Bipolar plate runner integrated structure capable of remarkably improving performance of all-vanadium redox flow battery stack and battery and stack thereof

Abstract

The utility model belongs to the technical field of flow battery energy storage, and discloses a bipolar plate and runner integrated structure capable of remarkably improving the electric pile performance of an all-vanadium flow battery, a battery and an electric pile, a bipolar plate and a runner are integrally formed, and the runner is directly separated on the surface of the bipolar plate and comprises a runner ridge and a runner groove; the flow channel grooves are divided into liquid inlet flow channel grooves and liquid outlet flow channel grooves, the flow channel grooves and the flow channel ridges on the same face are distributed in an interdigital staggered mode, and the flow channel is single-face or double-face. The working efficiency and the material utilization rate can be greatly improved, the stack assembly process is simplified, the production efficiency is improved, the labor cost is reduced, and the enterprise revenue is improved; the high-consistency bipolar plate can be produced by a mould pressing or rolling process, the precision of a formed product is high, batch production can be realized, and the labor intensity is reduced; the contact resistance between the bipolar plate and the flexible graphite plate is eliminated; concentration polarization and ohmic polarization are effectively reduced, voltage efficiency and energy efficiency are improved, pile performance is improved, and stable innovation of products and processes is facilitated.

Description

Technical Field

[0001] The utility model belongs to the technical field of liquid flow battery energy storage, and relates to a bipolar plate flow channel integrated structure, a battery and a stack that can significantly improve the performance of a vanadium redox flow battery stack. Background Art

[0002] In the currently known vanadium redox flow battery stacks, the assembly process of the bipolar plate and the flow channel is as follows:

[0003] ① Use a die to stamp a complete flow channel plate to obtain a flow channel with an electrolyte circulation area;

[0004] ② Shape the flow channel plate, measure the thickness and record it;

[0005] ③ Measure the thickness of the bipolar plate and record it;

[0006] ④ Use double-sided tape or dispensing method, and rely on a jig to manually fix the flow channel on the bipolar plate.

[0007] The prior art has the following defects or problems:

[0008] 1. When different materials come into contact, corresponding contact resistance will be generated. Among them, due to the addition of resin materials in the bipolar plate, a certain degree of contact resistance will be generated when it contacts the flow channel plate. The bulk density and conductivity of the two materials are different. When the bipolar plate contacts the flexible graphite flow channel, it will cause an obstacle to the movement of electrons. This resistance will generate local charges, which will in turn affect the conductivity, voltage efficiency, energy efficiency, etc. between the plate and the flow channel;

[0009] 2. The flexible graphite plate is a plate formed by roll-pressing pure expanded graphite worms, with a low bulk density. After being stamped by a die, fractures and other situations will occur, which limits the design of the flow channel depth and the number of flow channels; and during the assembly or handling process, fractures and other situations are likely to occur; on the other hand, the flow channel relies on manual bonding with a fixture, and often the liquid inlet and outlet of the electrode frame cannot be aligned, resulting in a non-optimal way of electrolyte circulation, ultimately affecting the performance of the stack;

[0010] 3. During the blanking process of the flexible graphite plate, the waste materials cut off from the flow channel part cannot be reused, which will increase the cost of the stack. Content of the Utility Model

[0011] In view of the above deficiencies, the utility model provides a bipolar plate flow channel integrated structure, a battery and a stack that can significantly improve the performance of a vanadium redox flow battery stack. The application field of the utility model is the liquid flow battery energy storage industry, and the application method is the vanadium redox flow battery and system. The potential application method is a high current density vanadium redox flow battery. Using the bipolar plate flow channel integration produced by the utility model, the energy efficiency can be increased by 2.5%, and it can operate stably for a long time without obvious attenuation, leakage, etc.

[0012] The technical solution is as follows:

[0013] A bipolar plate and flow channel integrated structure that significantly improves the performance of a vanadium redox flow battery stack, where the bipolar plate and the flow channel are integrally formed, and the flow channel is directly separated on the surface of the bipolar plate. The flow channel includes a flow channel ridge and a flow channel groove. The flow channel groove is divided into an inlet flow channel groove and an outlet flow channel groove. The flow channel grooves on the same side are distributed in a finger-shaped staggered pattern with the flow channel ridge. The flow channel can be single-sided or double-sided.

[0014] Further, the cross-sectional shapes of the inlet flow channel groove and the outlet flow channel groove are isosceles trapezoids.

[0015] Further, the width of the flow channel groove is 6 - 8 mm.

[0016] Further, the width of the flow channel ridge is 7.5 - 12 mm.

[0017] Further, the depth of the flow channel groove is 2.5 - 3.3 mm.

[0018] Further, the materials of the bipolar plate and the flow channel are the same, which is a mixed material of graphite and PP resin.

[0019] For a battery with a bipolar plate and flow channel integrated structure, the porous electrode and the integrated bipolar plate are symmetrically distributed around the ion membrane as the positive and negative electrodes to form a single battery.

[0020] For a stack with a bipolar plate and flow channel integrated structure, multiple batteries with a bipolar plate and flow channel integrated structure are stacked and assembled into a stack.

[0021] The beneficial effects of the present utility model compared with the prior art are as follows:

[0022] ① It can significantly improve work efficiency and material utilization rate, simplify the stack assembly process, improve production efficiency, reduce labor costs, and enhance enterprise benefits;

[0023] ② The molding or rolling process can produce bipolar plates with high consistency, the formed products have high precision, can be mass-produced, and reduce labor intensity;

[0024] ③ Eliminate the contact resistance between the bipolar plate and the flexible graphite plate; effectively reduce concentration polarization and ohmic polarization, improve voltage efficiency and energy efficiency, enhance the performance of the stack, and contribute to the stable innovation of products and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0026] Figure 1 It is a schematic diagram of the integrated structure of a double-sided flow channel bipolar plate;

[0027] Figure 2 It is a schematic diagram of the overall double-sided flow channel structure;

[0028] Figure 3 It is a schematic diagram of the local structure of a double-sided flow channel;

[0029] Figure 4 It is a schematic diagram of the integrated structure of a single-sided flow channel bipolar plate;

[0030] Figure 5 It is a schematic diagram of the overall structure of a single-sided flow channel;

[0031] Figure 6 It is a schematic diagram of the local structure of a single-sided flow channel;

[0032] Figure 7 It is a schematic diagram of the application of the integrated structure in the stack.

[0033] Markings in the figure: 1 - bipolar plate, 2 - flow channel, 3 - flow channel ridge, 4 - inlet liquid flow channel groove, 5 - outlet liquid flow channel groove, 6 - integrated bipolar plate, 7 - porous electrode, 8 - ion membrane, a - flow channel groove width, b - flow channel ridge width, c - flow channel groove depth. Specific embodiments

[0034] The present invention will be described in detail below through specific embodiments, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the materials used can be obtained from commercial channels.

[0035] Embodiment 1

[0036] The integrated structure described in the present invention is composed of a bipolar plate and a flexible graphite flow channel. The disclosed technology can form a set unit by a molding or rolling process for the bipolar plate and the flexible graphite flow channel that are in independent units in the all-vanadium redox flow battery. The integrated set unit prepared by this method can bring many advantages:

[0037] ① As a set unit, it can greatly save the material preparation time. In the traditional material preparation process, it takes a lot of manpower time and auxiliary jigs to bond the flow channel to the bipolar plate, and the new integration can directly omit this process;

[0038] ② Using the integrated mold can greatly reduce the material cost of the stack. In the traditional material preparation process, a large amount of non-reusable surplus materials will be generated during the engraving and stamping of the bipolar plate and the flexible graphite flow channel. Using the new integration can completely avoid the problem of material waste;

[0039] ③ The molding or rolling process can achieve high consistency of the product, the formed product has high precision, can be mass-produced, and reduces the labor intensity.

[0040] Such as Figure 1 、 Figure 2As shown in the figure, through the molding or rolling process according to requirements, it is made into a component to obtain a new integrated bipolar plate flow channel structure: Based on the optimized interdigitated flow field design, the electrolyte has good performance in terms of uniform distribution and pressure loss control. The upper and lower surface flow channels are designed with peaks facing peaks and grooves facing grooves, or a single-sided flow channel design is adopted. The flow channel grooves and flow channel ridges 3 on the same surface are interdigitated and staggered; the cross-sectional shapes of the inlet flow channel groove 4 and the outlet flow channel groove 5 are isosceles trapezoids, the flow channel groove width a = 6 - 8 mm, the flow channel ridge width b = 7.5 - 12 mm, and the flow channel groove depth c = 2.5 - 3.3 mm; reasonable cross-sectional dimensions can be selected according to the different requirements of the electrolyte flow rate, reaction zone size, and flow field in the stack design.

[0041] As Figure 3 As shown in the figure, the new integrated bipolar plate is assembled with other components such as the ion membrane 8 and the porous electrode 7 in the stack, and the double-sided or single-sided integrated bipolar plate 6 is selected according to actual requirements; the porous electrode 7 and the integrated bipolar plate 6 are symmetrically distributed around the ion membrane 8 as the positive and negative electrodes, forming a single cell, and multiple cells are stacked and assembled into a stack. The electrolyte enters the inlet flow channel groove 4, crosses the flow channel ridge, and then enters the outlet flow channel groove 5, and wets the porous electrode 7 during this process; during the charge and discharge process, the new integrated bipolar plate makes the electrolyte distribution more uniform and the flow resistance smaller; at the same time, due to its integrated structure, the contact resistance of the previous split structure is avoided, reducing the overall resistance of the stack; it can effectively reduce concentration polarization and ohmic polarization, improve voltage efficiency and energy efficiency, and thus enhance the performance of the stack.

[0042] Design concept:

[0043] The original split structure is transformed into an integrated structure, and single-sided and double-sided flow channel integrated bipolar plates are designed. With a reasonable flow channel design, the electrolyte distribution is optimized, reducing the concentration polarization caused by uneven electrolyte distribution; the contact resistance between the original bipolar plate and the flexible graphite flow channel plate is eliminated, improving the voltage efficiency.

[0044] Design principle:

[0045] PP resin material and graphite material are selected and combined to develop an integrated bipolar plate with flow channels. Through simulation, the best fluid distribution in the stack is obtained, and the corresponding number of flow channels and flow channel depth are designed. The original split mode of the two materials is transformed into an integrated mode, greatly reducing the contact resistance; the reasonable flow channel design optimizes the electrolyte distribution, reducing the concentration polarization between the inlet and outlet, and between different cell numbers, further improving the voltage efficiency and energy efficiency; the process method of the integrated bipolar plate with flow channels is molding or rolling. According to the drawing design, the corresponding mold is developed for the production of the integrated bipolar plate with flow channels.

[0046] Technical innovation points:

[0047] 1. Since the traditional bipolar plate is a split structure with the flexible graphite flow channel, contact resistance will be generated. The present utility model changes the split mode of the original two materials into an integrated mode, greatly reducing the contact resistance;

[0048] 2. The reasonable flow channel design optimizes the electrolyte distribution, reduces the concentration polarization between the inlet and outlet and different sections, further improves the voltage efficiency, and increases the energy efficiency;

[0049] 3. The new integrated structure is not easily broken and does not limit the design of the flow channel depth and the number of flow channels;

[0050] 4. This integrated structure does not need to rely on jigs for manual bonding, and the situation where the inlet and outlet of the electrode frame are misaligned with the flow channel will not occur.

[0051] Multiple all-vanadium redox flow battery stacks have been assembled using this integrated structure of the bipolar plate flow channel, and multiple cycles have been run on the stack evaluation bench and efficiency tests have been carried out; the test results are compared with those of the traditional split bipolar plate with surface-bonded flow channels. It is found that the energy efficiency of the new integrated bipolar plate flow channel stack has increased by 2.5%, and the stack has no leakage during long-term operation, and its mechanical properties and others have all passed the tests.

[0052] The above-described embodiments are only the preferred embodiments of the present utility model, and not all the feasible embodiments of the present utility model. For those of ordinary skill in the art, any obvious changes made without departing from the principle and spirit of the present utility model should be considered to be included within the protection scope of the claims of the present utility model.

Claims

1. A bipolar plate flow channel integrated structure that significantly improves the performance of all-vanadium liquid flow battery stack, characterized in that: The bipolar plate (1) and the flow channel (2) are integrally formed, and the flow channel (2) is directly separated on the surface of the bipolar plate (1). The flow channel (2) includes a flow channel ridge (3) and a flow channel groove. The flow channel groove is divided into a liquid inlet flow channel groove (4) and a liquid outlet flow channel groove (5). The flow channel grooves and the flow channel ridge (3) on the same surface are interlaced in a finger-shaped manner, and the flow channel (2) is single-sided or double-sided.

2. The bipolar plate flow channel integrated structure for significantly improving the performance of the all-vanadium liquid flow battery stack according to claim 1 is characterized in that: The cross-sectional shapes of the liquid inlet flow channel groove (4) and the liquid outlet flow channel groove (5) are isosceles trapezoids.

3. The bipolar plate flow channel integrated structure for significantly improving the performance of the all-vanadium liquid flow battery stack according to claim 1 is characterized in that: The flow channel width (a) of the liquid inlet flow channel (4) and the liquid outlet flow channel (5) is 6 to 8 mm.

4. The bipolar plate flow channel integrated structure for significantly improving the performance of the all-vanadium liquid flow battery stack according to claim 1 is characterized in that: The flow channel ridge width (b) of the liquid inlet flow channel groove (4) and the liquid outlet flow channel groove (5) is 7.5 to 12 mm.

5. The bipolar plate flow channel integrated structure for significantly improving the performance of the all-vanadium liquid flow battery stack according to claim 1 is characterized in that: The flow channel groove depth (c) of the liquid inlet flow channel groove (4) and the liquid outlet flow channel groove (5) is 2.5 to 3.3 mm.

6. The bipolar plate flow channel integrated structure for significantly improving the performance of the all-vanadium liquid flow battery stack according to claim 1 is characterized in that: Furthermore, the bipolar plate (1) and the flow channel (2) are made of the same material, which is a mixed material of graphite and PP resin.

7. A battery with a bipolar plate flow channel integrated structure as claimed in claim 1, characterized in that: The porous electrode (7) and the integrated bipolar plate (6) are symmetrically distributed as positive and negative poles with the ion membrane (8) as the center, forming a battery.

8. A fuel cell stack with a bipolar plate flow channel integrated structure as claimed in claim 1, characterized in that: A plurality of cells with the bipolar plate flow channel integrated structure as claimed in claim 7 are stacked and assembled into a battery stack.

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