Wherein the measuring unit comprises:
And an absorption cell for receiving the electrolyte solution for measuring the absorbance.
Flow capacity of the battery.
delete The method according to claim 1,
Wherein the bypass tube comprises:
And a first valve for controlling a flow rate of the electrolytic solution flowing into the bypass tube.
Flow capacity of the battery.
The method according to claim 1,
Wherein the bypass tube comprises:
And a second valve for controlling a flow rate of the electrolytic solution flowing out from the bypass tube.
Flow capacity of the battery.
The method according to claim 4 or 5,
Wherein when the remaining capacity of the flow battery is measured, the first and second valves are closed.
Flow capacity of the battery.
The method according to claim 1,
Wherein the measuring unit comprises:
Characterized in that it is an ultraviolet-visible light spectrophotometer.
Flow capacity of the battery.
The method according to claim 1,
Wherein the flow battery is a vanadium redox flow battery.
Flow capacity of the battery.
The method according to claim 1,
The calculating unit calculates,
Wherein the remaining capacity of the flow battery is calculated on the basis of a composition ratio of vanadium divalent or trivalent ions contained in the electrolytic solution.
Flow capacity of the battery.

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