Flow battery state of charge detection apparatus and method

Abstract

This invention relates to a device and method for detecting the state of charge (SOC) of a flow battery, applicable to the field of flow battery technology. Compared with existing technologies, this invention, by forming a reference detection chamber connected to bipolar plates, eliminates the need for a reference electrolyte storage tank, allowing for the replacement and replenishment of the reference electrolyte, thus improving the adaptability of the detection device. Furthermore, the reference detection chamber corresponds to the positive electrolyte detection chamber and / or the negative electrolyte detection chamber. A reference electrode is placed in the reference detection chamber, enabling real-time detection and calibration of the potential shift of the reference electrolyte. The calibration voltage value of the reference detection chamber is obtained, and by using 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, the concentration of each valence state ion is calculated online using a multi-parameter empirical formula. The SOC of the flow battery is then obtained in real time based on the concentration of each valence state ion, reducing detection errors, improving detection sensitivity, and enhancing the real-time monitoring accuracy of the SOC.

Description

Technical Field

[0001] This invention relates to the field of flow battery technology, and in particular to a flow battery state of charge detection device and method. Background Technology

[0002] Flow batteries, as a new generation of large-scale energy storage technology, have been widely used in large-scale energy storage scenarios such as grid peak shaving and renewable energy grid integration. Flow batteries store and release energy through the redox reaction of active ions in the electrolyte. Their state of charge (SOC) is a crucial parameter for measuring the battery's remaining capacity and determining the system's operating status. Accurately and in real-time obtaining the SOC of flow batteries is of great significance for ensuring system safety, optimizing operating strategies, and extending equipment lifespan.

[0003] Currently, the state of charge (SOC) of flow batteries is mainly detected using the voltage method, which involves measuring the voltage between the two electrodes and calculating the SOC using a specific electrochemical model. However, because the voltage plateau between the electrodes of a flow battery is relatively flat during actual operation, the concentration and valence state changes of the electrolyte at the positive and negative electrodes have a limited impact on the voltage. This results in poor sensitivity of the voltage method in the medium to high SOC range, making it difficult to achieve high-precision real-time monitoring of SOC. Summary of the Invention

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

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides a flow battery state of charge detection device, including a bipolar plate, an ion membrane, a reference detection chamber, and an electrolyte detection chamber. The electrolyte detection chamber includes a positive electrolyte detection chamber and / or a negative 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 electrolyte and / or negative electrolyte by the ion membrane.

[0007] The reference detection chamber is equipped with a reference electrode for real-time detection and calibration of the potential shift of the reference electrolyte to obtain a calibration voltage value. This allows the detection device to calculate the concentration of each valence state ion online using 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 calibration voltage value. The state of charge of the flow battery can then be obtained in real time based on the concentration of each valence state ion.

[0008] Compared with existing technologies, this invention forms a reference detection chamber connected to the bipolar plates, eliminating the need for a reference electrolyte storage tank and allowing for easy replacement and replenishment of the reference electrolyte. This improves the adaptability of the detection device. Furthermore, the reference detection chamber corresponds to the positive and / or negative electrolyte detection chambers. A reference electrode is placed within the reference detection chamber, enabling real-time detection and calibration of the reference electrolyte potential shift. The calibration voltage value of the reference detection chamber is obtained, and the concentration of each valence state ion is calculated online using a multi-parameter empirical formula based on the potentials of the positive and negative electrolytes relative to the reference electrode and the calibration voltage value. This allows for real-time acquisition of the flow battery's state of charge (SOC). The invention exhibits strong anti-interference capabilities, improved stability and reliability, strong engineering adaptability, suitability for large-scale deployment, reduced detection errors, increased detection sensitivity, and enhanced real-time accuracy of SOC monitoring.

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

[0010]

[0011] in, This indicates the potential of the positive electrode electrolyte relative to the reference electrode; This indicates the first calibration voltage value of the reference detection chamber; The empirical formula for the concentration coefficient of tetravalent vanadium ions in the positive electrode represents a multi-parameter formula. The empirical formula for the concentration coefficient of pentavalent vanadium ions in the positive electrode represents a multi-parameter formula. Represents the constant values ​​of the empirical formula for multiple parameters of the positive electrode; [ [This indicates the concentration of tetravalent vanadium ions;] [] indicates the concentration of pentavalent vanadium ions;

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

[0013]

[0014] in, The potential of the negative electrode electrolyte relative to the reference electrode; This indicates the second calibration voltage value of the reference detection cavity; The empirical formula for multi-parameter negative electrode is the concentration coefficient of divalent vanadium ions; The empirical formula for the concentration coefficient of trivalent vanadium ions, representing multiple parameters of the negative electrode; Represents the constant value of the negative pole multi-parameter empirical formula; [ [] indicates the concentration of divalent vanadium ions, [ [] indicates the concentration of trivalent vanadium ions;

[0015] Based on the relationship between electrolyte potential and concentration, a multi-parameter empirical formula for the positive electrode was obtained through fitting calculation. Value and negative electrode The value;

[0016] The concentrations of vanadium ions in each valence state are obtained using a multi-parameter empirical formula.

[0017] Compared with the prior art, the present invention, when the reference detection chambers correspond to the positive electrode electrolyte detection chamber and the negative electrode electrolyte detection chamber respectively, obtains a multi-parameter empirical formula for the positive electrode based on the relationship between electrolyte potential and concentration. Value and negative electrode The value of vanadium is determined by using a multi-parameter empirical formula to accurately obtain the concentration of vanadium ions in each valence state.

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

[0019]

[0020] in, This represents the measured voltage difference between the positive and negative electrolytes, when the reference detection chamber corresponds to either the positive or negative electrolyte detection chamber. equal , measured and One of them, through minus and One of the acquisitions and Another one of them.

[0021] Preferred positive state of charge With positive electrode [ Related to:

[0022]

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

[0024]

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

[0026] State of charge of a flow battery for:

[0027]

[0028] Preferably, the detection device obtains the state of health (SOH) of the flow battery by calculating the concentration of vanadium ions in each valence state;

[0029]

[0030] Where α is the temperature correction factor; T is the current measured temperature; Reference temperature; {[{V}^{5+}]}_{T} The concentration of pentavalent vanadium at temperature T under fully charged conditions; {[{V}^{2+}]}_{T} The concentration of divalent vanadium at temperature T under fully charged conditions; {[{V}^{5+}]}_{0} The concentration of pentavalent vanadium ions at the reference temperature under full charge; {[{V}^{2+}]}_{0} under full charge. The concentration of divalent vanadium ions at the reference temperature.

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

[0032] Preferably, 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 each has a reference electrode.

[0033] Compared with the prior art, the present invention has two independent reference liquid chambers, two insertable reference electrodes, and two reference electrolytes. Different reference electrolyte systems can be selected according to the different characteristics of the positive and negative electrodes, enabling more precise detection of positive and negative electrode potentials. The two reference liquid chambers are interconnected, and the positive and negative electrolyte chambers can be manufactured as a single piece with consistent positive and negative electrode references, making engineering applications simpler and more efficient.

[0034] Preferably, a flow hole is formed on the bipolar plate connecting the reference detection chamber.

[0035] Compared with the prior art, the present invention has a flow hole formed on the bipolar plate connected to the reference detection chamber, which allows the reference liquid to enter the electrode through the flow hole.

[0036] Preferably, 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, among electrolytes containing vanadium ions in one or more of the following valence states: +2, +3, +4, and +5 valence states; and / or, the reference electrode includes one or more of the following: a silver and silver chloride electrode, a saturated calomel electrode, a silver and silver sulfate electrode, or a platinum hydrogen electrode.

[0037] The present invention also provides a method for detecting the state of charge of a flow battery, comprising: establishing a reference detection chamber and an electrolyte detection chamber, wherein the reference detection chamber corresponds to the positive electrode electrolyte detection chamber and / or the negative electrode electrolyte detection chamber, the reference detection chamber is connected to a bipolar plate, the reference detection chamber is filled with a reference electrolyte, and the reference electrolyte is separated from the positive electrode electrolyte and / or the negative electrode electrolyte through an ion membrane;

[0038] A reference electrode is set in the reference detection chamber to detect and calibrate the potential shift of the reference electrolyte in real time, thereby obtaining the calibration voltage value. The concentration of each valence state ion is calculated online using 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 calibration voltage value. The state of charge of the flow battery is obtained in real time based on the concentration of each valence state ion. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a flow battery SOC detection device with a single-sided reference.

[0040] Figure 2 This is a first schematic diagram of the structure of a flow battery SOC detection device with dual-side reference.

[0041] Figure 3 A schematic diagram of the SOC detection device for a flow battery connected to a reference cell;

[0042] Figure 4 A schematic diagram of a variant structure of a flow battery SOC detection device connected to a reference cell;

[0043] Figure 5 This is a schematic diagram of the first bipolar plate structure;

[0044] Figure 6 This is a schematic diagram of a variant of the first bipolar plate structure;

[0045] Figure 7 To illustrate the schematic diagram of the tabs on the bipolar plate;

[0046] Figure 8 This is a second schematic diagram of the structure of a flow battery SOC detection device with dual-side reference.

[0047] Reference numerals: 1. Reference electrode; 2. First reference electrolyte; 3. First injection port; 4. First drain port; 5. Second reference electrolyte; 6. Second injection port; 7. Second drain port; 8. Positive electrolyte inlet; 9. Positive electrolyte outlet; 10. Negative electrolyte inlet; 11. Negative electrolyte outlet; 12. Bipolar plate; 13. Ion exchange membrane; 14. Battery electrode frame; 15. Tab. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0049] Through in-depth research and improvement of flow batteries, the applicant discovered that the voltage method used to detect the SOC of flow batteries cannot distinguish the specific states of the positive and negative electrolytes and is easily affected by factors such as polarization and electrolyte imbalance, resulting in a large error in SOC estimation.

[0050] Some methods for detecting the SOC of flow batteries attempt to indirectly estimate the SOC of the electrolyte through the analysis of physicochemical parameters such as density and spectroscopy. These methods typically require sampling and analysis of the electrolyte, making the detection process complex, unable to achieve online and real-time monitoring, and costly and difficult to maintain in practical engineering applications.

[0051] Existing methods for detecting the state of charge (SOC) of flow batteries, such as the open-circuit voltage method, suffer from low sensitivity, data deviation, and inability to reflect the specific state of the positive and negative electrodes. Other non-real-time monitoring methods suffer from poor real-time performance, complex detection processes, or high costs, making it difficult to meet the actual needs of large-scale energy storage systems for accurate and online SOC monitoring.

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

[0053] Based on this, the technical solutions provided by the various embodiments of the present invention will be described below with reference to the accompanying drawings.

[0054] This specification provides an embodiment of a flow battery state of charge (SOC) detection device, suitable for vanadium redox flow battery energy storage systems, which can be used to monitor the SOC of vanadium redox flow batteries in real time. Figure 1 and Figure 8 As shown, it includes multiple bipolar plates 12, multiple ion membranes 13, a reference detection chamber, and an electrolyte detection chamber. The electrolyte detection chamber includes a positive electrolyte detection chamber and / or a negative electrolyte detection chamber corresponding to the reference detection chamber. The reference detection chamber is connected to the bipolar plates 12 and is filled with a reference electrolyte. The reference electrolyte is separated from the positive electrolyte and / or negative electrode liquid corresponding to the electrode liquid detection chamber through the ion membranes 13.

[0055] The reference detection chamber is equipped with a reference electrode 1, which is used to detect and calibrate the potential shift of the reference electrolyte in real time to obtain a calibration voltage value. This allows the detection device to calculate the concentration of each valence state ion online using a multi-parameter empirical formula based on 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. The state of charge of the flow battery can then be obtained in real time based on the concentration of each valence state ion.

[0056] This invention uses a SOC detection device to collect the potential parameters of positive / negative electrolytes of different concentrations relative to a reference solution, the potential difference between the positive and negative electrolytes, and the voltage difference between the reference electrolyte and reference electrode 1. Simultaneously, it collects the total volume of the positive electrolyte and the total volume of the negative electrolyte.

[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 chamber, a negative electrolyte detection chamber, an ion exchange membrane, an insulating plate, a reference electrode 1, a reference detection chamber, and a second bipolar plate. For example... Figure 5 , Figure 6 as well as Figure 7 As shown, a flow hole is formed on the bipolar plate 12 connected to the reference chamber. The bipolar plate in the same electrolyte also has a flow hole. The shape of the flow hole is, for example, circular or rectangular. A tab 15 is formed on the bipolar plate 12.

[0058] like Figure 1 and Figure 2 As shown, the three fully filled vertical lines, from left to right, represent the first bipolar plate 12, the second bipolar plate, and the third bipolar plate; the diagonally filled vertical lines, from left to right, represent the first ion membrane and the second ion membrane 13.

[0059] like Figure 1 As shown, a through hole is formed on the first bipolar plate, allowing the reference liquid on one side to enter the electrode through the through hole, such as a carbon felt, carbon cloth, or carbon paper electrode; a through hole is formed on the second bipolar plate, allowing the electrolytes of the positive electrodes on both sides of the second bipolar plate to exchange with each other; the third bipolar plate has no electrode through holes, but only flow channels, allowing the negative electrode electrolyte to enter the negative electrode through the flow channels, such as a carbon felt, carbon cloth, or carbon paper electrode.

[0060] like Figure 2As shown, the two reference liquid chambers are independent of each other, with two insertable reference electrodes and two reference electrolytes. Different reference electrolyte systems can be selected based on the different characteristics of the positive and negative electrodes. For example, V4+ can be selected as the positive electrode reference electrolyte, and V3+ as the negative electrode reference electrolyte. This reduces the migration rate of the positive and negative electrode electrolytes and improves detection accuracy, allowing for more precise detection of positive and negative electrode potentials. The reference electrolyte flows through the through-holes on the first bipolar plate into the carbon felt electrode (not shown in the figure) between the first bipolar plate and the first ion membrane, located on the left side of the first ion membrane. The positive electrode electrolyte and the reference electrolyte are separated by the first ion membrane. The positive electrode electrolyte flows through the through-holes on the electrode frame into the left side of the second bipolar plate, and the negative electrode electrolyte flows through the through-holes on the electrode frame into the right side of the second bipolar plate. The positive and negative electrolytes are isolated by the second bipolar plate. The reference electrolyte flows through the through-holes on the third bipolar plate into the carbon felt electrode (not shown in the figure) between the third bipolar plate and the second ion membrane, located on the right side of the second ion membrane. The negative electrode electrolyte and the reference electrolyte are separated by a second ion-exchange membrane.

[0061] like Figure 3 As shown, the two reference liquid chambers are interconnected, and the positive and negative electrolyte chambers can be manufactured as a single piece, with consistent positive and negative electrode references, making engineering applications simpler and more efficient.

[0062] Each chamber is isolated from the main circulating electrolyte by an ion exchange membrane and is equipped with a conductive element. The positive electrolyte detection chamber, negative electrolyte detection chamber, and reference detection chamber are separated from the ion exchange membrane by insulating plates, and the reference detection chamber is filled with a reference solution. Reference electrode 1 is inserted into the reference electrolyte chamber to detect and calibrate the potential shift of the reference electrolyte. For example, the initial valence state of vanadium ions in the reference electrolyte is... .

[0063] Existing reference chambers, separated by ion-exchange membranes, have small capacities. Over prolonged use, the electrolyte in the reference chamber rapidly undergoes valence state shifts, leading to inaccurate detection results. Therefore, an external reference chamber is used, along with a circulation pump to refresh the reference solution. This process significantly increases structural complexity and introduces risks. Furthermore, external circulation of the reference solution can erode the electrodes and ion-exchange membranes on both sides of the reference chamber, reducing the device's lifespan. This invention, by biasing the chamber and increasing its capacity, avoids the drawbacks of requiring additional circulation pumps and reference tanks, resulting in higher reliability in engineering implementation.

[0064] This invention combines empirical formulas with a multi-parameter equation system. Utilizing the potential difference between the positive and negative electrode electrolytes and the reference electrode 1, and combining this with multi-parameter concentration empirical formulas based on the Nernst equation or experimental fitting, the concentration of vanadium ions in each valence state can be calculated in real-time and accurately through a system of simultaneous equations (or a database), achieving online quantitative monitoring of the electrolyte components in a vanadium redox flow battery. By real-time acquisition of the potential difference and volume parameters between the positive and negative electrode electrolytes and the reference chamber, and combining this with the Nernst equation or experimentally fitted multi-parameter empirical formulas, the concentration of vanadium ions in each valence state can be accurately calculated online, thereby achieving real-time, high-precision monitoring of the state of charge (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 as follows:

[0067]

[0068] in, The potential of the positive electrode electrolyte relative to the reference electrode 1 can be measured or calculated from the measured voltage difference between the positive and negative electrode electrolytes. This represents the first calibration voltage value of the reference detection chamber, which is also the calibration voltage value of the positive reference chamber; This represents the constant values ​​for calculating the concentrations of tetravalent and pentavalent ions at the positive electrode. The empirical formula for the concentration coefficient of tetravalent vanadium ions in the positive electrode represents a multi-parameter formula. The empirical formula for the concentration coefficient of pentavalent vanadium ions in the positive electrode represents a multi-parameter formula. Represents the constant values ​​of the empirical formula for multiple parameters of the positive electrode; [ [ indicates the concentration of tetravalent vanadium ions;] [] indicates the concentration of pentavalent vanadium ions.

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

[0070]

[0071] in, The potential of the negative electrode electrolyte relative to the reference electrode 1 can be measured or calculated from the measured voltage difference between the positive and negative electrode electrolytes. This represents the second calibration voltage value of the reference detection chamber, which is the calibration voltage value of the negative reference chamber; These represent the constant values ​​for calculating the concentrations of divalent and trivalent ions at the negative electrode, respectively. The empirical formula for multi-parameter negative electrode is the concentration coefficient of divalent vanadium ions; The empirical formula for the concentration coefficient of trivalent vanadium ions, representing multiple parameters of the negative electrode; Represents the constant value of the negative pole multi-parameter empirical formula; [ [] indicates the concentration of divalent vanadium ions, [ [] indicates the concentration of trivalent vanadium ions.

[0072] Based on the relationship between electrolyte potential and concentration, a multi-parameter empirical formula for the positive electrode was obtained through fitting calculation. Value and negative electrode The value of vanadium ions in each valence state is obtained using a multi-parameter empirical formula.

[0073] Based on the above relationship between voltage and ion concentration, the positive electrode can be calculated using a fitting method. Constant value and negative electrode Constant values. These are obtained through titration. The concentration, such as Figure 2 and Figure 8 As shown, when the reference detection chamber corresponds to the positive electrolyte detection chamber and the negative electrolyte detection chamber respectively, the measured values ​​are... and measured .

[0074] In one embodiment, the relationship between the liquid potential of the positive electrode and the liquid potential of the negative electrode is as follows:

[0075]

[0076] in, This represents the measured voltage difference between the positive and negative electrolytes, such as... Figure 1 As shown, when the reference detection chamber corresponds to either the positive electrolyte detection chamber or the negative electrolyte detection chamber, equal , measured and One of them, through minus and One of the acquisitions and Another one of them.

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

[0078] Positive state of charge With positive electrode [ Related to:

[0079]

[0080] The state of charge at the negative electrode is related to the negative electrode, and therefore:

[0081]

[0082] in, and These are constants related to temperature and charge / discharge strategies. This is the first constant term related to temperature and charge / discharge strategy; This is the second constant term related to temperature and charge / discharge strategy. and These are empirical parameters.

[0083] System SOC, or state of charge of a flow battery. for:

[0084]

[0085] In one embodiment, the detection device obtains the state of health (SOH) of the flow battery by calculating the concentration of vanadium ions in each valence state.

[0086]

[0087] Where α is the temperature correction factor; T is the current measured temperature; For reference temperature, 25℃ is usually taken; {[{V}^{5+}]}_{T} The concentration of pentavalent vanadium at temperature T under fully charged conditions; {[{V}^{2+}]}_{T} The concentration of divalent vanadium at temperature T under fully charged conditions is {[{V}^{5+}]}_{0}. The concentration of pentavalent vanadium ions at the reference temperature under fully charged conditions is {[{V}^{2+}]}_{0} The concentration of divalent vanadium ions at the reference temperature under fully charged conditions.

[0088] In one embodiment, such as Figure 1 and Figure 2 As shown, the reference detection chamber includes a positive reference chamber corresponding to the positive electrode liquid side and / or a negative reference chamber corresponding to the negative electrode electrolyte side.

[0089] In one embodiment, such as Figure 3 and Figure 4 As shown, the positive reference chamber and the negative reference chamber are connected and use the same reference electrode 1; or, as... Figure 2 and Figure 8 As shown, the positive reference chamber and the negative reference chamber are disconnected and each has a reference electrode 1.

[0090] In one embodiment, the reference detection chamber is provided with a flow port to facilitate the replenishment and replacement of the reference electrolyte.

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

[0092] The detection device of this invention features an independently replaceable structure for the positive electrode, negative electrode, and reference chamber. The chambers are isolated from the main circulation via diaphragms / membranes, and the internal conductive elements utilize inert carbon materials, improving electrochemical stability and durability. The reference chamber is equipped with a flow port for easy replenishment and replacement of the reference solution, further ensuring long-term stability of the reference potential.

[0093] In one embodiment, 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, which are electrolytes containing one or more combinations of valence states of vanadium ions in the forms of +2, +3, +4, and +5 valence ions; and / or, the reference electrode 1 includes one or more of the following: a silver and silver chloride electrode, a saturated calomel electrode, a silver and silver sulfate electrode, or a platinum hydrogen electrode.

[0094] In one embodiment, a reference detection chamber is connected to a bipolar plate fixed on the outside. The cavity structure of the reference detection chamber includes a connected bias cavity and a bias electrode cavity. The bias cavity is disposed on the outside of the bipolar plate that connects and fixes the reference detection chamber. The bias electrode cavity is an electrode cavity that connects the bipolar plate that fixes the reference detection chamber and the ion membrane that separates the reference electrolyte. The connection between the bias cavity and the bias electrode cavity increases the capacity of the reference detection chamber and reduces the valence state shift rate of the reference electrolyte. The reference electrode is located in the bias cavity.

[0095] The reference detection chamber of this application is connected and fixed to an outer bipolar plate. The cavity structure of the reference detection chamber includes a connected bias cavity and a bias electrode cavity. The bias cavity is located on the outer side of the bipolar plate connected to the fixed reference detection chamber. The bias electrode cavity is the electrode cavity connecting the bipolar plate of the fixed reference detection chamber and the ion membrane separating the reference electrolyte. This increases the capacity of the reference detection chamber by connecting the bias cavity and the bias electrode cavity, reduces the valence state shift rate of the reference electrolyte, and improves the SOC detection accuracy of the flow battery. Furthermore, it eliminates the need for... By incorporating a reference electrolyte storage tank, along with valves and pipelines, the detection device can be miniaturized, making it suitable for large-scale deployment, extending its service life, and facilitating the replacement and replenishment of the reference electrolyte. This also avoids eroding the reference chamber electrodes and ion exchange membrane. Furthermore, the inclusion of a bias cavity allows for the placement of reference electrodes within the bias chamber, enabling the detection of the potential shift in the reference electrolyte to obtain the actual potential values ​​of the positive and negative electrode liquid phases relative to the reference electrolyte. This further improves the accuracy of flow battery state-of-charge detection, enhancing stability, reliability, and anti-interference capabilities.

[0096] Generally, the capacity of the internal cavity of an electrode is a few milliliters, while the capacity of the reference detection cavity (including the bias cavity and the bias electrode cavity) of this application can reach 500 ml to 2.5 L, which is more than 100 times the capacity. Among them, the first bipolar plate and / or the second bipolar plate are the outer bipolar plates connected to the reference detection cavity.

[0097] The device comprises a positive electrolyte detection chamber, a negative electrolyte detection chamber, and a reference detection chamber, isolated from the main circulating electrolyte by an ion exchange membrane. Each chamber is equipped with a conductive element. The reference detection chamber is filled with a vanadium electrolyte with the same composition and acidity as the main system and a constant potential. Combined with a standard reference electrode, it achieves long-term stability and real-time calibration of the reference system. By real-time acquisition of the potential difference and volume parameters between the positive and negative electrolytes and the reference chamber, and using the Nernst equation or experimentally fitted multi-parameter empirical formulas, the concentration of vanadium ions in each valence state can be accurately calculated online, thereby achieving real-time, high-precision monitoring of the state of charge (SOC) of the flow battery system. This method is simple in structure, easy to maintain, and has strong anti-interference capabilities, making it suitable for the intelligent management and safe operation of large-scale energy storage systems.

[0098] This invention innovatively selects a reference solution. The reference detection chamber is filled with a vanadium electrolyte that has the same composition and acidity as the main system and a constant potential. Combined with a standard reference electrode, this achieves long-term stability and real-time calibration of the reference system. By using a vanadium electrolyte with the same composition and acidity as the main reaction system and a constant potential as the reference solution, and by using a standard reference electrode to calibrate the reference electrolyte in real time, a long-term online, chemically compatible reference system is achieved, providing a reliable potential benchmark for electrolyte state monitoring.

[0099] The reference system of this invention significantly improves accuracy and stability, and has strong anti-interference capabilities. In existing flow battery SOC detection systems, vanadium electrolyte is used alone as the reference solution. However, with battery charging and discharging, the electrolyte is easily contaminated by transmembrane permeation, leading to a decrease in accuracy and reliability. This solution combines a commercially available reference electrode with a vanadium electrolyte reference solution, enabling real-time calibration of the offset and improving SOC detection accuracy.

[0100] This invention has strong real-time, online, and automated monitoring capabilities. It only needs to collect the potential difference and volume parameters between the positive and negative electrodes and the reference cavity in real time. Through multi-parameter calculation formulas or databases, it can automatically calculate the concentration of vanadium ions in each valence state, realize online, real-time, and automated monitoring of key indicators such as battery SOC / SOH, and meet the intelligent needs of large-scale energy storage systems.

[0101] The present invention has a simple structure, low maintenance, and strong engineering adaptability. The detection device of the present invention has an integrated and modular design, the reference chamber can be flexibly replenished, and the internal components can operate stably for a long time, which greatly reduces the difficulty and cost of operation and maintenance. It is suitable for large-scale engineering deployment, and there is no need to use pumps or other means to circulate the reference electrolyte during operation, which makes it highly adaptable to engineering.

[0102] This invention provides a flow battery SOC detection device and method, which overcomes the shortcomings of existing flow battery SOC detection methods, such as low sensitivity, poor real-time performance, inability to distinguish the specific states of the positive and negative electrodes of the electrolyte, and complex or high-cost detection processes. It can realize real-time and accurate monitoring of the state of the positive and negative electrolytes of the flow battery, and can assist in evaluating the valence state migration ratio of the system electrolyte, thus meeting the actual needs of large-scale energy storage systems for online and accurate SOC detection.

[0103] This invention also discloses a method for detecting the state of charge of a flow battery, comprising: establishing a reference detection chamber and an electrolyte detection chamber, wherein the reference detection chamber corresponds to the positive electrode electrolyte detection chamber and / or the negative electrode electrolyte detection chamber, the reference detection chamber is connected to a bipolar plate 12, the reference detection chamber is filled with a reference electrolyte, and the reference electrolyte is separated from the positive electrode electrolyte and / or the negative electrode electrolyte through an ion membrane 13.

[0104] A reference electrode 1 is set in the reference detection chamber to detect and calibrate the potential shift of the reference electrolyte in real time, thereby obtaining the calibration voltage value. The concentration of each valence state ion is calculated online using a multi-parameter empirical formula based on 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. The state of charge of the flow battery is obtained in real time based on the concentration of each valence state ion.

[0105] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A flow battery state-of-charge detection device, characterized in that, It includes a bipolar plate, an ion exchange membrane, a reference detection chamber, and an electrolyte detection chamber. The electrolyte detection chamber includes a positive electrolyte detection chamber and / or a negative 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 electrolyte and / or the negative electrode liquid by the ion exchange membrane. The reference detection chamber is equipped with a reference electrode for real-time detection and calibration of the potential shift of the reference electrolyte to obtain a calibration voltage value. This allows the detection device to calculate the concentration of each valence state ion online using 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 calibration voltage value. The state of charge of the flow battery can then be obtained in real time based on the concentration of each valence state ion. The reference detection chamber is connected to and fixed to the bipolar plate on the outside. The cavity structure of the reference detection chamber includes a connected bias cavity and a bias electrode cavity. The bias cavity is located on the outside of the bipolar plate that connects and fixes the reference detection chamber. The bias electrode cavity is an electrode cavity that connects the bipolar plate that fixes the reference detection chamber and the ion membrane that separates the reference electrolyte. The connection between the bias cavity and the bias electrode cavity increases the capacity of the reference detection chamber and reduces the valence state shift rate of the reference electrolyte. The reference electrode is located in the bias cavity.

2. The 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 as follows: ;in, This indicates the potential of the positive electrode electrolyte relative to the reference electrode; This indicates the first calibration voltage value of the reference detection chamber; The empirical formula for the concentration coefficient of tetravalent vanadium ions in the positive electrode represents a multi-parameter formula. The empirical formula for the concentration coefficient of pentavalent vanadium ions in the positive electrode represents a multi-parameter formula. This represents the constant value of the empirical formula for multiple parameters of the positive electrode; [ indicates the concentration of tetravalent vanadium ions;] [] indicates the concentration of pentavalent vanadium ions; The relationship between the negative electrode electrolyte potential and concentration is as follows: ;in, This indicates the potential of the negative electrode electrolyte relative to the reference electrode; This indicates the second calibration voltage value of the reference detection cavity; The empirical formula for multi-parameter negative electrode is the concentration coefficient of divalent vanadium ions; The empirical formula for the concentration coefficient of trivalent vanadium ions, representing multiple parameters of the negative electrode; Represents the constant value of the negative pole multi-parameter empirical formula; [ [] indicates the concentration of divalent vanadium ions, [ [] indicates the concentration of trivalent vanadium ions; Based on the relationship between electrolyte potential and concentration, a multi-parameter empirical formula for the positive electrode was obtained through fitting calculation. Value and negative electrode The value; The concentrations of vanadium ions in each valence state are obtained using a multi-parameter empirical formula.

3. The flow battery state-of-charge detection device according to claim 2, characterized in that, The relationship between the liquid potential of the positive electrode and the liquid potential of the negative electrode is as follows: ;in, This represents the measured voltage difference between the positive and negative electrolytes, when the reference detection chamber corresponds to either the positive or negative electrolyte detection chamber. equal , measured and One of them, through minus and One of the acquisitions and Another one of them.

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

5. The flow battery state-of-charge detection device according to claim 2, characterized in that, The detection device obtains the state of health (SOH) of the flow battery by calculating the concentration of vanadium ions in various valence states; Where α is the temperature correction factor; T is the current measured temperature; Reference temperature; {[{V}^{5+}]}_{T} The concentration of pentavalent vanadium at temperature T under fully charged conditions; {[{V}^{2+}]}_{T} The concentration of divalent vanadium at temperature T under fully charged conditions; {[{V}^{5+}]}_{0} The concentration of pentavalent vanadium ions at the reference temperature under fully charged conditions; {[{V}^{2+}]}_{0} The concentration of divalent vanadium ions at the reference temperature under fully charged conditions.

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

7. The 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 each has a reference electrode.

8. The 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 that connects to the reference detection chamber.

9. The 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, among electrolytes containing vanadium ions in one or more of the following valence states: +2, +3, +4, and +5 valence states; and / or, the reference electrode includes one or more of the following: a silver and silver chloride electrode, a saturated calomel electrode, a silver and silver sulfate electrode, or a platinum hydrogen electrode.

10. A method for detecting the state of charge of a flow battery, characterized in that, The flow battery state of charge detection device according to any one of claims 1 to 9 includes: 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 a 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 electrolyte through an ion membrane; A reference electrode is set in the reference detection chamber to detect and calibrate the potential shift of the reference electrolyte in real time, thereby obtaining the calibration voltage value. The concentration of each valence state ion is calculated online using 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 calibration voltage value. The state of charge of the flow battery is obtained in real time based on the concentration of each valence state ion.

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