Square aluminum shell battery cell shell and square aluminum shell battery cell

Abstract

The embodiment of the application provides a square aluminum shell battery cell shell and a square aluminum shell battery cell, which comprise a shell body, a top cover and a bottom cover, the top cover and the bottom cover are fixedly connected with the shell body, at least one first protrusion is arranged on the top cover, the protruding direction of the first protrusion is away from the bottom cover, and one side of the first protrusion facing the bottom cover is hollow; and / or a second protrusion is arranged on the bottom cover, the protruding direction of the second protrusion is away from the top cover, and one side of the second protrusion facing the top cover is hollow. The hollow cavity of the first protrusion and / or the second protrusion stores electrolyte, the amount of electrolyte injected in the shell can be increased under the premise that the design of the pole piece is unchanged, the size of the battery cell is unchanged and the performance of the battery cell is not sacrificed, for a high-energy-density large storage battery cell, more electrolyte can be used for consumption in the middle and later stages of the cycle, so that the battery cell has a longer cycle life and better electrical performance.

Description

Technical Field

[0001] This application relates to the field of energy storage cells, and more particularly to a square aluminum-cased cell casing and a square aluminum-cased cell. Background Technology

[0002] As market demands for cost reduction, efficiency improvement, and extended battery life continue to rise, the energy density of prismatic aluminum-cased battery cells faces ongoing technological challenges. In the current technological development path, the industry generally achieves breakthroughs in energy density through core methods such as adopting high-specific-capacity positive and negative electrode materials, increasing electrode areal density and compaction density, and optimizing the assembly ratio of electrodes and the casing. Especially under relatively fixed material system conditions, extreme electrode structure design and assembly space optimization have become key pathways to improving energy density.

[0003] However, the implementation of the aforementioned technical solutions has significantly accelerated the densification process within the battery cell. Specifically, the continuous decrease in electrode porosity leads to a reduction in electrolyte storage space, and the utilization rate of the internal space of the casing approaches its theoretical limit. Taking a typical energy storage cell as an example, when achieving an energy density of 160Wh / kg in a 100Ah lithium iron phosphate system, the electrolyte injection coefficient can be maintained at 4.1g / Ah; when the capacity is increased to 314Ah and the energy density reaches 175Wh / kg, the electrolyte injection coefficient has decreased to 3.8g / Ah; and in the design of the new generation of 600+Ah high-capacity cells, to achieve an ultra-high energy density of 190Wh / kg, the electrolyte injection coefficient will be forced to be compressed to ≤3.2g / Ah. This structural contradiction leads to a serious conflict between the electrolyte content and the cell performance parameters.

[0004] Existing solutions have significant technical limitations: First, while sacrificing some electrical performance indicators (such as appropriately relaxing internal resistance or cycle life requirements) through a balanced design can temporarily meet the electrolyte injection requirements, it leads to a deterioration in the overall product performance. Second, although optimizing the electrolyte formulation can lower the minimum requirement threshold, it poses compatibility risks in high-nickel / silicon-carbon systems and cannot overcome the limitations of physical storage space. In particular, for the technical requirements of third-generation high-capacity energy storage cells (energy density ≥190Wh / kg, cycle life ≥10,000 cycles, and 70% capacity retention), traditional solutions have shown systemic defects—excessive compression of the electrolyte injection coefficient will lead to deterioration of electrochemical kinetic performance, a sharp increase in lithium-ion transport impedance, and ultimately affect high-temperature cycling stability and safety. Utility Model Content

[0005] This application provides a square aluminum-cased battery cell casing and a square aluminum-cased battery cell. By providing a first protrusion of a hollow structure on the top cover and / or a second protrusion of a hollow structure on the bottom cover, the electrolyte injection volume can be increased without changing the electrode design, the battery cell size, or the battery cell performance, thereby overcoming the defects caused by excessive compression of the electrolyte injection coefficient in traditional solutions.

[0006] In a first aspect, embodiments of this application provide a square aluminum-cased battery cell housing, including a housing, a top cover, and a bottom cover. The top cover and the bottom cover are both fixedly connected to the housing. At least one first protrusion is provided on the top cover. The protrusion direction of the first protrusion is away from the bottom cover, and the side of the first protrusion facing the bottom cover is hollow.

[0007] And / or, a second protrusion is provided on the bottom cover, the protrusion direction of the second protrusion is opposite to that of the top cover, and the side of the second protrusion facing the top cover is hollow.

[0008] In one possible implementation, a second protrusion is provided on the bottom cover, the protrusion direction of the second protrusion is away from the top cover, and the side of the second protrusion facing the top cover is hollow;

[0009] The height of the second protrusion is ≥0.3mm.

[0010] In one feasible implementation, the area on the bottom cover where the second protrusion is not located is covered with a blue film, the thickness of which is flush with the second protrusion.

[0011] In one feasible implementation, at least one first protrusion is provided on the top cover, the protrusion direction of the first protrusion is away from the bottom cover, and the side of the first protrusion facing the bottom cover is hollow;

[0012] The top cover is also provided with a terminal post, which includes a positive terminal post and a negative terminal post, and the first protrusion is disposed between the positive terminal post and the negative terminal post;

[0013] The height of the pole post is greater than the height of the first protrusion, and the height difference between the pole post and the first protrusion is 0.3-0.5mm.

[0014] In one feasible implementation, an explosion-proof valve is also provided on the top cover, and the first protrusion is disposed between the pole and the explosion-proof valve.

[0015] In one feasible implementation, two first protrusions are provided on the top cover, and the two first protrusions are respectively located on both sides of the explosion-proof valve.

[0016] In one feasible implementation, an injection port is provided on one side of the explosion-proof valve.

[0017] In one feasible implementation, at least one first protrusion is provided on the top cover, and a second protrusion is provided on the bottom cover, wherein the first protrusion and / or the second protrusion is rectangular, square, or circular.

[0018] In one feasible implementation, the top cover is welded to the housing, and the bottom cover is an integral structure with the housing.

[0019] Secondly, embodiments of this application provide a square aluminum-cased battery cell, including the square aluminum-cased battery cell outer shell as described above, wherein a positive electrode plate and a negative electrode plate are wound inside the outer shell, the positive electrode plate and the negative electrode plate are separated by a separator, and the outer shell is filled with electrolyte.

[0020] This application provides a square aluminum-cased battery cell casing and a square aluminum-cased battery cell. The electrolyte is stored in the hollow cavity of the first and / or second protrusions. This increases the amount of electrolyte injected into the casing without changing the electrode design, cell size, or sacrificing cell performance. For high-energy-density, large-capacity batteries, this better ensures more electrolyte is available for consumption in the later stages of cycling, resulting in a longer cycle life and superior electrical performance. Furthermore, the top and bottom covers can be manufactured using existing aluminum casing production lines and processes by adjusting the stamping die dimensions, enabling mass production without significantly increasing costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a square aluminum-cased battery cell casing provided in one embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the top cover of the square aluminum battery cell casing provided in an embodiment of this application in the first state;

[0023] Figure 3 This is a schematic diagram of the top cover of the square aluminum battery cell casing provided in an embodiment of this application in the second state;

[0024] Figure 4 This is a schematic diagram of the bottom cover of a square aluminum battery cell casing provided in one embodiment of this application.

[0025] Explanation of reference numerals in the attached figures:

[0026] 100 - Shell; 200 - Top cover; 300 - Bottom cover;

[0027] 210 - First protrusion; 220 - Pole post; 230 - Explosion-proof valve; 240 - Injection port;

[0028] 310 - Second protrusion. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application.

[0030] Energy density includes mass energy density and volumetric energy density. Mass energy density equals cell capacity divided by cell mass, with units of Wh / kg; volumetric energy density equals cell capacity divided by cell volume, with units of Wh / L.

[0031] Liquid injection coefficient: The amount of liquid injected into the cell divided by the cell capacity, expressed in g / Ah.

[0032] Figure 1 This is a schematic diagram of the structure of a square aluminum-cased battery cell casing provided in one embodiment of this application. Figure 2 This is a schematic diagram of the top cover of a square aluminum-cased battery cell casing provided in an embodiment of this application in its first state. Figure 3 This is a schematic diagram of the top cover of the square aluminum battery cell casing provided in an embodiment of this application in a second state. Figure 4 This is a schematic diagram of the bottom cover of a square aluminum-cased battery cell casing according to an embodiment of this application. (Refer to...) Figures 1 to 4 As shown, this application embodiment provides a square aluminum battery cell housing, including a housing 100, a top cover 200 and a bottom cover 300. The top cover 200 and the bottom cover 300 are both fixedly connected to the housing 100. The top cover 200 is provided with at least one first protrusion 210. The protrusion direction of the first protrusion 210 is away from the bottom cover 300, and the side of the first protrusion 210 facing the bottom cover 300 is hollow.

[0033] And / or, a second protrusion 310 is provided on the bottom cover 300, the protrusion direction of the second protrusion 310 is away from the top cover 200, and the side of the second protrusion 310 facing the top cover 200 is hollow.

[0034] It is easy to understand that the outer shell consists of a shell 100, a top cover 200 and a bottom cover 300 forming a fully enclosed cavity. The shell 100 is a rectangular aluminum shell. The top cover 200 is fixed to the top opening of the shell 100 by laser welding. The bottom cover 300 is located at the bottom of the shell 100 and is an integral structure with the shell 100. The bottom cover 300 can be integrally stamped with the shell 100 to form an airtight encapsulation structure.

[0035] It should be noted that the sidewall thickness of the first protrusion 210 gradually decreases from the root to the top. In some specific examples, the root thickness is 0.5-1.2 mm and the top thickness is 0.3-0.8 mm, achieving a balance between lightweight and structural strength. The thinner top thickness also helps to increase the electrolyte capacity.

[0036] In the above embodiments, by storing electrolyte in the hollow cavity of the first protrusion 210 and / or the second protrusion 310, the amount of electrolyte injected into the outer shell can be increased without changing the electrode design, the cell size, or the cell performance. For high-energy-density large-capacity cells, this can better ensure that more electrolyte is available for consumption in the later stages of the cycle, thereby giving the cell a longer cycle life and better electrical performance.

[0037] Moreover, the top cover 200 and bottom cover 300 can be manufactured based on existing aluminum shell production lines and processes by adjusting the size of the stamping die, thus enabling mass production without significantly increasing costs.

[0038] In some examples, the protrusion height of the second protrusion 310 is ≥0.3mm.

[0039] It should be noted that the protrusion height refers to the maximum distance from the second protrusion 310 to its outer apex in the direction perpendicular to the main body plane of the bottom cover 300 (i.e., the flat area where no protrusion is formed) in the direction perpendicular to the main body plane.

[0040] A second protrusion 310 is provided on the bottom cover 300, and its protruding direction is opposite to that of the first protrusion 210 on the top cover 200. In some specific examples, taking a 73*302*218mm battery cell as an example, the internal space of the casing increases by ≥5426.85mm. 2 .

[0041] This application does not limit the number of the second protrusion 310, which can be one or more, preferably one.

[0042] It is easy to understand that the height of the second protrusion 310 is preferably 0.3-5mm, with gradients based on cell capacity. In some specific examples, a protrusion height of 0.3-1.0mm is suitable for cells with a capacity ≤200Ah; a protrusion height of 1.0-3.0mm is suitable for cells with a capacity of 200-500Ah; and a protrusion height of 3.0-5.0mm is suitable for cells with a capacity ≥500Ah.

[0043] In the above embodiments, a protrusion height ≥ 0.3 mm can form a more obvious internal recessed cavity, which helps to alleviate the problem of low liquid injection coefficient (≤ 3.2 g / Ah) in high energy density cells (especially 600+ Ah ​​level, target energy density 190 Wh / kg), so as to achieve the expected effect of increasing the liquid injection volume.

[0044] Moreover, the second protrusion 310 with a height of ≥0.3mm can act as a reinforcing rib, which helps to resist the gas pressure generated inside the battery cell and prevents the bottom cover 300 from undergoing irreversible deformation (such as bulging) during battery cell cycling, thereby ensuring the sealing and safety of the battery cell for long-term use.

[0045] In some examples, the area on the bottom cover 300 where the second protrusion 310 is not located is covered with a blue film, the thickness of which is flush with the second protrusion 310.

[0046] In the above embodiment, by covering the bottom cover with a blue film whose thickness is flush with the height of the second protrusion 310, the overall outer surface of the bottom cover maintains a uniform height, avoiding stress concentration during assembly caused by the height difference between the protruding and non-protruding areas. Furthermore, the blue film, as an insulating layer, isolates the bottom cover 300 from external conductive components, preventing accidental short circuits and reducing the probability of scratches on the surface of the bottom cover 300 during transportation and assembly. More importantly, given the requirement for coating the battery cell casing, the height of the blue film after coverage is flush with the second protrusion 310, ensuring that the overall height of the battery cell casing remains consistent with the existing casing (with a flat bottom surface), avoiding inconvenience during subsequent assembly and use.

[0047] In some examples, the top cover 200 is also provided with a terminal post 220, the terminal post 220 including a positive terminal post and a negative terminal post, and the first protrusion 210 is disposed between the positive terminal post and the negative terminal post;

[0048] The height of the pole post 220 is greater than the height of the first protrusion 210, and the height difference between the pole post 220 and the first protrusion 210 is 0.3-0.5mm.

[0049] At least one first protrusion 210 is provided on the top cover 200. The protrusion is perpendicular to the plane of the top cover and extends outward toward the outside of the shell, forming an outwardly convex dome structure. In some specific examples, taking a 73*302*218mm battery cell and a first protrusion 210 on the top cover 200 as an example, the internal space of the shell increases by ≥862.5mm. 2 It is easy to understand that when multiple first protrusions 210 are provided on the top cover 200, the internal space of the outer shell increases by a corresponding multiple.

[0050] It should be noted that the top cover 200 is provided with a positive terminal and a negative terminal, which are symmetrically distributed at both ends of the length of the top cover 200 to realize the power input and output of the battery cell, and are respectively connected to the positive and negative terminals inside the battery cell casing.

[0051] It is easy to understand that the height of the pole post 220 is greater than the height of the first protrusion 210, that is, the overall height of the pole post 220 from its mounting base surface (the main body plane of the top cover 200) to its top is greater than the protrusion height of the first protrusion 210 from the main body plane of the top cover 200 where it is located to its outer protrusion apex.

[0052] In the above embodiment, the first protrusion 210 is disposed between the positive terminal and the negative terminal, making full use of the central area or space between the two terminals 220 on the top cover 200 without interfering with the connection of the interfering terminal 220 or other functional components; and forming physical isolation between the two terminals 220, effectively increasing the creepage distance and electrical clearance, significantly reducing the risk of electrochemical corrosion or accidental short circuit between the positive and negative terminals during the use of the battery cell (especially in high humidity environments or when there is electrolyte vapor / condensate), and improving the long-term safety and reliability of the battery cell.

[0053] In addition, during the cell assembly process, the top of the terminal post 220 is often used as a positioning or pressure reference point. The first protrusion 210 is lower than the top of the terminal post 220, which can prevent the first protrusion 210 from being deformed due to excessive pressure before the terminal post 220 during the assembly process, thus helping to protect the structural integrity of the first protrusion 210.

[0054] It should be noted that the first protrusion 210 and / or the second protrusion 310 may contain a lithium replenishing agent that is released under certain conditions to improve the energy density and cycle life of the battery cell; or, a flame retardant that is released under certain conditions may be placed there to improve the safety performance of the battery cell.

[0055] In some examples, the top cover 200 is also provided with an explosion-proof valve 230, and the first protrusion 210 is disposed between the pole post 220 and the explosion-proof valve 230.

[0056] It is easy to understand that the explosion-proof valve 230 is a key safety component of the battery cell. It can precisely rupture or open when the internal pressure of the battery cell rises abnormally (such as in the early stage of thermal runaway), thereby quickly releasing the internal pressure, preventing the casing from being explosively damaged, and ensuring safe use.

[0057] It should be noted that the distance between the first protrusion 210 and the explosion-proof valve 230 is ≥5mm. In some specific examples, the distance between the two is preferably 10-15mm.

[0058] In the above embodiment, the first protrusion 210 is positioned between the pole post 220 and the explosion-proof valve 230, rather than directly covering or adjacent to the explosion-proof valve 230. This ensures that the space above the explosion-proof valve 230 is unobstructed, providing sufficient space for the normal and timely opening (explosion) of the explosion-proof valve 230 in an emergency, and preventing the protrusion from obstructing pressure release or the path of flying debris. Moreover, the first protrusion 210 maintains a certain distance from the explosion-proof valve 230, preventing the stress or deformation generated by the protrusion structure from being directly transmitted and affecting the structural integrity of the explosion-proof valve 230 during the stamping, subsequent assembly, or use of the top cover 200.

[0059] In some examples, the top cover 200 is provided with two first protrusions 210, which are located on both sides of the explosion-proof valve 230.

[0060] In the above embodiment, the two first protrusions 210 are located on the left and right sides of the explosion-proof valve 230, respectively, which can form a protective structure on both sides of the explosion-proof valve 230. This helps to block or reduce accidental mechanical impacts, scratches or metal splashes that may be caused to the vulnerable areas of the explosion-proof valve 230 from the side, thereby reducing the risk of accidental damage to the explosion-proof valve 230.

[0061] In addition, the two first protrusions 210 can act as "reinforcing ribs", which help to disperse the stress of the top cover 200 when it is subjected to pressure or external load, and prevent the stress from being excessively concentrated in the area of ​​the explosion-proof valve 230.

[0062] In some examples, the explosion-proof valve 230 has an injection port 240 located adjacent to one side.

[0063] It is easy to understand that the electrolyte injection hole 240 is used to inject electrolyte into the inside of the battery cell casing after the battery cell is packaged, and then seal it to ensure the airtightness of the battery cell. In some specific examples, the distance between the electrolyte injection hole 240 and the explosion-proof valve 230 is ≤3mm.

[0064] In the above embodiment, the injection hole 240 is located close to the explosion-proof valve 230. In extreme cases, it can serve as a passive pressure relief point, thereby concentrating the pressure relief point in an area far away from the pole post 220. This prevents pressure from being released at multiple points in different areas of the top cover 200, reducing pressure relief efficiency, and ensuring that high-temperature and high-pressure gas and ejected materials are kept away from the pole post 220 area, thus minimizing the risk of external electrical short circuits or secondary accidents caused by the pressure relief process.

[0065] In some examples, the first protrusion 210 and / or the second protrusion 310 are rectangular, square, or circular. In other examples, elliptical or other polygonal shapes may also be used, and this application is not limited thereto.

[0066] In the above embodiments, the first protrusion 210 or the second protrusion 310 can be set according to the shape and size of a specific area on the top cover 200 or the bottom cover 300 and the layout of surrounding components (such as pole post 220, explosion-proof valve 230, and injection hole 240). The most matching and space-efficient contour shape can be selected. Moreover, the above shapes are easy to achieve by standard stamping dies, with high processing efficiency, low cost, and high yield.

[0067] In some examples, the top cover 200 is welded to the housing 100, and the bottom cover 300 is an integral structure with the housing 100.

[0068] It is easy to understand that the top cover 200 is welded to the top opening end of the housing 100, and the bottom cover 300 is integrally formed with the housing 100. Laser welding is preferably used for this welding because it has significant advantages such as high energy density, small heat-affected zone, fast welding speed, small deformation, and ease of automation, making it suitable for joining aluminum or aluminum alloy materials. Welding is performed at the lap or butt joint of the top opening end faces of the top cover 200 and the housing 100 to form a continuous circumferential weld. Multiple welds can be used to enhance sealing reliability and connection strength.

[0069] In the above embodiments, welding and integral molding can provide reliable sealing for the cell casing, effectively preventing leakage or evaporation of electrolyte throughout the cell's life cycle and ensuring the stability of the electrolyte level inside the cell.

[0070] Another embodiment of this application provides a square aluminum-cased battery cell, including the square aluminum-cased battery cell outer shell as described above, wherein a positive electrode plate and a negative electrode plate are wound inside the outer shell, the positive electrode plate and the negative electrode plate are separated by a separator, and the outer shell is filled with electrolyte.

[0071] In the above embodiments, the amount of electrolyte injected into the casing can be increased without changing the electrode design, the cell size, or the cell performance. For high-energy-density large-capacity battery cells, this can better ensure that more electrolyte is available for consumption in the later stages of the cycle, thereby giving the battery cell a longer cycle life and better electrical performance.

[0072] It is readily understood that, based on the several embodiments provided in this application, those skilled in the art can combine, split, or reorganize the embodiments of this application to obtain other embodiments, none of which exceed the protection scope of this application.

[0073] The above detailed embodiments further illustrate the purpose, technical solution, and beneficial effects of the embodiments of this application. It should be understood that the above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solutions of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A square aluminum battery cell casing, comprising a housing (100), a top cover (200), and a bottom cover (300), wherein the top cover (200) and the bottom cover (300) are both fixedly connected to the housing (100), characterized in that, At least one first protrusion (210) is provided on the top cover (200), the protrusion direction of the first protrusion (210) is away from the bottom cover (300), and the side of the first protrusion (210) facing the bottom cover (300) is hollow; And / or, a second protrusion (310) is provided on the bottom cover (300), the protrusion direction of the second protrusion (310) is away from the top cover (200), and the side of the second protrusion (310) facing the top cover (200) is hollow.

2. The square aluminum-cased battery cell casing according to claim 1, characterized in that, The bottom cover (300) is provided with a second protrusion (310), the protrusion direction of the second protrusion (310) is away from the top cover (200), and the side of the second protrusion (310) facing the top cover (200) is hollow; The protrusion height of the second protrusion (310) is ≥0.3mm.

3. The square aluminum-cased battery cell casing according to claim 2, characterized in that, The area on the bottom cover (300) where the second protrusion (310) is not provided is covered with a blue film, and the thickness of the blue film is flush with the second protrusion (310).

4. The square aluminum-cased battery cell casing according to any one of claims 1-3, characterized in that, At least one first protrusion (210) is provided on the top cover (200), the protrusion direction of the first protrusion (210) is away from the bottom cover (300), and the side of the first protrusion (210) facing the bottom cover (300) is hollow; The top cover (200) is also provided with a pole post (220), the pole post (220) includes a positive pole post and a negative pole post, and the first protrusion (210) is disposed between the positive pole post and the negative pole post; The height of the pole post (220) is greater than the height of the first protrusion (210), and the height difference between the pole post (220) and the first protrusion (210) is 0.3-0.5mm.

5. The square aluminum-cased battery cell casing according to claim 4, characterized in that, An explosion-proof valve (230) is also provided on the top cover (200), and the first protrusion (210) is disposed between the pole post (220) and the explosion-proof valve (230).

6. The square aluminum-cased battery cell casing according to claim 5, characterized in that, The top cover (200) is provided with two first protrusions (210), which are located on both sides of the explosion-proof valve (230).

7. The square aluminum-cased battery cell casing according to claim 5, characterized in that, The explosion-proof valve (230) has an injection hole (240) located adjacent to one side.

8. The square aluminum-cased battery cell casing according to any one of claims 1-3, characterized in that, The top cover (200) is provided with at least one first protrusion (210), and the bottom cover (300) is provided with a second protrusion (310). The first protrusion (210) and / or the second protrusion (310) are rectangular, square or circular.

9. The square aluminum-cased battery cell casing according to any one of claims 1-3, characterized in that, The top cover (200) is welded to the housing (100), and the bottom cover (300) is an integral structure with the housing (100).

10. A square aluminum-cased battery cell, comprising a square aluminum-cased battery cell casing as described in any one of claims 1-9, wherein a positive electrode plate and a negative electrode plate are wound inside the casing, the positive electrode plate and the negative electrode plate are separated by a separator, and the casing is filled with an electrolyte.

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