Battery shell

Abstract

The battery shell comprises a first wall and a second wall which are connected with each other, the included angle alpha between the first wall and the second wall is larger than or equal to 80 degrees and smaller than or equal to 120 degrees, the first wall is provided with a liquid injection hole, the second wall is provided with a plurality of grooves which are formed in the circumferential direction of the second wall at intervals, and the first wall and the second wall are connected with each other. The distance L1 between the liquid injection hole and the second wall and the distance L2 between the liquid injection hole and the two adjacent grooves meet the condition that L1 / L2 is larger than or equal to 32 and smaller than or equal to 3000. According to the battery shell, the liquid injection efficiency can be improved, and the groove can enlarge the capacity of the battery shell under the condition that the size of the battery shell is not changed, so that the energy density of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a battery casing. Background Technology

[0002] Lithium-ion batteries have a wide range of applications, from everyday electronic products to large-scale energy storage systems. The electrolyte in a lithium-ion battery serves as the charging and discharging medium, conducting ions between the positive and negative electrodes. Electrolyte injection is a crucial step in the lithium-ion battery manufacturing process; its quality not only affects battery performance but also limits production efficiency. Electrolyte injection involves two steps: first, injecting the electrolyte into the battery; and second, wetting, where the cell absorbs the electrolyte. Because the cell occupies a large portion of the internal space of the casing, the contact between the cell and the casing is tight, leaving limited space for the electrolyte. This makes the wetting process very time-consuming, posing a significant challenge to the electrolyte injection process. Improving electrolyte injection efficiency is a pressing issue that needs to be addressed. Utility Model Content

[0003] The battery casing provided in this application can improve liquid injection efficiency and liquid storage capacity.

[0004] This application provides a battery casing, which includes: a first wall and a second wall connected to each other, wherein the included angle α between the first wall and the second wall satisfies 80°≤α≤120°, the first wall is provided with an injection hole, and the second wall is provided with a plurality of grooves spaced apart along the circumferential direction of the second wall, wherein the distance L1 between the injection hole and the second wall and the distance L2 between two adjacent grooves satisfies: 32≤L1 / L2≤3000.

[0005] In the above embodiment, during electrolyte injection, the edges of the battery cell are prone to electrolyte deficiency. The grooves in the second wall can store electrolyte, allowing the battery cell to be simultaneously wetted from both the outside in and the inside out, thus improving the injection efficiency. During battery charging and discharging, the electrolyte stored in the grooves can also replenish the battery cell. The grooves also indirectly increase the distance between the second wall and the battery cell, further improving injection efficiency. By comprehensively adjusting the relationship between the distance L1 between the injection hole and the second wall and the spacing L2 between two adjacent grooves, the electrolyte storage capacity of the battery casing is improved, resulting in better wetting of the battery cell. Attached Figure Description

[0006] Figure 1 A schematic diagram of the structure of a battery casing provided for an embodiment of this application;

[0007] Figure 2 A schematic diagram of the structure of a prismatic battery provided for an embodiment of this application;

[0008] Figure 3A schematic diagram of another battery casing provided for an embodiment of this application;

[0009] Figure 4 A schematic diagram of another battery casing provided for an embodiment of this application;

[0010] Figure 5 A schematic diagram of another battery casing provided for an embodiment of this application;

[0011] Figure 6 This is a schematic diagram of another battery casing structure provided for an embodiment of this application.

[0012] Figure label:

[0013] 1-Second wall; 2-First wall; 21-Top plate; 22-Bottom plate; 4-Injection hole; 5-Groove; 11-First sub-wall; 12-Second sub-wall; 51-First sub-groove; 52-Second sub-groove; 53-Third sub-groove; 54-Fourth sub-groove; 55-Fifth guide groove; 56-Sixth guide groove. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description of the application is provided in conjunction with the accompanying drawings and embodiments.

[0015] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more” unless the context clearly indicates otherwise.

[0016] References to “an embodiment” or “a specific embodiment” as used in this specification mean that one or more embodiments of this application include a particular feature, structure, or characteristic described in connection with that embodiment. The terms “comprising,” “including,” “having,” and variations thereof mean “including, but not limited to,” unless otherwise specifically emphasized.

[0017] A lithium-ion battery consists of a battery casing and a battery cell housed within the casing, the cell being immersed in an electrolyte. The electrolyte's primary function is to act as a carrier for ion transport within the battery, conducting ions. The battery cell is mainly composed of a positive electrode, a negative electrode, and a separator wound together. The positive and negative electrode are positioned on opposite sides of the separator. During charging, lithium ions at the positive electrode are released and enter the electrolyte, then pass through the microporous structure of the separator, migrate to the negative electrode, and combine with electrons that have arrived at the negative electrode via an external circuit. In this process, lithium ions are released from the positive electrode material, enter the electrolyte, and migrate to the negative electrode under the influence of an external electric field, forming compounds with the carbon material of the negative electrode. During discharge, electrons and lithium ions move simultaneously, but via different paths. Electrons flow from the negative electrode to the positive electrode through the external circuit, while lithium ions enter the electrolyte from the negative electrode, pass through the separator, migrate to the positive electrode, and combine with electrons that have already arrived.

[0018] Electrolyte is injected into the battery casing through the injection port. Since the air inside the battery casing has been removed before injection, the electrolyte enters the casing relatively quickly. However, because the battery cell occupies a significant amount of space within the casing, and its outer periphery is tightly fitted to the casing, there is no space for electrolyte flow. The electrolyte can only flow into the cell through gaps in the center and gradually penetrates the electrode layers from the inside out via capillary action. This results in a longer immersion time and can also lead to poor immersion of the core, causing inconsistent electrical performance and capacity.

[0019] To address the aforementioned issues, this application provides a battery casing that improves liquid injection and wetting efficiency.

[0020] Figure 1 A schematic diagram of a battery casing provided for an embodiment of this application is shown below. Figure 1 As shown, an embodiment of this application provides a battery casing comprising: a first wall and a second wall 1 connected to each other, wherein the included angle α between the first wall and the second wall 1 satisfies 80°≤α≤120°, the first wall 2 is provided with an injection hole 4, and the second wall 1 is provided with a plurality of grooves 5 spaced apart along the circumferential direction of the second wall 1, wherein the distance L1 between the injection hole 4 and the second wall 1 and the distance L2 between the injection hole 4 and two adjacent grooves 5 satisfies: 32≤L1 / L2≤3000.

[0021] In the above embodiment, the injection hole 4 can be located at the center of the first wall 2. Electrolyte enters the battery casing through the injection hole 4. As the liquid level gradually rises, the electrolyte reaches the center of the battery cell and simultaneously enters and is stored in the groove 5. This allows the battery cell to be simultaneously wetted from both the outside in and the inside out, improving the injection efficiency. During battery charging and discharging, the electrolyte stored in the groove 5 can also replenish the battery cell. The groove 5 effectively increases the distance between the second wall 1 and the battery cell, further improving the injection efficiency.

[0022] By comprehensively adjusting the relationship between the distance L1 between the injection hole 4 and the second wall 1 and the distance L2 between the two adjacent grooves 5 (32≤L1 / L2≤3000), the electrolyte storage capacity of the battery casing is improved. During electrolyte injection, the edges of the cell are prone to electrolyte deficiency. The grooves 5 in the second wall 1 can store electrolyte, allowing the cell to be simultaneously wetted from both the outside in and the inside out, resulting in better wetting and improved injection efficiency. The amount of electrolyte injected has a significant impact on battery performance. An appropriate amount of electrolyte ensures sufficient wetting of the electrode materials, allowing lithium ions to migrate smoothly between the electrodes, thereby reducing internal resistance and improving the battery's charge / discharge efficiency and cycle life.

[0023] In one embodiment, the depth 'a' of the groove 5 and the thickness 'b' of the battery casing satisfy 0 < a / b ≤ 1 / 3. This allows the groove 5 to hold a larger amount of electrolyte, and within this range, it also provides the battery casing with greater rigidity, improving battery safety. The groove 5 can also increase the capacity of the battery casing without changing its dimensions, thereby allowing the battery casing to hold more electrolyte and increasing the battery's energy density. The thickness of the battery casing refers to the thickness of the first wall and the second wall. The thickness of the first wall and the second wall can be the same.

[0024] Battery energy density refers to the amount of energy stored per unit volume or unit mass of battery. Specifically, battery energy density can be divided into gravimetric energy density and volumetric energy density, measured in watt-hours per kilogram (Wh / kg) and watt-hours per liter (Wh / L), respectively. The formula for gravimetric energy density is: battery capacity × discharge plateau / weight; the formula for volumetric energy density is: battery capacity × discharge plateau / volume. The electrolyte occupies a significant proportion of the battery's volume, especially for volumetric energy density, where the electrolyte capacity directly affects the overall energy density of the battery. Therefore, increasing the capacity of the battery casing to increase the electrolyte content can effectively improve the energy density of lithium batteries, thereby enhancing battery range and overall performance.

[0025] In one embodiment, the distance L1 between the injection hole 4 and the second wall 1 satisfies 7mm≤L1≤200mm; the distance L2 between two adjacent grooves 5 satisfies 4mm≤L2≤20mm.

[0026] In one embodiment, the battery casing is cylindrical, meaning the battery is a cylindrical battery, and the distance L1 between the aforementioned injection hole 4 and the second wall 1 is the inner diameter of the cylinder. 32 ≤ L1 / L2 ≤ 700. By satisfying this ratio, the groove 5 has a higher electrolyte storage capacity, which is beneficial for replenishing the electrolyte in the cell during battery charging and discharging.

[0027] In one specific embodiment, the distance L1 between the injection hole 4 and the second wall 1 satisfies 7mm≤L1≤40mm, and the distance L2 between two adjacent grooves 5 satisfies 4mm≤L2≤20mm.

[0028] Figure 2 A schematic diagram of the structure of the prismatic battery provided for an embodiment of this application is shown below. Figure 2 As shown, in one embodiment, the battery casing is a quadrangular prism, i.e., the battery is a square-shell battery. The first wall 2 is rectangular, and the first wall 2 includes a pair of long sides and a pair of short sides. The second wall 1 includes a pair of large sidewalls (i.e., the first sub-wall 11) and a pair of small sidewalls (i.e., the second sub-wall 12), with the long sides connected to the large sidewalls and the short sides connected to the small sidewalls. The distance L1 between the injection hole 4 and the second wall 1 includes L11 and L12, where L11 refers to the distance from the injection hole 4 to the first sub-wall 11, and L12 refers to the distance from the injection hole 4 to the second sub-wall 12. The spacing L2 between two adjacent grooves 5 includes the spacing L21 between two adjacent grooves 5 located on the first sub-wall 11 and the spacing L22 between two adjacent grooves 5 located on the second sub-wall 12. L11 and L21 satisfy 40 ≤ L11 / L21 ≤ 700, and L12 and L22 satisfy 220 ≤ L12 / L22 ≤ 3000. The distance between the injection hole 4 and the first sub-wall 11 is small, resulting in a shorter flow path for the electrolyte to reach the first sub-wall 11. This reduces the likelihood of electrolyte shortage at the cell edge near the first sub-wall 11, allowing for a relatively larger spacing between the grooves 5 on the first sub-wall 11. Conversely, the distance between the injection hole 4 and the second sub-wall 12 is larger, making the cell edge near the second sub-wall 12 prone to electrolyte shortage. Therefore, the spacing between the grooves 5 on the second sub-wall 12 can be relatively smaller, allowing the second sub-wall 12 to store more electrolyte and replenish the electrolyte at the cell edge near the second sub-wall 12.

[0029] In a further embodiment, the parameters L11 and L21 of the first sub-wall 11 satisfy 8mm≤L11≤140mm and 5mm≤L21≤20mm. The parameters L12 and L22 of the second sub-wall 12 satisfy 50mm≤L12≤200mm and 4mm≤L22≤15mm.

[0030] In one embodiment, the second wall 1 includes a top plate 21 and a bottom plate 22 disposed opposite to each other. The included angle α between the first wall 2 and the second wall 1 is preferably 90°. The injection hole 4 is located on the top plate 21 or on the bottom plate 22. It is worth noting that the top plate 21 and the bottom plate 22 are determined according to the placement posture of the battery, and the positions of the top plate 21 and the bottom plate 22 can be interchanged.

[0031] The width of the groove 5 cannot be too small; if it is too small, the electrolyte storage capacity and the ability to improve electrolyte injection efficiency will be low. The width of the groove 5 also cannot be too wide, as this can significantly affect the structural strength of the battery casing. In a specific embodiment, the width c of the groove 5 satisfies: 0.5mm ≤ c ≤ 15mm, where the width of the groove 5 refers to the width of the groove opening. This width can be, for example, 0.5mm, 1mm, 5mm, 10mm, 12mm, or 15mm. The groove 5 meeting these conditions can improve the electrolyte injection efficiency and maintain good structural strength of the battery casing.

[0032] In one embodiment, the number N of grooves 5 satisfies: 2≤N≤20.

[0033] In one embodiment, the cross-section of the groove 5 is semi-circular or square, preferably semi-circular. The electrolyte is generally composed of high-purity organic solvents, lithium electrolyte salts, necessary additives, and other raw materials. Setting the cross-section of the groove 5 to square or semi-circular allows the electrolyte to maintain good fluidity, thereby improving the injection efficiency.

[0034] In one embodiment, the first wall 2 may be provided with a plurality of second grooves (not shown in the figure), one end of each second groove being connected to a groove 5. These second grooves are distributed around the periphery of the injection hole 4. Electrolyte enters the battery casing from the injection hole 4, flows into the second grooves, and flows along the second grooves towards the periphery of the first wall 2, then enters the groove 5. The second grooves can accelerate the flow of electrolyte from the injection hole 4 to the periphery of the battery casing. This avoids a situation where the battery cell is tightly adhered to the first wall, causing slow electrolyte flow to the periphery of the casing and affecting the injection efficiency.

[0035] In a further embodiment, the end of the second groove away from the groove 5 can be connected to the injection hole 4. The second groove is located on the periphery of the injection hole 4 and forms a diverging pattern. In this way, after the electrolyte enters the battery casing, it can directly enter the second groove, which accelerates the speed at which the electrolyte flows to the periphery of the battery casing.

[0036] The groove 5 can come in various forms. The following describes several different forms of the groove 5.

[0037] Please continue to refer to Figure 1 In one embodiment, the groove 5 includes a first sub-groove 51, the first sub-groove 51 extending perpendicularly to the first wall, and the end of the first sub-groove 51 extending to the bottom plate 22. The injection hole 4 is located on the bottom plate 22. The first sub-groove 51 is a straight groove, which flows along a straight path during the rise of the electrolyte level, resulting in a faster flow rate and faster filling of the battery casing, thus improving the injection efficiency.

[0038] Figure 3 A schematic diagram of another battery casing structure provided for an embodiment of this application is shown below. Figure 3 As shown, in another embodiment, the groove 5 includes a second sub-groove 52. The edge where the bottom plate 22 intersects with the second wall 1 forms an angle β with the second sub-groove 52, satisfying 11°≤β≤80°. The second sub-groove 52 is also a straight groove, but unlike the first sub-groove 51, it is inclined. The two ends of the second sub-groove 52 extend to the top plate 21 and the bottom plate 22, respectively. The second sub-groove 52 is longer than the first sub-groove 51, thus it can store more electrolyte and improve the energy density of the battery.

[0039] Figure 4 A schematic diagram of another battery casing structure provided for an embodiment of this application is shown below. Figure 4 As shown, in another embodiment, the groove 5 includes a plurality of third sub-grooves 53, all of which are perpendicular to the base plate 22. The plurality of third sub-grooves 53 are spaced apart along a direction perpendicular to the base plate 22, meaning that the plurality of third sub-grooves 53 are located on the extension of the same straight line. Specifically, the number of third sub-grooves 53 located on the same straight line can be two, three, four, etc. Figure 4 Two third sub-grooves 53 located on the same straight line are shown as an example. Adjacent third sub-grooves 53 are spaced a predetermined distance apart along the height direction of the battery. The height direction of the battery also refers to the direction perpendicular to the base plate 22.

[0040] Figure 5 A schematic diagram of another battery casing structure provided for an embodiment of this application is shown below. Figure 5 As shown, in another embodiment, the groove 5 includes a plurality of fourth sub-grooves 54, all of which are perpendicular to the base plate 22 and spaced apart along the height direction of the battery. Unlike the third sub-grooves 53 in the above embodiment, the plurality of fourth sub-grooves 54 are staggered. That is, the plurality of fourth sub-grooves 54 are not on the same straight line extension along the direction perpendicular to the base plate. The plurality of fourth sub-grooves 54 can be arranged in groups, and the number of fourth sub-grooves 54 in each group can be multiple. Figure 5 An example is shown of two staggered fourth sub-grooves 54 in a set. A set may also include three, four, or other fourth sub-grooves 54.

[0041] Figure 6 A schematic diagram of another battery casing structure provided for an embodiment of this application is shown below. Figure 6 As shown, in a further embodiment, a set of staggered fourth sub-grooves 54 includes a fifth guide groove 55 and a sixth guide groove 56. The end of the fifth guide groove 55 near the bottom plate 22 is located between two adjacent sixth guide grooves 56.

[0042] It is worth noting that the straight grooves in some of the above embodiments can also be replaced by wavy grooves.

[0043] In one embodiment, a chamfer is provided at the connection between the first wall 2 and the second wall 1. That is, the top plate 21 and the second wall 1 are chamfered, and the bottom plate 22 and the second wall 1 are chamfered. The groove 5 is located between the two chamfers, meaning that the groove 5 is completely located within the second wall 1 and does not extend to the chamfer position. This reduces the accumulation of electrolyte at the chamfer.

[0044] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A battery casing, characterized in that, include: The first wall and the second wall are connected to each other. The angle α between the first wall and the second wall satisfies 80°≤α≤120°. The first wall is provided with an injection hole. The second wall is provided with a plurality of grooves spaced apart along the circumferential direction of the second wall. The distance L1 between the injection hole and the second wall and the distance L2 between two adjacent grooves satisfy: 32≤L1 / L2≤3000.

2. The battery casing according to claim 1, characterized in that, The distance L1 between the injection hole and the second wall satisfies 7mm≤L1≤200mm; the distance L2 between two adjacent grooves satisfies 4mm≤L2≤20mm.

3. The battery casing according to claim 1, characterized in that, The depth a of the groove and the thickness b of the battery casing satisfy: 0 < a / b ≤ 1 / 3; the width c of the groove satisfies: 0.5mm ≤ c ≤ 15mm; the number N of the grooves satisfies: 2 ≤ N ≤ 20.

4. The battery casing according to claim 1, characterized in that, The battery casing is cylindrical, with a radius of 32 ≤ L1 / L2 ≤ 700.

5. The battery casing according to claim 4, characterized in that, The distance L1 between the injection hole and the second wall satisfies 7mm≤L1≤40mm, and the distance L2 between two adjacent grooves satisfies 4mm≤L2≤20mm.

6. The battery casing according to claim 1, characterized in that, The battery casing is a quadrangular prism. The first wall includes a long side and a short side that are connected to each other. The second wall includes a first sub-wall and a second sub-wall. The first sub-wall is connected to the long side, and the second sub-wall is connected to the short side. The distance L1 between the injection hole and the second wall includes: the distance L11 between the injection hole and the first sub-wall and the distance L12 between the injection hole and the second sub-wall; the spacing L2 between two adjacent grooves includes the spacing L21 between two adjacent grooves on the first sub-wall and the spacing L22 between two adjacent grooves on the second sub-wall. The distance L11 between the injection hole and the first sub-wall, and the distance L21 between the injection hole and two adjacent grooves on the first sub-wall, satisfy: 40≤L11 / L21≤700; the distance L12 between the injection hole and the second sub-wall, and the distance L22 between the injection hole and two adjacent grooves on the second sub-wall, satisfy: 220≤L12 / L22≤3000.

7. The battery casing according to claim 1, characterized in that, The first wall includes a top plate and a bottom plate disposed opposite each other, and the injection hole is located on the top plate or the bottom plate.

8. The battery casing according to claim 7, characterized in that, The groove includes a first sub-groove, the first sub-groove extending perpendicularly to the base plate, and the end of the first sub-groove extending to the base plate, with the injection hole located on the base plate.

9. The battery casing according to claim 7, characterized in that, The groove includes a second sub-groove, and the edge of the bottom plate intersecting the second wall has an angle β with the second sub-groove, satisfying 11°≤β≤80°.

10. The battery casing according to claim 7, characterized in that, The groove includes multiple third sub-grooves, all of which are perpendicular to the base plate and are spaced apart along the direction perpendicular to the base plate.

11. The battery casing according to claim 7, characterized in that, The groove includes a plurality of fourth sub-grooves, all of which are perpendicular to the base plate and are staggered along the direction perpendicular to the base plate.

12. The battery casing according to claim 1, characterized in that, The first wall is provided with a plurality of second grooves, and the second grooves are in communication with the grooves.

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