A sealing structure for a flow battery stack frame

Abstract

The present invention provides a sealing structure for a flow battery stack frame, which consists of a sealing wire with a special axial cross-sectional configuration and an electrode frame designed with corresponding grooves for accommodating the sealing wire. Annular sealing grooves A and B for accommodating the sealing wire are respectively provided at the outer edge of the electrode frame and near the electrolyte through-hole, and another annular sealing groove C is provided adjacent to the two annular sealing grooves for connecting the above two annular grooves. An annular sealing ring A, an annular sealing ring B and an annular sealing ring C are respectively provided in the annular sealing grooves A, B and C. The shape of the axial cross-sections of the annular sealing ring A and the annular sealing ring B can achieve multi-layer sealing and improve the reliability of the sealing. The annular sealing ring C is in contact with the outer edge of the annular groove C, which can realize the positioning of the sealing ring and improve the installation efficiency of the sealing ring.

Description

Technical Field

[0001] The present invention relates to a liquid flow battery structure, in particular to a sealing structure of a liquid flow battery electrode frame. Background Art

[0002] The overuse of traditional fossil fuels is causing increasingly severe environmental damage, necessitating a greater share of renewable energy sources, such as photovoltaics, wind power, and tidal energy, in the energy mix. However, these energy sources suffer from instability and discontinuity, and their widespread grid connection can impact the power grid and threaten its security. Therefore, a buffering device between renewable energy and the grid is urgently needed to improve the quality of the grid for renewable energy and help the grid safely accommodate more renewable energy. Consequently, energy storage technology has made significant progress. Energy storage technology can address the peak load shifting and valley shifting of renewable energy sources and the frequency and peak load regulation of the power grid, significantly mitigating the uncertainty of renewable energy and enhancing the robustness of the power grid. Among various energy storage technologies, chemical energy storage stands out due to its independence from third-party factors such as site conditions, high efficiency, and low cost. Flow batteries, an emerging battery technology within chemical energy storage, offer advantages such as high safety, deep charge and discharge capabilities, high efficiency, long life, and the ability to independently design power and capacity, making them particularly suitable for large-scale, long-duration energy storage applications.

[0003] The battery system is the smallest complete unit that enables the technical characteristics of a flow battery. It consists of core components such as the stack, electrolyte, electrolyte storage tank, magnetic pump, piping circulation system, cooling system, and battery management system. Large-scale battery systems in practice are often constructed by stringing together single-cell battery systems. The stack is the most critical component in a battery system, directly determining its performance and reliability and serving as the key site for chemical reactions. The electrolyte is a corrosive aqueous solution of a strong acid or base, or a highly oxidizing substance containing a halogen element, placing higher demands on the stack's sealing. Generally speaking, stack sealing focuses on two key aspects: preventing electrolyte leakage from the stack, causing runaway and contamination; and preventing electrolyte permeation between the positive and negative electrodes, which could cause overheating and capacity loss. These sealing requirements are achieved through the sealing structure of the sealing material on the electrode frame. Excellent sealing design directly determines the reliability, lifespan, performance, and cost of the stack, making it a key component in stack design. Summary of the Invention

[0004] In order to improve the sealing reliability of the battery stack, increase the service life and performance of the battery stack, and reduce the cost of the battery stack, the present invention provides a sealing structure for a liquid flow battery battery stack frame, the battery stack frame is a flat plate with a through hole A for accommodating a positive (or negative) electrode in the middle, a pair of through holes B are provided on the flat plate surface on two opposite sides where the two opening ends of the through hole A are located as a positive electrode electrolyte inlet and a positive electrode electrolyte outlet, and a pair of through holes C are provided on the flat plate surface on two opposite sides where the two opening ends of the through hole A are located as a negative electrode electrolyte inlet and a negative electrode electrolyte outlet.

[0005] The above-mentioned stack frame is provided with: an annular sealing groove C is provided on one side surface or both side surfaces of the flat plate around the opening end of through hole B or through hole C, an annular sealing groove B is provided on the bottom surface of the annular sealing groove C, and a gap is formed between the wall surface of the annular sealing groove B away from through hole B or through hole C and the wall surface of the annular sealing groove C away from through hole B or through hole C. Through hole B or through hole C is located in the area surrounded by the annular sealing groove B.

[0006] An annular sealing groove A is provided on the four edges of one side surface or both side surfaces of the flat plate of the above-mentioned stack frame, the through hole A and the annular sealing groove B are located in the area surrounded by the annular sealing groove A, and the annular sealing groove A close to the annular sealing groove B is provided on the bottom surface of the annular sealing groove C.

[0007] An annular sealing ring A is provided in the annular sealing groove A, an annular sealing ring B is provided in the annular sealing groove B, and an annular sealing ring C is provided in the annular sealing groove C. The outer wall surface and the inner wall surface of the annular sealing ring C located between the annular sealing ring A and the annular sealing ring B are fixedly connected to the annular sealing ring A and the annular sealing ring B respectively.

[0008] The axial (perpendicular to the surface of the flat plate) cross-sections of the annular sealing ring A and the annular sealing ring B respectively have one of the following shapes:

[0009] A rectangular surface, wherein the middle portion of the upper bottom edge of the rectangle is provided with a concave surface that is concave downwards;

[0010] Or, a rectangular surface, wherein the middle portion of the upper base of the rectangle is provided with a downwardly concave surface, and the four top corners of the rectangular surface are all chamfered arc corners or chamfered angles;

[0011] Or, an elliptical surface, wherein the middle portion of the upper side of the ellipse is provided with an inner concave surface that is concave downwards;

[0012] Alternatively, the central rectangular surface and the left and right sides of the rectangular surface are arc-shaped surfaces convex outward (towards away from the rectangular surface) along the left and right sides of the rectangular surface, and a concave surface is provided downwardly in the middle of the upper bottom edge of the rectangle.

[0013] In the sealing structure of the stack frame described above, the axial (perpendicular to the surface of the flat plate) cross-section of the annular sealing ring C is a rectangular surface, the height of which is the same as the depth from the bottom surface of the annular sealing groove C to the open end.

[0014] In the sealing structure of the stack frame described above, the outer edge of the annular sealing ring C close to the through hole A is in contact with the wall surface of the annular sealing groove C close to the through hole A.

[0015] In the above-mentioned sealing structure of the stack frame, the height of annular sealing ring A (the height perpendicular to the flat plate surface) is greater than the depth from the bottom surface of annular sealing groove A to the open end; and the value of (height - depth) / height is 5-50%, preferably 20-35%. The height of annular sealing ring B (the height perpendicular to the flat plate surface) is greater than the depth from the bottom surface of annular sealing groove B to the open end; and the value of (height - depth) / height is 5-50%, preferably 20-35%.

[0016] In the sealing structure of the above-mentioned battery stack frame, the depths from the bottom surface of the annular sealing groove B and the annular sealing groove A to the open end are the same, and the gap between the wall surface of the annular sealing groove B away from the through hole B or the through hole C and the wall surface of the annular sealing groove A close to the through hole A makes the annular sealing groove B and the annular sealing groove A separated by part of the bottom surface of the annular sealing groove C.

[0017] In the sealing structure of the stack frame, the width of the annular seal ring A (parallel to the flat surface) is smaller than the width of the annular seal groove A. The width of the annular seal ring B (parallel to the flat surface) is smaller than the width of the annular seal groove B.

[0018] The sealing structure formed by the above-mentioned sealing ring and the stack frame can achieve double-layer or multi-layer sealing due to the shape of the sealing ring on the axial cross-section, thereby improving the reliability of the sealing; the annular sealing ring C is in contact with the outer edge of the annular groove C, which can realize the positioning of the sealing ring and improve the installation efficiency of the sealing ring.

[0019] The present invention has the following advantages:

[0020] 1. The sealing structure of a flow battery stack frame in the present invention can achieve double-layer or multi-layer sealing due to the shape of the sealing ring on the axial section, thereby improving the reliability of the sealing.

[0021] 2. In the sealing structure of a flow battery stack frame of the present invention, the annular sealing ring C is in contact with the outer edge of the annular groove C, which can realize the positioning of the sealing ring and improve the installation efficiency of the sealing ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1The positional relationship between the stack frame and the sealing ring in the sealing structure of the flow battery stack frame proposed by the present invention;

[0023] Among them: 1. Sealing ring; 2. Stack frame.

[0024] Figure 2 This is a diagram of the actual assembly of the stack frame and the sealing ring in the sealing structure of the flow battery stack frame proposed by the present invention;

[0025] Among them 9. Section line.

[0026] Figure 3 This is a sealing ring in the sealing structure of a flow battery stack frame proposed by the present invention;

[0027] Among them: 3. Ring-shaped sealing ring A; 4. Ring-shaped sealing ring B; 5. Ring-shaped sealing ring C.

[0028] Figure 4 The stack frame of the sealing structure of the flow battery stack frame proposed by the present invention has an enlarged portion of an annular sealing groove structure near the through hole B or the through hole C, through which the positive electrode electrolyte or the negative electrode electrolyte flows;

[0029] Among them: 6. Annular sealing groove A; 7. Annular sealing groove B; 8. Annular sealing groove C.

[0030] Figure 5 for Figure 2 A cross-sectional view of the negative electrode (or positive electrode) electrolyte through hole B or through hole C near the section line 9. DETAILED DESCRIPTION

[0031] Example:

[0032] A sealing structure for a flow battery stack frame, comprising a sealing ring (1) and a stack frame (2), the positional relationship of which is as follows: Figure 1 As shown in . Figure 2 The figure below is the actual assembly diagram of the stack frame and the sealing ring in the sealing structure proposed by the present invention.

[0033] Figure 3Specifically shown is a sealing ring in a sealing structure of a flow battery stack frame proposed by the present invention. The shape of the annular sealing ring A (3) on the axial cross section of the sealing ring (perpendicular to the flat surface) is a rectangular surface, and a concave surface is provided in the middle of the upper bottom edge of the rectangle, and the four top corners of the rectangular surface are all chamfered arc angles. Both sides of the concave surface in the cross section shape can be deformed when under pressure, playing a sealing role. The annular sealing ring B (4) is provided, and its axial cross section shape is the same as the axial cross section shape of the annular sealing ring A (3) mentioned above. The seal at this location can prevent the positive or negative electrode electrolyte from flowing into the opposite negative electrode or positive electrode electrolyte through the through hole B or through hole C, and interpenetrating and forming self-discharge. An annular sealing ring C (5) is provided, and the outer wall surface and inner wall surface of the annular sealing ring C (5) located between the annular sealing ring A (3) and the annular sealing ring B (4) are respectively fixed to the annular sealing ring A (3) and the annular sealing ring B (4). The axial (perpendicular to the surface of the flat plate) cross-section of the annular seal ring C (5) is a rectangular surface, the height of which is the same as the depth from the bottom surface of the annular seal groove C (8) to the open end. The outer edge of the annular seal ring C (5) near the through hole A is in contact with the wall surface of the annular seal groove C (8) near the through hole A. The thickness of the annular seal ring A (3) and the annular seal ring B (4) is 1.5 mm and the width is 4 mm. The thickness of the annular seal ring C (5) is 0.6 mm, and the compression ratio of the sealing line is 33%.

[0034] Figure 4 Specifically shown is a stack frame in a liquid flow battery stack frame sealing structure proposed by the present invention, wherein the enlarged portion is an annular sealing groove structure near the through hole B or through hole C, through which the positive electrode electrolyte or the negative electrode electrolyte flows. An annular sealing ring A (3) is set in the annular sealing groove A (6); an annular sealing ring B (4) is set in the annular sealing groove B (7); and an annular sealing ring C (5) is set in the annular sealing groove C (8). The depth of the annular sealing groove A (6) and the annular sealing groove B (7) are 1 mm and the width is 5 mm. The depth of the annular sealing groove C (8) is 0.6 mm, and the outer edge of the annular sealing ring C (5) near the through hole A is in contact with the wall surface of the annular sealing groove C (8) near the through hole A.

[0035] During assembly, the outer edge of the annular sealing ring C (5) near the through hole A can be used to contact the wall of the annular sealing groove C (8) near the through hole A to help the entire sealing ring achieve positioning. The annular sealing ring A (3) is bonded or welded into the annular sealing groove A (6). The annular sealing ring B (4) is bonded or welded into the annular sealing groove B (7) to complete the assembly of the sealing ring on the stack frame.

[0036] After assembly, the cross-sectional interface diagram shown by the section line 9 near the through hole B or through hole C of the positive or negative electrolyte is as follows Figure 5As shown, it specifically shows the shape of the axial cross-section of the annular sealing ring A (3); the annular sealing ring B (4); the annular sealing ring C (5) and the positional relationship between the corresponding annular sealing groove A (6); the annular sealing groove B (7); and the annular sealing groove C (8). The shape of the axial cross-section helps to improve the stability during compression and avoid the dislocation of the sealing ring caused by the rolling of the sealing ring. At the same time, both sides of the inner concave surface of the cross-sectional shape can be deformed when under pressure, which can achieve double sealing and improve the reliability of the seal. The outer edge of the annular sealing ring C (5) near the through hole A is in contact with the wall surface of the annular sealing groove C (8) near the through hole A to help the entire sealing ring to achieve positioning and improve assembly efficiency.

[0037] A stack assembled using one of the aforementioned flow battery stack frame sealing structures underwent a 3-bar compressed air pressure test, revealing no leakage of compressed air outside the stack, exceeding the stack's required sealing pressure of 2 bar. The stack also underwent an internal leakage pressure test at 0.5 bar compressed air, revealing no leakage of compressed air from the positive electrode cavity to the negative electrode cavity or from the negative electrode cavity to the positive electrode cavity, exceeding the stack's required sealing pressure of 0.3 bar. The cost of this sealing line is only 40% of that of a sealing gasket with the same function, significantly reducing stack costs and improving product competitiveness in high-power flow battery stacks.

Claims

1. A sealing structure for a flow battery stack frame, wherein the stack frame is a flat plate having a through hole A in the middle for accommodating a positive or negative electrode, a pair of through holes B provided on the flat plate surface on opposite sides of the through hole A's two open ends as a positive electrode electrolyte inlet and a positive electrode electrolyte outlet, and a pair of through holes C provided on the flat plate surface on opposite sides of the through hole A's two open ends as a negative electrode electrolyte inlet and a negative electrode electrolyte outlet; characterized in that: An annular sealing groove C is provided on one or both side surfaces of the plate around the opening end of the through hole B or through hole C, and an annular sealing groove B is provided on the bottom surface of the annular sealing groove C. The through hole B or through hole C is located in the area surrounded by the annular sealing groove B. An annular sealing groove A is provided on the periphery of one or both side surfaces of the flat plate, the through hole A and the annular sealing groove B are located in the area surrounded by the annular sealing groove A; and the annular sealing groove A adjacent to the annular sealing groove B is provided on the bottom surface of the annular sealing groove C; An annular sealing ring A is provided in the annular sealing groove A, an annular sealing ring B is provided in the annular sealing groove B, and an annular sealing ring C is provided in the annular sealing groove C. The outer wall surface and the inner wall surface of the annular sealing ring C located between the annular sealing ring A and the annular sealing ring B are respectively fixedly connected to the annular sealing ring A and the annular sealing ring B; The cross sections of the annular sealing ring A and the annular sealing ring B perpendicular to the surface of the flat plate are respectively one of the following: A rectangular surface, wherein the middle portion of the upper bottom edge of the rectangle is provided with a concave surface that is concave downwards; Or, a rectangular surface, wherein the middle portion of the upper base of the rectangle is provided with a downwardly concave surface, and the four top corners of the rectangular surface are all chamfered arc corners or chamfered angles; Or, an elliptical surface, wherein the middle portion of the upper side of the ellipse is provided with an inner concave surface that is concave downwards; Or, the middle rectangular surface and the left and right sides of the rectangular surface are arc-shaped surfaces convex along the left and right sides of the rectangular surface away from the rectangular surface, and the middle of the upper bottom edge of the rectangle is provided with an inner concave surface concave downwards, The cross section of the annular sealing ring C perpendicular to the surface of the flat plate is a rectangular surface, and its height is the same as the depth from the bottom surface of the annular sealing groove C to the open end; The outer edge of the annular sealing ring C close to the through hole A is in contact with the wall surface of the annular sealing groove C close to the through hole A; The height of the annular sealing ring A perpendicular to the surface of the flat plate is greater than the depth from the bottom surface of the annular sealing groove A to the open end; the height of the annular sealing ring B perpendicular to the surface of the flat plate is greater than the depth from the bottom surface of the annular sealing groove B to the open end; The depths from the bottom surfaces of the annular sealing groove B and the annular sealing groove A to the open end are the same, and the gap between the wall surface of the annular sealing groove B away from the through hole B or the through hole C and the wall surface of the annular sealing groove A close to the through hole A separates the annular sealing groove B and the annular sealing groove A through a portion of the bottom surface of the annular sealing groove C.

2. The sealing structure according to claim 1, characterized in that: In the annular seal A, the value of (height - depth) / height is 5-50%.

3. The sealing structure according to claim 2, characterized in that: In the annular seal A, the value of (height-depth) / height is 20-35%.

4. The sealing structure according to claim 1, wherein: In the annular seal B, the value of (height - depth) / height is 5-50%.

5. The sealing structure according to claim 4, characterized in that: In the annular seal B, the value of (height - depth) / height is 20-35%.

6. The sealing structure according to claim 1, wherein: The width of the annular sealing ring A in a direction parallel to the surface of the flat plate is smaller than the width of the annular sealing groove A.

7. The sealing structure according to claim 1, wherein: The width of the annular sealing ring B in a direction parallel to the surface of the flat plate is smaller than the width of the annular sealing groove B.

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