Flow battery stack bipolar plate and flow battery

Abstract

The invention relates to the technical field of redox flow batteries, in particular to a flow battery electric pile bipolar plate and a flow battery. The flow battery stack bipolar plate comprises a bipolar plate body, the bipolar plate body is provided with more than two annular spiral grooves, each annular spiral groove forms an annular spiral flow channel, the annular spiral flow channels are used for flowing of electrolyte, the annular spiral flow channels are nested, each annular spiral flow channel is provided with a liquid inlet and a liquid outlet, and the liquid inlet and the liquid outlet are communicated with each other. A liquid inlet and a liquid outlet in each annular spiral flow channel are independent from each other; the annular spiral flow channels on the bipolar plate of the redox flow battery stack can be independently controlled and do not influence one another, the flowing speed, the flow and the distribution uniformity are completely kept consistent, and the performance of a redox flow battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of redox flow batteries, and in particular to a flow battery stack bipolar plate and a flow battery. Background Art

[0002] As a new type of battery, flow battery is widely used in large-scale energy storage systems. Its working principle is based on the reversible redox reaction of active substances in the positive and negative electrolytes. The stack is the core part of the flow battery. The stack is mainly composed of a stacked structure of multiple battery cells such as (positive and negative) bipolar plates, diaphragms, liquid circulation systems and casings. The bipolar plates are provided with channels for electrolyte flow. The performance of the flow battery is highly dependent on the flow efficiency and uniformity of the electrolyte. Therefore, a good flow channel design can ensure the uniformity of the flow velocity distribution of the electrolyte in the electrode and the distribution of reactive ions, thereby reducing the concentration overpotential and improving the voltage efficiency.

[0003] Traditional bipolar plate flow channels in flow batteries mainly include serpentine, cross-shaped, and parallel channels. Serpentine channels provide more uniform electrolyte distribution but have a higher pressure drop. Cross-shaped channels can reduce pressure drop through branching, but their structure is complex and difficult to process, which can easily lead to uneven electrolyte distribution. Parallel channels have a simple structure and lower electrolyte flow resistance, but compared to serpentine and cross-shaped channels, parallel channels have less uniform electrolyte distribution. To address the problems of traditional bipolar plate flow channels, a Chinese invention patent with authorization publication number CN115911439B and authorization publication date of May 24, 2024, discloses a flow channel for a bipolar plate of a flow battery with a double helix structure. The structure is a double channel structure arranged in two square spirals. The two channels have a central outlet that overlaps and two inlets at each end. The electrolyte flows into each spiral channel from the two inlets, and after the reaction at the porous electrode is completed, it is discharged at the central outlet. The electrolyte inlet and outlet can also be arranged in the opposite direction to achieve electrolyte flow.

[0004] In the above scheme, if the electrolyte enters from the middle outlet, it will be diverted along the double flow channels arranged in a square spiral. Since the pressure in the two flow channels is difficult to maintain complete consistency, the electrolyte will flow from the high pressure area to the low pressure area, and the electrolyte distribution in various parts of the flow channel will be uneven, the flow rate will be inconsistent, and the degree of reaction with the porous electrode will also be inconsistent, affecting the performance of the liquid flow battery. The same problem also exists when the electrolyte flows in the opposite direction. Summary of the Invention

[0005] The present invention aims to provide a flow battery stack bipolar plate to address the issues of uneven electrolyte distribution, inconsistent flow velocities, and inconsistent reaction with porous electrodes within the bipolar plate flow channels, which can affect flow battery performance. Furthermore, the present invention aims to provide a flow battery utilizing the aforementioned flow battery stack bipolar plate to address the issue of poor flow battery performance.

[0006] To achieve the above objectives, the bipolar plate of the flow battery stack of the present invention adopts the following technical solutions:

[0007] A bipolar plate for a liquid flow battery stack includes a bipolar plate body, wherein the bipolar plate body is provided with two or more annular spiral grooves, each of which forms an annular spiral flow channel, and the annular spiral flow channel is used for the flow of electrolyte. Multiple annular spiral flow channels are nested, and each annular spiral flow channel has a liquid inlet and a liquid outlet, and the liquid inlet and liquid outlet on each annular spiral flow channel are independent of each other.

[0008] Furthermore, the annular spiral flow channel is a circular spiral flow channel.

[0009] Furthermore, the inner end of each of the annular spiral grooves is arranged on the outer side surface of the same boss, so that the boss forms an impeller shape.

[0010] Furthermore, the annular spiral flow channels have the same shape and are evenly staggered around the center of the boss.

[0011] Furthermore, the inner wall of the annular spiral flow channel is a smooth wall surface.

[0012] Beneficial Effects: The bipolar plate for the flow battery stack of the present invention is an improved invention. Providing two or more annular spiral grooves on the bipolar plate allows the electrolyte to flow along their respective channels, increasing the contact area between the electrolyte and the porous electrode, allowing the electrolyte and the porous electrode to fully react and improving reaction efficiency. At the same time, each annular spiral channel has a liquid inlet and a liquid outlet, meaning that each annular spiral channel has its own liquid inlet and outlet, which are independently controlled and do not affect each other. By simply ensuring the consistency of pressure in each annular spiral channel, the flow velocity, flow rate, and distribution uniformity of the electrolyte in each annular spiral channel can be completely consistent, thereby improving the convection effect and distribution uniformity of the electrolyte in the entire flow battery and enhancing the performance of the flow battery.

[0013] The flow battery of the present invention adopts the following technical solutions:

[0014] A liquid flow battery includes a bipolar plate body, which is provided with two or more annular spiral grooves, each of which forms an annular spiral flow channel for the flow of electrolyte. Multiple annular spiral flow channels are nested, and each annular spiral flow channel has a liquid inlet and a liquid outlet. The liquid inlet and liquid outlet on each annular spiral flow channel are independent of each other.

[0015] Furthermore, the annular spiral flow channel is a circular spiral flow channel.

[0016] Furthermore, the inner end of each of the annular spiral grooves is arranged on the outer side surface of the same boss, so that the boss forms an impeller shape.

[0017] Furthermore, the annular spiral flow channels have the same shape and are evenly staggered around the center of the boss.

[0018] Furthermore, the inner wall of the annular spiral flow channel is a smooth wall surface.

[0019] Beneficial Effects: The liquid flow battery of the present invention is an improved invention. Providing two or more annular spiral grooves on the bipolar plate allows the electrolyte to flow along their respective flow channels, increasing the contact area between the electrolyte and the porous electrode, allowing the electrolyte and the porous electrode to fully react and improving the reaction efficiency. At the same time, each annular spiral flow channel has a liquid inlet and a liquid outlet, meaning that each annular spiral flow channel has its own liquid inlet and outlet, which are independently controlled and do not affect each other. Simply by ensuring the consistency of pressure in each annular spiral flow channel, the flow velocity, flow rate, and distribution uniformity of the electrolyte in each annular spiral flow channel can be completely consistent, thereby improving the convection effect and distribution uniformity of the electrolyte in the entire liquid flow battery and enhancing the performance of the liquid flow battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of an embodiment of a bipolar plate flow channel of a flow battery stack according to the present invention;

[0021] Figure 2 Schematic diagram of the positions of the liquid inlet and the liquid outlet in one embodiment of the flow channel of the bipolar plate of the flow battery stack of the present invention;

[0022] Figure 3 Schematic diagram of the positions of the liquid inlet and the liquid outlet in another embodiment of the bipolar plate flow channel of the liquid flow battery stack of the present invention.

[0023] In the figure: 1. Bipolar plate body; 2. Circular spiral flow channel; 3. Liquid inlet; 4. Liquid outlet; 5. Boss. DETAILED DESCRIPTION

[0024] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0025] Embodiments of the flow battery stack bipolar plate of the present invention:

[0026] The flow channels of traditional liquid flow battery bipolar plates are usually serpentine, cross-shaped or parallel. The electrolyte distribution of serpentine flow channels is more uniform, but the pressure drop is larger. The cross-shaped flow channels reduce the pressure drop through the branch design, but it is easy to cause uneven electrolyte distribution. The electrolyte flow resistance of parallel flow channels is small, but the distribution uniformity is poor. Compared with the traditional liquid flow battery bipolar plate flow channels, the existing bipolar plate flow channels are set as double spiral flow channels with a square cross-section and an overlapping middle outlet. It is difficult to maintain the pressure in the two flow channels completely consistent, which will cause the electrolyte to flow from the high pressure area to the low pressure area, thereby making the electrolyte distribution uneven in various parts of the flow channel, the flow speed is also inconsistent, and the reaction degree with the porous electrode is also inconsistent, affecting the performance of the liquid flow battery. To address this problem, the present invention proposes a liquid flow battery stack bipolar plate, in which each flow channel is independent of each other and does not affect each other, and the electrolyte distribution uniformity in each flow channel remains consistent.

[0027] See Figure 1 As a basic embodiment of the present invention, the bipolar plate of the flow battery stack of the present invention includes a bipolar plate body 1, and the bipolar plate body 1 is provided with two or more annular spiral grooves, each of which forms an annular spiral flow channel 2. The annular spiral flow channel 2 is used for the flow of electrolyte. The multiple annular spiral flow channels 2 are nested, similar to the disc-shaped mosquito coils used in life. Each annular spiral flow channel 2 has an inlet 3 and an outlet 4. The inlet 3 and the outlet 4 of the annular spiral flow channel 2 are independent of each other. When in use, the electrolyte is introduced from the inlet 3 of each annular spiral flow channel 2, and the electrolyte flows along the annular spiral flow channel 2 to the outlet 4. In this process, the electrolyte will fully contact and react with the porous electrode, and the inlet and outlet of each annular spiral flow channel 2 are independently controlled without affecting each other. It is only necessary to ensure that the pressure in each annular spiral flow channel 2 is consistent to achieve the flow velocity, flow rate and distribution uniformity of the electrolyte in each annular spiral flow channel 2. It is also consistent with the reaction degree of the porous electrode.

[0028] In the basic embodiment of the present invention, a quad-helix arrangement is employed, i.e., four annular spiral grooves are provided, each forming four annular spiral channels 2. Each of the four annular spiral channels 2 is arranged along the thickness of the bipolar plate body 1. Directly machining the annular spiral grooves into the bipolar plate reduces machining complexity and enhances ease of use. In other embodiments, other numbers of spirals, such as double, six, or eight, may be employed. The specific number is determined based on the specific charging and discharging requirements of the flow battery.

[0029] As a preferred embodiment of the present invention, the annular spiral flow channel 2 is set as a circular spiral flow channel. The circular spiral flow channel can reduce the flow resistance of the electrolyte and increase the flow speed of the electrolyte. In other embodiments, the annular spiral flow channel can also be set as a rectangular spiral flow channel.

[0030] As a preferred embodiment of the present invention, the inner ends of each annular spiral groove are arranged on the outer side of the same boss, so that the boss groove is impeller-shaped, that is, a boss 5 is provided at the center of the bipolar plate body 1, and the inner ends of each annular spiral groove are on the outer side of the boss 5. Such an arrangement can keep the height of the electrolyte inlet or outlet consistent, and thus keep the pressure consistent, which is beneficial to the uniformity of the pressure in each annular spiral flow channel 2.

[0031] See Figures 2 to 3 As a preferred embodiment of the present invention, the annular spiral flow channels 2 have the same shape and are evenly staggered around the center of the boss 5 to avoid conflict between the positions of the liquid inlets 3 or liquid outlets 4 of the annular spiral flow channels 2, thereby ensuring that the electrolyte can enter and flow out smoothly. In this embodiment, the end of the annular spiral groove close to the edge of the bipolar plate body 1 is set as the liquid inlet 3, and the end of the annular spiral groove close to the center of the bipolar plate body 1 is set as the liquid outlet 4. At this time, the flow direction of the electrolyte in the annular spiral flow channels 2 is consistent, that is, it flows in a spiral from the edge of the bipolar plate body 1 to the center of the bipolar plate body 1 along each annular spiral flow channel 2. During the flow process, the electrolyte reacts with the porous electrode to charge or discharge the liquid flow battery. In other embodiments, the end of the annular spiral groove close to the edge of the bipolar plate body 1 can be set as the liquid outlet 4, and the end of the annular spiral groove close to the center of the bipolar plate body 1 can be set as the liquid inlet 3. At this time, the electrolyte flows spirally from the center of the bipolar plate body 1 to the edge of the bipolar plate body 1 along the respective annular spiral flow channels 2; in other embodiments, the liquid inlet 3 of the annular spiral flow channel 2 can be separately set at the edge and center of the bipolar plate, and the corresponding liquid outlet 4 can also be separately set at the center and edge of the bipolar plate, as long as the normal flow of the electrolyte is guaranteed.

[0032] As a preferred embodiment of the present invention, the inner wall of the annular spiral flow channel 2 is smoothed to form a smooth wall surface. The smoothed inner wall of the annular spiral flow channel 2 can further reduce the resistance of the electrolyte flowing in the annular spiral flow channel 2, and can make the electrolyte flow smoothly, which is beneficial to improving the flow efficiency and distribution uniformity of the electrolyte.

[0033] Embodiments of the flow battery of the present invention:

[0034] The liquid flow battery of the present invention includes a bipolar plate body 1, which is the bipolar plate body 1 in the above-mentioned liquid flow battery stack bipolar plate. The specific structure is also consistent with the structure of the above-mentioned liquid flow battery stack bipolar plate. The liquid flow battery stack bipolar plate is installed in the liquid flow battery to complete charging or discharging of the liquid flow battery, which can improve the performance of the liquid flow battery. It will not be repeated here.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be based on the claims. Any equivalent structural changes made using the description and drawings of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A bipolar plate for a flow battery stack, comprising a bipolar plate body, characterized in that: The bipolar plate body is provided with more than two annular spiral grooves, each of which forms an annular spiral flow channel, which is used for the flow of electrolyte. Multiple annular spiral flow channels are nested, and each annular spiral flow channel has a liquid inlet and a liquid outlet. The liquid inlet and liquid outlet on each annular spiral flow channel are independent of each other.

2. The bipolar plate for a flow battery stack according to claim 1, characterized in that: The annular spiral flow channel is a circular spiral flow channel.

3. The bipolar plate for a flow battery stack according to claim 2, characterized in that: The inner end of each of the annular spiral grooves is arranged on the outer side surface of the same boss, so that the boss forms an impeller shape.

4. The bipolar plate for a flow battery stack according to claim 3, characterized in that: The annular spiral flow channels have the same shape and are evenly staggered around the center of the boss.

5. The bipolar plate for a flow battery stack according to any one of claims 1 to 4, characterized in that: The inner wall of the annular spiral flow channel is a smooth wall surface.

6. A flow battery comprising a bipolar plate body, characterized in that: The bipolar plate body is provided with more than two annular spiral grooves, each of which forms an annular spiral flow channel, which is used for the flow of electrolyte. Multiple annular spiral flow channels are nested, and each annular spiral flow channel has a liquid inlet and a liquid outlet. The liquid inlet and liquid outlet on each annular spiral flow channel are independent of each other.

7. The liquid flow battery according to claim 6, characterized in that: The annular spiral flow channel is a circular spiral flow channel.

8. The liquid flow battery according to claim 7, characterized in that: The inner end of each of the annular spiral grooves is arranged on the outer side surface of the same boss, so that the boss forms an impeller shape.

9. The liquid flow battery according to claim 8, characterized in that: The annular spiral flow channels have the same shape and are evenly staggered around the center of the boss.

10. The liquid flow battery according to any one of claims 6 to 9, characterized in that: The inner wall of the annular spiral flow channel is a smooth wall surface.

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