An apparatus for testing the permeability of a vanadium redox flow battery electrode

Abstract

This invention belongs to the field of flow battery technology, specifically a device for testing the electrode permeability of a vanadium redox flow battery. The invention comprises three parts: an electrode encapsulation component, a corrosion-resistant piping system, and a parameter monitoring system. It can obtain the electrode permeability under different compression ratios, electrolyte temperatures, and charge / discharge states. Using the electrode permeability obtained by this invention for multiphysics simulation calculations of vanadium redox flow batteries, the momentum and mass transfer processes of the electrolyte inside the electrode can be obtained more accurately, improving the accuracy of multiphysics simulation calculations and providing more accurate information on the internal parameters of the electrode for the design and development of higher-performance vanadium redox flow batteries.

Description

Technical Field

[0001] This invention belongs to the field of flow battery technology, specifically a device for testing the permeability of electrodes in a vanadium redox flow battery. Background Technology

[0002] The vanadium redox flow battery (VRB) was proposed by Professor Skylas-Kazacos of the University of New South Wales in 1985 and has received widespread attention in recent years due to the demand for large-scale, long-term energy storage technology. The VRB utilizes the conversion between the tetravalent and pentavalent, and divalent and trivalent valences of vanadium at the positive and negative electrodes to achieve the charging and discharging process. During battery operation, the electrolytes at the positive and negative electrodes are propelled by circulation pumps from the electrolyte storage tank to the stack. Within the stack, the electrolytes flow through porous electrodes, where redox reactions occur before flowing back into the storage tank. Carbon-based electrodes, such as carbon felt, carbon cloth, carbon paper, and graphite felt, are commonly used in VRBs due to their good stability, high conductivity, and high mechanical tensile strength. The porous electrodes, as the site of electrochemical reactions in the VRB, have physical properties that significantly influence battery performance.

[0003] Within the porous electrode, the electrolyte simultaneously undergoes momentum transfer, mass transfer, energy transfer, and electrochemical reactions. The mass transfer of vanadium ions from the bulk solution to the electrode surface involves both convective and diffusion mass transfer. Momentum transfer simultaneously affects both mass and energy transfer, which in turn influence the electrochemical reaction process, making it a typical multiphysics coupling process. Simulation is a highly effective method for solving multiphysics coupling problems. Through simulation, parameters such as electrolyte velocity and concentration distribution, as well as voltage and current, can be obtained within the electrode, making it a commonly used method in the early stages of battery structure design. Furthermore, the parameter information obtained from simulation can be used to optimize existing battery structures using more targeted methods, leading to the development of batteries with superior performance.

[0004] Electrode permeability is an inherent property of porous electrodes. Research on the permeability of porous electrodes with fibrous structures in vanadium redox flow batteries is relatively limited. To reduce the battery's internal resistance, the electrodes typically need to be compressed to some extent. When porous electrodes are compressed, their microstructure changes, the electrode porosity decreases, and the pore size also changes. Currently, there is no device available for testing the electrode permeability of vanadium redox flow batteries. Utility Model Content

[0005] The purpose of this invention is to provide a device for testing the permeability of electrodes in a vanadium redox flow battery.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] This utility model includes an electrode encapsulation assembly, a pressure sensor, an electrolyte container, a heating device, a circulating pump, a flow regulating valve, a flow meter, and a temperature sensor. The electrolyte container is placed inside the heating device and contains electrolyte. The electrode encapsulation assembly, from bottom to top, consists of a lower end plate (sealed connection), a lower electrode encapsulation cover plate, a sealing gasket, an upper electrode encapsulation cover plate, and an upper end plate. The upper surface of the lower electrode encapsulation cover plate has electrode grooves along its thickness direction. Each electrode groove accommodates a compression ratio regulating plate and an electrode to be measured. The segment is located below the electrode to be tested. The electrode encapsulation cover plate is provided with an inlet pipe and an outlet pipe. One end of the inlet pipe and the outlet pipe are in contact with the electrode. The other end of the inlet pipe and the outlet pipe are respectively extended into the electrolyte inside the electrolyte container through pipelines. A temperature sensor, a pressure sensor, a flow meter, a flow regulating valve and a circulation pump are respectively provided on the pipeline between the other end of the inlet pipe and the electrolyte container. A temperature sensor and a pressure sensor are respectively provided on the pipeline between the other end of the outlet pipe and the electrolyte container.

[0008] Wherein: both the lower end plate and the upper end plate are annular plates, and the other ends of the inlet pipe and the outlet pipe extend from the inner side of the annular plate of the upper end plate.

[0009] The sealing gasket is annular, and the width of the electrode to be tested is the same as the inner width of the sealing gasket annular.

[0010] The lower end plate, the lower cover plate of the electrode package, the sealing gasket, the upper cover plate of the electrode package, and the upper end plate are all provided with through holes, and fasteners for connecting the lower end plate, the lower cover plate of the electrode package, the sealing gasket, the upper cover plate of the electrode package, and the upper end plate are provided in the through holes.

[0011] The inlet of the circulating pump is connected to the electrolyte container via a pipeline. The outlet of the circulating pump is connected to the inlet of the flow regulating valve via a pipeline. The outlet of the flow regulating valve is connected to the inlet of the flow meter via a pipeline. The outlet of the flow meter is connected to the first port of the first tee connector via a pipeline. The second port of the first tee connector is connected to a pressure sensor. The third port of the first tee connector is connected to the first port of the second tee connector via a pipeline. The second port of the second tee connector is connected to a temperature sensor. The third port of the second tee connector is connected to the other end of the inlet pipe via a pipeline.

[0012] The other end of the outlet pipe is connected to the first interface of the third tee connector via a pipeline. The second interface of the third tee connector is connected to a temperature sensor. The third interface of the third tee connector is connected to the first interface of the fourth tee connector via a pipeline. The second interface of the fourth tee connector is connected to a pressure sensor. The third interface of the fourth tee connector is connected to the electrolyte container via a pipeline.

[0013] The advantages and positive effects of this utility model are as follows:

[0014] This invention has a simple structure and accurate measurement. The parameters measured by this invention can be used to obtain the permeability of the electrode at different compression ratios. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0016] Figure 2 for Figure 1 Exploded view of the middle electrode packaging assembly;

[0017] Figure 3 This is a schematic diagram of the structure of the present invention, in which the compression ratio adjustment plate is placed inside the lower cover plate of the electrode package;

[0018] Wherein: 1 is the electrode encapsulation assembly, 2 is the pressure sensor, 3 is the electrode tank, 4 is the electrolyte, 5 is the electrolyte container, 6 is the heating device, 7 is the circulating pump, 8 is the flow regulating valve, 9 is the flow meter, 10 is the temperature sensor, 11 is the lower end plate, 12 is the lower cover plate of the motor encapsulation, 13 is the electrode, 14 is the sealing gasket, 15 is the upper cover plate of the electrode encapsulation, 16 is the upper end plate, 17 is the inlet pipe, 18 is the outlet pipe, 19 is the compression ratio regulating plate, and 20 is the through hole. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] like Figures 1-3As shown, this utility model includes an electrode encapsulation assembly 1, a pressure sensor 2, an electrolyte container 5, a heating device 6, a circulating pump 7, a flow regulating valve 8, a flow meter 9, and a temperature sensor 10. The electrolyte container 5 is placed inside the heating device 6 and contains electrolyte. The electrode encapsulation assembly 1, from bottom to top, consists of a lower end plate 11 (sealed connection), a lower electrode encapsulation cover plate 12, a sealing gasket 14, an upper electrode encapsulation cover plate 15, and an upper end plate 16. The upper surface of the lower electrode encapsulation cover plate 12 has an electrode groove 3 along its thickness direction. The electrode groove 3 accommodates a compression ratio regulating plate 19 and an electrode 13 to be tested, respectively. The compression ratio regulating plate... The plate 19 is located below the electrode 13 to be tested. The electrode encapsulation cover plate 15 is provided with an inlet pipe 17 and an outlet pipe 18. One end of the inlet pipe 17 and the outlet pipe 18 are in contact with the electrode 13. The other end of the inlet pipe 17 and the outlet pipe 18 are respectively extended into the electrolyte inside the electrolyte container 5 through pipelines. A temperature sensor 10, a pressure sensor 2, a flow meter 9, a flow regulating valve 8 and a circulation pump 7 are respectively provided on the pipeline between the other end of the inlet pipe 17 and the electrolyte container 5. A temperature sensor 10 and a pressure sensor 2 are respectively provided on the pipeline between the other end of the outlet pipe 18 and the electrolyte container 5.

[0021] In this embodiment, the lower end plate 11, the sealing gasket 14 and the upper end plate 16 are all annular plates. The other ends of the inlet pipe 17 and the outlet pipe 18 extend from the inner side of the annular plate 16. The width of the electrode 13 to be tested is the same as the width of the inner side of the annular sealing gasket 14.

[0022] In this embodiment, the lower end plate 11, the lower electrode encapsulation cover plate 12, the sealing gasket 14, the upper electrode encapsulation cover plate 15, and the upper end plate 16 are all provided with through holes 20. Fasteners for connecting the lower end plate 11, the lower electrode encapsulation cover plate 12, the sealing gasket 14, the upper electrode encapsulation cover plate 15, and the upper end plate 16 are provided in the through holes 20. The fasteners can be screws or nuts. The screws pass through each through hole 20 and are tightened and fixed by nuts.

[0023] In this embodiment, the inlet of the circulating pump 7 is connected to the electrolyte container 5 through a pipeline, the outlet of the circulating pump 7 is connected to the inlet of the flow regulating valve 8 through a pipeline, the outlet of the flow regulating valve 8 is connected to the inlet of the flow meter 9 through a pipeline, the outlet of the flow meter 9 is connected to the first interface of the first tee connector through a pipeline, the second interface of the first tee connector is connected to the pressure sensor 2, the third interface of the first tee connector is connected to the first interface of the second tee connector through a pipeline, the second interface of the second tee connector is connected to the temperature sensor 10, and the third interface of the second tee connector is connected to the other end of the inlet pipe 17 through a pipeline.

[0024] In this embodiment, the other end of the outlet pipe 18 is connected to the first interface of the third tee connector via a pipeline. The second interface of the third tee connector is connected to the temperature sensor 10. The third interface of the third tee connector is connected to the first interface of the fourth tee connector via a pipeline. The second interface of the fourth tee connector is connected to the pressure sensor 2. The third interface of the fourth tee connector is connected to the electrolyte container 5 via a pipeline.

[0025] The heating device 6 of this invention can be a water bath as in the prior art. The electrolyte of this invention can be a sulfuric acid solution containing vanadium ions of different valence states.

[0026] The device of this invention can be used to measure electrode permeability under different electrode compression ratios and electrolyte SOC conditions.

[0027] The installation of this utility model is as follows:

[0028] Based on the thickness of the electrode 13 to be tested and the required electrode compression ratio, a suitable compression ratio adjustment plate 19 is selected and adjusted. The compression ratio adjustment plate 19 is placed into the electrode slot 3 on the lower cover plate 12 of the electrode package, and the electrode 13 to be tested is placed into the lower cover plate 12 of the electrode package. Figure 3 As shown. Figure 2 As shown, the sealing gasket 14 is placed on the lower cover plate 12 of the electrode package, the upper cover plate 15 of the electrode package is placed on the sealing gasket 14, the upper end plate 16 and the lower end plate 11 are installed respectively, and then the fasteners are used to fasten the various components of the electrode package assembly 1.

[0029] Place the heating device 6 on the test platform, and put the electrolyte container 5 into the heating device 6. Connect the inlet of the circulation pump 7 to the electrolyte container 5 through a pipeline. Connect the inlet of the flow regulating valve 8 to the outlet of the circulation pump 7 through a pipeline. Connect the outlet of the flow regulating valve 8 to the inlet of the flow meter 9 through a pipeline. Connect the outlet of the flow meter 9 to the inlet connector 17 through a pipeline. Connect the outlet connector 18 to the electrolyte container 5 through a pipeline. Select a predetermined position on the pipeline between the flow meter 9 and the inlet connector 17 and connect the pressure sensor 2 and the temperature sensor 10 using a tee fitting (in this embodiment, the pressure sensor 2 and the temperature sensor 10 are connected to the pipeline near the inlet connector 17). Select a predetermined position on the pipeline between the outlet connector 18 and the electrolyte container 5 and connect the pressure sensor 2 and the temperature sensor 10 using a tee fitting (in this embodiment, the pressure sensor 2 and the temperature sensor 10 are connected to the pipeline near the outlet connector 18).

[0030] The present invention describes a method for testing the electrode permeability of a vanadium redox flow battery. Using the aforementioned apparatus, pressure sensor 2, temperature sensor 10, and flow meter 9 are connected to a computer. 1L of a positive electrode electrolyte with a vanadium ion concentration of 1.66M (tetravalent and / or pentavalent), a sulfuric acid concentration of 3M, and a state of charge (SOC) of 0.2 is poured into the electrolyte container 5. The thickness of the electrode 13 to be tested is 5mm, the thickness of the sealing gasket 14 is 1mm, the depth of the electrode groove on the lower cover plate 12 is 5mm, and the thickness of the compression ratio adjustment plate 19 is 1mm. The electrode compression ratio CR (the ratio of the original thickness of the electrode before and after compression to the thickness after compression) is obtained as 1.25. With the flow regulating valve 8 closed and the power supply to the circulating pump 7 turned on, the opening of the flow regulating valve 8 was slowly adjusted. The electrolyte flow rate measured by the flow meter 9 was 0.17 L / min, 0.30 L / min, 0.50 L / min, 0.72 L / min, and 0.92 L / min, corresponding to inlet pressures of 6 kPa, 10 kPa, 14 kPa, 19 kPa, and 23 kPa, and outlet pressures of 0.9 kPa, 0.9 kPa, 0.8 kPa, 0.9 kPa, and 1 kPa. The temperature measured by the temperature sensor was close to room temperature, 25°C.

[0031] According to Darcy's Law (Formula 1), the electrode permeability calculation method (Formula 2) can be obtained. In Formula (2), L is the length of the electrode 13 to be tested in the direction of electrolyte 4 flow, A is the cross-sectional area of ​​the electrode 13 to be tested perpendicular to the direction of electrolyte 4 flow, Δp is the pressure difference between the inlet pressure and the outlet pressure, Q is the permeation flow rate, and μ is the dynamic viscosity of the fluid. The test was repeated 3 times according to the above test method, and the average value was taken as the electrode permeability κ corresponding to the electrode compression ratio CR. The electrode permeability measured in this experiment is approximately 2.35778 × 10⁻⁶. -10 m 2 .

[0032]

Claims

1. An apparatus for testing vanadium redox flow battery electrode permeability, characterized in that: The device includes an electrode encapsulation assembly (1), a pressure sensor (2), an electrolyte container (5), a heating device (6), a circulating pump (7), a flow regulating valve (8), a flow meter (9), and a temperature sensor (10). The electrolyte container (5) is placed inside the heating device (6) and contains electrolyte. The electrode encapsulation assembly (1) consists of, from bottom to top, a lower end plate (11) with a sealed connection, a lower electrode encapsulation cover plate (12), a sealing gasket (14), an upper electrode encapsulation cover plate (15), and an upper end plate (16). The lower electrode encapsulation cover plate (12) has an electrode groove (3) along its thickness direction on its upper surface. The electrode groove (3) contains a compression ratio regulating plate (19) and the electrode to be tested (13). The compression ratio regulating plate (19) Located below the electrode (13) to be tested, the electrode encapsulation cover plate (15) is provided with an inlet pipe (17) and an outlet pipe (18). One end of the inlet pipe (17) and the outlet pipe (18) are in contact with the electrode (13). The other end of the inlet pipe (17) and the outlet pipe (18) are respectively extended through pipelines into the electrolyte inside the electrolyte container (5). A temperature sensor (10), a pressure sensor (2), a flow meter (9), a flow regulating valve (8) and a circulation pump (7) are respectively provided on the pipeline between the other end of the inlet pipe (17) and the electrolyte container (5). A temperature sensor (10) and a pressure sensor (2) are respectively provided on the pipeline between the other end of the outlet pipe (18) and the electrolyte container (5).

2. The device for testing the permeability of a vanadium redox flow battery electrode according to claim 1, characterized in that: Both the lower end plate (11) and the upper end plate (16) are annular plates, and the other ends of the inlet pipe (17) and the outlet pipe (18) extend from the inner side of the annular plate (16).

3. The device for testing the permeability of a vanadium flow battery electrode of claim 1, wherein: The sealing gasket (14) is annular, and the width of the electrode (13) to be tested is the same as the width of the inner side of the annular sealing gasket (14).

4. The device for testing the permeability of a vanadium flow battery electrode of claim 1, wherein: The lower end plate (11), the lower electrode encapsulation cover plate (12), the sealing gasket (14), the upper electrode encapsulation cover plate (15), and the upper end plate (16) are all provided with through holes (20), and fasteners for connecting the lower end plate (11), the lower electrode encapsulation cover plate (12), the sealing gasket (14), the upper electrode encapsulation cover plate (15), and the upper end plate (16) are provided in the through holes (20).

5. The device for testing the permeability of a vanadium redox flow battery electrode of claim 1, wherein: The inlet of the circulating pump (7) is connected to the electrolyte container (5) through a pipeline. The outlet of the circulating pump (7) is connected to the inlet of the flow regulating valve (8) through a pipeline. The outlet of the flow regulating valve (8) is connected to the inlet of the flow meter (9) through a pipeline. The outlet of the flow meter (9) is connected to the first interface of the first tee connector through a pipeline. The second interface of the first tee connector is connected to the pressure sensor (2). The third interface of the first tee connector is connected to the first interface of the second tee connector through a pipeline. The second interface of the second tee connector is connected to the temperature sensor (10). The third interface of the second tee connector is connected to the other end of the inlet pipe (17) through a pipeline.

6. The device for testing the permeability of a vanadium redox flow battery electrode of claim 1, wherein: The other end of the outlet pipe (18) is connected to the first interface of the third tee connector via a pipeline. The second interface of the third tee connector is connected to the temperature sensor (10). The third interface of the third tee connector is connected to the first interface of the fourth tee connector via a pipeline. The second interface of the fourth tee connector is connected to the pressure sensor (2). The third interface of the fourth tee connector is connected to the electrolyte container (5) via a pipeline.

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