A device for measuring electrolyte concentration distribution of flow battery

Abstract

The present invention belongs to the technical field of liquid flow batteries, and relates to a device for measuring the electrolyte concentration distribution of a liquid flow battery, which is provided with a liquid flow battery, and at least two sub-batteries are embedded inside the liquid flow battery. The device for measuring the electrolyte concentration distribution of a liquid flow battery also includes a negative terminal plate, a negative current collector plate frame, a negative electrode, a diaphragm, a positive electrode, a positive current collector plate frame, and a positive terminal plate stacked in sequence; a negative electrode sub-current collector, a sub-negative electrode, a diaphragm, a sub-positive electrode, and a positive electrode sub-current collector are stacked in sequence to form a sub-battery. After these components are stacked in sequence, they are fastened with bolts to form a measuring device inlaid with n (n≧2) sub-batteries. The device for measuring the electrolyte concentration distribution of a liquid flow battery can obtain the distribution of the electrolyte concentration, which is used to improve the distribution of the flow field and improve the performance of the battery.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid flow batteries, and in particular relates to a device for measuring electrolyte concentration distribution of a liquid flow battery. Background Art

[0002] The electrolyte of the all-vanadium liquid flow battery is pumped from the storage tank into the battery stack through a liquid pump. The ampere-hour (Ah) capacity of the battery depends on the amount of active substances in the electrolyte, and the power depends on the output voltage and current of the battery stack. The output voltage of the battery stack is determined by the number of single cells in series, and the output current of the battery stack is determined by the product of the area of ​​the single cell and the current density. Since the electrolyte is transported between each single cell through the main infusion pipe, the electrolyte in the single cell is transported from the inlet of the single cell to the outlet of the single cell through a branch. Therefore, the electrolyte distribution in the single cell is uneven. The larger the area, the longer the path that the electrolyte passes through in the single cell, and the more uneven the electrolyte concentration distribution, which will cause the local concentration of the electrolyte to be too high and affect the battery life.

[0003] In order to improve battery performance, safe operation and extend service life, it is necessary to study the distribution of electrolyte in a single cell. So far, there are many theoretical studies on the distribution of electrolyte concentration in a single cell, but there is a lack of experimental data.

[0004] Prior art CN200910248844 A proton exchange membrane fuel cell split end plate structure for measuring current distribution, prior art CN201010148360 A proton exchange membrane fuel cell structure for measuring oxygen concentration distribution is for measuring hydrogen ion concentration distribution in fuel cells. Currently, there is no solution to measure the concentration distribution of vanadium batteries.

[0005] During charging, the vanadium ions with a valence of 3 and 4 are converted into vanadium ions with a valence of 2 and 5, respectively. At this time, H + moves from the positive electrode to the negative electrode through the ion conduction membrane, and the free electrons e - The electrical neutrality is maintained by moving from the positive electrode to the negative electrode through an external circuit, and the opposite is true during discharge.

[0006] Negative electrode reaction: (1)

[0007] Positive electrode reaction: (2)

[0008] Overall reaction: (3)

[0009] According to the Nernst equation, the relationship between open circuit voltage and concentration can be obtained:

[0010] (4)

[0011] In the formula E MC is the open circuit voltage of the subcell, V; E e 0 It is the standard electrode potential when the effect of hydrogen ion concentration on the potential change is ignored and the effect of hydrogen ions on the standard electrode potential is considered. E e 0 = E 0 +2 RT / F ・ln C HP ; T is the temperature, K; R =8.31J・K -1 ・mol -1 ; F is the Faraday constant, C·mol -1 ; C j is the concentration of vanadium ions with valence j, mol・L -1 To simplify the explanation, it is assumed that the total vanadium ion concentrations of the positive and negative electrodes are equal, and when fully charged, the positive electrode only has pentavalent vanadium ions and the negative electrode only has divalent vanadium ions. The concentration of divalent vanadium ions at this time is C max , then equation (4) can be simplified to equation (5). In this way, the relationship between concentration and open circuit voltage is established.

[0012] (5)

[0013] In summary, the problems existing in the prior art are:

[0014] (1) Existing devices cannot measure the electrolyte concentration distribution data in a single cell.

[0015] (2) Existing technology cannot measure the concentration of vanadium batteries. Summary of the invention

[0016] In view of the problems existing in the prior art, the present invention provides a device for measuring the electrolyte concentration distribution of a flow battery.

[0017] The present invention is implemented as follows: n sub-batteries are embedded in the liquid flow battery, n≥2, and the sub-batteries do not participate in the reaction during the charging / discharging process of the liquid flow battery, but are used to measure the open circuit voltage of each sub-battery to characterize the concentration distribution of vanadium ions. The device for measuring the concentration distribution of the electrolyte of the liquid flow battery can obtain the distribution of the electrolyte concentration, which is used to improve the distribution of the flow field and improve the performance of the battery.

[0018] The device for measuring the concentration distribution of electrolyte in a flow battery comprises a negative terminal plate, a negative current collector plate frame, a negative electrode, a diaphragm, a positive electrode, a positive current collector plate frame, and a positive terminal plate stacked in sequence, characterized in that: the negative terminal plate has n holes, and n independent sub-current collectors insulated from the negative current collector plate frame are separated at positions corresponding to the n holes on the negative current collector plate frame, and n independent sub-current collectors insulated from the negative current collector plate frame are separated at positions corresponding to the n sub-current collectors on the negative electrode. A sub-negative electrode insulated from the positive electrode, n ≥ 2; and on the positive electrode, at the position corresponding to the sub-negative electrode, n independent sub-positive electrodes insulated from the positive electrode are divided out, and on the positive electrode collector end plate, at the position corresponding to the sub-positive electrode, n independent sub-current collectors insulated from the positive electrode collector plate frame are divided out, and the positive electrode end plate, at the position corresponding to the sub-positive electrode, has n holes, n ≥ 2; the negative electrode sub-current collector, the sub-negative electrode, the separator, the sub-positive electrode, and the positive electrode sub-current collector are stacked in sequence to form a sub-battery.

[0019] Furthermore, the wire passes through n holes on the negative terminal plate and is connected to the negative electrode current collector, and the wire and the negative terminal plate are insulated and sealed with insulating glue.

[0020] Furthermore, the sub-current collector on the negative electrode current collector plate frame is insulated and sealed from the negative electrode current collector plate frame by using insulating glue.

[0021] Furthermore, the sub-negative electrode on the negative electrode is insulated from the negative electrode by an insulating material.

[0022] Furthermore, the sub-positive electrode on the positive electrode is insulated from the positive electrode by an insulating material.

[0023] Furthermore, the sub-current collector on the positive electrode current collector plate frame is insulated and sealed from the positive electrode current collector plate frame by using insulating glue.

[0024] Furthermore, the wire passes through n holes on the positive terminal plate and is connected to the positive electrode current collector, and the wire and the positive terminal plate are insulated and sealed with insulating glue.

[0025] Furthermore, the area of ​​the sub-negative electrode and the sub-positive electrode in the sub-battery should be as small as one thousandth to one fiftieth of the area of ​​the battery, and should not exceed one tenth at most.

[0026] Furthermore, the number n of the sub-batteries is preferably greater than 4 and is evenly distributed in the battery.

[0027] Furthermore, the sub-batteries do not participate in the reaction when the main battery is charged or discharged, and the open circuit voltage of these sub-batteries is measured to characterize the concentration distribution of vanadium ions.

[0028] In summary, the advantages and positive effects of the present invention are as follows: the device for measuring the electrolyte concentration distribution of a flow battery can obtain the distribution of the electrolyte concentration, which is used to improve the distribution of the flow field and improve the performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the negative terminal plate provided in an embodiment of the present invention.

[0030] Figure 2 It is a schematic diagram of the structure of the negative electrode current collector plate frame provided in an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the structure of the negative electrode provided by an embodiment of the present invention.

[0032] Figure 4 Schematic diagram of the structure of the diaphragm provided in an embodiment of the present invention.

[0033] Figure 5 Schematic diagram of the structure of the positive electrode provided by an embodiment of the present invention.

[0034] Figure 6 It is a schematic diagram of the structure of the positive electrode current collector plate frame provided in an embodiment of the present invention.

[0035] Figure 7 It is a schematic diagram of the structure of the positive terminal plate provided in an embodiment of the present invention.

[0036] Figure 8 It is a schematic diagram of the structure of a device for measuring electrolyte concentration distribution in a flow battery provided in an embodiment of the present invention.

[0037] In the figure: 1. negative terminal plate; 2. insulating glue; 3. wire; 4. negative electrode collector plate frame; 5. positive electrode collector plate frame; 6. sub-collector; 7. negative electrode; 8. insulating material; 9. sub-negative electrode; 10. positive electrode; 11. positive terminal plate; 12. sub-positive electrode. DETAILED DESCRIPTION

[0038] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings.

[0039] In view of the problems existing in the prior art, the present invention provides a device for measuring the electrolyte concentration distribution of a flow battery. Figures 1 to 8 The present invention is described in detail.

[0040] n sub-batteries are embedded in the liquid flow battery, n≥2. The sub-batteries do not participate in the reaction during the charge / discharge process of the liquid flow battery, but are used to measure the open circuit voltage of each sub-battery to characterize the concentration distribution of vanadium ions. The device for measuring the concentration distribution of the electrolyte of the liquid flow battery can obtain the distribution of the electrolyte concentration, which is used to improve the distribution of the flow field and improve the performance of the battery.

[0041] The device for measuring the concentration distribution of electrolyte in a flow battery comprises a negative terminal plate 1, a negative current collector plate frame 4, a negative electrode 7, a diaphragm, a positive electrode, a positive current collector plate frame 5, and a positive terminal plate 11 which are stacked in sequence, wherein the negative terminal plate 1 has n holes, and n independent sub-current collectors 6 insulated from the negative current collector plate frame 4 are separated at positions corresponding to the n holes on the negative current collector plate frame 4, and n independent sub-current collectors insulated from the negative electrode are separated at positions corresponding to the n sub-current collectors 6 on the negative electrode 7. Pole 9, n ≥ 2; and on the positive electrode, at the position corresponding to the sub-negative electrode 9, n independent sub-positive electrodes 12 insulated from the positive electrode are divided out, and on the positive electrode collector end plate, at the position corresponding to the sub-positive electrode 12, n independent sub-current collectors 6 insulated from the positive electrode collector plate frame 5 are divided out, and on the positive terminal plate 11, at the position corresponding to the sub-positive electrode 12 collector, there are n holes, n ≥ 2; the negative electrode sub-current collector 6, the sub-negative electrode 9, the separator, the sub-positive electrode 12, and the positive electrode sub-current collector 6 are stacked in sequence to form a sub-battery.

[0042] The wire 3 passes through n holes on the negative terminal plate 1 and is connected to the negative electrode sub-current collector 6, and the wire 3 and the negative terminal plate 1 are insulated and sealed with an insulating glue 2. The sub-current collector 6 on the negative electrode collector plate frame 4 is insulated and sealed with the negative electrode collector plate frame 4 with an insulating glue 2. The sub-negative electrode 9 on the negative electrode is insulated from the negative electrode 7 with an insulating material 8. The sub-positive electrode 12 on the positive electrode is insulated from the positive electrode with an insulating material 8. The sub-current collector 6 on the positive electrode collector plate frame is insulated and sealed with an insulating glue 2. The wire 3 passes through n holes on the positive terminal plate 11 and is connected to the positive electrode sub-current collector 6, and the wire 3 and the positive terminal plate 11 are insulated and sealed with an insulating glue 2. The area of ​​the sub-negative electrode 9 and the sub-positive electrode 12 in the sub-battery should be as small as one thousandth to one fiftieth of the area of ​​the battery, and should not exceed one tenth at most. The number n of the sub-batteries is preferably greater than 4 and evenly distributed in the battery. The sub-batteries do not participate in the reaction when the main battery is charged or discharged, and the open circuit voltage of these sub-batteries is measured to characterize the concentration distribution of vanadium ions.

[0043] The device for measuring the concentration distribution of electrolyte in a flow battery can measure the concentration distribution of electrolyte in a flow battery stack. The method for measuring the concentration distribution in a single cell is as follows: in a single cell, a plurality of independent cells are built in to measure the open circuit voltage, and the distribution of electrolyte concentration is obtained by the Nernst equation.

[0044] F1. Negative electrode 7: Negative electrode 7 (carbon felt) is divided into 9 parts of 120mm×150mm. Dig out a 10mm diameter carbon felt in the center of the 9 parts for later use. Then, dig out a 15mm ring in the same way, insert an insulating ring at this position and then put the 10mm carbon felt in. The other 8 parts are handled in the same way. Figure 3 .

[0045] F2. Negative electrode current collector plate frame 4: Divide the part of the negative electrode current collector plate frame 4 that contacts the negative electrode carbon felt into 9 parts, and make the same treatment as the carbon felt in the 9 parts, that is, dig out 10mm and 15mm holes in the center of each part, put the 10mm bipolar plate in, and seal it with insulating glue 2, such as Figure 2 .

[0046] F3. Negative terminal plate 1: drill through 9 holes, connect wire 3, and glue wire 3 with insulating glue 2. Figure 1 .

[0047] F4. Diaphragm: Figure 4 .

[0048] F5. Positive electrode: refer to F1 negative electrode 7, such as Figure 5 .

[0049] F6. Positive electrode current collector plate frame 5: refer to F2 negative electrode current collector plate frame 4, such as Figure 6 .

[0050] F7. Positive terminal plate 11: Refer to F3 negative terminal plate 1, such as Figure 7 .

[0051] like Figure 8 , stack the F3 negative terminal plate 1, F2 negative electrode collector plate frame 4, F1 negative electrode 7, F4 separator, F5 positive electrode, F6 positive electrode collector plate frame 5, and F7 positive terminal plate 11 in sequence and tighten them with bolts to form a device for measuring electrolyte concentration distribution. Nine sub-cells are embedded in the main battery. The open circuit voltage of each sub-cell is measured, and the relationship between the open circuit voltage and the electrolyte concentration (5) is used By calculating, the concentration distribution can be obtained.

[0052] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A device for measuring the concentration distribution of electrolyte in a flow battery, characterized in that: The device for measuring the electrolyte concentration distribution of a flow battery is provided with a flow battery, and at least two sub-batteries are embedded in the flow battery; The negative terminal plate, the negative current collector plate frame, the negative electrode, the separator, the positive electrode, the positive current collector plate frame, and the positive terminal plate are stacked and installed in sequence; the negative electrode sub-current collector, the sub-negative electrode, the separator, the sub-positive electrode, and the positive electrode sub-current collector are stacked in sequence to form a sub-battery; The negative electrode end plate has n holes, and n independent sub-current collectors insulated from the negative electrode current collector plate frame are divided at positions corresponding to the n holes on the negative electrode current collector plate frame; On the negative electrode, at positions corresponding to the n sub-current collectors, n independent sub-negative electrodes insulated from the negative electrode are divided, where n≥2; And on the positive electrode, at the position corresponding to the sub-negative electrode, n independent sub-positive electrodes insulated from the positive electrode are divided; on the positive electrode current collector end plate, at the position corresponding to the sub-positive electrode, n independent sub-current collectors insulated from the positive electrode current collector plate frame are divided; There are n holes on the positive terminal plate at positions corresponding to the sub-positive electrode current collector, where n≥2; The wire passes through n holes on the negative terminal plate and is connected to the negative electrode current collector, and the wire and the negative terminal plate are insulated and sealed with insulating glue; The wire passes through n holes on the positive terminal plate and is connected to the positive sub-current collector, and the wire and the positive terminal plate are insulated and sealed with insulating glue; The sub-cells do not participate in the reaction during the charging or discharging process of the flow battery, but are used to measure the open circuit voltage of each sub-cell to characterize the concentration distribution of vanadium ions.

2. The device for measuring electrolyte concentration distribution of a flow battery according to claim 1, characterized in that: The sub-current collector on the negative electrode current collector plate frame is insulated and sealed from the negative electrode current collector plate frame by using insulating glue.

3. The device for measuring electrolyte concentration distribution of a flow battery according to claim 1, characterized in that: The sub-negative electrode on the negative electrode is insulated from the negative electrode by an insulating material.

4. The device for measuring electrolyte concentration distribution of a flow battery according to claim 1, characterized in that: The sub-positive electrode on the positive electrode is insulated from the positive electrode by an insulating material.

5. The device for measuring electrolyte concentration distribution of a flow battery according to claim 1, characterized in that: The sub-current collector on the positive electrode current collector plate frame is insulated and sealed from the positive electrode current collector plate frame by using insulating glue.

6. The device for measuring electrolyte concentration distribution of a flow battery according to claim 1, characterized in that: The area of ​​the negative sub-electrode and the positive sub-electrode in the sub-battery is one thousandth to one fiftieth of the area of ​​the battery.

7. The device for measuring electrolyte concentration distribution of a flow battery according to claim 1, characterized in that: The number n of the sub-batteries is greater than 2 and is evenly distributed in the battery.

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