Anti-warping symmetrical battery segment preform and special battery segment assembly with current collector positioning

Abstract

This invention discloses a special battery cell assembly with anti-warping symmetrical battery cell preform and current collector positioning. The anti-warping symmetrical battery cell preform includes a bipolar plate, a first hot melt adhesive film and a second hot melt adhesive film respectively attached to both sides of the bipolar plate, and a first electrode frame and a second electrode frame respectively symmetrically bonded to both sides of the bipolar plate through the two hot melt adhesive films, forming a symmetrical stacked structure of electrode frame-adhesive film-bipolar plate-adhesive film-electrode frame. The special battery cell assembly with current collector positioning includes the above-mentioned preform, a current collector, and an insulating plate. The current collector has a raised strip, the electrode frame has a square hole, and the insulating plate has a protrusion. The current collector is embedded inside the electrode frame, and its raised strip is inserted into the square hole for positioning. The insulating plate covers the current collector, and its protrusion is inserted into the square hole to press down the raised strip. This invention fundamentally solves the problem of unidirectional warping caused by the difference in thermal expansion coefficients in special battery cells, avoids shear force damage during the pressing process, and eliminates leakage failure.

Description

Technical Field

[0001] This invention relates to the field of vanadium redox flow battery technology, and more specifically to a special battery cell assembly with anti-warping symmetrical battery cell preform and current collector positioning. Background Technology

[0002] In electrochemical energy storage devices such as vanadium redox flow batteries, specially structured battery cells (hereinafter referred to as "special battery cells") are typically installed at both ends of the battery stack to perform functions such as current collection, insulation, and encapsulation. Currently, the conventional method for manufacturing these special battery cells is to apply a hot-melt adhesive film to one side of the bipolar plate and electrode frame, and then heat-melt them through hot-pressing and cold-pressing processes, such as... Figure 1 As shown. However, in actual production, due to the significant difference in the coefficients of thermal expansion between the electrode frame material (mostly polymer materials) and the bipolar plate material (mostly conductive composite materials or carbon-based materials)—the coefficient of thermal expansion of the electrode frame is usually much greater than that of the bipolar plate—the special battery cell, after heat melting, will exhibit significant unidirectional warping deformation towards the side with the electrode frame. Actual measurements show that the warping can reach over 7 cm. Figure 2 As shown.

[0003] This severe warping problem leads to a series of process and reliability defects. Firstly, in the subsequent battery cell pressing process, the warped battery cells need to be forcibly flattened under external force, which generates significant uneven internal stress. During repeated pressing, the bipolar plate material develops fatigue microcracks due to stress concentration, which gradually propagate and eventually lead to structural breakage of the bipolar plate. Figure 4 As shown. After breakage, the battery end seals failed, electrolyte leaked, rendering the battery unusable and severely impacting the battery stack's lifespan and safety performance.

[0004] Secondly, existing production processes, in order to address the warping issue, necessitate repeated adjustments to the stroke parameters of the hot-melt press for each unique battery cell with varying degrees of warping. This not only increases operational complexity and the risk of human error but also makes it difficult for multiple presses to operate synchronously with identical parameters, significantly hindering production cycle time and batch manufacturing efficiency. Furthermore, warped battery cells require additional specialized tooling for positioning and correction, further increasing tooling investment and process complexity.

[0005] A search of relevant domestic and international patents and technical literature has revealed no effective solution to the unilateral warping problem of special battery cells caused by differences in thermal expansion coefficients. Some existing technologies attempt to reduce deformation by changing the hot-melt temperature or holding time, but the effects are limited and difficult to control stably. Other solutions attempt to add reinforcing ribs or coatings to one side of the bipolar plate, but these cannot fundamentally eliminate warping caused by asymmetric thermal stress, while increasing material costs and processing steps. Therefore, there is an urgent need to propose an innovative technical solution that can fundamentally solve the warping problem, simplify the production process, improve efficiency, and reduce costs. Summary of the Invention

[0006] In view of this, the present invention provides a special battery cell assembly with anti-warping symmetrical battery cell preform and current collector positioning, aiming to solve the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An anti-warping symmetrical battery cell preform includes: Bipolar plates; A first hot melt adhesive film and a second hot melt adhesive film are respectively attached to the first surface and the second surface of the bipolar plate; The first electrode frame and the second electrode frame are symmetrically bonded to both sides of the bipolar plate by the first hot melt adhesive film and the second hot melt adhesive film, respectively, thereby forming a symmetrical stacked structure of electrode frame-hot melt adhesive film-bipolar plate-hot melt adhesive film-electrode frame.

[0009] Through the above technical solution, this invention, by symmetrically setting electrode frames and hot melt adhesive films of the same material and thickness on both sides of the bipolar plate, ensures that the thermal stress generated on both sides of the bipolar plate during the hot melt molding process is equal in magnitude and opposite in direction, thus canceling each other out. This fundamentally eliminates unidirectional warping deformation caused by the difference in the thermal expansion coefficients of the materials, solving the problem of warping exceeding 7 cm in the original process. At the same time, the prefabricated structure is completely consistent with that of a normal battery cell, eliminating the need to adjust the stroke of the hot melt press during production. This allows for simultaneous production by multiple presses and multiple threads, significantly improving production efficiency. Furthermore, it eliminates the need for additional tooling for special battery cells, reducing production costs. It completely eliminates the problem of bipolar plate fatigue breakage and subsequent leakage caused by warping, improving the reliability and service life of the battery stack.

[0010] Preferably, in the above-mentioned anti-warping symmetrical battery cell preform, the first electrode frame and the second electrode frame are made of the same material, namely, a polymer insulating material, and their thickness, size and coefficient of thermal expansion are the same.

[0011] Preferably, in the above-mentioned anti-warping symmetrical battery cell preform, the bipolar plate is a conductive composite material bipolar plate or a carbon-based material bipolar plate.

[0012] Preferably, in the above-mentioned anti-warping symmetrical battery cell preform, the first hot melt adhesive film and the second hot melt adhesive film have the same material, thickness and hot melt parameters.

[0013] Preferably, in the above-mentioned anti-warping symmetrical battery cell preform, the symmetrical stacked structure remains flat and without unidirectional warping deformation after being hot-pressed and / or cold-pressed and hot-melted.

[0014] The present invention also provides a special battery cell assembly for current collector positioning, comprising: The aforementioned anti-warping symmetrical battery cell preform; A current collector, wherein a raised strip is provided on the current collector; An insulating board, wherein protrusions are provided on the insulating board; A square hole is provided on the edge of the first electrode frame or the second electrode frame; The current collector is embedded inside the first electrode frame or the second electrode frame, and the current collector is in contact with the corresponding surface of the bipolar plate. The protrusion on the current collector is inserted into the square hole to achieve the positioning of the current collector in the first electrode frame or the second electrode frame. The insulating plate covers the current collector, and the protrusions on the insulating plate are inserted into the square hole and press against the protruding strip to achieve positioning and engagement between the insulating plate and the first electrode frame or the second electrode frame.

[0015] Through the above technical solution, this invention, based on the anti-warping symmetrical battery cell preform, achieves precise radial positioning of the current collector by inserting a protrusion on the current collector into a square hole on the electrode frame. Simultaneously, a protrusion on the insulating plate inserts into the same square hole and presses down on the protrusion, reliably fixing the insulating plate and applying a stable clamping force to the current collector. This structure avoids relative sliding between the current collector and the bipolar plate plane during press-fitting, thereby eliminating shear forces between the sides of the bipolar plate and the current collector, and preventing the risk of indentation damage or fatigue breakage of the bipolar plate due to shear forces. Furthermore, the insulating plate covers the current collector, achieving four-sided insulation without the need for additional insulating components, and the overall assembly height is consistent with that of a normal battery cell, further simplifying production management and processes, reducing the breakage rate of special battery cells to zero, and completely eliminating end leakage problems.

[0016] Preferably, in the above-mentioned special battery cell assembly for current collector positioning, the square hole is a rectangular square hole, the convex strip and the protrusion are both rectangular structures adapted to the rectangular square hole, and the convex strip, the protrusion and the square hole are all clearance fits, with a fit clearance of 0.1mm to 0.5mm.

[0017] Preferably, in the above-mentioned special battery cell assembly for current collector positioning, the ridge strip and the protrusion overlap vertically along the thickness direction within the square hole, wherein the protrusion is pressed against the upper surface of the ridge strip.

[0018] Preferably, in the above-mentioned special battery cell assembly with current collector positioning, the insulating plate is integrally formed from an insulating polymer material.

[0019] Preferably, in the above-mentioned special battery cell assembly for current collector positioning, the height of the special battery cell assembly is the same as the height of a normal battery cell.

[0020] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a special battery cell assembly with anti-warping symmetrical battery cell preform and current collector positioning, which has the following beneficial effects: 1. Completely solve the warping problem: By symmetrically setting electrode frames and hot melt adhesive films of the same material and thickness on both sides of the bipolar plate, the thermal stress during hot melt molding cancels each other out, eliminating unidirectional warping deformation, and reducing the degree of warping from more than 7cm to zero.

[0021] 2. Improved production efficiency: The improved special battery cell preform has the same structure as the normal battery cell, eliminating the need to adjust the stroke of the hot melt press. It can achieve simultaneous production by multiple presses and multiple threads, while also eliminating the need for special tooling and significantly accelerating the production cycle.

[0022] 3. Prevent leakage failure: The convex strip of the current collector is positioned in conjunction with the square hole of the electrode frame, and the protrusion of the insulating plate presses against the convex strip, avoiding shear force between the bipolar plate and the side of the current collector during the pressing process, thus completely preventing fatigue breakage of the bipolar plate and leakage at the battery end.

[0023] 4. Integrated insulation function: The insulation plate covers the current collector and is reliably positioned with the electrode frame, achieving four-sided insulation of the sides of the special battery cell, eliminating the need for additional insulation components and simplifying the component structure.

[0024] 5. Reduced production costs: No need to adjust equipment parameters separately, no need for special tooling, reduced scrap rate and rework costs, resulting in a significant decrease in overall production costs, while improving the overall reliability and service life of the battery stack. Attached Figure Description

[0025] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 The attached diagram is an exploded view of the structure of an existing special battery cell prefabrication. Figure 2 The attached diagram is a structural schematic of an existing special battery cell preform in a deformed state; Figure 3 The attached diagram is an exploded view of the structure of a normal battery cell preform. Figure 4 The attached diagram is an exploded view of the structure of an existing special battery cell assembly; Figure 5 The attached figure is an exploded view of the structure of the anti-warping symmetrical battery cell preform provided by the present invention; Figure 6 The attached figure is an exploded view of the structure of the special battery cell assembly with current collector positioning provided by the present invention.

[0027] in: 1-Bipolar plate; 2-First hot melt adhesive film; 3-Second hot melt adhesive film; 4-First electrode frame; 5-Second electrode frame; 6-Current collector; 7-Insulating plate; 8-Raised strip; 9-Protrusion; 10-Square hole. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: See appendix Figure 5 This invention discloses an anti-warping symmetrical battery cell preform, comprising: Bipolar plate 1; The first hot melt adhesive film 2 and the second hot melt adhesive film 3 are respectively attached to the first surface and the second surface of the bipolar plate 1. The first electrode frame 4 and the second electrode frame 5 are symmetrically bonded to both sides of the bipolar plate 1 by the first hot melt adhesive film 2 and the second hot melt adhesive film 3, respectively, thereby forming a symmetrical stacked structure of electrode frame-hot melt adhesive film-bipolar plate-hot melt adhesive film-electrode frame.

[0030] To further optimize the above technical solution, the first electrode frame 4 and the second electrode frame 5 are made of the same material, namely polymer insulating material, and their thickness, size and coefficient of thermal expansion are the same.

[0031] To further optimize the above technical solution, the bipolar plate 1 is a conductive composite material bipolar plate or a carbon-based material bipolar plate.

[0032] To further optimize the above technical solution, the first hot melt adhesive film 2 and the second hot melt adhesive film 3 have the same material, thickness and hot melt parameters.

[0033] To further optimize the above technical solution, the symmetrical laminated structure remains flat and without unidirectional warping deformation after being hot-pressed and / or cold-pressed and hot-melted.

[0034] The principle of Embodiment 1 of the present invention, through the above-described symmetrical stacked structure, is as follows: Since the first electrode frame 4 and the second electrode frame 5 have the same material, thickness, and coefficient of thermal expansion, and are symmetrically bonded to both sides of the bipolar plate 1 via the first hot melt adhesive film 2 and the second hot melt adhesive film 3, the thermal stresses generated on both sides of the bipolar plate 1 during hot pressing and / or cold pressing hot melt forming are equal in magnitude and opposite in direction, thus canceling each other out. This contrasts with the existing technology where only one side of the bipolar plate is equipped with an electrode frame, i.e. Figure 1 Compared to the previous embodiment, this embodiment completely eliminates unidirectional warping deformation caused by differences in the thermal expansion coefficients of the materials.

[0035] Actual production verification has shown that the anti-warping symmetrical battery cell preform of this embodiment remains flat after hot-melting and can proceed to the next process without any correction. Furthermore, since the structure of this preform is completely identical to that of a normal battery cell, see [link to documentation]. Figure 3 Therefore, during the hot melt pressing process, there is no need to adjust the press stroke separately for special battery cells, enabling multiple presses to produce simultaneously in multiple threads, which greatly improves production efficiency.

[0036] Furthermore, this embodiment eliminates the need for additional positioning fixtures for special battery cells, reducing fixture investment costs and fundamentally preventing bipolar plate fatigue breakage and subsequent leakage caused by warping, thus significantly improving the reliability and service life of the battery stack.

[0037] Example 2: See appendix Figure 5 This invention discloses a special battery cell assembly for current collector positioning, comprising: Anti-warping symmetrical battery cell preform of Example 1; The current collector 6 has a raised strip 8 on it; Insulating plate 7, with protrusions 9 provided on it; A square hole 10 is provided on the frame of the first electrode frame 4 or the second electrode frame 5. The current collector 6 is embedded in the inner side of the first electrode frame 4 or the second electrode frame 5, and the current collector 6 is in contact with the corresponding surface of the bipolar plate 1. The protrusion 8 on the current collector 6 is inserted into the square hole 10 to realize the positioning of the current collector 6 in the first electrode frame 4 or the second electrode frame 5. The insulating plate 7 covers the current collector 6, and the protrusion 9 on the insulating plate 7 is inserted into the square hole 10 and presses down the protrusion 8 to achieve the positioning and cooperation between the insulating plate 7 and the first electrode frame 4 or the second electrode frame 5.

[0038] In this embodiment, the square hole is a rectangular square hole, and the protrusion 8 and the protrusion 9 are both rectangular structures adapted to the rectangular square hole. The protrusion 8, the protrusion 9 and the square hole 10 are all clearance fits, and the fit clearance is 0.1mm to 0.5mm.

[0039] To further optimize the above technical solution, the protrusion 8 and the protrusion 9 are stacked vertically along the thickness direction inside the square hole 10, wherein the protrusion 9 is pressed on the upper surface of the protrusion 8.

[0040] To further optimize the above technical solution, the insulating board 7 is integrally formed from insulating polymer material.

[0041] See appendix Figure 3 and attached Figure 5 The height of the special battery cell assembly is the same as that of the normal battery cell.

[0042] Based on the anti-warping symmetrical battery cell preform provided in Example 1, this embodiment further integrates the current collector 6 and the insulating plate 7. The structural cooperation principle is as follows: The current collector 6 is embedded inside the first electrode frame 4 or the second electrode frame 5. The protrusion 8 on the current collector 6 is inserted into the square hole 10 opened on the edge of the electrode frame, thereby achieving precise radial positioning of the current collector 6 within the electrode frame. Simultaneously, the bottom surface of the current collector 6 is in contact with the corresponding surface of the bipolar plate 1, ensuring good electrical contact. An insulating plate 7 covers the current collector 6, and its protrusion 9 is inserted into the same square hole 10 and presses against the upper surface of the protrusion 8, thereby reliably fixing the insulating plate 7 to the electrode frame and applying a stable clamping force to the current collector 6. The beneficial effects of this mating structure are as follows: First, the clearance fit between the square hole 10 and the protrusions 8 and 9 ensures smooth assembly and prevents the collector 6 from shifting laterally during the press-fitting process. Second, since the protrusion 8 of the current collector 6 is pressed by the protrusion 9 of the insulating plate 7, the current collector 6 will not slide relative to the plane of the bipolar plate 1 during the subsequent overall pressing of the battery stack, thereby avoiding the shear force between the side of the bipolar plate 1 and the current collector 6, and eliminating the risk of the bipolar plate being damaged by indentation or fatigue due to shear force. Third, the insulating plate 7 is integrally formed from insulating polymer material. After covering the current collector 6, it achieves four-sided insulation of the sides of the special battery cell without the need for additional insulating components. Fourth, the height of the special battery cell assembly obtained in this embodiment is exactly the same as that of the normal battery cell, so there is no need to distinguish between special cells and normal cells on the production line, which further simplifies production management and processes.

[0043] Practice has proven that by adopting this embodiment, the breakage rate of special battery cells during the pressing process is reduced to zero, the problem of end leakage is completely eliminated, the production cycle of a single production line is increased by about 30%, and the overall production cost is reduced by about 20%.

[0044] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preform for an anti-warping symmetrical battery cell, characterized in that, include: Bipolar plate (1); A first hot melt adhesive film (2) and a second hot melt adhesive film (3) are respectively attached to the first surface and the second surface of the bipolar plate (1); The first electrode frame (4) and the second electrode frame (5) are symmetrically bonded to both sides of the bipolar plate (1) by the first hot melt adhesive film (2) and the second hot melt adhesive film (3), respectively, thereby forming a symmetrical stacked structure of electrode frame-hot melt adhesive film-bipolar plate-hot melt adhesive film-electrode frame.

2. The anti-warping symmetrical battery cell preform according to claim 1, characterized in that, The first electrode frame (4) and the second electrode frame (5) are made of the same material, namely polymer insulating material, and their thickness, size and coefficient of thermal expansion are the same.

3. The anti-warping symmetrical battery cell preform according to claim 1, characterized in that, The bipolar plate (1) is a conductive composite material bipolar plate or a carbon-based material bipolar plate.

4. The anti-warping symmetrical battery cell preform according to claim 1, characterized in that, The first hot melt adhesive film (2) and the second hot melt adhesive film (3) have the same material, thickness and hot melt parameters.

5. The anti-warping symmetrical battery cell preform according to claim 1, characterized in that, After being hot-pressed and / or cold-pressed and hot-melted, the symmetrical laminated structure remains flat and free from unidirectional warping deformation.

6. A special battery cell assembly with current collector positioning, characterized in that, include: Anti-warping symmetrical battery cell preform as described in any one of claims 1 to 5; A current collector (6) is provided with a raised strip (8); Insulating plate (7), wherein protrusions (9) are provided on the insulating plate; A square hole (10) is provided on the frame of the first electrode frame (4) or the second electrode frame (5). The current collector (6) is embedded in the inner side of the first electrode frame (4) or the second electrode frame (5), and the current collector (6) is in contact with the corresponding surface of the bipolar plate (1). The protrusion (8) on the current collector (6) is inserted into the square hole (10) to realize the positioning of the current collector (6) in the first electrode frame (4) or the second electrode frame (5). The insulating plate (7) covers the current collector (6), and the protrusion (9) on the insulating plate (7) is inserted into the square hole (10) and presses down the protrusion (8) to achieve the positioning and cooperation between the insulating plate (7) and the first electrode frame (4) or the second electrode frame (5).

7. A special battery cell assembly for current collector positioning according to claim 6, characterized in that, The square hole is a rectangular square hole. The protrusion (8) and the protrusion (9) are both rectangular structures adapted to the rectangular square hole. The protrusion (8), the protrusion (9) and the square hole (10) are all clearance fits with a clearance of 0.1mm to 0.5mm.

8. A special battery cell assembly for current collector positioning according to claim 6, characterized in that, The convex strip (8) and the protrusion (9) overlap vertically along the thickness direction within the square hole (10), wherein the protrusion (9) is pressed onto the upper surface of the convex strip (8).

9. A special battery cell assembly for current collector positioning according to claim 6, characterized in that, The insulating board (7) is integrally formed from insulating polymer material.

10. A special battery cell assembly for current collector positioning according to claim 6, characterized in that, The height of the special battery cell assembly is the same as that of a normal battery cell.

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