A production method for improving the consistency of a flow battery

Abstract

The application provides a production method for improving consistency of a flow battery, which comprises the following steps: cutting a carbon felt roll into a carbon felt sheet with a target size; detecting the thickness of each carbon felt sheet to measure the average value and the extreme value of the thickness of each carbon felt sheet; classifying all the carbon felt sheets according to the average value of the thickness; selecting a sealing gasket with a corresponding thickness for each type of carbon felt sheet to ensure that the compression ratio of the carbon felt sheet is within a target range; assembling each type of carbon felt sheet and the sealing gasket with the corresponding thickness into an electric pile; detecting the charging and discharging of the electric pile and monitoring the voltage data of each single cell in the electric pile; calculating the consistency of the electric pile according to the voltage data of each single cell; and removing unqualified electric piles according to the consistency of the electric pile. The thickness of the carbon felt sheet is detected, the carbon felt sheets are classified according to the thickness, and the sealing gaskets with the corresponding thickness are matched with the carbon felt sheets of different types, so that the thickness consistency of each single cell in the electric pile can be effectively controlled, and the consistency of the electric pile is improved.

Description

Technical Field

[0001] This invention relates to the field of flow battery manufacturing technology, and in particular to a production method for improving the consistency of flow batteries. Background Technology

[0002] With the increasing global demand for renewable energy, energy storage technology has become a key support, and vanadium redox flow batteries occupy an important position in this field due to their long lifespan, high safety, and scalability. Vanadium redox flow batteries are mainly used for large-scale energy storage, such as grid peak shaving, renewable energy grid integration, and backup power.

[0003] Consistency in vanadium redox flow batteries is a key factor in ensuring long battery life and high-efficiency operation. Therefore, improving battery consistency is an urgent problem to be solved in the vanadium redox flow battery industry. Currently, most companies and high-efficiency manufacturers focus their R&D on improving battery efficiency and reducing costs, with relatively little research on battery consistency. Variations in material thickness within vanadium redox flow batteries significantly affect battery performance; therefore, reducing material thickness deviations is an effective way to improve stack consistency. The separator and bipolar plates in the stack are relatively thin, with small dimensional deviations, and their impact on battery thickness is relatively small and generally negligible. Currently, the carbon felt in the stack suffers from thickness deviations of ±10% due to manufacturing processes, and this cannot be resolved in the short term, resulting in poor stack thickness consistency and consequently affecting battery performance. Summary of the Invention

[0004] This invention proposes a production method to improve the consistency of flow batteries, solving the problems in the prior art where large deviations in carbon felt thickness lead to poor stack thickness consistency, which in turn affects battery performance.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a manufacturing method for improving the consistency of flow batteries, comprising the following steps:

[0007] The thickness of each carbon felt is measured, and the average and extreme values ​​of the thickness of each carbon felt are determined.

[0008] All carbon felts were classified according to their average thickness.

[0009] Select a sealing gasket of the appropriate thickness for each type of carbon felt;

[0010] Each type of carbon felt is assembled with a sealing gasket of corresponding thickness to form a fuel cell stack.

[0011] Specifically, before the carbon felt is tested for thickness, the carbon felt roll needs to be cut into carbon felt sheets of the target size.

[0012] Specifically, the method for thickness detection of each carbon felt is as follows: Based on the length and width of each carbon felt, a corresponding number of detection points are selected on the surface of the carbon felt, with the number of detection points on each carbon felt being greater than... m The distance between one or more adjacent detection points is less than x .

[0013] Specifically, after the thickness of each carbon felt is measured, the carbon felt is screened based on the average and extreme values ​​of the carbon felt thickness. Unqualified carbon felts are removed, and qualified carbon felts are screened and classified. The criteria for judging whether a carbon felt is qualified are: the difference between the maximum and average carbon felt thickness is less than a preset value, and the difference between the minimum and average carbon felt thickness is less than a preset value.

[0014] Specifically, the method for classifying carbon felt is as follows:

[0015] Set classification thresholds: D1, D2, D3, D4;

[0016] Sort the carbon felt pieces in ascending order of average thickness;

[0017] Category 1 carbon felt: D1 <Dave≤D2;

[0018] Second type of carbon felt: D2 <Dave≤D3;

[0019] Category 3 carbon felt: D3 <Dave≤D4;

[0020] Category 4 carbon felt: Dave ≤ D1 or Dave > D4;

[0021] Among them, Dave is the average thickness of a carbon felt, and the fourth type of carbon felt is a substandard carbon felt.

[0022] Specifically, the goal of selecting sealing gaskets of corresponding thickness for each type of carbon felt is to ensure that the compression ratio of all carbon felts combined with their corresponding sealing gaskets is within 20%-30%, and that the difference between the maximum and minimum compression ratios within the same type of carbon felt is less than 2%; the selected sealing gasket thickness... D s Calculate using the following formula:

[0023] D s = (1+ e ) D carbon - D frame，

[0024] in, e The target compression ratio for each type of carbon felt. D carbon The average thickness of each type of carbon felt;D frame The average thickness of the fluid flow frame.

[0025] Preferably, the production method further includes a fuel cell stack testing and screening step, specifically comprising the following steps:

[0026] The assembled fuel cell stack is subjected to charge and discharge tests, and the voltage data of each individual cell in the stack is monitored.

[0027] Stack consistency is calculated based on the voltage data of each individual cell;

[0028] Defective fuel cells are eliminated based on their consistency.

[0029] Specifically, the voltage of each cell at each recording time is statistically analyzed, and the voltage range or variance of all cells in the stack is used to evaluate the consistency of the stack. If the range or variance meets the preset conditions, the stack is qualified.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) By detecting the thickness of the carbon felt, classifying the carbon felt according to the thickness, and matching sealing gaskets of corresponding thickness to different types of carbon felt, the present invention can effectively control the thickness consistency of each single cell in the stack, thereby improving the consistency of the stack.

[0032] (2) By performing multi-site thickness detection on the slit carbon felt and removing carbon felt with poor thickness consistency, the present invention can control the thickness consistency of a single piece of carbon felt and improve the quality of carbon felt.

[0033] (3) By performing consistency testing on the assembled fuel cell stacks, the present invention can effectively eliminate fuel cell stacks with poor consistency, thereby further improving the consistency of the fuel cell stacks. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic flowchart of a production method for improving the consistency of flow batteries according to the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Reference Figure 1 This invention provides a production method for improving the consistency of flow batteries, comprising the following steps:

[0038] The first step is to cut the carbon felt rolls to the target size (the cutting equipment can be a high-precision laser cutter or a CNC cutting machine) to obtain carbon felt sheets of the target size;

[0039] The second step is to take samples at each carbon felt point to measure the thickness, and measure the average and extreme values ​​of the thickness of each carbon felt.

[0040] Specifically, the method for thickness measurement of each carbon felt is as follows: Based on the length and width of each carbon felt, a corresponding number of measurement points are selected on the surface of the carbon felt. The number of measurement points on each carbon felt is greater than 10 (the specific number can be adjusted flexibly according to actual conditions) or the spacing between adjacent measurement points is less than 20cm (the specific value can be adjusted flexibly according to actual conditions). This embodiment uses a non-contact laser thickness gauge (accuracy ±0.01mm) to avoid compression errors on the carbon felt surface caused by contact measurement.

[0041] Furthermore, statistical methods can be used to dynamically determine the number and location of detection points, avoiding the limitations of fixed point numbers or spacing.

[0042] Number of detection points m The minimum value is determined by the area of ​​the carbon felt. A and thickness standard deviation s Decide:

[0043] ,

[0044] in, k For empirical coefficients (e.g.) k =10 cm 2 (mm), area A The unit is cm 2 , s The unit is mm.

[0045] First, calculate the standard deviation of carbon felt thickness based on historical data. s ;

[0046] Then calculate the minimum number of detection points according to the formula. m And evenly distributed on the surface of the carbon felt, avoiding the edge areas;

[0047] If the thickness difference between adjacent detection points exceeds 2 s Then, the detection points are encrypted in the abnormal area.

[0048] Specifically, after the thickness of each carbon felt is measured, the carbon felt is screened based on the average and extreme values ​​of the carbon felt thickness. Unqualified carbon felts are removed, and qualified carbon felts are screened and classified. The criteria for judging whether a carbon felt is qualified are: the difference between the maximum and average carbon felt thickness is less than a preset value, and the difference between the minimum and average carbon felt thickness is less than a preset value.

[0049] In this embodiment, n points are taken on each carbon felt, and the thickness detection value Di (where i = 1, 2, 3, ..., n) of each point is recorded. The average thickness Dave, the maximum thickness Dmax, and the minimum thickness Dmin of each carbon felt are calculated. The standard for qualified carbon felt is Dave - Dmin < 0.1 mm and Dmax - Dave < 0.1 mm. The preset value of 0.1 mm can be flexibly adjusted according to the actual carbon felt qualification rate.

[0050] The third step is to classify all the carbon felts according to their average thickness.

[0051] Specifically, the method for classifying carbon felt is as follows:

[0052] Set classification thresholds: D1, D2, D3, D4;

[0053] Sort the carbon felt pieces in ascending order of average thickness;

[0054] Category 1 carbon felt: D1 <Dave≤D2;

[0055] Second type of carbon felt: D2 <Dave≤D3;

[0056] Category 3 carbon felt: D3 <Dave≤D4;

[0057] Category 4 carbon felt: Dave ≤ D1 or Dave > D4;

[0058] Among them, Dave is the average thickness of a piece of carbon felt, and the fourth type of carbon felt is unqualified and needs to be rejected.

[0059] In this embodiment, by appropriately adjusting the values ​​of D1, D2, D3, and D4, the utilization rate of carbon felt is ensured to be above 90%, and different thicknesses of carbon felt are applicable; so that the average thickness of the cut carbon felt follows a normal distribution, with about 5% being unqualified and 95% being qualified; among the qualified carbon felt, the first type accounts for 25% of the qualified carbon felt, the second type accounts for 50% of the qualified carbon felt, and the third type accounts for 25% of the qualified carbon felt.

[0060] This embodiment uses standard-sized 4.5mm carbon felt as an example, where D1, D2, D3, and D4 are 4.25mm, 4.4mm, 4.6mm, and 4.75mm, respectively. A batch of carbon felt rolls was cut into 1300 sheets, with a carbon felt qualification rate of 95.8%. The carbon felt is classified as shown in Table 1 below:

[0061] Table 1. Classification of Carbon Felt

[0062]

[0063] In this embodiment, the classification interval is automatically optimized based on real-time production data to improve the utilization rate of carbon felt:

[0064] The classification thresholds D1, D2, D3, and D4 are dynamically calculated based on the normal characteristics of the carbon felt thickness distribution.

[0065] D1= m -2.5 s D2= m - s D3= m + s D4= m +2.5 s

[0066] in, m This represents the average thickness of the carbon felt in the current batch. s The standard deviation is denoted as .

[0067] For every N carbon felt pieces produced (e.g., N=100), update m and s ;

[0068] Recalculate the classification threshold according to the formula;

[0069] Remove carbon felts with Dave≤D1 or Dave>D4.

[0070] The fourth step is to select a sealing gasket of the corresponding thickness for each type of carbon felt;

[0071] Specifically, the goal of selecting sealing gaskets of corresponding thickness for each type of carbon felt is to ensure that the compression ratio of all carbon felts combined with corresponding sealing gaskets is within 20%-30%, and the difference between the maximum and minimum compression ratios of the same type of carbon felt is less than 2%. The compression ratio is the ratio of the thickness of the carbon felt after compression to the thickness before compression. Since the sealing gaskets are molded and their thickness can be adjusted according to requirements, selecting sealing gaskets of corresponding thickness can ensure that the compression ratio of the carbon felt is controlled within the target range.

[0072] The thickness of the selected sealing gasket D s Calculate using the following formula:

[0073] D s = (1+ e ) D carbon - D frame，

[0074] in, e The target compression ratio for each type of carbon felt. D carbon The average thickness of each type of carbon felt; D frame The average thickness of the fluid flow frame.

[0075] In this embodiment, the sealing gasket is made of EPDM rubber or fluororubber that is resistant to electrolyte corrosion, with a hardness range of 60-70 Shore A, to ensure compression resilience.

[0076] In this embodiment, the optimal compression ratio is derived by combining the mechanical properties of the materials. e ;

[0077] Based on the elastic modulus of carbon felt E and the resilience coefficient of the sealing gasket K The compression ratio must meet the following requirements:

[0078] ,

[0079] in, P contact For fuel cell stack assembly pressure, D carbon The average thickness of the carbon felt; D s The thickness of the sealing gasket;

[0080] The elastic modulus of carbon felt was determined by compression test. E and the resilience coefficient of the sealing gasket K For example, the resilience coefficient K of EPDM rubber gaskets is approximately 50 MPa / mm, and the elastic modulus of carbon felt is... E ≈200 MPa;

[0081] Based on the target compression ratio e Reverse push D s :

[0082] ,

[0083] If the actual compression ratio deviates from the target value, adjust accordingly. D s .

[0084] The fifth step is to assemble each type of carbon felt with a sealing gasket of corresponding thickness into a fuel cell stack.

[0085] The sixth step is to perform charge and discharge tests on the assembled fuel cell stack and monitor the voltage data of each individual cell in the stack.

[0086] To monitor the voltage of individual cells in the fuel cell stack, a voltage monitoring instrument is needed to collect the voltage of each individual cell. The collection interval should be no less than 10 seconds, and the recording time should be no less than 5 seconds in the later stages of charging or discharging.

[0087] Step 7: Calculate stack consistency based on the voltage data of each individual cell;

[0088] Step 8: Discard unqualified fuel cells based on their consistency.

[0089] Specifically, the voltage of each cell at each recording time is statistically analyzed, and the voltage range or variance of all cells in the stack is used to evaluate the consistency of the stack. If the range or variance meets the preset conditions, the stack is qualified. The range represents the difference between the maximum and minimum values ​​of all cell voltages in a single stack. The range should be less than 1V to indicate that the stack is qualified in terms of consistency.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A production method for improving the consistency of flow batteries, characterized in that, Includes the following steps: The thickness of each carbon felt is measured, and the average and extreme values ​​of the thickness of each carbon felt are determined. All carbon felts are classified according to their average thickness. The method for classifying carbon felts is as follows: Set classification thresholds: D1, D2, D3, D4; Sort the carbon felt pieces in ascending order of average thickness; Category 1 carbon felt: D1 <Dave≤D2; Second type of carbon felt: D2 <Dave≤D3; Category 3 carbon felt: D3 <Dave≤D4; Category 4 carbon felt: Dave ≤ D1 or Dave > D4; Where Dave is the average thickness of a piece of carbon felt, and the fourth type of carbon felt is unqualified carbon felt; For each type of carbon felt, select a sealing gasket of appropriate thickness to ensure that the compression ratio of all carbon felts combined with the corresponding sealing gaskets is within 20%-30%, and the difference between the maximum and minimum compression ratios within the same type of carbon felt is less than 2%; the selected sealing gasket thickness... D s Calculate using the following formula: D s = (1+ ε )* D carbon - D frame ； in, ε The target compression ratio for each type of carbon felt. D carbon The average thickness of each type of carbon felt; D frame The average thickness of the fluid flow frame; Each type of carbon felt is assembled with a sealing gasket of corresponding thickness to form a fuel cell stack.

2. The production method for improving the consistency of flow batteries as described in claim 1, characterized in that, Before measuring the thickness of the carbon felt, the carbon felt roll needs to be cut into sheets of the target size.

3. The production method for improving the consistency of flow batteries as described in claim 1, characterized in that, The method for thickness detection of each carbon felt is as follows: Based on the length and width of each carbon felt, a corresponding number of detection points are selected on the surface of the carbon felt. The number of detection points on each carbon felt is greater than... m The distance between one or more adjacent detection points is less than x .

4. The production method for improving the consistency of flow batteries as described in claim 1, characterized in that, After the thickness of each carbon felt is measured, the carbon felt is screened based on the average and extreme values ​​of the carbon felt thickness. Unqualified carbon felts are removed, and qualified carbon felts are screened and classified. The criteria for judging whether the carbon felt is qualified are: the difference between the maximum and average carbon felt thickness is less than a preset value, and the difference between the minimum and average carbon felt thickness is less than a preset value.

5. A production method for improving the consistency of flow batteries as described in claim 1, characterized in that, It also includes a fuel cell stack testing and screening process, specifically comprising the following steps: The assembled fuel cell stack is subjected to charge and discharge tests, and the voltage data of each individual cell in the stack is monitored. Stack consistency is calculated based on the voltage data of each individual cell; Defective fuel cells are eliminated based on their consistency.

6. A production method for improving the consistency of flow batteries as described in claim 5, characterized in that, The voltage of each cell at each recording time is statistically analyzed. The voltage range or variance of all cells in the stack is used to evaluate the consistency of the stack. If the range or variance meets the preset conditions, the stack is qualified.

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