Single-battery conductance diffusion combined testing device and method for all-vanadium redox flow battery

Abstract

The invention provides an all-vanadium redox flow battery single cell conductance diffusion combined test device and method, which are applied to the detection of all-vanadium redox flow battery single cells. A plurality of electrolyte leading-out ports are formed in an electrode frame of the single battery, electrolyte leading-out pipes are arranged in the electrolyte leading-out ports, and valves are arranged on the electrolyte leading-out pipes; the conductance-diffusion combined testing device comprises a diffusion cell assembly, an electrolyte conveying assembly and a detection assembly, the electrolyte conveying assembly is communicated with an electrolyte outlet pipe and used for pumping a positive electrode electrolyte and a negative electrode electrolyte in a single cell into the diffusion cell assembly, and the detection assembly is used for detecting the positive electrode electrolyte and the negative electrode electrolyte in the single cell. Or the positive electrode electrolyte and the negative electrode electrolyte in the diffusion cell assembly are pumped back into the single cell. By analyzing and comparing the H < + > content, conductivity, charge and discharge data of the electrolyte measured at different single battery structures, different positions and different time, the internal impedance distribution and change of the single battery in the charge and discharge process are effectively judged, and the result is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of all-vanadium redox flow batteries, and in particular to a test device and method for combined conductance and diffusion of a single cell of an all-vanadium redox flow battery. Background Art

[0002] An all-vanadium redox flow battery is a redox battery with vanadium as the active substance in a circulating liquid state, and mainly uses the change of the valence state of vanadium ions to realize the storage and release of electric energy. A single cell of an all-vanadium redox flow battery is the basic unit for charging and discharging. After being amplified and stacked, it becomes a flow battery stack in actual industrial applications, and finally forms an energy storage system. In current daily production work, a single cell is generally used as a test tool to simulate and evaluate the reliability of components and links such as electrodes, bipolar plates, diaphragms, electrolytes, and flow field designs for all-vanadium redox flow batteries.

[0003] The internal impedance of a single cell is an important factor affecting its charge and discharge performance, in addition to material-related factors such as electrode activity, bipolar plate conductivity, and diaphragm impedance. The electrolyte distribution and polarization resistance caused by the internal flow field design of the battery are key factors affecting the battery impedance. Currently, the commonly used methods generally detect the open-circuit internal resistance of a single cell, or use the alternating current impedance method (Appendix A of NBT 42081-2016) to measure the impedance of a single cell. However, the detection process is relatively independent of the charge and discharge process, and may also cause a certain impact on the internal structure of the single cell. It can only be used as a reference for subsequent charge and discharge tests, and cannot reflect the real-time effects of electrolyte distribution, polarization, flow field, etc. during the charge and discharge process. The traditional analysis method is to use mold flow analysis software to simulate the flow distribution of the electrolyte, and judge the impedance caused by it through experience, which often does not match the subsequent actual test results.

[0004] Currently, the internal resistance of a single cell is generally detected in an open-circuit state. After the charge and discharge start, the internal resistance can only be judged by experience through the input voltage and current. The electrolyte generally enters the single cell from the bottom up at the positive and negative electrodes respectively, infiltrates the electrodes and reacts at the active sites of the electrodes. In actual use, there will be uneven electrolyte distribution on electrodes with a slightly larger area. The uneven electrolyte distribution is generally caused by two aspects. The first aspect is the problem of flow field design, which causes the electrolyte to not flow to or accumulate in some positions; this aspect is generally alleviated by the diversion design of the liquid flow frame of the single cell, and the flow field uniformity is simulated and analyzed by mold flow analysis software. The second aspect is that side reactions occur in some positions in the single cell (such as hydrogen evolution and oxygen evolution causing bubbles and voids, precipitation due to over-oxidation or reduction of vanadium ions, and electrolysis of water causing an increase in vanadium concentration). The causes of this are particularly complex, and there is no general method for analysis, especially when both the first aspect and the second aspect exist. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a combined conductance and diffusion test device and method for a single cell of a vanadium redox flow battery, which is used to solve the problem that in the prior art, a mold flow analysis software is used to simulate the flow distribution of the electrolyte, and the impedance caused by it is judged by experience, which is inconsistent with the actual test results.

[0006] To achieve the above and other related purposes, the present invention provides a combined conductance and diffusion test device for a single cell of a vanadium redox flow battery, which is applied to the detection of a single cell of a vanadium redox flow battery; a plurality of electrolyte outlets are provided on the electrode frame of the single cell, and electrolyte outlet pipes are arranged in the electrolyte outlets, and valves are arranged on the electrolyte outlet pipes; the combined conductance and diffusion test device includes a diffusion cell assembly, an electrolyte delivery assembly, and a detection assembly. The electrolyte delivery assembly is communicated with the electrolyte outlet pipe, and is used to pump the positive electrolyte and the negative electrolyte in the single cell into the diffusion cell assembly, or pump the positive electrolyte and the negative electrolyte in the diffusion cell assembly back into the single cell; the detection assembly is arranged in the diffusion cell assembly and is used to detect the positive electrolyte and the negative electrolyte in the single cell.

[0007] Preferably, the electrode frame of the single cell includes a positive electrode frame and a negative electrode frame, and electrolyte outlets are provided on both the positive electrode frame and the negative electrode frame; a plurality of electrolyte outlets are distributed at different positions on the positive electrode frame and the negative electrode frame, and the positions of the electrolyte outlets on the positive electrode frame and the positions of the electrolyte outlets on the negative electrode frame correspond one by one.

[0008] Preferably, the diffusion cell assembly includes a positive electrolyte storage tank and a negative electrolyte storage tank. The positive electrolyte storage tank is communicated with the electrolyte outlet on the positive electrode frame through the electrolyte delivery assembly, and the negative electrolyte storage tank is communicated with the electrolyte outlet on the negative electrode frame through the electrolyte delivery assembly; the detection assembly includes conductivity probes, and two conductivity probes are respectively arranged in the positive electrolyte storage tank and the negative electrolyte storage tank.

[0009] Preferably, a contactor is further arranged between the positive electrolyte storage tank and the negative electrolyte storage tank. The contactor includes a contactor diaphragm and shut-off valves. The number of shut-off valves is two and they are located on both sides of the contactor diaphragm; when the shut-off valves are opened, the positive electrolyte in the positive electrolyte storage tank and the negative electrolyte in the negative electrolyte storage tank contact through the contactor diaphragm; the detection assembly further includes a storage tank positive connector and a storage tank negative connector. One end of the storage tank positive connector is located inside the positive electrolyte storage tank, and the other end is located outside the positive electrolyte storage tank; one end of the storage tank negative connector is located inside the negative electrolyte storage tank, and the other end is located outside the negative electrolyte storage tank.

[0010] Preferably, the diffusion cell assembly further includes a positive electrolyte diffusion cell and a negative electrolyte diffusion cell, and the positive electrolyte diffusion cell is connected to the positive electrolyte storage cell through a contactor; the negative electrolyte diffusion cell is connected to the negative electrolyte storage cell through a contactor; the detection assembly further includes a pH probe, and the two pH probes are respectively arranged in the positive electrolyte diffusion cell and the negative electrolyte diffusion cell.

[0011] Preferably, a liquid inlet pipeline is arranged in the positive electrolyte diffusion cell and the negative electrolyte diffusion cell for injecting deionized water or liquid to be diffused into the positive electrolyte diffusion cell and the negative electrolyte diffusion cell.

[0012] Preferably, a liquid outlet pipeline is arranged in the positive electrolyte diffusion cell and the negative electrolyte diffusion cell for discharging the liquid in the positive electrolyte diffusion cell and the negative electrolyte diffusion cell.

[0013] Preferably, the positive electrolyte storage cell, the negative electrolyte storage cell, the positive electrolyte diffusion cell, and the negative electrolyte diffusion cell are all sealed containers; the diffusion cell assembly further includes an inflation assembly for inflating the positive electrolyte storage cell, the negative electrolyte storage cell, the positive electrolyte diffusion cell, and the negative electrolyte diffusion cell.

[0014] Preferably, the volumes of the positive electrolyte storage cell, the negative electrolyte storage cell, the positive electrolyte diffusion cell, and the negative electrolyte diffusion cell are 1‰ - 2‰ of the volume of the electrolyte storage tank in a single cell; the effective area of the contactor diaphragm is 5% - 10% of the effective area of the electrode diaphragm in a single cell.

[0015] To achieve the above object or other objects, the present invention also discloses a method for testing the combined conductivity and diffusion of a single cell of a vanadium redox flow battery. Using the above-mentioned device for testing the combined conductivity and diffusion of a single cell of a vanadium redox flow battery, the steps are as follows: Connect the electrolyte outlet pipe on the electrode frame of the single cell to the diffusion cell assembly through the electrolyte conveying assembly, pump the positive electrolyte and the negative electrolyte in the single cell into the diffusion cell assembly, and the detection assembly detects the positive electrolyte and the negative electrolyte; after the detection is completed, the positive electrolyte and the negative electrolyte in the diffusion cell assembly are pumped back into the single cell through the electrolyte conveying assembly.

[0016] As described above, the device and method for testing the combined conductivity and diffusion of a single cell of a vanadium redox flow battery of the present invention have the following beneficial effects:

[0017] 1. The detection of the single cell in the present invention includes the detection of the conductivity of the single-pole electrolyte itself, the detection of the conductivity between the positive and negative electrolytes, and the detection of H in the single-pole electrolyte. +The content is detected, and a plurality of electrolyte outlets are provided on the electrode frame of the single cell, so that the electrolytes at different positions in the electrode frame can be analyzed, and a more accurate and real-time scenario of the electrolyte flow field, concentration, and polarization distribution inside the single cell can be obtained.

[0018] 2. In the present invention, the electrolyte in the single cell is introduced into an independent diffusion cell assembly, which ensures the independence from the charge and discharge test of the single cell as much as possible. By controlling the proportional relationship between the single cell and the external diffusion cell, as well as the test time, etc., it is ensured that factors such as the migration of hydrogen ions, vanadium ions, and water molecules will not affect the original charge and discharge process of the single cell.

[0019] 3. When detecting the content of H + in the single-pole electrolyte of the present invention, through a preliminary experiment of ion diffusion of electrolytes with different H + contents and a specific membrane, after establishing a model, the pH data measured in the experiment of the present invention is converted to obtain the H + content in the electrolyte.

[0020] 4. By analyzing and comparing the data of the H + content, conductivity, charge and discharge, etc. of the electrolytes measured in different single cell structures, different positions, and different times of the present invention, the internal impedance distribution and changes in the single cell during the charge and discharge process can be effectively judged, and the results are more accurate. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the internal structure of the single cell adopted in the present invention;

[0022] Figure 2 It is a schematic diagram showing that a plurality of electrolyte outlets are provided on the electrode frame of the single cell in the present invention;

[0023] Figure 3 It is a top view of the diffusion cell assembly in the present invention;

[0024] Figure 4 It is a front view of the diffusion cell assembly in the present invention;

[0025] Figure 5 It is a schematic diagram of the overall structure of the combined conductivity and diffusion test device for a single cell of a vanadium redox flow battery in the present invention.

[0026] Description of the Reference Numerals:

[0027] 1. Positive electrode electrolyte storage tank; 2. Electrode diaphragm; 3. Positive electrode current collector plate; 4. Positive electrode bipolar plate; 5. Positive electrode electrode frame; 6. Positive electrode; 7. Negative electrode; 8. Negative electrode bipolar plate; 9. Negative electrode electrode frame; 901. First liquid outlet lead-out port; 902. Second liquid outlet lead-out port; 903. First liquid inlet lead-out port; 904. Second liquid inlet lead-out port; 905. Valve; 10. Negative electrode current collector plate; 11. Frame plate; 12. Negative electrode electrolyte storage tank; 13. Positive electrode electrolyte storage pool; 1301. Storage pool positive electrode connector; 14. Negative electrode electrolyte storage pool; 1401. Storage pool negative electrode connector; 15. Positive electrode electrolyte diffusion pool; 16. Negative electrode electrolyte diffusion pool; 17. Conductivity probe; 18. PH meter probe; 19. Contactor; 1901. Tight shut-off valve; 1902. Contactor diaphragm; 20. Inflation assembly; 2001. Inflation pipeline; 21. Liquid storage tank to be diffused; 2101. Liquid inlet pipeline; 22. Liquid receiving tray; 23. Liquid outlet; 24. Delivery pipeline. Detailed implementation manners

[0028] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0029] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the limited conditions for the implementation of the present invention. Therefore, they do not have technical essential significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of clear narration and are not used to limit the scope for the implementation of the present invention. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope for the implementation of the present invention.

[0030] Such as Figures 1 - 5As shown in the figure, the present invention provides a combined conductance and diffusion testing device for a single cell of a vanadium redox flow battery, which is applied to the detection of a single cell of a vanadium redox flow battery. A plurality of electrolyte outlets are provided on the electrode frame of the single cell, and electrolyte outlet pipes are arranged in the electrolyte outlets. A valve 905 is arranged on the electrolyte outlet pipe. The combined conductance and diffusion testing device includes a diffusion cell assembly, an electrolyte delivery assembly, and a detection assembly. The electrolyte delivery assembly is communicated with the electrolyte outlet pipe and is used to pump the positive electrolyte and the negative electrolyte in the single cell into the diffusion cell assembly, or pump the positive electrolyte and the negative electrolyte in the diffusion cell assembly back into the single cell. The detection assembly is arranged in the diffusion cell assembly and is used to detect the positive electrolyte and the negative electrolyte in the single cell.

[0031] The combined conductance and diffusion testing device for a single cell of a vanadium redox flow battery involved in the present invention pumps the electrolyte in the single cell into the diffusion cell assembly by providing a plurality of electrolyte outlets on the electrode frame and through the electrolyte delivery assembly. The detection assembly in the diffusion cell assembly is used to detect the positive electrolyte and the negative electrolyte. The detected contents include data such as the conductivity of the single-pole electrolyte itself, the conductivity between the positive and negative electrolytes, and the H + content in the single-pole electrolyte. Then, the above data is combined with the charge and discharge data corresponding to the single cell, so as to analyze and evaluate the disadvantages existing in the structural design of the single cell itself and propose corresponding improvement solutions for the disadvantages.

[0032] Preferably, as Figure 1 、 Figure 2 shown, the electrode frame of the single cell includes a positive electrode frame 5 and a negative electrode frame 9. Electrolyte outlets are provided on both the positive electrode frame 5 and the negative electrode frame 9. A plurality of electrolyte outlets are distributed at different positions on the positive electrode frame 5 and the negative electrode frame 9. The positions of the electrolyte outlets are determined according to actual needs. Generally, in the design of a single cell, the liquid paths at both poles are mirror images of each other, so the positions of the electrolyte outlets can be mirror images of each other. However, there are also cases where the flow channels of the positive and negative electrodes of a single cell adopt completely different designs, so the extraction points of the positive and negative electrodes need to be determined according to the actual flow channels of the single cell.

[0033] Further, as Figure 1As shown in the figure, the single cell further includes a positive electrolyte storage tank 1, a positive current collector plate 3, a positive bipolar plate 4, a positive electrode 6, an electrode separator 2, a negative electrode 7, a negative bipolar plate 8, a negative current collector plate 10, two frame plates 11, and a negative electrolyte storage tank 12. The positive electrode 6 and the negative electrode 7 are arranged on both sides of the electrode separator 2; a positive electrode frame 5 is arranged on the outer periphery of the positive electrode 6, and a negative electrode frame 9 is arranged on the outer periphery of the negative electrode 7; the positive bipolar plate 4 is arranged on the side of the positive electrode 6 away from the electrode separator 2, and the negative bipolar plate 8 is arranged on the side of the negative electrode 7 away from the electrode separator 2; the positive current collector plate 3 is arranged on the side of the positive bipolar plate 4 away from the electrode separator 2, and the negative current collector plate 10 is arranged on the side of the negative bipolar plate 8 away from the electrode separator 2; the two frame plates 11 are respectively arranged on the side of the positive current collector plate 3 away from the electrode separator 2 and on the side of the negative current collector plate 10 away from the electrode separator 2; the positive electrolyte storage tank 1 is connected to the positive electrode frame 5 through a pipeline to inject positive electrolyte into the positive electrode frame 5, and the negative electrolyte storage tank 12 is connected to the negative electrode frame 9 through a pipeline to inject negative electrolyte into the negative electrode frame 9.

[0034] Further, as Figure 2 shown, this figure is a right view of the single cell, and the electrode frame shown is the negative electrode frame 9. Liquid electrolyte outlets are respectively opened at the upper, lower, left, and right corners of the negative electrode frame 9. Among them, the two liquid electrolyte outlets on the upper side are respectively the first liquid outlet 901 and the second liquid outlet 902; the two liquid electrolyte outlets on the lower side are respectively the first liquid inlet 903 and the second liquid inlet 904. In this embodiment, the positions and quantities of the liquid electrolyte outlets are determined according to the internal flow channel design of the electrode frame.

[0035] Correspondingly, liquid electrolyte outlets are also provided at the corresponding positions on the positive electrode frame 5, which will not be repeated here.

[0036] When detection is required, during the charge and discharge process of the single cell, the valve 905 on the first liquid inlet 903 can be opened, and the valves 905 on other liquid electrolyte outlets are closed. In this way, the negative electrolyte at the first liquid inlet 903 is pumped into the diffusion cell assembly; at the same time, the valve 905 on the liquid electrolyte outlet at the corresponding position on the positive electrode frame 5 is opened, and the positive electrolyte is pumped into the diffusion cell assembly, so as to realize the detection of the positive electrolyte and the negative electrolyte.

[0037] Preferably, as Figure 1 、 Figure 2 、 Figure 3As shown, the diffusion cell assembly includes a positive electrolyte storage tank 13 and a negative electrolyte storage tank 14. The positive electrolyte storage tank 13 is connected to the electrolyte outlet on the positive electrode frame 5 through an electrolyte delivery assembly, and the negative electrolyte storage tank 14 is connected to the electrolyte outlet on the negative electrode frame 9 through an electrolyte delivery assembly. The detection assembly includes conductivity probes 17, and two conductivity probes 17 are respectively arranged in the positive electrolyte storage tank 13 and the negative electrolyte storage tank 14. The conductivity probe 17 is a micro conductivity probe.

[0038] In this embodiment, the electrolyte delivery assembly includes a delivery pump and a delivery pipeline 24. The delivery pump can deliver the electrolyte forward or backward. The number of conductivity probes 17 is two, which are respectively used to detect the conductivity of the positive electrolyte and the negative electrolyte itself.

[0039] Preferably, as Figure 3 As shown, a contactor 19 is further arranged between the positive electrolyte storage tank 13 and the negative electrolyte storage tank 14. The contactor 19 includes a contactor diaphragm 1902 and a shut-off valve 1901. The number of shut-off valves 1901 is two and they are located on both sides of the contactor diaphragm 1902. When the shut-off valve 1901 is opened, the positive electrolyte in the positive electrolyte storage tank 13 and the negative electrolyte in the negative electrolyte storage tank 14 come into contact through the contactor diaphragm 1902. The detection assembly further includes a storage tank positive terminal 1301 and a storage tank negative terminal 1401. One end of the storage tank positive terminal 1301 is located inside the positive electrolyte storage tank 13, and the other end is located outside the positive electrolyte storage tank 13. One end of the storage tank negative terminal 1401 is located inside the negative electrolyte storage tank 14, and the other end is located outside the negative electrolyte storage tank 14. Further, the material of the contactor diaphragm 1902 is the same as the model of the electrode diaphragm 2. The storage tank positive terminal 1301 and the storage tank negative terminal 1401 are corrosion-resistant metal electrode terminals.

[0040] When detecting the conductivity between the positive electrolyte and the negative electrolyte, the shut-off valve 1901 of the contactor 19 between the positive electrolyte storage tank 13 and the negative electrolyte storage tank 14 is opened, the positive electrolyte and the negative electrolyte come into contact through the contactor diaphragm 1902. At the same time, the storage tank positive terminal 1301 and the storage tank negative terminal 1401 are connected to an external electrochemical workstation, and then the conductivity between the positive electrolyte and the negative electrolyte is measured by the AC impedance method.

[0041] Preferably, as Figure 3As shown in the figure, the diffusion cell assembly further includes a positive electrolyte diffusion cell 15 and a negative electrolyte diffusion cell 16. The positive electrolyte diffusion cell 15 is connected to the positive electrolyte storage cell 13 through a contactor 19; the negative electrolyte diffusion cell 16 is connected to the negative electrolyte storage cell 14 through a contactor 19; the detection assembly further includes a pH probe 18, and the two pH probes 18 are respectively arranged in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16. Among them, there is no contact between the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16. The positive electrolyte storage cell 13, the negative electrolyte storage cell 14, the positive electrolyte diffusion cell 15, and the negative electrolyte diffusion cell 16 constitute a 2*2 four-connected diffusion cell assembly. The pH probe 18 is a micro pH probe.

[0042] Further, as Figure 4 shown in the figure, a liquid inlet pipeline 2101 is arranged in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 for injecting deionized water or the liquid to be diffused into the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16. The liquid to be diffused can be a MgSO4 solution, and the liquid to be diffused is stored in the liquid storage tank 21 to be diffused.

[0043] When detecting the H + content in the positive electrolyte and the negative electrolyte, the shut-off valve 1901 of the contactor 19 between the positive electrolyte diffusion cell 15 and the positive electrolyte storage cell 13 is opened, and the H + in the positive electrolyte passes through the contactor diaphragm 1902 and enters the positive electrolyte diffusion cell 15. The shut-off valve 1901 of the contactor 19 between the negative electrolyte diffusion cell 16 and the negative electrolyte storage cell 14 is opened, and the H + in the negative electrolyte passes through the contactor diaphragm 1902 and enters the negative electrolyte diffusion cell 16. The shut-off valve 1901 of the contactor 19 between the positive electrolyte storage cell 13 and the negative electrolyte storage cell 14 is closed. Within a specific time (5 minutes in this embodiment), the pH values in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 are respectively measured by the two pH probes 18, and then the H + content in the positive electrolyte and the negative electrolyte is inversely deduced through the data model of the pH value and the H + content in the electrolyte.

[0044] Further, the data model of the pH value and the H + content in the electrolyte is to place the same contactor diaphragm 1902 in electrolytes with different concentrations for ion diffusion pre-experiments, and establish a model of the H + concentration diffused within a specific time and the initial H + content in the electrolyte according to the results of the ion diffusion pre-experiments. And the H +The conversion formula between concentration and pH value is prior art, so the H+ content in the electrolyte can be deduced by measuring the pH value. + content.

[0045] Preferably, as shown in Figure 4 and Figure 5 , liquid discharge pipelines are provided in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 for discharging the liquid in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16. Further, in this embodiment, a liquid receiving tray 22 is provided below the liquid discharge pipeline for receiving deionized water or liquid to be diffused in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16.

[0046] Preferably, as shown in Figure 4 and Figure 5 , the positive electrolyte storage tank 13, the negative electrolyte storage tank 14, the positive electrolyte diffusion cell 15, and the negative electrolyte diffusion cell 16 are all closed containers; the diffusion cell assembly further includes an air filling assembly 20, and the air filling assembly 20 fills the positive electrolyte storage tank 13, the negative electrolyte storage tank 14, the positive electrolyte diffusion cell 15, and the negative electrolyte diffusion cell 16 with gas through an air filling pipeline 2001. Further, in this embodiment, the gas filled by the air filling assembly 20 is argon or other inert gases. After the gas enters the closed space, the liquid in each closed space can be quickly emptied for the next test cycle.

[0047] Preferably, in this embodiment, the effective area of the contactor diaphragm 1902 is 5% - 10% of the effective area of the electrode diaphragm 2 in the single cell.

[0048] In this embodiment, since the diffusion tests of the positive electrolyte and the negative electrolyte in the single cell are carried out, in order to minimize the influence of the conductance diffusion test on the charge and discharge test to the greatest extent. The volumes of the positive electrolyte storage tank 13, the negative electrolyte storage tank 14, the positive electrolyte diffusion cell 15, and the negative electrolyte diffusion cell 16 are 1‰ - 2‰ of the volume of the electrolyte storage tank in the single cell; for example: when the positive electrolyte and the negative electrolyte in the single cell are each 100 mL, the volumes of the positive electrolyte storage tank 13, the negative electrolyte storage tank 14, the positive electrolyte diffusion cell 15, and the negative electrolyte diffusion cell 16 are in the range of 100 μL - 200 μL. At the same time, the effective area of the contactor diaphragm 1902 is 5% - 10% of the effective area of the electrode diaphragm 2 in the single cell; for example: when the effective contact area between the electrode diaphragm 2 and the positive electrode 6 and the negative electrode 7 in the single cell is 10 cm 2 , then the effective area range of the contactor diaphragm 1902 is 0.5 cm 2 to 1.0 cm 2 .

[0049] Further, to facilitate the calculation of the effective area of the contactor diaphragm 1902, the contactor diaphragm 1902 is preferably circular or square. In summary, the above ratio can effectively prevent the migration of hydrogen ions and vanadium ions in the positive electrolyte and the negative electrolyte to deionized water or the liquid to be diffused during the test, and also prevent the water in deionized water or the diffused liquid from migrating into the positive electrolyte and the negative electrolyte. Through a large number of previous experiments, it is demonstrated that within the above ratio, the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 have a relatively small ratio to the single cell, and the detection time is short, and the amount of water molecules migrating into the positive electrolyte and the negative electrolyte will not have an obvious impact on the charge-discharge process.

[0050] To achieve the above or other purposes, the present invention also discloses a method for testing the conductivity and diffusion of a single cell of a vanadium redox flow battery, using the above-mentioned testing device for the conductivity and diffusion of a single cell of a vanadium redox flow battery. The steps are as follows:

[0051] S1: According to the above attachment Figures 1 - 5 and the descriptions of each component, a plurality of electrolyte outlets are respectively opened on the negative electrode frame 9, and a plurality of electrolyte outlets are respectively opened on the positive electrode frame 5. An electrolyte outlet at a certain position on the positive electrode frame 5 and an electrolyte outlet at the same position on the negative electrode frame 9 share a set of diffusion cell components, that is, the number of sets of diffusion cell components required is equal to the number of electrolyte outlets opened on the negative electrode frame 9; according to the attachment Figure 5 Connect the above components in combination.

[0052] S2: Detect the performance of the single cell.

[0053] S2.1: Detect the conductivity of the positive electrolyte and the negative electrolyte; during the charge-discharge process, the operator opens the valve 905 at a certain position of the electrolyte outlet, and conveys the positive electrolyte to the positive electrolyte storage tank 13 and the negative electrolyte to the negative electrolyte storage tank 14 through the electrolyte conveying component. The conductivity probe 17 in the positive electrolyte storage tank 13 directly measures the conductivity of the positive electrolyte, and the conductivity probe 17 in the negative electrolyte storage tank 14 directly measures the conductivity of the negative electrolyte.

[0054] S2.2: Detect the conductivity between the positive electrolyte and the negative electrolyte; on the basis of step S2.1, the positive electrolyte has been transported to the positive electrolyte storage tank 13, and the negative electrolyte has been transported to the negative electrolyte storage tank 14. At this time, open the shut-off valve 1901 of the contactor 19 between the positive electrolyte storage tank 13 and the negative electrolyte storage tank 14, and the positive electrolyte and the negative electrolyte come into contact through the contactor diaphragm 1902. At the same time, connect the storage tank positive terminal 1301 and the storage tank negative terminal 1401 to an external electrochemical workstation, and then measure the conductivity between the positive electrolyte and the negative electrolyte by the AC impedance method.

[0055] S2.3: Detect the H + content in the positive electrolyte and the negative electrolyte; on the basis of step S2.1, open the shut-off valve 1901 of the contactor 19 between the positive electrolyte diffusion cell 15 and the positive electrolyte storage tank 13, and the H + in the positive electrolyte penetrates through the contactor diaphragm 1902 and enters the positive electrolyte diffusion cell 15. Open the shut-off valve 1901 of the contactor 19 between the negative electrolyte diffusion cell 16 and the negative electrolyte storage tank 14, and the H + in the negative electrolyte penetrates through the contactor diaphragm 1902 and enters the negative electrolyte diffusion cell 16. Close the shut-off valve 1901 of the contactor 19 between the positive electrolyte storage tank 13 and the negative electrolyte storage tank 14. Deionized water or the liquid to be diffused is injected into the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 through the liquid inlet pipeline 2101.

[0056] Measure the pH values in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 respectively through two pH probe 18 within a specific time, and then inversely deduce the H + content in the positive electrolyte and the negative electrolyte through the data model of the pH value and the H + content in the electrolyte.

[0057] S3: After the various detections in step S2 are completed, pump the positive electrolyte in the positive electrolyte storage tank 13 back into the single cell through the electrolyte delivery assembly, and pump the negative electrolyte in the negative electrolyte storage tank 14 back into the single cell. The deionized water or the liquid to be diffused in the positive electrolyte diffusion cell 15 and the negative electrolyte diffusion cell 16 is discharged into the liquid receiving tray 22 through the liquid outlet pipeline. During the liquid discharge process, introduce gas into each sealed container to accelerate the liquid drainage for the next test until all the electrolyte outlets have completed the test.

[0058] Preferably, in step S3, the liquid outlets 23 of the positive electrolyte storage tank 13, the negative electrolyte storage tank 14, the positive electrolyte diffusion tank 15, and the negative electrolyte diffusion tank 16 are all opened at the bottom to facilitate the drainage of the liquid. The liquid outlet 23 of the positive electrolyte storage tank 13 and the liquid outlet 23 of the negative electrolyte storage tank 14 are connected to the single cell, and the liquid outlet 23 of the positive electrolyte diffusion tank 15 and the liquid outlet 23 of the negative electrolyte diffusion tank 16 are connected to the liquid receiving tray 22 through a liquid outlet pipeline.

[0059] Preferably, during the process of liquid extraction and return, the airtight structure of the single cell will not be damaged. At the same time, due to the protection of the inert gas, no other gases will be mixed into the electrolyte, and the influence of the conductance diffusion test on the charge and discharge of the single cell itself can be minimized to the greatest extent.

[0060] To show that the method of introducing the positive electrolyte and the negative electrolyte into the diffusion cell assembly for detection in this application and then pumping the positive electrolyte and the negative electrolyte back into the single cell will not cause changes in the performance of the single cell, the following experiment was conducted, and the experimental data is as follows:

[0061]

[0062] The above table shows the data of the 2nd - 4th cycles of charge and discharge of a certain model of single cell before this application was adopted.

[0063]

[0064] The above table shows the same model of single cell, but this application was used to transform the single cell. Three electrolyte outlets were made in the upper and lower centers of the positive electrode frame 5 and the negative electrode frame 9. 100 ML of the positive electrolyte and the negative electrolyte of the single cell were each led out. The effective area of the electrode diaphragm 2 is 10 cm 2 , the volume of each sealed container in the diffusion cell assembly is 100 μL, and the effective area of the contactor diaphragm 1902 is 0.5 cm 2 ; the liquid to be diffused is deionized water. The transformed single cell was subjected to 4 cycles of charge and discharge, and the data of the 2nd - 4th cycles are shown.

[0065] From the data analysis in the above two tables, it can be seen that the changes in the discharge capacity, charge - discharge efficiency, discharge energy, and energy efficiency in the two charge - discharge tests are not significant, which also indicates that the influence of the method of leading out the positive electrolyte and the negative electrolyte from the single cell for detection in this application on the single cell can be ignored.

[0066] In addition, during the above charge - discharge cycles, the conductivity and pH values of the positive electrolyte and the negative electrolyte were detected twice at the end of charging and the end of discharging respectively. The detection steps are as in steps S1 - S3 above, and will not be repeated here. The detection data is as follows in the table:

[0067]

[0068] As can be seen from the data in the above table, the electrolyte distribution inside the single cell is uneven. In particular, the concentration of the effective components of the electrolyte near the outlet side is relatively low, resulting in a waste of the effective area between the positive electrode 6, the negative electrode 7, and the electrode diaphragm 2. At the end of charging and discharging, the performance gap of the electrolyte at a certain position on the positive electrode frame 5 and the corresponding position on the negative electrode frame 9 is relatively obvious, indicating that the vanadium and liquid blocking performance of the electrode diaphragm 2 is not ideal.

[0069] The full vanadium redox flow battery single cell conductance and diffusion combined test device and method involved in the present invention obtain electrolytes at different positions inside the single cell by opening holes at different positions of the electrode frame, and can analyze and detect the electrolytes. By setting the diffusion cell assembly, the common compatibility of detection items such as the self-conductivity of the electrolyte, the conductivity between the positive electrolyte and the negative electrolyte, and the H + content in the positive electrolyte and the negative electrolyte is realized. By pre-designing the ratio of the volume in the diffusion cell assembly, the effective area of the contactor diaphragm 1902 to the single cell, it is ensured that the detection will not affect the charge and discharge process of the single cell itself. By establishing a model of the diffusion measurement of hydrogen ion concentration and the initial H + content of the electrolyte at a specific time through preliminary tests, the pH measured in the tests of the present invention is restored to the H + content in the electrolyte according to this model.

[0070] The present invention transforms the single cell so that a small amount of electrolyte can be extracted as a sample at any time during the charge and discharge process. At the same time, in cooperation with the diffusion cell assembly, the concentration and conductivity of the electrolyte are detected regularly and multiple times during the charge and discharge test of the single cell, and it will not affect the charge and discharge of the single cell itself. The internal impedance of the single cell and the rationality of the flow field design can be judged by comparing the detection data with the charge and discharge data of the single cell.

[0071] Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0072] The above embodiments are only illustrative of the principles and effects of the present invention, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A vanadium redox flow battery single cell conductivity diffusion test device, used in the detection of all-vanadium redox flow battery single cells; characterized by: The electrode frame of the single cell is provided with a plurality of electrolyte outlets, the electrolyte outlets are provided with electrolyte outlet pipes, and the electrolyte outlet pipes are provided with valves (905); The conductivity-diffusion test device comprises a diffusion cell assembly, an electrolyte delivery assembly, and a detection assembly. The electrolyte delivery assembly is connected to an electrolyte outlet pipe and is used to draw the positive electrode electrolyte and the negative electrode electrolyte in the single cell into the diffusion cell assembly, or to draw the positive electrode electrolyte and the negative electrode electrolyte in the diffusion cell assembly back into the single cell. The detection component is arranged in the diffusion cell component and is used for detecting the positive electrode electrolyte and the negative electrode electrolyte in the single cell.

2. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 1, characterized in that: The electrode frame of the single cell comprises a positive electrode frame (5) and a negative electrode frame (9), and both the positive electrode frame (5) and the negative electrode frame (9) are provided with electrolyte outlets; a plurality of electrolyte outlets are distributed at different positions of the positive electrode frame (5) and the negative electrode frame (9).

3. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 2, characterized in that: The diffusion cell assembly comprises a positive electrode electrolyte storage tank (13) and a negative electrode electrolyte storage tank (14); the positive electrode electrolyte storage tank (13) is connected to an electrolyte outlet on a positive electrode frame (5) via an electrolyte transport assembly, and the negative electrode electrolyte storage tank (14) is connected to an electrolyte outlet on a negative electrode frame (9) via an electrolyte transport assembly; The detection component comprises a conductivity probe (17), wherein two conductivity probes (17) are respectively arranged in the positive electrode electrolyte storage tank (13) and the negative electrode electrolyte storage tank (14).

4. The all-vanadium liquid flow battery single cell conductivity-diffusion test device according to claim 3, characterized in that: A contactor (19) is further provided between the positive electrode electrolyte storage tank (13) and the negative electrode electrolyte storage tank (14), wherein the contactor (19) comprises a contactor diaphragm (1902) and a tight-closing valve (1901), wherein the number of the tight-closing valves (1901) is two and they are located on both sides of the contactor diaphragm (1902); when the tight-closing valves (1901) are opened, the positive electrode electrolyte in the positive electrode electrolyte storage tank (13) and the negative electrode electrolyte in the negative electrode electrolyte storage tank (14) are in contact through the contactor diaphragm (1902); The detection component further comprises a storage tank positive electrode connector (1301) and a storage tank negative electrode connector (1401), wherein one end of the storage tank positive electrode connector (1301) is located inside the positive electrode electrolyte storage tank (13), and the other end is located outside the positive electrode electrolyte storage tank (13); one end of the storage tank negative electrode connector (1401) is located inside the negative electrode electrolyte storage tank (14), and the other end is located outside the negative electrode electrolyte storage tank (14).

5. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 4, characterized in that: The diffusion cell assembly further comprises a positive electrode electrolyte diffusion cell (15) and a negative electrode electrolyte diffusion cell (16); the positive electrode electrolyte diffusion cell (15) is connected to the positive electrode electrolyte storage cell (13) via a contactor (19); the negative electrode electrolyte diffusion cell (16) is connected to the negative electrode electrolyte storage cell (14) via a contactor (19); The detection component also includes a pH meter probe (18), and the two pH meter probes (18) are respectively arranged in the positive electrode electrolyte diffusion cell (15) and the negative electrode electrolyte diffusion cell (16).

6. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 5, characterized in that: The positive electrode electrolyte diffusion cell (15) and the negative electrode electrolyte diffusion cell (16) are provided with a liquid inlet pipeline (2101) for injecting deionized water or liquid to be diffused into the positive electrode electrolyte diffusion cell (15) and the negative electrode electrolyte diffusion cell (16).

7. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 5, characterized in that: The positive electrode electrolyte diffusion cell (15) and the negative electrode electrolyte diffusion cell (16) are provided with liquid outlet pipelines for discharging liquid in the positive electrode electrolyte diffusion cell (15) and the negative electrode electrolyte diffusion cell (16).

8. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 5, characterized in that: The positive electrode electrolyte storage tank (13), the negative electrode electrolyte storage tank (14), the positive electrode electrolyte diffusion tank (15), and the negative electrode electrolyte diffusion tank (16) are all closed containers; the diffusion tank assembly further comprises an aeration assembly (20), and the aeration assembly (20) is used to inflate the positive electrode electrolyte storage tank (13), the negative electrode electrolyte storage tank (14), the positive electrode electrolyte diffusion tank (15), and the negative electrode electrolyte diffusion tank (16).

9. The all-vanadium redox flow battery single cell conductivity-diffusion test device according to claim 5, characterized in that: The volume of the positive electrode electrolyte storage tank (13), the negative electrode electrolyte storage tank (14), the positive electrode electrolyte diffusion tank (15), and the negative electrode electrolyte diffusion tank (16) is 1‰ to 2‰ of the volume of the electrolyte storage tank in the single cell; the effective area of ​​the contactor diaphragm (1902) is 5% to 10% of the effective area of ​​the electrode diaphragm (2) in the single cell.

10. A method for testing the conductivity-diffusion combination of a single cell of an all-vanadium redox flow battery, using the device for testing the conductivity-diffusion combination of a single cell of an all-vanadium redox flow battery as claimed in any one of claims 1 to 9, characterized in that: Here are the steps: The electrolyte outlet pipe on the electrode frame of the single cell is connected to the diffusion cell assembly through the electrolyte transport assembly, the positive electrode electrolyte and the negative electrode electrolyte in the single cell are pumped into the diffusion cell assembly, and the detection assembly detects the positive electrode electrolyte and the negative electrode electrolyte; after the detection is completed, the positive electrode electrolyte and the negative electrode electrolyte in the diffusion cell assembly are pumped back into the single cell through the electrolyte transport assembly.

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