Device and method for detecting charge state of flow battery

Abstract

The invention relates to a flow battery charge state detection device and method, and is applied to the technical field of flow batteries. Compared with the prior art, the reference detection cavity connected with the bipolar plate is formed, the reference electrolyte can be replaced and supplemented without arranging a reference electrolyte storage tank, the adaptability of the detection device is improved, and the reference detection cavity corresponds to the positive electrolyte detection cavity and / or the negative electrolyte detection cavity, so that the detection efficiency is improved. A reference electrode is arranged in a reference detection cavity, the potential deviation of a reference electrolyte can be detected and calibrated in real time, and a calibration voltage value of the reference detection cavity is obtained, so that the potential of a positive electrode electrolyte relative to the reference electrode, the potential of a negative electrode electrolyte relative to the reference electrode and the calibration voltage value are used for calibrating the potential deviation of the reference electrolyte. The concentration of each valence ion is calculated on line through a multi-parameter empirical formula, and the charge state of the flow battery is obtained in real time through the concentration of each valence ion, so that the detection error is reduced, the detection sensitivity is improved, and the real-time monitoring precision of the charge state is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid flow battery, in particular to a liquid flow battery state of charge detection device and method. BACKGROUND

[0002] As a new generation of large-scale energy storage technology, liquid flow battery has been widely used in large-scale energy storage scenarios such as grid peak shaving and renewable energy grid connection. Liquid flow battery realizes energy storage and release through the oxidation and reduction reaction of active ions in electrolyte, and the state of charge (SOC) is an important parameter for measuring the remaining capacity of the battery and judging the running state of the system. Accurate and real-time acquisition of the SOC of the liquid flow battery is of great significance to ensure system safety, optimize operation strategy and prolong equipment life.

[0003] At present, the detection of the SOC of the liquid flow battery mainly adopts the voltage method, that is, by detecting the voltage between the two poles of the battery, and combining a specific electrochemical model to calculate the SOC of the battery. However, due to the flat voltage platform between the two poles of the battery in the actual working process, the concentration and valence state changes of the positive and negative electrolytes have limited effect on the voltage, resulting in poor sensitivity of the voltage method in the medium and high SOC interval, and it is difficult to realize high-precision real-time monitoring of the SOC. SUMMARY

[0004] The purpose of the present application is to overcome the defects of the prior art and provide a liquid flow battery state of charge detection device and method.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] The present application provides a liquid flow battery state of charge detection device, comprising a bipolar plate, an ion membrane, a reference detection cavity and an electrolyte detection cavity, the electrolyte detection cavity comprising a positive electrolyte detection cavity and / or a negative electrolyte detection cavity corresponding to the reference detection cavity, the reference detection cavity being connected to the bipolar plate, the reference detection cavity being filled with reference electrolyte, the reference electrolyte being separated from the positive electrolyte and / or the negative electrolyte by the ion membrane;

[0007] The reference detection cavity is provided with a reference electrode for real-time detection and calibration of the potential deviation of the reference electrolyte to obtain a calibrated voltage value, so that the detection device obtains the state of charge of the liquid flow battery by online calculation of the concentration of each valence state ion through the potential of the positive electrolyte relative to the reference electrode, the potential of the negative electrolyte relative to the reference electrode and the calibrated voltage value.

[0008] Compared with the prior art, the present invention forms a reference detection cavity connected to the bipolar plate, and the reference electrolyte can be replaced and replenished without setting up a reference electrolyte storage tank, thereby improving the adaptability of the detection device. The reference detection cavity corresponds to the positive electrode electrolyte detection cavity and / or the negative electrode electrolyte detection cavity. A reference electrode is set in the reference detection cavity, which can perform real-time detection and calibration of the potential offset of the reference electrolyte, and obtain the calibration voltage value of the reference detection cavity. The concentration of each valence ion is calculated online through the potential of the positive electrode electrolyte relative to the reference electrode, the potential of the negative electrode electrolyte relative to the reference electrode, and the calibration voltage value through a multi-parameter empirical formula. The charge state of the liquid flow battery is obtained in real time through the concentration of each valence ion. The invention has strong anti-interference ability, improves stability and reliability, has strong engineering adaptability, is suitable for large-scale deployment, reduces detection error, improves detection sensitivity, and improves the real-time monitoring accuracy of the charge state.

[0009] Preferably, the relationship between the potential and concentration of the positive electrode electrolyte is:

[0010]

[0011] in, It represents the potential of the positive electrolyte relative to the reference electrode; Indicates the first calibration voltage value of the reference detection chamber; It represents the concentration coefficient of tetravalent vanadium ion in the multi-parameter empirical formula of the positive electrode; It represents the concentration coefficient of pentavalent vanadium ion in the multi-parameter empirical formula of the positive electrode; Represents the constant value of the positive electrode multi-parameter empirical formula; [ ] indicates the concentration of tetravalent vanadium ions; [ ] represents the concentration of pentavalent vanadium ions;

[0012] The relationship between the potential and concentration of the negative electrode electrolyte is:

[0013]

[0014] in, Indicates the potential of the negative electrolyte relative to the reference electrode; Represents the second calibration voltage value of the reference detection chamber; It represents the divalent vanadium ion concentration coefficient of the multi-parameter empirical formula of the negative electrode; It represents the trivalent vanadium ion concentration coefficient of the negative electrode multi-parameter empirical formula; Indicates the constant value of the multi-parameter empirical formula of the negative electrode; [ ] represents the concentration of divalent vanadium ions, [ ] represents the concentration of trivalent vanadium ions;

[0015] According to the relationship between electrolyte potential and concentration, the positive electrode of the multi-parameter empirical formula is obtained by fitting and calculation. The value and negative pole The value of

[0016] The concentration of vanadium ions in various valence states is obtained according to a multi-parameter empirical formula.

[0017] Compared with the prior art, the present invention obtains the positive electrode electrolyte detection chamber and the negative electrode electrolyte detection chamber by fitting and calculating the relationship between the electrolyte potential and concentration under the condition that the reference detection chamber corresponds to the positive electrode electrolyte detection chamber and the negative electrode electrolyte detection chamber respectively. The value and negative pole The concentration of vanadium ions in various valence states can be accurately obtained based on the multi-parameter empirical formula.

[0018] Preferably, the relationship between the positive electrode liquid potential and the negative electrode liquid potential is:

[0019]

[0020] in, Indicates the measured voltage difference between the positive electrode electrolyte and the negative electrode electrolyte, when the reference detection chamber corresponds to the positive electrode electrolyte detection chamber or the negative electrode electrolyte detection chamber, equal , measured and One of the minus and Get one of and Another one in.

[0021] Preferably, the positive electrode charge state With positive electrode[ Related:

[0022]

[0023] Negative electrode state of charge With negative electrode[ Related:

[0024]

[0025] in, is the first constant term related to temperature and charge-discharge strategy; is the second constant term related to temperature and charge-discharge strategy;

[0026] State of charge of flow batteries for:

[0027]

[0028] Preferably, the detection device obtains the state of health SOH of the flow battery through the calculated concentration of each valence state of vanadium ions.

[0029]

[0030] Wherein, alpha is the temperature correction coefficient; T is the current measurement temperature; is the reference temperature;{[{V}^{5+}]}_{T} is the concentration of pentavalent vanadium at temperature T under full charging condition;{[{V}^{2+}]}_{T} is the concentration of divalent vanadium at temperature T under full charging condition;{[{V}^{5+}]}_{0} is the concentration of pentavalent vanadium ions at the reference temperature under full charging condition;{[{V}^{2+}]}_{0} is the concentration of divalent vanadium ions at the reference temperature.

[0031] Preferably, the reference detection cavity includes a positive electrode reference chamber corresponding to the side of the positive electrode electrolyte and / or a negative electrode reference chamber corresponding to the side of the negative electrode electrolyte.

[0032] Preferably, the positive electrode reference chamber and the negative electrode reference chamber are in communication and use the same reference electrode; or, the positive electrode reference chamber and the negative electrode reference chamber are disconnected and each has a reference electrode.

[0033] Compared with the prior art, the two reference liquid cavities are independent of each other, have two plug-in reference electrodes, and have two reference electrolytes, so that different reference electrolyte systems can be selected according to the different characteristics of the positive and negative electrodes, more accurate positive and negative electrode potential detection can be performed, the two reference liquid cavities are in communication with each other, the positive and negative electrolyte cavities can be integrally formed and manufactured, and the positive and negative electrode references are consistent, so that the engineering application is simpler and more efficient.

[0034] Preferably, flow-through holes are formed on the bipolar plate connected to the reference detection cavity.

[0035] Compared with the prior art, the flow-through holes are formed on the bipolar plate connected to the reference detection cavity, allowing the reference liquid to pass through the through holes and enter the electrode.

[0036] Preferably, the reference electrolyte includes one or more valence state combinations of sulfuric acid and sulfate mixed solutions, hydrochloric acid and hydrochloride mixed solutions, and phosphoric acid and phosphate mixed solutions of +2, +3, +4, and +5 valence vanadium ions; and / or, the reference electrode includes one or more of silver and silver chloride electrodes, saturated mercury electrodes, silver and silver sulfate electrodes, and platinum hydrogen electrodes.

[0037] The application also provides a flow battery state of charge detection method, comprising: establishing a reference detection cavity and an electrolyte detection cavity, the reference detection cavity corresponding to the positive electrolyte detection cavity and / or the negative electrolyte detection cavity, the reference detection cavity being connected to a bipolar plate, the reference detection cavity being filled with a reference electrolyte, the reference electrolyte being separated from the positive electrolyte and / or the negative electrolyte by an ion membrane;

[0038] A reference electrode is arranged in the reference detection cavity, the potential deviation of the reference electrolyte is detected and calibrated in real time, a calibrated voltage value is obtained, the concentration of each valence state ion is calculated on line through a multi-parameter empirical formula based on the potential of the positive electrolyte relative to the reference electrode, the potential of the negative electrolyte relative to the reference electrode and the calibrated voltage value, and the state of charge of the flow battery is obtained in real time based on the concentration of each valence state ion. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Structure schematic diagram of the flow battery SOC detection device with single-side reference;

[0040] Figure 2 First schematic diagram of the flow battery SOC detection device structure with double-side reference;

[0041] Figure 3 Structure schematic diagram of the flow battery SOC detection device with reference pool interconnection;

[0042] Figure 4 Structure schematic diagram of the flow battery SOC detection device with reference pool interconnection;

[0043] Figure 5 First bipolar plate structure schematic diagram;

[0044] Figure 6 First bipolar plate structure variant schematic diagram;

[0045] Figure 7 Schematic diagram of the display bipolar plate tab;

[0046] Figure 8 Second schematic diagram of the flow battery SOC detection device structure with double-side reference.

[0047] The reference numerals are as follows: 1, reference electrode; 2, first reference electrolyte; 3, first liquid inlet; 4, first liquid outlet; 5, second reference electrolyte; 6, second liquid inlet; 7, second liquid outlet; 8, positive electrolyte inlet; 9, positive electrolyte outlet; 10, negative electrolyte inlet; 11, negative electrolyte outlet; 12, bipolar plate; 13, ion membrane; 14, battery electrode frame plate; 15, tab. DETAILED DESCRIPTION

[0048] The application will be described in detail below in combination with the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0049] Through in-depth research and improvement exploration of the flow battery, the applicant found that the voltage method used for detecting the SOC of the flow battery cannot distinguish the specific state of the positive and negative electrolytes, is easily interfered by factors such as polarization and electrolyte imbalance, and leads to a large SOC estimation error.

[0050] Some methods for detecting the SOC of the flow battery attempt to indirectly calculate the SOC of the electrolyte through density, spectrum and other physical and chemical parameter analysis means. These methods usually need to sample and analyze the electrolyte, the detection process is complex, online and real-time monitoring cannot be achieved, and the cost is high in actual engineering application and the operation and maintenance difficulty is great.

[0051] In the existing SOC detection method of the flow battery, the open-circuit voltage method has low sensitivity, the detection data deviates, and the specific state of the positive and negative electrolytes cannot be reflected; using other non-real-time monitoring means has poor real-time performance, a complex detection process or high cost, and cannot meet the actual needs of large-scale energy storage systems for accurate and online SOC monitoring.

[0052] Therefore, it is urgent to develop a new type of SOC detection device and method that can accurately reflect the state of the positive and negative electrolytes of the flow battery in real time and has good engineering applicability, so as to improve the intelligent and fine management level of the flow battery system.

[0053] Based on this, the technical solutions provided by the embodiments of the application will be described below in combination with the drawings.

[0054] The embodiments of the present specification propose a flow battery state of charge (SOC) detection device, which is suitable for a full vanadium flow battery energy storage system and can be used for real-time monitoring of the SOC of the full vanadium flow battery, as shown in Figure 1 and Figure 8 The device includes a plurality of bipolar plates 12, a plurality of ion membranes 13, a reference detection cavity and an electrolyte detection cavity. The electrolyte detection cavity includes a positive electrolyte detection cavity and / or a negative electrolyte detection cavity corresponding to the reference detection cavity. The reference detection cavity is connected to the bipolar plate 12, the reference detection cavity is filled with reference electrolyte, and the reference electrolyte is separated from the positive electrolyte and / or negative electrolyte corresponding to the electrode liquid detection cavity by the ion membrane 13.

[0055] The reference detection cavity is provided with a reference electrode 1 for detecting and calibrating the potential deviation of the reference electrolyte in real time, obtaining a calibration voltage value, so that the detection device obtains the state of charge of the flow battery through the potential of the positive electrolyte relative to the reference electrode 1, the potential of the negative electrolyte relative to the reference electrode 1 and the calibration voltage value, and calculates the concentration of each valence state ion through a multi-parameter empirical formula.

[0056] The SOC detection device collects the potential parameters of the positive / negative electrolyte relative to the reference solution, the potential difference between the positive and negative electrolyte, and the voltage difference between the reference electrolyte and the reference electrode 1. At the same time, the total volume of the positive electrolyte and the total volume of the negative electrolyte are collected.

[0057] The detection device can be composed of an end plate, a first bipolar plate, a battery electrode frame plate 14, a positive electrolyte detection cavity, a negative electrolyte detection cavity, an ion exchange membrane, an insulating plate, a reference electrode 1, a reference detection cavity and a second bipolar plate. Figure 5 、 Figure 6 and Figure 7 As shown in the drawings, the bipolar plate 12 connected with the reference cavity is provided with a flow-through hole, and the bipolar plate in the same electrolyte is also provided with a flow-through hole, for example, the shape of the flow-through hole is circular or rectangular, and the bipolar plate 12 is provided with a tab 15.

[0058] As shown in the drawings, Figure 1 and Figure 2 Three completely filled vertical lines, from left to right, the bipolar plate 12 is respectively the first bipolar plate, the second bipolar plate and the third bipolar plate; the diagonal filled vertical line, from left to right, the ion membrane 13 is respectively the first ion membrane and the second ion membrane.

[0059] As shown in the drawings, Figure 1 The first bipolar plate is provided with a through hole, allowing the reference liquid on one side to pass through the through hole and enter the electrode, for example, a carbon felt or carbon cloth, carbon paper electrode; the second bipolar plate is provided with a through hole, allowing the electrolyte of the positive electrode on both sides of the second bipolar plate to exchange with each other; the third bipolar plate is not provided with an electrode through hole, but only a flow channel, allowing the negative electrolyte to enter the negative electrode through the flow channel, for example, a carbon felt or carbon cloth, carbon paper electrode.

[0060] As shown in the drawings, Figure 2As shown, the two reference liquid chambers are independent of each other, have two plug-in reference electrodes, and two reference electrolytes, which can be selected according to the different characteristics of the positive and negative electrodes, for example, the positive reference electrolyte is V4+, and the negative reference electrolyte is V3+, which can reduce the migration rate of the positive and negative electrolytes and improve the detection accuracy, and can make more precise positive and negative potential detection. The reference electrolyte flows into the carbon felt electrode (not shown in the figure) between the first bipolar plate and the first ion exchange membrane through the through hole on the first bipolar plate, and is located on the left side of the first ion exchange membrane. The positive electrolyte is separated from the reference electrolyte by the first ion exchange membrane. The positive electrolyte flows into the left side of the second bipolar plate through the through hole on the electrode frame, and the negative electrolyte flows into the right side of the second bipolar plate through the through hole on the electrode frame, and the positive and negative electrolytes are separated by the second bipolar plate. The reference electrolyte flows into the carbon felt electrode (not shown in the figure) between the third bipolar plate and the second ion exchange membrane through the through hole on the third bipolar plate, and is located on the right side of the second ion exchange membrane. The negative electrolyte is separated from the reference electrolyte by the second ion exchange membrane.

[0061] As shown in Figure 3 , the two reference liquid chambers are interconnected, the positive and negative electrolyte chambers can be integrally formed and manufactured, and the positive and negative reference electrodes are consistent, which is more simple and efficient in engineering application.

[0062] The ion exchange membrane is separated from the main circulating electrolyte, and each chamber is provided with a conductive element. The positive electrolyte detection chamber, the negative electrolyte detection chamber and the reference detection chamber are separated by the insulating plate and the ion exchange membrane, and the reference detection chamber is filled with reference solution. The reference electrode 1 is inserted into the reference electrolyte chamber, which is used to implement detection and calibrate the potential deviation of the reference electrolyte. For example, the initial valence state of vanadium ions in the reference electrolyte is .

[0063] The existing reference chamber is separated by an ion membrane, has a small capacity, and the electrolyte in the reference chamber quickly deviates in valence state after long-term use, resulting in inaccurate detection results. Therefore, an external reference chamber is used to complete the reference liquid update with a circulating pump, which greatly increases the structural complexity and introduces risk items in engineering. The external circulation of the reference liquid will cause erosion to the reference chamber electrode and the ion membranes on both sides, reducing the service life of the device. The present application avoids the drawbacks of the need for additional circulating pumps and reference tanks in the prior art by offsetting the chamber and expanding the capacity, which has higher reliability in engineering implementation.

[0064] The present invention combines empirical formulas with a multi-parameter set of equations. Using the potential difference between the positive and negative electrolytes and the reference electrode 1, combined with a multi-parameter empirical concentration formula based on the Nernst equation or experimental fit, the simultaneous equations (or database) can accurately and real-timely estimate the concentration of vanadium ions in various valence states, enabling online quantitative monitoring of all-vanadium redox flow battery electrolyte components. By real-time acquisition of the potential difference and volume parameters between the positive and negative electrolytes and the reference chamber, combined with the Nernst equation or experimental fit of the multi-parameter empirical formula, accurate online estimation of the concentration of vanadium ions in various valence states can be achieved, thereby enabling real-time, high-precision monitoring of the SOC of the flow battery system.

[0065] In one embodiment, the positive and negative electrode ion concentrations and ion offsets are calculated as follows:

[0066] The relationship between the positive electrode electrolyte potential and concentration is:

[0067]

[0068] in, It represents the potential of the positive electrolyte relative to the reference electrode 1, which can be measured or calculated from the measured voltage difference between the positive and negative electrolytes; Indicates the first calibration voltage value of the reference detection chamber, that is, the calibration voltage value of the positive reference chamber; Indicates the calculation constant value of the tetravalent and pentavalent concentration of the positive electrode, It represents the concentration coefficient of tetravalent vanadium ion in the multi-parameter empirical formula of the positive electrode; It represents the concentration coefficient of pentavalent vanadium ion in the multi-parameter empirical formula of the positive electrode; Represents the constant value of the positive electrode multi-parameter empirical formula; [ ] represents the concentration of tetravalent vanadium ions; [ ] represents the concentration of pentavalent vanadium ions.

[0069] Similarly, the relationship between the potential and concentration of the negative electrode electrolyte is:

[0070]

[0071] in, It represents the potential of the negative electrolyte relative to the reference electrode 1, which can be measured or calculated from the measured voltage difference between the positive and negative electrolytes; Indicates the second calibration voltage value of the reference detection chamber, that is, the calibration voltage value of the negative reference chamber; They represent the calculation constants of the divalent and trivalent concentrations of the negative electrode, It represents the divalent vanadium ion concentration coefficient of the multi-parameter empirical formula of the negative electrode; It represents the trivalent vanadium ion concentration coefficient of the negative electrode multi-parameter empirical formula; Indicates the constant value of the multi-parameter empirical formula of the negative electrode; [ represents the concentration of divalent vanadium ions, represents the concentration of trivalent vanadium ions.

[0072] According to the relationship between the electrolyte potential and the concentration, the values of the positive electrode and the values of the negative electrode are obtained by fitting calculation. The concentrations of vanadium ions of various valence states are obtained according to the multi-parameter empirical formula.

[0073] That is, according to the above voltage and ion concentration relationship, the values of the positive electrode and the values of the negative electrode are obtained by fitting calculation. The concentration of is obtained by titration, as shown in Figure 2 and Figure 8 , in the case of the reference detection cavity corresponding to the positive electrolyte detection cavity and the negative electrolyte detection cavity respectively, the value of is measured and the value of is measured.

[0074] In an embodiment, the relationship between the positive electrode potential and the negative electrode potential is:

[0075]

[0076] wherein, represents the measured voltage difference between the positive electrolyte and the negative electrolyte, as shown in Figure 1 , when the reference detection cavity corresponds to the positive electrolyte detection cavity or the negative electrolyte detection cavity, is equal to , one of and is measured, and the other of and is obtained by subtracting one of and from .

[0077] In an embodiment, the system SOC is calculated as:

[0078] The positive state of charge is related to the positive , and has:

[0079]

[0080] The negative state of charge is related to the negative , and has:

[0081]

[0082] and are constant terms related to temperature and charge-discharge strategy, respectively. is a first constant term related to temperature and charge-discharge strategy; is a second constant term related to temperature and charge-discharge strategy. and are empirical parameters.

[0083] System SOC, i.e. the state of charge of the flow battery is:

[0084]

[0085] In an embodiment, the detection device obtains the battery health state SOH of the flow battery by calculating the concentration of each valence state vanadium ion.

[0086]

[0087] wherein a is a temperature correction coefficient; T is the current measured temperature; is a reference temperature, commonly taken as 25℃;{[{V}^{5+}]}_{T} is the concentration value of pentavalent vanadium at temperature T under full charging condition;{[{V}^{2+}]}_{T} is the concentration value of divalent vanadium at temperature T under full charging condition,{[{V}^{5+}]}_{0} is the concentration value of pentavalent vanadium at the reference temperature under full charging condition,{[{V}^{2+}]}_{0} is the concentration value of divalent vanadium at the reference temperature under full charging condition.

[0088] In an embodiment, as shown in Figure 1 and Figure 2 The reference detection cavity comprises a positive electrode reference chamber corresponding to the side of the positive electrode electrolyte and / or a negative electrode reference chamber corresponding to the side of the negative electrode electrolyte.

[0089] In an embodiment, as shown in Figure 3 and Figure 4 The positive electrode reference chamber and the negative electrode reference chamber are in communication and use the same reference electrode 1; or, as shown in Figure 2 and Figure 8 The positive electrode reference chamber and the negative electrode reference chamber are disconnected and each has a reference electrode 1.

[0090] In an embodiment, the reference detection cavity is provided with a flow port to facilitate the replenishment and update of the reference electrolyte.

[0091] The positive electrode reference cavity contains a first reference electrolyte 2, and the upper and lower sides of the positive electrode reference cavity are formed with a first liquid injection port 3 and a first liquid discharge port 4. The negative electrode reference cavity contains a second reference electrolyte 5, and the upper and lower sides of the negative electrode reference cavity are formed with a second liquid injection port 6 and a second liquid discharge port 7. The positive electrode electrolyte part is formed with a positive electrode electrolyte inlet 8 and a positive electrode electrolyte outlet 9, and the negative electrode electrolyte part is formed with a negative electrode electrolyte inlet 10 and a negative electrode electrolyte outlet 11.

[0092] The structure of the detection device of the present application realizes independent replacement of the positive electrode, the negative electrode and the reference cavity. The cavity is isolated from the main cycle through a diaphragm / membrane. The internal conductive element adopts inert carbon material, which improves the electrochemical stability and durability. The reference cavity is provided with a flow port, which facilitates the replenishment and updating of the reference liquid, and further ensures the long-term stability of the reference potential.

[0093] In an embodiment, the reference electrolyte includes one or more valence state combinations of sulfuric acid and sulfate mixed solutions, hydrochloric acid and chloride mixed solutions, and phosphoric acid and phosphate mixed solutions in the electrolyte of +2, +3, +4, and +5 valence vanadium ions; and / or, the reference electrode 1 includes one or more of silver and silver chloride electrodes, saturated mercury-mercury electrodes, silver and silver sulfate electrodes, and platinum hydrogen electrodes.

[0094] In an embodiment, the reference detection cavity is connected and fixed to the bipolar plate on the outside. The cavity structure of the reference detection cavity includes a bias cavity and a bias electrode cavity in communication. The bias cavity is arranged on the outside of the bipolar plate connected and fixed to the reference detection cavity. The bias electrode cavity is an electrode cavity between the bipolar plate connected and fixed to the reference detection cavity and the ion membrane separating the reference electrolyte. The capacity of the reference detection cavity is increased by the communication of the bias cavity and the bias electrode cavity, and the valence state shift speed of the reference electrolyte is reduced. The reference electrode is located in the bias cavity.

[0095] The reference detection cavity of the present application is connected and fixed to the bipolar plate on the outside. The cavity structure of the reference detection cavity includes a bias cavity and a bias electrode cavity in communication. The bias cavity is arranged on the outside of the bipolar plate connected and fixed to the reference detection cavity. The bias electrode cavity is an electrode cavity between the bipolar plate connected and fixed to the reference detection cavity and the ion membrane separating the reference electrolyte. The capacity of the reference detection cavity is increased by the communication of the bias cavity and the bias electrode cavity, and the valence state shift speed of the reference electrolyte is reduced. The capacity of the reference detection cavity is increased by the communication of the bias cavity and the bias electrode cavity, and the valence state shift speed of the reference electrolyte is reduced. The SOC detection accuracy of the flow battery is improved, and there is no need to set a reference liquid storage tank to cooperate with a valve and a pipeline, realizing the miniaturization of the detection device, being suitable for large-scale deployment, improving the service life of the device, and being convenient for replacing and supplementing the reference electrolyte, also avoiding the flushing of the reference cavity electrode and the ion membrane. At the same time, since the bias cavity is arranged, the reference electrode can be arranged in the bias cavity, the potential shift of the reference electrolyte is realized, the actual potential value of the positive and negative electrode liquid phase compared with the reference electrolyte is obtained, the accuracy of the state of charge detection of the flow battery is further improved, and the stability and reliability and the anti-interference ability are improved.

[0096] Generally, the capacity of the electrode internal cavity is several milliliters, while the capacity of the cavity of the reference detection chamber (including the bias cavity and the bias electrode cavity) of the application can reach 500ml-2.5L, which can be increased by more than 100 times. The first bipolar plate and / or the second bipolar plate are the outer bipolar plates connected to the reference detection chamber.

[0097] The device comprises a positive electrolyte detection chamber, a negative electrolyte detection chamber and a reference detection chamber, which are isolated from the main circulating electrolyte by an ion exchange membrane, and each chamber is provided with a conductive element. The reference detection chamber is filled with vanadium electrolyte with consistent composition and acidity with the main system and constant potential, and combined with a standard reference electrode, the long-term stability and real-time calibration of the reference system are realized. By real-time acquisition of the potential difference and volume parameters between the positive and negative electrolyte and the reference chamber, combined with the Nernst equation or the experimental fitting of the multi-parameter empirical formula, the concentration of each valence state vanadium ion can be accurately calculated online, and then the real-time and high-precision monitoring of the SOC of the flow battery system is realized. The method has simple structure, convenient maintenance and strong anti-interference ability, and is suitable for intelligent management and safe operation of large-scale energy storage systems.

[0098] The application innovatively selects a reference solution, fills the reference detection chamber with vanadium electrolyte with consistent composition and acidity with the main system and constant potential, and combines a standard reference electrode to realize long-term stability and real-time calibration of the reference system. The vanadium electrolyte with consistent composition and acidity with the main reaction system and constant potential is used as the reference solution, and the standard reference electrode is used to calibrate the reference electrolyte in real time, which realizes long-term online and chemically compatible reference system, and provides a reliable potential reference for electrolyte state monitoring.

[0099] The accuracy and stability of the reference system of the application are significantly improved, and the anti-interference ability is strong. In the existing SOC detection system of the flow battery, the vanadium electrolyte is used as the reference solution alone, and with the charging and discharging of the battery, the electrolyte is easily contaminated by transmembrane penetration, which leads to the decrease of accuracy and reliability. The commercial reference electrode is combined with the vanadium electrolyte reference solution in the present application, which can calibrate the offset in real time and improve the SOC detection accuracy.

[0100] The application has strong real-time, online and automatic monitoring capability, only needs to real-time acquire the potential difference and volume parameters of the positive and negative electrodes and the reference chamber, and through the multi-parameter calculation formula or database, the concentration of each valence state vanadium ion can be automatically calculated, the online, real-time and automatic monitoring of the key indicators such as battery SOC / SOH is realized, and the intelligent demand of large-scale energy storage system is met.

[0101] The application has the advantages of simple structure, small maintenance amount, strong engineering adaptability, integrated and modularized design of the detection device, flexible liquid supplement of the reference cavity, long-term stable operation of internal elements, greatly reduced operation and maintenance difficulty and cost, suitability for large-scale engineering deployment, no need for circulating the reference electrolyte by pumps during operation, and strong engineering adaptability.

[0102] The application provides a liquid flow battery SOC detection device and method, which can overcome the low sensitivity, poor real-time performance, inability to distinguish the specific state of electrolyte anode and cathode, complex detection process or high cost of the prior art, realize real-time and accurate monitoring of the state of the liquid flow battery anode and cathode electrolyte, assist in evaluating the valence state migration ratio of the system electrolyte, and meet the actual needs of large-scale energy storage systems for online and accurate SOC detection.

[0103] The application further discloses a liquid flow battery state of charge detection method, which comprises the following steps: establishing a reference detection cavity and an electrolyte detection cavity, the reference detection cavity corresponding to the anode electrolyte detection cavity and / or the cathode electrolyte detection cavity, the reference detection cavity being connected with a bipolar plate 12, and the reference detection cavity being filled with reference electrolyte, the reference electrolyte being separated from the anode electrolyte and / or the cathode electrolyte by an ion membrane 13.

[0104] A reference electrode 1 is arranged in the reference detection cavity, the potential deviation of the reference electrolyte is detected and calibrated in real time, a calibrated voltage value is obtained, the concentration of each valence state ion is calculated online through a multi-parameter empirical formula based on the potential of the anode electrolyte relative to the reference electrode 1, the potential of the cathode electrolyte relative to the reference electrode 1 and the calibrated voltage value, and the state of charge of the liquid flow battery is obtained in real time based on the concentration of each valence state ion.

[0105] The above describes the preferred embodiments of the application in detail. It should be understood that those skilled in the art can make many modifications and changes without creative efforts based on the concept of the application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiments based on the prior art according to the concept of the application should be within the protection scope defined by the claims.

Claims

1. A flow battery state of charge detection device, characterized in that: It includes a bipolar plate, an ion membrane, a reference detection chamber and an electrolyte detection chamber. The electrolyte detection chamber includes a positive electrode electrolyte detection chamber and / or a negative electrode electrolyte detection chamber corresponding to the reference detection chamber. The reference detection chamber is connected to the bipolar plate and is filled with a reference electrolyte. The reference electrolyte is separated from the positive electrode electrolyte and / or the negative electrode liquid by the ion membrane. The reference detection chamber is provided with a reference electrode for real-time detection and calibration of the potential offset of the reference electrolyte to obtain a calibration voltage value, so that the detection device can calculate the concentration of each valence ion online through a multi-parameter empirical formula based on the potential of the positive electrode electrolyte relative to the reference electrode, the potential of the negative electrode electrolyte relative to the reference electrode, and the calibration voltage value, and obtain the state of charge of the flow battery in real time through the concentration of each valence ion; In which, the reference detection cavity is connected to the bipolar plate fixed on the outside, and the cavity structure of the reference detection cavity includes a connected bias cavity and a bias electrode cavity; the bias cavity is arranged on the outside of the bipolar plate connected to and fixed to the reference detection cavity, and the bias electrode cavity is an electrode cavity between the bipolar plate connected to and fixed to the reference detection cavity and the ion membrane separating the reference electrolyte, so as to increase the capacity of the reference detection cavity and reduce the valence state offset speed of the reference electrolyte by connecting the bias cavity and the bias electrode cavity; the reference electrode is located in the bias cavity.

2. The liquid flow battery state of charge detection device according to claim 1, characterized in that: The relationship between the positive electrode electrolyte potential and concentration is: ;in, It represents the potential of the positive electrolyte relative to the reference electrode; Indicates the first calibration voltage value of the reference detection chamber; It represents the concentration coefficient of tetravalent vanadium ion in the multi-parameter empirical formula of the positive electrode; It represents the concentration coefficient of pentavalent vanadium ion in the multi-parameter empirical formula of the positive electrode; represents the constant value of the positive electrode multi-parameter empirical formula; [ ] represents the concentration of tetravalent vanadium ions; [ ] represents the concentration of pentavalent vanadium ions; The relationship between the potential and concentration of the negative electrode electrolyte is: ;in, Indicates the potential of the negative electrolyte relative to the reference electrode; Represents the second calibration voltage value of the reference detection chamber; It represents the divalent vanadium ion concentration coefficient of the multi-parameter empirical formula of the negative electrode; It represents the trivalent vanadium ion concentration coefficient of the negative electrode multi-parameter empirical formula; Indicates the constant value of the negative electrode multi-parameter empirical formula; [ ] represents the concentration of divalent vanadium ions, [ ] represents the concentration of trivalent vanadium ions; According to the relationship between electrolyte potential and concentration, the positive electrode of the multi-parameter empirical formula is obtained by fitting and calculation. The value and negative pole The value of The concentration of vanadium ions in various valence states is obtained according to a multi-parameter empirical formula.

3. The liquid flow battery state of charge detection device according to claim 2, characterized in that: The relationship between the positive electrode liquid potential and the negative electrode liquid potential is: ;in, Indicates the measured voltage difference between the positive electrode electrolyte and the negative electrode electrolyte, when the reference detection chamber corresponds to the positive electrode electrolyte detection chamber or the negative electrode electrolyte detection chamber, equal , measured and One of the minus and Get one of and Another one in.

4. The liquid flow battery state of charge detection device according to claim 2, characterized in that: Positive electrode state of charge With positive electrode[ ]Related, ; Negative electrode state of charge With negative electrode[ ]Related, ;in, is the first constant term related to temperature and charge-discharge strategy; is the second constant term related to temperature and charge-discharge strategy; State of charge of flow batteries for: .

5. The device for detecting the state of charge of a flow battery according to claim 2, wherein: The detection device obtains the battery health status SOH of the flow battery by calculating the concentration of vanadium ions in each valence state; ; Where α is the temperature correction coefficient; T is the current measured temperature; is the reference temperature; {[{V}^{5+}]}_{T} is the pentavalent vanadium concentration value at temperature T under full charge condition; {[{V}^{2+}]}_{T} is the divalent vanadium concentration value at temperature T under full charge condition; {[{V}^{5+}]}_{0} is the concentration of pentavalent vanadium ions at the reference temperature under full charge conditions; {[{V}^{2+}]}_{0} is the concentration of divalent vanadium ions at the reference temperature under full charge conditions.

6. The liquid flow battery state of charge detection device according to any one of claims 1 to 5, characterized in that: The reference detection cavity includes a positive electrode reference chamber corresponding to the positive electrode liquid side and / or a negative electrode reference chamber corresponding to the negative electrode electrolyte side.

7. The liquid flow battery state of charge detection device according to claim 6, characterized in that: The positive reference chamber and the negative reference chamber are connected and use the same reference electrode; or, the positive reference chamber and the negative reference chamber are disconnected and both have reference electrodes.

8. The liquid flow battery state of charge detection device according to any one of claims 1 to 5, characterized in that: A flow hole is formed on the bipolar plate connected to the reference detection cavity.

9. The liquid flow battery state of charge detection device according to any one of claims 1 to 5, characterized in that: The reference electrolyte includes a mixed solution of sulfuric acid and sulfate, a mixed solution of hydrochloric acid and hydrochloride, or a mixed solution of phosphoric acid and phosphate, of one or more valence combinations of electrolytes of +2, +3, +4, and +5 vanadium ions; and / or the reference electrode includes one or more of a silver and silver chloride electrode, a saturated calomel electrode, a silver and silver sulfate electrode, and a platinum hydrogen electrode.

10. A method for detecting the state of charge of a flow battery, characterized in that: The liquid flow battery state of charge detection device according to any one of claims 1 to 9 comprises: establishing a reference detection chamber and an electrolyte detection chamber, the reference detection chamber corresponding to the positive electrode electrolyte detection chamber and / or the negative electrode electrolyte detection chamber, the reference detection chamber being connected to the bipolar plate, the reference detection chamber being filled with a reference electrolyte, and the reference electrolyte being separated from the positive electrode electrolyte and / or the negative electrode liquid by an ion membrane; A reference electrode is set in the reference detection chamber to detect and calibrate the potential offset of the reference electrolyte in real time to obtain the calibration voltage value. The concentration of each valence ion is calculated online through the potential of the positive electrolyte relative to the reference electrode, the potential of the negative electrolyte relative to the reference electrode and the calibration voltage value through a multi-parameter empirical formula, and the charge state of the liquid flow battery is obtained in real time through the concentration of each valence ion.

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