Method and system for identification and recovery of redox state shift in flow battery electrolyte

Abstract

The application provides a liquid flow battery electrolyte valence state deviation identification recovery method and system, which can collect liquid flow battery valence state deviation identification data and calculate the deviation rate of electrolyte valence state deviation, determine that the identification result is positive electrode valence state deviation when the open circuit voltage deviation rate is greater than the open circuit voltage threshold or the charging voltage platform deviation rate is greater than the charging voltage platform threshold and the positive electrode absorbance deviation rate is greater than the positive electrode absorbance threshold, and the coulomb efficiency deviation rate is less than the coulomb efficiency threshold, determine that the identification result is negative electrode valence state deviation when the open circuit voltage deviation rate is greater than the open circuit voltage threshold or the discharge voltage platform deviation rate is less than the discharge voltage platform threshold and the negative electrode absorbance deviation rate is less than the negative electrode absorbance threshold, and the coulomb efficiency deviation rate is less than the coulomb efficiency threshold, and then execute the corresponding electrolyte valence state recovery process according to the identification result, so as to accurately distinguish the positive and negative electrode valence state imbalance types, provide accurate guidance for targeted capacity recovery measures, and realize battery capacity recovery.

Description

Technical Field

[0001] This invention relates to the field of flow battery capacity testing technology, and in particular to a method and system for identifying and recovering the valence state shift of the electrolyte in a flow battery. Background Technology

[0002] Vanadium redox flow batteries (VRFBs) offer unique advantages in safety, cycle life, and decoupled power and capacity design, making them particularly suitable for applications such as renewable energy grid-connected peak shaving, grid-side frequency regulation, and emergency backup power. They have become one of the most promising technologies in large-scale stationary energy storage. However, VRFBs suffer from a critical issue of continuous capacity decay during cycles; the actual discharge capacity may drop to 60%-70% of its initial value after 300-500 cycles, severely limiting their economic viability and large-scale application.

[0003] The continuous capacity decay of vanadium redox flow batteries is mainly caused by the valence state shift (valence imbalance) of vanadium ions in the electrolyte. Traditional methods for monitoring electrolyte valence state, such as titration and UV-Vis spectroscopy, require periodic sampling and testing of the electrolyte, resulting in long testing cycles and making real-time monitoring of the electrolyte valence state impossible. Furthermore, when the electrolyte valence imbalance in vanadium redox flow batteries is in its early stages, such as when the state of charge (SOC) shift is less than 5%, the battery voltage shows no obvious abnormal changes, making the problem easily overlooked and ultimately leading to irreversible capacity decay.

[0004] Currently, there are some research results on the capacity decay and recovery of vanadium redox flow batteries. For example, Chinese patents such as "A method for suppressing capacity decay and online capacity recovery of vanadium redox flow batteries" (Publication No. CN114744253B), "A flow battery capacity recovery system and method" (Publication No. CN115051005B), "A vanadium redox flow battery capacity recovery method" (Publication No. CN106876814B), and "A vanadium redox flow battery capacity retention and recovery device" (Publication No. CN216435950U) provide corresponding solutions. However, there are still problems such as relying on a single parameter, such as open circuit voltage, which leads to inaccurate results in judging the electrolyte valence state shift, and the inability to accurately distinguish and judge the asymmetric shift of positive and negative electrodes, resulting in misjudgment of valence state.

[0005] In addition, the operation and maintenance of flow batteries mainly rely on the experience of maintenance personnel to judge the electrolyte condition, which is highly subjective and inaccurate. Different maintenance personnel also have different judgment standards for the electrolyte condition, making it difficult to ensure that the flow battery is always in the best operating condition.

[0006] Therefore, a solution is needed that can accurately determine the valence state shift of the positive and negative electrolytes in a flow battery and quantify the degree of valence state shift. Summary of the Invention

[0007] One objective of this application is to provide a method and system for identifying and recovering the valence state shift of the electrolyte in a flow battery, in order to solve the problem that it is difficult to accurately identify and recover the capacity of the positive and negative electrode valence state shifts in a flow battery under the existing technology.

[0008] To achieve the above objectives, some embodiments of this application provide a method for identifying and recovering the valence state shift of a flow battery electrolyte, the method comprising:

[0009] Valence state shift identification data of flow batteries are collected. The valence state shift identification data includes: open circuit voltage data, charge and discharge voltage plateau data, positive and negative electrode absorbance data, and coulombic efficiency data.

[0010] Based on the valence state shift identification data, the shift rate of the electrolyte valence state shift is calculated. The shift rate of the electrolyte valence state shift includes: open circuit voltage shift rate, charging voltage plateau shift rate, discharging voltage plateau shift rate, positive electrode absorbance shift rate, negative electrode absorbance shift rate, and coulombic efficiency shift rate.

[0011] If the open-circuit voltage offset rate is greater than the open-circuit voltage threshold or the charging voltage plateau offset rate is greater than the charging voltage plateau threshold, and the positive electrode absorbance offset rate is greater than the positive electrode absorbance threshold and the coulombic efficiency offset rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state offset is determined as the positive electrode valence state offset.

[0012] If the open-circuit voltage offset rate is greater than the open-circuit voltage threshold or the discharge voltage plateau offset rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance offset rate is less than the negative electrode absorbance threshold and the coulombic efficiency offset rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state offset is determined as the negative electrode valence state offset.

[0013] Based on the identification results, the corresponding electrolyte valence state recovery process is executed.

[0014] Furthermore, based on the valence state shift identification data, the shift rate of the electrolyte valence state shift is calculated, including:

[0015] The positive electrode absorbance shift rate is determined based on the positive electrode absorbance data corresponding to the first positive electrode wavelength and the positive electrode absorbance data corresponding to the second positive electrode wavelength.

[0016] The negative electrode absorbance offset rate is determined based on the negative electrode absorbance data corresponding to the first negative electrode wavelength and the negative electrode absorbance data corresponding to the second negative electrode wavelength.

[0017] Furthermore, the first positive electrode wavelength is 760 nanometers, the second positive electrode wavelength is 580 nanometers, the first negative electrode wavelength is 400 nanometers, and the second negative electrode wavelength is 650 nanometers.

[0018] Furthermore, the absorbance threshold for the positive electrode is 1.5, and the absorbance threshold for the negative electrode is 1.0.

[0019] Furthermore, the charging voltage plateau threshold is 0.05, and the discharging voltage plateau threshold is -0.05.

[0020] Furthermore, the method also includes:

[0021] Based on the open-circuit voltage offset rate or charging voltage plateau offset rate, positive electrode absorbance offset rate, and coulombic efficiency offset rate, the cumulative degree corresponding to the positive electrode valence state offset is determined by a weighted method.

[0022] The cumulative degree corresponding to the negative electrode valence state shift is determined by weighting the open-circuit voltage shift rate or discharge voltage plateau shift rate, negative electrode absorbance shift rate, and coulombic efficiency shift rate.

[0023] Furthermore, the weights corresponding to the open-circuit voltage offset rate, charging voltage plateau offset rate, discharging voltage plateau offset rate, positive electrode absorbance offset rate, and negative electrode absorbance offset rate are 0.4, and the weight corresponding to the coulombic efficiency offset rate is 0.2.

[0024] Further, based on the identification result, a corresponding electrolyte valence state recovery process is executed, including:

[0025] If the identification result is a shift in the positive electrode valence state, inject oxalic acid solution into the positive electrode electrolyte or extract the negative electrode electrolyte into the positive electrode electrolyte to restore the positive electrode valence state.

[0026] If the identification result indicates a shift in the negative electrode valence state, external electrolysis of the negative electrode electrolyte or extraction of the positive electrode electrolyte into the negative electrode electrolyte can be performed to restore the negative electrode valence state.

[0027] Furthermore, after calculating the offset rate of the electrolyte valence state shift, the following is also included:

[0028] A valence state shift warning is issued when the positive electrode absorbance shift rate is between the positive electrode absorbance warning threshold and the positive electrode absorbance threshold, or when the negative electrode absorbance shift rate is between the negative electrode absorbance warning threshold and the negative electrode absorbance threshold.

[0029] Other embodiments of this application also provide a system for identifying and recovering the valence state shift of a flow battery electrolyte, the system comprising:

[0030] The battery management module is used to collect valence state shift identification data of the flow battery. This data includes: open-circuit voltage data, charge / discharge voltage plateau data, positive and negative electrode absorbance data, and coulombic efficiency data. Based on this data, it calculates the electrolyte valence state shift rate, which includes: open-circuit voltage shift rate, charging voltage plateau shift rate, discharging voltage plateau shift rate, positive electrode absorbance shift rate, negative electrode absorbance shift rate, and coulombic efficiency shift rate. When the open-circuit voltage shift rate exceeds the open-circuit voltage threshold or the charging voltage plateau shift rate exceeds the charging voltage threshold, the battery management module will detect any deviations in the valence state shift data. If the positive electrode absorbance shift rate is greater than the positive electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the electrolyte valence state shift is identified as a positive electrode valence state shift. If the open circuit voltage shift rate is greater than the open circuit voltage threshold or the discharge voltage plateau shift rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance shift rate is less than the negative electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the electrolyte valence state shift is identified as a negative electrode valence state shift. Based on the identification results, the corresponding electrolyte valence state recovery process is executed.

[0031] OCV battery module, used to provide open-circuit voltage data;

[0032] The fuel cell stack voltage acquisition module is used to acquire the charging and discharging voltage platform data of the fuel cell stack module.

[0033] Positive UV fiber optic probe, used to collect positive absorbance data;

[0034] A negative electrode UV fiber optic probe is used to collect negative electrode absorbance data.

[0035] Positive electrode mixing valve is used to control the mixing process of negative electrode electrolyte flowing to positive electrode electrolyte;

[0036] The negative electrode mixing valve is used to control the mixing process of the positive electrode electrolyte flowing to the negative electrode electrolyte;

[0037] A positive electrode pump is used to drive the flow of positive electrode electrolyte to negative electrode electrolyte.

[0038] A negative electrode pump is used to drive the flow of negative electrode electrolyte to positive electrode electrolyte.

[0039] The reducing agent module is used to add a reducing agent to the positive electrode electrolyte;

[0040] The electrolytic cell module is used to electrolyze the introduced negative electrode electrolyte.

[0041] Compared with existing technologies, the solution provided in this application can collect valence state shift identification data of flow batteries, and calculate the shift rate of electrolyte valence state shift based on the valence state shift identification data. When the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the charging voltage plateau shift rate is greater than the charging voltage plateau threshold, and the positive electrode absorbance shift rate is greater than the positive electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state shift is determined as a positive electrode valence state shift. When the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the discharge voltage plateau shift rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance shift rate is less than the negative electrode absorbance threshold and the coulombic efficiency shift rate is less than the negative electrode absorbance threshold, the valence state shift is determined as a positive electrode valence state shift. When the efficiency is less than the coulombic efficiency threshold, the electrolyte valence state shift is identified as a negative electrode valence state shift. Based on the identification result, the corresponding electrolyte valence state recovery process is executed. This enables the collaborative judgment of positive and negative electrode valence state shifts based on multiple parameters, accurately distinguishing the types of positive and negative electrode valence state imbalances. This provides precise guidance for targeted capacity recovery measures, enables quantitative assessment of the degree of imbalance, provides data support for refined management, and triggers early warnings in the early stages of valence state shifts, allowing timely measures to prevent battery performance degradation. Furthermore, it enables battery capacity recovery based on valence state shift monitoring results, resulting in a high battery capacity retention rate and reduced operation and maintenance costs. Attached Figure Description

[0042] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0043] Figure 1 A flowchart illustrating a method for identifying and recovering the valence state shift of a flow battery electrolyte, provided for some embodiments of this application.

[0044] Figure 2 A schematic diagram showing the curve offset between open-circuit voltage and state of charge for some embodiments of this application.

[0045] Figure 3 A schematic diagram illustrating the changes in the characteristic absorption peaks of the positive electrode electrolyte in the ultraviolet-visible spectrum, provided for some embodiments of this application.

[0046] Figure 4 A schematic diagram illustrating the changes in the characteristic absorption peaks of the negative electrode electrolyte in the ultraviolet-visible spectrum, provided for some embodiments of this application.

[0047] Figure 5 A schematic diagram of the structure of a flow battery electrolyte valence state shift identification and recovery system provided for some embodiments of this application.

[0048] Reference numerals: 101, Positive electrode storage tank; 102, Positive electrode pump; 103, Positive electrode UV fiber optic probe; 104, Positive electrode mixing valve; 105, OCV battery module; 106, Battery stack module; 107, Battery management module; 108, Reducing agent module; 201, Negative electrode storage tank; 202, Negative electrode pump; 203, Negative electrode UV fiber optic probe; 204, Negative electrode mixing valve; 205, Battery stack voltage acquisition module; 206, Electrolyte module. Detailed Implementation

[0049] 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.

[0050] Here, the method for identifying and recovering the electrolyte valence state shift in a flow battery according to the embodiments of this application is suitable for scenarios where the electrolyte valence state shift of a flow battery is detected in real time and the battery capacity is recovered when the valence state shift is large.

[0051] In this scenario, energy storage-related data and electrolyte state data of the flow battery are collected, and valence state shift is determined based on the collected data. After determining that the electrolyte valence state has shifted, targeted measures are taken to restore the capacity of the flow battery.

[0052] Existing methods rely on a single parameter to determine electrolyte valence state shifts, resulting in a false positive rate exceeding 20%. This application's embodiment integrates multiple parameters, including electrochemical parameters, optical characteristics, and efficiency parameters, to reflect the electrolyte state from multiple dimensions, effectively reducing the false positive rate to below 5%. This significantly improves the accuracy and reliability of judging electrolyte valence state shifts in flow batteries, providing strong support for precise maintenance of flow battery systems. Furthermore, existing methods often only detect problems when the electrolyte imbalance is severe and capacity loss is significant. This application's embodiment can trigger an early warning and initiate rebalancing measures when the electrolyte valence state shift is between 3-5%. Early intervention effectively reduces battery capacity decay. Actual testing shows that the flow battery capacity decay rate can be reduced to 0.8% / thousand cycles, while existing solutions typically exceed 3% / thousand cycles. Therefore, it can significantly extend the lifespan of flow batteries and reduce the operating costs of energy storage systems.

[0053] The method for identifying and recovering the electrolyte valence state shift in a flow battery provided in this application can collect valence state shift identification data of the flow battery, and calculate the shift rate of the electrolyte valence state shift based on the valence state shift identification data. If the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the charging voltage plateau shift rate is greater than the charging voltage plateau threshold, and the positive electrode absorbance shift rate is greater than the positive electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state shift is determined as a positive electrode valence state shift. If the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the discharge voltage plateau shift rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance shift rate is less than the negative electrode absorbance threshold, the method can be determined as a positive electrode valence state shift. When the coulombic efficiency deviation rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state deviation is determined to be a negative electrode valence state deviation. Then, based on the identification result, the corresponding electrolyte valence state recovery process is executed. This enables the judgment of positive and negative electrode valence state deviation based on multiple parameters, accurately distinguishes the types of positive and negative electrode valence state imbalance, provides precise guidance for targeted capacity recovery measures, and enables quantitative assessment of the degree of imbalance, providing data support for refined management. Furthermore, it triggers early warnings in the early stages of valence state deviation, enabling timely measures to prevent battery performance deterioration. It also enables battery capacity recovery based on valence state deviation monitoring results, resulting in a high battery capacity retention rate and reduced operation and maintenance costs.

[0054] The flowchart of the method for identifying and recovering the valence state shift of the electrolyte in a flow battery in some embodiments of this application is as follows: Figure 1 As shown, the method may include the following steps:

[0055] Step S101: Collect valence state shift identification data of flow battery.

[0056] Here, the flow battery is a vanadium redox flow battery, and its valence state shift identification data may include, but are not limited to: open circuit voltage data, charge and discharge voltage plateau data, positive and negative electrode absorbance data, and coulombic efficiency data.

[0057] Open-circuit voltage data describes the open-circuit voltage of the flow battery acquired in real time. Charge / discharge voltage plateau data includes charging and discharging voltage plateau data. Charging voltage plateau data describes the slowly changing voltage of the flow battery during charging, while discharging voltage plateau data describes the slowly changing voltage of the flow battery during discharging. Positive and negative electrode absorbance data includes positive and negative electrode absorbance data. Positive electrode absorbance data describes the absorbance of the positive electrode electrolyte of the flow battery under a specific wavelength of ultraviolet-visible light, while negative electrode absorbance data describes the absorbance of the negative electrode electrolyte under a specific wavelength of ultraviolet-visible light. Coulombic efficiency data describes the ratio of charge to volume during charging and discharging of the flow battery.

[0058] In some embodiments of this application, the flow battery includes an open circuit voltage (OCV) battery module for providing open circuit voltage data. When collecting open circuit voltage data from the flow battery, the open circuit voltage battery module can be measured in real time using a voltage sensor to obtain real-time open circuit voltage data.

[0059] Similarly, in some embodiments of this application, the flow battery includes a stack voltage acquisition module for acquiring charge and discharge voltage plateau data of the stack module in the flow battery. When acquiring the charge and discharge voltage plateau data of the flow battery, the charging voltage plateau data and discharging voltage plateau data of the stack module in the flow battery can be measured by a voltage sensor during the charging and discharging processes of the flow battery, respectively.

[0060] In some embodiments of this application, the flow battery includes a positive ultraviolet-visible (UV) fiber optic probe and a negative ultraviolet-visible (UV) fiber optic probe. The positive UV fiber optic probe is used to collect positive absorbance data, and the negative UV fiber optic probe is used to collect negative absorbance data. Furthermore, both the positive and negative UV fiber optic probes are integrated with an electromagnetic flowmeter, which can calculate the molar concentration of vanadium ions in real time and plot spectral characteristic curves based on the valence state changes of the electrolyte.

[0061] In some embodiments of this application, the coulombic efficiency data is obtained by measuring the amount of charge in the flow battery during charging and discharging, and then calculating the ratio of the discharged charge to the charged charge.

[0062] Step S102: Calculate the offset rate of electrolyte valence state shift based on the valence state shift identification data.

[0063] Here, the offset rate of electrolyte valence state shift may include, but is not limited to: open circuit voltage offset rate, charging voltage plateau offset rate, discharging voltage plateau offset rate, positive electrode absorbance offset rate, negative electrode absorbance offset rate, and coulombic efficiency offset rate.

[0064] In some embodiments of this application, the open-circuit voltage offset rate is calculated based on the collected real-time open-circuit voltage data and nominal open-circuit voltage data. Specifically, the difference between the real-time open-circuit voltage data and the nominal open-circuit voltage data is calculated, and the ratio of this difference to the nominal open-circuit voltage data is determined as the open-circuit voltage offset rate. The open-circuit voltage offset rate can be used to reflect the overall state change of the electrolyte.

[0065] Open circuit voltage deviation rate The calculation formula can be expressed as follows:

[0066]

[0067] in, For real-time open-circuit voltage data, This is the nominal open-circuit voltage data.

[0068] Here, Changes exceeding At 3%, it indicates that there may be a valence imbalance in the electrolyte. Figure 2 This illustration shows the offset between open-circuit voltage and state of charge (SOC) in some embodiments of this application, such as... Figure 2 As shown, the open-circuit voltage-state-of-charge curve of a normal flow battery is compared with V. 5+ The open-circuit voltage-state-of-charge curve of the accumulated flow battery has changed.

[0069] In some embodiments of this application, the charging voltage platform offset rate is calculated based on the collected real-time charging voltage platform data and nominal charging voltage platform data. Specifically, the difference between the real-time charging voltage platform data and the nominal charging voltage platform data is calculated, and the ratio of this difference to the nominal charging voltage platform data is determined as the charging voltage platform offset rate.

[0070] Charging voltage plateau offset The calculation formula can be expressed as follows:

[0071]

[0072] in, For real-time charging voltage platform data, This is the nominal charging voltage platform data.

[0073] Here, When the change exceeds 5%, it indicates that the electrolyte may have an imbalance in the positive electrode valence state.

[0074] In some embodiments of this application, the discharge voltage platform offset rate is calculated based on the collected real-time discharge voltage platform data and nominal discharge voltage platform data. Specifically, the difference between the real-time discharge voltage platform data and the nominal discharge voltage platform data is calculated, and the ratio of this difference to the nominal discharge voltage platform data is determined as the discharge voltage platform offset rate.

[0075] Discharge voltage plateau offset The calculation formula can be expressed as follows:

[0076]

[0077] in, For real-time discharge voltage platform data, This is the nominal discharge voltage platform data.

[0078] Here, When the change exceeds -5%, it indicates that the electrolyte may be in an unbalanced negative electrode state.

[0079] In some embodiments of this application, the positive electrode absorbance offset rate is determined based on the positive electrode absorbance data corresponding to the first positive electrode wavelength and the positive electrode absorbance data corresponding to the second positive electrode wavelength.

[0080] Here, the positive electrode UV fiber optic probe measures the corresponding positive electrode absorbance data in real time using ultraviolet-visible light with a wavelength of the first positive electrode wavelength, and measures the corresponding positive electrode absorbance data in real time using ultraviolet-visible light with a wavelength of the second positive electrode wavelength.

[0081] In some embodiments of this application, the first positive electrode wavelength is 760 nm, and the second positive electrode wavelength is 580 nm. Here, vanadium ions of different valence states in the electrolyte reach characteristic absorption peaks at different wavelengths in the ultraviolet-visible light band. This characteristic is used to distinguish the concentration of vanadium ions of different valence states in the electrolyte. For example, V in the positive electrode electrolyte... 5+ (VO2) + Vanadium ions reach a characteristic absorption peak in ultraviolet-visible light at a wavelength of 760 nm. 4+ (VO) 2+ It reaches its characteristic absorption peak in ultraviolet-visible light with a wavelength of 580 nanometers. Figure 3 This document illustrates schematic diagrams showing the changes in characteristic absorption peaks of the positive electrode electrolyte in the ultraviolet-visible spectrum in some embodiments of this application, such as... Figure 3 As shown, with the accumulation of V5+ vanadium ions in the positive electrode electrolyte, the absorbance of the positive electrode electrolyte at a wavelength of 760 nm gradually increases, while with the decrease of V4+ vanadium ions in the positive electrode electrolyte, the absorbance of the positive electrode electrolyte at a wavelength of 580 nm gradually decreases.

[0082] In some embodiments of this application, the ratio of the positive electrode absorbance data corresponding to the first positive electrode wavelength to the positive electrode absorbance data corresponding to the second positive electrode wavelength is determined as the positive electrode absorbance offset rate. The calculation formula can be expressed as follows:

[0083]

[0084] in, This refers to the absorbance data of the positive electrode corresponding to the first positive electrode wavelength. This is the absorbance data for the positive electrode corresponding to the second positive electrode wavelength.

[0085] In some embodiments of this application, the negative electrode absorbance offset rate is determined based on the negative electrode absorbance data corresponding to the first negative electrode wavelength and the negative electrode absorbance data corresponding to the second negative electrode wavelength.

[0086] Here, the negative electrode UV fiber optic probe measures the corresponding negative electrode absorbance data in real time using ultraviolet-visible light with a wavelength of the first negative electrode wavelength, and measures the corresponding negative electrode absorbance data in real time using ultraviolet-visible light with a wavelength of the second negative electrode wavelength.

[0087] In some embodiments of this application, the first negative electrode wavelength is 400 nanometers, and the second negative electrode wavelength is 650 nanometers. Similarly, V in the negative electrode electrolyte... 3+ Vanadium ions reach a characteristic absorption peak in ultraviolet-visible light at a wavelength of 400 nm. 2+ Vanadium ions reach a characteristic absorption peak in ultraviolet-visible light at a wavelength of 650 nm. Figure 4 This document illustrates schematic diagrams showing the changes in characteristic absorption peaks of the negative electrode electrolyte in the ultraviolet-visible spectrum in some embodiments of this application, such as... Figure 4 As shown, with the accumulation of V2+ vanadium ions in the negative electrode electrolyte, the absorbance of the negative electrode electrolyte at a wavelength of 650 nm gradually decreases, while with the decrease of V3+ vanadium ions in the negative electrode electrolyte, the absorbance of the negative electrode electrolyte at a wavelength of 400 nm gradually increases.

[0088] In some embodiments of this application, the ratio of the negative electrode absorbance data corresponding to the first negative electrode wavelength to the negative electrode absorbance data corresponding to the second negative electrode wavelength is determined as the negative electrode absorbance offset rate. The calculation formula can be expressed as follows:

[0089]

[0090] in, This refers to the absorbance data of the negative electrode corresponding to the first negative electrode wavelength. This is the absorbance data of the negative electrode corresponding to the second negative electrode wavelength.

[0091] When the absorbance shift rate of the positive electrode exceeds a certain threshold or the absorbance shift rate of the negative electrode is less than a certain threshold, an early warning of electrolyte valence state shift can be issued.

[0092] In some embodiments of this application, multiple coulomb efficiency data are continuously acquired according to a preset number of statistical iterations. When all multiple coulomb efficiency data are less than a preset coulomb efficiency threshold, a coulomb efficiency offset rate is determined based on the multiple coulomb efficiency data. Here, the number of statistical iterations can be determined according to the statistical requirements for coulomb efficiency, for example, 3 times. The coulomb efficiency threshold is a preset threshold that can be set as needed, for example, 95%.

[0093] The formula for calculating the coulomb efficiency (CE) can be expressed as follows:

[0094]

[0095] in, This represents the discharge charge of the flow battery. This refers to the amount of charge generated by the flow battery.

[0096] Here, the coulomb efficiency offset rate can be determined based on multiple coulomb efficiency data. Various methods can be used, such as determining the average value of multiple coulomb efficiency data as the coulomb efficiency offset rate, or determining the minimum value among multiple coulomb efficiency data as the coulomb efficiency offset rate, etc. This application embodiment does not impose specific limitations on this.

[0097] When the coulombic efficiency offset rate is less than the coulombic efficiency threshold, it indicates that there may be electrolyte imbalance or other abnormalities inside the flow battery, affecting the charge transfer efficiency.

[0098] In some embodiments of this application, after calculating the electrolyte valence state shift rate, the following steps can be performed: A valence state shift warning is issued when the positive electrode absorbance shift rate is between the positive electrode absorbance warning threshold and the positive electrode absorbance threshold, or when the negative electrode absorbance shift rate is between the negative electrode absorbance warning threshold and the negative electrode absorbance threshold. The positive electrode absorbance warning threshold is less than the positive electrode absorbance threshold, and the negative electrode absorbance warning threshold is greater than the negative electrode absorbance threshold. For example, if the positive electrode absorbance warning threshold is 1.3 and the positive electrode absorbance threshold is 1.5, then a positive electrode valence state shift warning is issued when the positive electrode absorbance shift rate is 1.4; similarly, if the negative electrode absorbance warning threshold is 1.2 and the negative electrode absorbance threshold is 1.0, then a negative electrode valence state shift warning is issued when the negative electrode absorbance shift rate is 1.1. By issuing valence state shift warnings, the flow battery is informed of the relevant valence state shift risk, and the user can assess whether to take appropriate measures based on the warning.

[0099] Step S103: If the open circuit voltage offset rate is greater than the open circuit voltage threshold or the charging voltage plateau offset rate is greater than the charging voltage plateau threshold, and the positive electrode absorbance offset rate is greater than the positive electrode absorbance threshold and the coulombic efficiency offset rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state offset is determined as the positive electrode valence state offset.

[0100] Here, identifying and judging the valence state shift of the electrolyte requires meeting multiple conditions. Once all conditions are met, the corresponding judgment is made, and the identification result is obtained.

[0101] In some embodiments of this application, the open-circuit voltage threshold is 0.03, i.e., 3%. When the open-circuit voltage offset rate calculated in step S102 is greater than the open-circuit voltage threshold, condition one is met.

[0102] In some embodiments of this application, the charging voltage platform threshold is 0.05, i.e., 5%. When the charging voltage platform offset rate calculated in step S102 is greater than the charging voltage platform threshold, condition two is met.

[0103] In some embodiments of this application, the positive electrode absorbance threshold is 1.5. When the positive electrode absorbance offset rate calculated in step S102 is greater than the positive electrode absorbance threshold, condition three is met.

[0104] In some embodiments of this application, the coulomb efficiency threshold is 95%. When the coulomb efficiency offset rate calculated in step S102 is less than the coulomb efficiency threshold, condition four is met.

[0105] Therefore, if conditions one, three, and four are all true, or if conditions two, three, and four are all true, the identification result is determined to be a positive valence state shift.

[0106] Step S104: If the open circuit voltage offset rate is greater than the open circuit voltage threshold or the discharge voltage plateau offset rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance offset rate is less than the negative electrode absorbance threshold and the coulombic efficiency offset rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state offset is determined as the negative electrode valence state offset.

[0107] Similarly, in some embodiments of this application, the discharge voltage plateau threshold is -0.05, or -5%. When the discharge voltage plateau offset rate calculated in step S102 is less than the discharge voltage plateau threshold, condition five is met.

[0108] In some embodiments of this application, the negative electrode absorbance threshold is 1.0. When the negative electrode absorbance offset rate calculated in step S102 is less than the negative electrode absorbance threshold, condition six is ​​met.

[0109] Therefore, if conditions one, four, and six are all true, or if conditions four, five, and six are all true, the identification result is determined to be a negative valence state shift.

[0110] In some embodiments of this application, the cumulative degree corresponding to the valence state shift can also be determined based on the shift rate of the electrolyte valence state shift, which may include the following steps:

[0111] (1) Based on the open-circuit voltage offset rate or charging voltage plateau offset rate, positive electrode absorbance offset rate and coulombic efficiency offset rate, the cumulative degree corresponding to the positive electrode valence state offset is determined by weighted method;

[0112] (2) Based on the open-circuit voltage offset rate or discharge voltage plateau offset rate, negative electrode absorbance offset rate and coulomb efficiency offset rate, the cumulative degree corresponding to the negative electrode valence state offset is determined by weighting method.

[0113] The specific calculation formula can be expressed as follows:

[0114] Cumulative degree corresponding to positive valence state shift (Open-circuit voltage offset or charging voltage plateau offset) Weight A (Positive absorbance shift rate) (Positive electrode absorbance threshold) / Positive electrode absorbance threshold Weight B (Coulomb efficiency offset) Coulomb efficiency threshold / Coulomb efficiency threshold Weight C.

[0115] Cumulative degree corresponding to negative valence state shift (Open circuit voltage offset rate or discharge voltage plateau offset rate) Weight A (Negative electrode absorbance shift rate) (Negative electrode absorbance threshold) / negative electrode absorbance threshold Weight B (Coulomb efficiency offset) Coulomb efficiency threshold / Coulomb efficiency threshold Weight C.

[0116] In some embodiments of this application, the weight A corresponding to the open-circuit voltage offset rate, the charging voltage plateau offset rate, and the discharging voltage plateau offset rate is 0.4, the weight B corresponding to the positive electrode absorbance offset rate and the negative electrode absorbance offset rate is 0.4, and the weight C corresponding to the coulombic efficiency offset rate is 0.2.

[0117] For example, after 200 cycles of operation of a 100kW / 400kWh vanadium redox flow battery system, the electrolyte state was monitored and analyzed. At a SOC of 50%, the open-circuit voltage measured by a high-precision voltage sensor was 1.355V, while its nominal open-circuit voltage is 1.30V. The open-circuit voltage deviation rate was calculated to be 4.2%, exceeding the open-circuit voltage threshold of 3%. Furthermore, absorbance data at a wavelength of 760 nm was obtained by measuring the positive electrode electrolyte using a UV-Vis fiber optic probe. and absorbance data at 580 nm wavelength The positive absorbance shift rate was calculated using the formula. The value was 1.52, exceeding the positive electrode absorbance threshold of 1.5. Furthermore, continuous monitoring of the coulombic efficiency yielded three consecutive coulombic efficiency data points, all of which were below the 95% coulombic efficiency threshold, with the lowest reaching 92.5%. Based on the aforementioned open-circuit voltage deviation rate, positive electrode absorbance deviation rate, and coulombic efficiency deviation rate, it can be determined that this flow battery exhibits a positive electrode V... 5+ The accumulation phenomenon is a positive electrode valence state shift, with a cumulative valence state shift degree of 0.4. 4.2% + 0.4 (1.52-1.5) / 1.5+0.2 (95%-92.5%) / 92.5%=2.74%.

[0118] For example, after 300 cycles of operation of the same 100kW / 400kWh vanadium redox flow battery system, the electrolyte state was monitored and analyzed again. During the discharge process, the measured discharge voltage plateau decreased to 1.18V using a high-precision voltage sensor, while the nominal discharge voltage plateau value was 1.28V. The discharge voltage plateau offset rate was calculated to be -7.8%, which is less than the discharge voltage plateau threshold of -5%. Furthermore, absorbance data at a wavelength of 400 nm were obtained by measuring the negative electrode electrolyte using a UV-Vis fiber optic probe. and absorbance data at 650 nm wavelength The negative electrode absorbance shift rate was calculated using the formula. The value was 0.85, which is less than the negative electrode absorbance threshold of 1.0. Furthermore, continuous monitoring of the coulombic efficiency yielded three consecutive coulombic efficiency data points, all of which were less than the coulombic efficiency threshold of 95%, with the lowest reaching 93%. Based on the aforementioned open-circuit voltage deviation rate, positive electrode absorbance deviation rate, and coulombic efficiency deviation rate, it can be determined that the flow battery exhibits a negative electrode V... 2+ The cumulative phenomenon is a negative valence state shift, with a cumulative degree of valence state shift of 0.4. 7.8% + 0.4 (1.0-0.85) / 1.0+0.2 (95%-93%) / 95%=9.54%.

[0119] Step S105: Based on the identification results, execute the corresponding electrolyte valence state recovery process.

[0120] In some embodiments of this application, when the identification result indicates a shift in the positive electrode valence state, an oxalic acid solution is injected into the positive electrode electrolyte or the negative electrode electrolyte is drawn into the positive electrode electrolyte to restore the positive electrode valence state. Specifically, one method is to inject a 0.1 mol / L oxalic acid solution into the positive electrode electrolyte, according to... The injection volume is determined by 90% of the excess molar amount of vanadium ions. By precisely controlling the injection volume, the reducing properties of oxalic acid are used to remove the excess vanadium. Vanadium ion reduction adjusts the valence state distribution of vanadium ions in the positive electrode electrolyte, restoring the capacity of the flow battery. Another method is to open the mixing valve from the negative electrode to the positive electrode after the flow battery has discharged, and start the negative electrode pump to draw the negative electrode electrolyte into the positive electrode storage tank, utilizing the vanadium ion content in the negative electrode electrolyte. Vanadium ions remove excess vanadium in the positive electrode electrolyte. Vanadium ions are reduced, thereby restoring the capacity of the flow battery.

[0121] In some embodiments of this application, when the identification result indicates a negative electrode valence state shift, the negative electrode electrolyte is subjected to external electrolysis or the positive electrode electrolyte is extracted into the negative electrode electrolyte to restore the negative electrode valence state. Specifically, one method is to start an external electrolytic cell and introduce the negative electrode electrolyte into the electrolytic cell for electrolysis. For example, the electrolysis current density can be set to 20 mA / cm², and the electrolysis time can be 2 hours. Through the electrolysis process, excess negative electrode electrolyte in the negative electrode electrolyte is removed. Vanadium ions are oxidized to Vanadium ions are used to adjust the valence state of the vanadium ions in the negative electrode electrolyte, restoring the electrolyte to equilibrium. Another method is to open the mixing valve from the positive to the negative electrode after the flow battery has discharged, and start the positive electrode pump to draw the positive electrode electrolyte into the negative electrode storage tank, utilizing the vanadium ions in the positive electrode electrolyte. Vanadium ions remove excess vanadium from the negative electrode electrolyte. Vanadium ion oxidation adjusts the valence state distribution of vanadium ions in the negative electrode electrolyte, restoring the capacity of the flow battery.

[0122] Some embodiments of this application also provide a system for identifying and recovering the valence state shift of a flow battery electrolyte, the system comprising:

[0123] The battery management module is used to collect valence state shift identification data of the flow battery. This data includes: open-circuit voltage data, charge / discharge voltage plateau data, positive and negative electrode absorbance data, and coulombic efficiency data. Based on this data, it calculates the electrolyte valence state shift rate, which includes: open-circuit voltage shift rate, charging voltage plateau shift rate, discharging voltage plateau shift rate, positive electrode absorbance shift rate, negative electrode absorbance shift rate, and coulombic efficiency shift rate. When the open-circuit voltage shift rate exceeds the open-circuit voltage threshold or the charging voltage plateau shift rate exceeds the charging voltage threshold, the battery management module will detect any deviations in the valence state shift data. If the positive electrode absorbance shift rate is greater than the positive electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the electrolyte valence state shift is identified as a positive electrode valence state shift. If the open circuit voltage shift rate is greater than the open circuit voltage threshold or the discharge voltage plateau shift rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance shift rate is less than the negative electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the electrolyte valence state shift is identified as a negative electrode valence state shift. Based on the identification results, the corresponding electrolyte valence state recovery process is executed.

[0124] OCV battery module, used to provide open-circuit voltage data;

[0125] The fuel cell stack voltage acquisition module is used to acquire the charging and discharging voltage platform data of the fuel cell stack module.

[0126] Positive UV fiber optic probe, used to collect positive absorbance data;

[0127] A negative electrode UV fiber optic probe is used to collect negative electrode absorbance data.

[0128] Positive electrode mixing valve is used to control the mixing process of negative electrode electrolyte flowing to positive electrode electrolyte;

[0129] The negative electrode mixing valve is used to control the mixing process of the positive electrode electrolyte flowing to the negative electrode electrolyte;

[0130] A positive electrode pump is used to drive the flow of positive electrode electrolyte to negative electrode electrolyte.

[0131] A negative electrode pump is used to drive the flow of negative electrode electrolyte to positive electrode electrolyte.

[0132] The reducing agent module is used to add a reducing agent to the positive electrode electrolyte;

[0133] The electrolytic cell module is used to electrolyze the introduced negative electrode electrolyte.

[0134] Figure 5 This application illustrates a flow battery electrolyte valence state shift identification and recovery system in some embodiments, such as... Figure 5 As shown, the battery management module 107 collects valence state shift identification data of the flow battery through the OCV battery module 105, the stack voltage acquisition module 205, the positive electrode UV fiber optic probe 103, and the negative electrode UV fiber optic probe 203, and calculates the corresponding open circuit voltage shift rate, charging voltage plateau shift rate, discharging voltage plateau shift rate, positive electrode absorbance shift rate, negative electrode absorbance shift rate, and coulombic efficiency shift rate. During the positive electrode valence state shift recovery process, the reducing agent module 108 can be controlled to add reducing agent to the positive electrode storage tank 101, or the positive electrode mixing valve 104 can be opened to start the negative electrode pump 202 to pump the negative electrode electrolyte into the positive electrode storage tank 101. During the negative electrode valence state shift recovery process, the negative electrode electrolyte can be introduced into the electrolytic cell module 206 for electrolysis, or the negative electrode mixing valve 204 can be opened to start the positive electrode pump 102 to pump the positive electrode electrolyte into the negative electrode storage tank 201.

[0135] Here, a UV fiber optic probe is used to replace the traditional offline spectrometer for monitoring the electrolyte optical properties of flow batteries. Due to the advantages of UV fiber optic probes such as small size, low cost, and online real-time monitoring, the cost can be reduced by more than 60% compared to offline spectrometers. In addition, while ensuring monitoring accuracy, the configuration of other hardware in the flow battery system is optimized, effectively controlling hardware costs and improving the system's cost-effectiveness. This is conducive to the promotion and application of vanadium redox flow batteries in the field of large-scale energy storage.

[0136] Furthermore, the electrolyte valence state shift identification and recovery system of the flow battery embodiment of this application fully considers compatibility with existing vanadium redox flow battery systems. Only appropriate modifications are needed to the electrolyte pipeline of the existing flow battery to integrate the online monitoring module. There is no need for large-scale and complex modifications to the flow battery system. This allows existing vanadium redox flow battery systems to be easily and quickly upgraded to flow battery systems with high-precision electrolyte valence state monitoring functions, protecting the user's initial investment and improving the versatility and practicality of the flow battery system.

[0137] In summary, the solution provided in this application can collect valence state shift identification data of flow batteries and calculate the shift rate of electrolyte valence state shift based on the valence state shift identification data. When the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the charging voltage plateau shift rate is greater than the charging voltage plateau threshold, and the positive electrode absorbance shift rate is greater than the positive electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state shift is determined as a positive electrode valence state shift. When the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the discharge voltage plateau shift rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance shift value is less than the negative electrode absorbance threshold and the coulombic efficiency shift rate is less than the negative electrode absorbance threshold, the solution can be determined as a positive electrode valence state shift. Under the condition of the coulomb efficiency threshold, the identification result of electrolyte valence state shift is determined as negative electrode valence state shift. Then, based on the identification result, the corresponding electrolyte valence state recovery process is executed. This enables the judgment of positive and negative electrode valence state shift based on multiple parameters, accurately distinguishes the type of positive and negative electrode valence state imbalance, provides precise guidance for targeted capacity recovery measures, and enables quantitative assessment of the degree of imbalance, providing data support for refined management. Furthermore, it triggers early warning in the early stage of valence state shift, enabling timely measures to avoid battery performance deterioration. It also enables battery capacity recovery based on valence state shift monitoring results, resulting in a high battery capacity retention rate and reduced operation and maintenance costs.

[0138] It should be noted that this application can be implemented in software and / or a combination of software and hardware, for example, using an application-specific integrated circuit (ASIC), a general-purpose computer, or any other similar hardware device. In one embodiment, the software program of this application can be executed by a processor to implement the steps or functions described above. Similarly, the software program of this application (including related data structures) can be stored in a computer-readable recording medium, such as RAM memory, a magnetic or optical drive, a floppy disk, or similar devices. Furthermore, some steps or functions of this application can be implemented in hardware, for example, as circuitry that cooperates with a processor to perform the various steps or functions.

[0139] In a typical configuration of this application, both the terminal and the network device include one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0140] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0141] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include non-transitory computer-readable media, such as modulated data signals and carrier waves.

[0142] Furthermore, a portion of this application can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to this application through the operation of the computer. The program instructions invoking the methods of this application may be stored in a fixed or removable recording medium, and / or transmitted via a data stream in a broadcast or other signal carrying medium, and / or stored in the working memory of a computer device operating according to the program instructions. Here, one embodiment of this application includes a device comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein, when the computer program instructions are executed by the processor, the device is triggered to run methods and / or technical solutions based on the foregoing embodiments of this application.

[0143] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices recited in the apparatus claims may also be implemented by a single unit or device in software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

Claims

1. A method for identifying and recovering the valence state shift of an electrolyte in a flow battery, characterized in that, The method includes: Collect valence state shift identification data of flow batteries, wherein the valence state shift identification data includes: open circuit voltage data, charge and discharge voltage plateau data, positive and negative electrode absorbance data, and coulombic efficiency data; Based on the valence state shift identification data, the offset rate of the electrolyte valence state shift is calculated, wherein the offset rate of the electrolyte valence state shift includes: open circuit voltage offset rate, charging voltage plateau offset rate, discharging voltage plateau offset rate, positive electrode absorbance offset rate, negative electrode absorbance offset rate, and coulombic efficiency offset rate. If the open circuit voltage offset rate is greater than the open circuit voltage threshold or the charging voltage plateau offset rate is greater than the charging voltage plateau threshold, and the positive electrode absorbance offset rate is greater than the positive electrode absorbance threshold and the coulombic efficiency offset rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state offset is determined as the positive electrode valence state offset. If the open circuit voltage offset rate is greater than the open circuit voltage threshold or the discharge voltage plateau offset rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance offset rate is less than the negative electrode absorbance threshold and the coulombic efficiency offset rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state offset is determined to be a negative electrode valence state offset. Based on the identification result, the corresponding electrolyte valence state recovery process is performed, including: if the identification result is a positive electrode valence state shift, injecting oxalic acid solution into the positive electrode electrolyte or extracting the negative electrode electrolyte into the positive electrode electrolyte to restore the positive electrode valence state; if the identification result is a negative electrode valence state shift, performing external electrolysis on the negative electrode electrolyte or extracting the positive electrode electrolyte into the negative electrode electrolyte to restore the negative electrode valence state.

2. The method according to claim 1, characterized in that, Based on the valence state shift identification data, the shift rate of the electrolyte valence state shift is calculated, including: The positive electrode absorbance shift rate is determined based on the positive electrode absorbance data corresponding to the first positive electrode wavelength and the positive electrode absorbance data corresponding to the second positive electrode wavelength. The negative electrode absorbance offset rate is determined based on the negative electrode absorbance data corresponding to the first negative electrode wavelength and the negative electrode absorbance data corresponding to the second negative electrode wavelength.

3. The method according to claim 2, characterized in that, The first positive electrode wavelength is 760 nanometers, the second positive electrode wavelength is 580 nanometers, the first negative electrode wavelength is 400 nanometers, and the second negative electrode wavelength is 650 nanometers.

4. The method according to claim 1, characterized in that, The absorbance threshold of the positive electrode is 1.5, and the absorbance threshold of the negative electrode is 1.

0.

5. The method according to claim 1, characterized in that, The charging voltage plateau threshold is 0.05, and the discharging voltage plateau threshold is -0.

05.

6. The method according to claim 1, characterized in that, The method also includes: Based on the open-circuit voltage offset rate or the charging voltage plateau offset rate, the positive electrode absorbance offset rate and the coulombic efficiency offset rate, the cumulative degree corresponding to the positive electrode valence state offset is determined by a weighted method. The cumulative degree corresponding to the negative electrode valence state shift is determined by a weighted method based on the open circuit voltage shift rate or the discharge voltage plateau shift rate, the negative electrode absorbance shift rate, and the coulombic efficiency shift rate.

7. The method according to claim 6, characterized in that, The weights corresponding to the open-circuit voltage offset rate, the charging voltage plateau offset rate, the discharging voltage plateau offset rate, the positive electrode absorbance offset rate, and the negative electrode absorbance offset rate are 0.4, and the weight corresponding to the coulombic efficiency offset rate is 0.

2.

8. The method according to claim 1, characterized in that, After calculating the offset rate of the electrolyte valence state shift, the following is also included: A valence state shift warning is issued when the positive electrode absorbance shift rate is between the positive electrode absorbance warning threshold and the positive electrode absorbance threshold, or when the negative electrode absorbance shift rate is between the negative electrode absorbance warning threshold and the negative electrode absorbance threshold.

9. A system for identifying and recovering the valence state shift of an electrolyte in a flow battery, characterized in that, The system includes: The battery management module is used to: collect valence state shift identification data of the flow battery, wherein the valence state shift identification data includes: open-circuit voltage data, charge / discharge voltage plateau data, positive and negative electrode absorbance data, and coulombic efficiency data; calculate the offset rate of electrolyte valence state shift based on the valence state shift identification data, wherein the offset rate of electrolyte valence state shift includes: open-circuit voltage offset rate, charging voltage plateau offset rate, discharging voltage plateau offset rate, positive electrode absorbance offset rate, negative electrode absorbance offset rate, and coulombic efficiency offset rate; and, if the open-circuit voltage offset rate is greater than an open-circuit voltage threshold or the charging voltage plateau offset rate is greater than a charging voltage plateau threshold, and the positive electrode absorbance offset rate is greater than a positive electrode absorbance threshold and the coulombic efficiency offset rate is less than a coulombic efficiency threshold, adjust the electrolyte valence state shift data accordingly. The identification result is determined to be a positive electrode valence state shift. If the open-circuit voltage shift rate is greater than the open-circuit voltage threshold or the discharge voltage plateau shift rate is less than the discharge voltage plateau threshold, and the negative electrode absorbance shift rate is less than the negative electrode absorbance threshold and the coulombic efficiency shift rate is less than the coulombic efficiency threshold, the identification result of the electrolyte valence state shift is determined to be a negative electrode valence state shift. Based on the identification result, a corresponding electrolyte valence state recovery process is executed, including: if the identification result is a positive electrode valence state shift, injecting oxalic acid solution into the positive electrode electrolyte or extracting the negative electrode electrolyte into the positive electrode electrolyte to perform positive electrode valence state recovery; if the identification result is a negative electrode valence state shift, performing external electrolysis on the negative electrode electrolyte or extracting the positive electrode electrolyte into the negative electrode electrolyte to perform negative electrode valence state recovery. OCV battery module, used to provide open-circuit voltage data; The fuel cell stack voltage acquisition module is used to acquire the charging and discharging voltage platform data of the fuel cell stack module. Positive UV fiber optic probe, used to collect positive absorbance data; A negative electrode UV fiber optic probe is used to collect negative electrode absorbance data. Positive electrode mixing valve is used to control the mixing process of negative electrode electrolyte flowing to positive electrode electrolyte; The negative electrode mixing valve is used to control the mixing process of the positive electrode electrolyte flowing to the negative electrode electrolyte; A positive electrode pump is used to drive the flow of positive electrode electrolyte to negative electrode electrolyte. A negative electrode pump is used to drive the flow of negative electrode electrolyte to positive electrode electrolyte. The reducing agent module is used to add a reducing agent to the positive electrode electrolyte; The electrolytic cell module is used to electrolyze the introduced negative electrode electrolyte.

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