Battery case, battery and battery pack

Abstract

This application provides a battery case, a battery, and a battery pack. The battery case comprises a bottom plate and a surrounding plate, the surrounding plate and the bottom plate jointly defining a housing chamber having an opening, and the opening and the bottom plate are positioned opposite each other. The bottom plate has a center point, and an explosion-proof notch groove is provided in the bottom plate, the explosion-proof notch groove has an inner edge closest to the center point and an outer edge furthest from the center point, the distance between the inner edge and the center point is 1 / 2 or more of the radius of the bottom plate, and the distance between the outer edge and the center point is 4 / 5 or less of the radius of the bottom plate.

Description

Technical Field

[0001] This application claims priority from a Chinese patent application with application number 202420713967.3, filed with the China National Intellectual Property Administration on April 8, 2024, and the entire content of that application is incorporated herein by reference.

[0002] This application relates to the field of battery technology, particularly to battery cases, batteries, and battery packs.

Background Art

[0003] When a battery is in a state such as high temperature, overcharging, or short circuit, a large amount of gas is generated inside the battery, and the gas pressure inside the battery case rises rapidly. To prevent the explosion of the battery, usually, an explosion-proof notch groove is formed in the battery case, and pressure release and exhaust are realized by the rupture of the explosion-proof notch groove.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, after the explosion-proof notch groove is formed in the battery case, usually, the core pack is installed, and it is necessary to conduct a safety performance test on the battery strength. In related technologies, the explosion-proof notch groove is often prone to early rupture. For example, when installing the core pack, it is necessary to weld the area near the center of the battery case. The heat during welding easily affects the strength of the surrounding materials, and the explosion-proof notch groove may rupture prematurely before reaching the set internal pressure. Also, for example, in subsequent battery strength safety tests, it is necessary to drop the battery from a high position, and the explosion-proof notch groove of the battery case may easily rupture after dropping, making it unusable.

Means for Solving the Problems

[0005] In a first embodiment, the present invention provides a battery case comprising a bottom plate and a surrounding plate arranged around the bottom plate, wherein the surrounding plate and the bottom plate jointly define a housing chamber having an opening, the opening and the bottom plate are arranged opposite each other, the bottom plate has a center point, the bottom plate is provided with an explosion-proof notch groove, the explosion-proof notch groove has an inner edge closest to the center point and an outer edge furthest from the center point, the distance between the inner edge and the center point is 1 / 2 or more of the radius of the bottom plate, and the distance between the outer edge and the center point is 4 / 5 or less of the radius of the bottom plate.

[0006] In a second embodiment, the present application provides a battery comprising the battery case described in the first embodiment.

[0007] In a third embodiment, the present application provides a battery pack comprising the battery described in the second embodiment. [Effects of the Invention]

[0008] In the battery case provided in the embodiment of this application, the explosion-proof notch is positioned at a distance of at least 1 / 2 of the radius from the center point. This avoids the positioning of the explosion-proof notch being too close to the center point, thereby preventing the heat generated by welding the bottom plate during welding from affecting the strength of the material at the position of the explosion-proof notch, and further preventing the explosion-proof notch from easily rupturing prematurely. In addition, by positioning the explosion-proof notch within an area of ​​4 / 5 of the radius from the center point, the problem of the explosion-proof notch being damaged by a large impact on the edge of the bottom plate during subsequent strength safety tests of the battery can be avoided. Therefore, the battery case provided in this application ensures the stability of the explosion-proof notch and further ensures the stability of the battery during use. [Brief explanation of the drawing]

[0009] [Figure 1] This is a stereoscopic view of a battery case provided by an embodiment of this application at a first viewing angle. [Figure 2] This is a stereoscopic view of the battery case provided by the embodiment of this application at a second viewing angle. [Figure 3] This is a schematic diagram of the structure of the base plate according to several embodiments of this application. [Figure 4A] This is a schematic diagram of the structure of the base plate according to some other embodiments of this application. [Figure 4B] This is a schematic diagram of the structure of the base plate according to several other embodiments of this application. [Figure 5] This is a cross-sectional view of a battery case provided by an embodiment of this application. [Figure 6] Figure 5 is a schematic diagram of the enlarged structure of area F. [Modes for carrying out the invention]

[0010] In the description of this application, unless otherwise expressly specified and limited, the terms “connection,” “joining,” and “fixing” should be understood in a broad sense. For example, they may be fixed connections or removable connections, or integral connections; they may be mechanical connections or electrical connections; they may be direct connections or indirect connections via an intermediate medium; or they may be internal communication between two components or interaction between two components. A person skilled in the art will understand the specific meaning of the foregoing terms in this application according to the specific context.

[0011] In this application, unless otherwise expressly specified and defined, the presence of the first element "above" or "below" the second element may include direct contact between the first and second elements, or contact between them via other elements between them without direct contact. Furthermore, the presence of the first element "above," "above," or "upper part" of the second element may mean that the first element is directly above or diagonally above the second element, or that the first element is at a higher horizontal altitude than the second element. The presence of the first element "below," "below," or "lower part" of the second element may mean that the first element is directly below or diagonally below the second element, or that the first element is at a lower horizontal altitude than the second element.

[0012] In the description of this embodiment, directional or positional relationships such as "up," "down," and "right" are directional or positional relationships shown based on the drawings, and are provided for the purpose of facilitating explanation and simplifying operation. It is not explicitly or implicitly stated that the indicated device or element has a specific orientation or must be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of this application. The terms "first" and "second" are used for explanatory distinction and have no special meaning.

[0013] After the battery case has explosion-proof notches formed, a core pack is usually installed, and the battery strength safety performance must be tested.

[0014] Conventional technology requires welding a region near the center of the battery case when installing the core pack. The heat generated during welding easily affects the strength of the surrounding material, potentially causing the explosion-proof notches to rupture prematurely before the set internal pressure is reached. Furthermore, subsequent strength safety tests of the batteries require dropping them from a height, which could easily cause the explosion-proof notches in the battery case to rupture and render them unusable.

[0015] Based on the above, the embodiment of this application provides a battery case. As shown in Figure 1, the battery case 100 comprises a bottom plate 10 and a surrounding plate 20 arranged to surround the bottom plate 10.

[0016] As shown in Figures 1 and 2, the enclosure plate 20 and the bottom plate 10 jointly define a housing chamber having an opening 201, with the opening 201 and the bottom plate 10 facing each other. After the enclosure plate 20 surrounds the bottom plate 10, the inner surface of the enclosure plate 20 surrounds a chamber with openings at both ends, and the bottom plate 10 closes the opening at one end of the chamber. Thus, the inner surface of the enclosure plate 20 and the surface of the bottom plate 10 on the side closest to the enclosure plate 20 jointly form the housing chamber having the opening 201. This housing chamber can accommodate a core pack, and the battery case 100 can protect the core pack well, thus ensuring stable operation of the core pack.

[0017] As shown in FIGS. 1 and 3, the bottom plate 10 has a center point O. An explosion-proof notch groove 111 is formed in the bottom plate 10. The explosion-proof notch groove 111 has an inner edge 101 closest to the center point O and an outer edge 102 farthest from the center point O. The explosion-proof notch groove 111 may have a plurality of edges. Among all the edges, the distance between the inner edge 101 and the center point O is the smallest, and the distance between the outer edge 102 and the center point O is the largest.

[0018] The distance L1 between the inner edge 101 and the center point O is at least 1 / 2 of the radius R of the bottom plate 10, and the distance L2 between the outer edge 102 and the center point O is at most 4 / 5 of the radius R of the bottom plate 10.

[0019] With the above configuration, since the explosion-proof notch groove 111 is arranged at a position at least 1 / 2 away from the center point O, it is possible to avoid the situation that the arrangement position of the explosion-proof notch groove 111 is too close to the center point O. Thus, the heat generated by the welding of the bottom plate 10 during welding does not affect the strength of the material at the arrangement position of the explosion-proof notch groove 111, and it is possible to avoid the explosion-proof notch groove 111 being easily ruptured early. Also, by arranging the explosion-proof notch groove 111 in an area within 4 / 5 of the radius from the center point, it is possible to avoid the problem that the explosion-proof notch groove 111 is damaged due to a large collision on the edge of the bottom plate 10 during subsequent strength safety tests of the battery. Therefore, in the battery case provided by the present application, the stability of the explosion-proof notch groove 111 can be ensured, and furthermore, the use stability of the battery can be ensured.

[0020] In some examples, the ratio of the distance L1 between the inner edge 101 and the center point O to the radius R of the bottom plate 10 may also be not less than 1 / 2 and not more than 13 / 20. That is, 1 / 2 ≤ L1 / R ≤ 13 / 20. For example, the ratio may be 1 / 2, 3 / 5, 4 / 7, 5 / 8, 5 / 9, and 13 / 20, etc.

[0021] In some examples, the ratio of the distance L2 between the outer edge 102 and the center point O to the radius R of the bottom plate 10 may be greater than 13 / 20 and less than or equal to 4 / 5. That is, 13 / 20 < L2 / R ≤ 4 / 5. For example, the ratio may be values such as 2 / 3, 3 / 4, 4 / 5, 5 / 7, 7 / 9, etc., but all are not listed here.

[0022] In some embodiments, the distance L1 between the inner edge 101 and the center point O is at least 3 / 5 of the radius R of the bottom plate 10, and the distance L2 between the outer edge 102 and the center point O is at most 7 / 10 of the radius R of the bottom plate 10.

[0023] In this case, since the position where the explosion-proof notch groove 111 is formed is relatively far from the edge of the bottom plate 10, it is possible to avoid the problem that the explosion-proof notch groove 111 is damaged due to a large collision against the edge of the bottom plate 10 during the strength safety test of the battery. At the same time, since the position where the explosion-proof notch groove 111 is formed is also relatively far from the center point O, the heat generated by the welding of the bottom plate 10 during welding does not affect the strength of the material at the position where the explosion-proof notch groove 111 is arranged, and it is possible to avoid the situation that the explosion-proof notch groove 111 is more likely to rupture prematurely.

[0024] In some embodiments, as shown in FIG. 3, the explosion-proof notch groove 111 includes an explosion-proof sub-notch groove 1110. The sub-inner edge 1001 closest to the center point O of the explosion-proof sub-notch groove 1110 is the above-mentioned inner edge 101, and the sub-outer edge 1002 farthest from the center point O of the explosion-proof sub-notch groove 1110 is the above-mentioned outer edge 102.

[0025] In some examples, the explosion-proof sub-notch groove 1110 may be arranged on one side of the center point O and may have an open shape such as a "one" character shape or other shapes. When the explosion-proof sub-notch groove 1110 is in a "one" character shape and its extending direction is towards the center point O, the edges at both ends in the extending direction of the explosion-proof sub-notch groove 1110 are the above-mentioned inner edge 101 and outer edge 102 respectively.

[0026] In some other examples, the explosion-proof sub-notch groove 1110 may have a closed shape around the center point O. For example, the explosion-proof sub-notch groove 1110 may be square, circular, elliptical, heart-shaped, or other shapes. If the explosion-proof sub-notch groove 1110 is circular and its center coincides with the center point O, the two opposite edges of the explosion-proof sub-notch groove 1110 become the inner edge 101 and the outer edge 102, respectively. If the explosion-proof sub-notch groove 110 has a closed shape around the center point O, it helps to ensure the continuity of the explosion-proof notch groove 111 so that if the pressure inside the battery case becomes too high, the explosion-proof notch groove 111 can be evenly split, thereby allowing the battery pressure to be released smoothly.

[0027] In some other embodiments, as shown in Figures 4A and 4B, the explosion-proof notch groove 111 includes a plurality of explosion-proof sub-notches 1110 that are spaced apart from each other. That is, no two explosion-proof sub-notches 1110 are consecutive. Each explosion-proof sub-notch groove 1110 has a sub-inner edge 1001 closest to the center point O and a sub-outer edge 1002 furthest from the center point O. Of the plurality of sub-inner edges 1001, the sub-inner edge 1001 closest to the center point O becomes the inner edge 101, and of the plurality of sub-outer edges 1002, the sub-outer edge 1002 furthest from the center point O becomes the outer edge 102.

[0028] In some examples, multiple explosion-proof sub-notches 1110 are arranged around a central point O. In this way, the distribution of the multiple explosion-proof sub-notches 1110 can be made relatively uniform, which is advantageous for these explosion-proof sub-notches 1110 to rupture simultaneously, and furthermore, the operational stability of the explosion-proof notches 111 can be ensured.

[0029] In some examples, for all explosion-proof sub-notches 1110, at least some of the explosion-proof sub-notches 1110 are arranged in an annular pattern. This improves the uniformity of the positional arrangement of the explosion-proof sub-notches 1110, which is advantageous for these explosion-proof sub-notches 1110 to rupture simultaneously, and ensures the operational stability of the explosion-proof notches 111.

[0030] As an example, as shown in Figure 4A, all explosion-proof sub-notches 1110 are arranged in a ring shape. In this case, the inner edge 101 may be the sub-inner edge 1001 of any explosion-proof sub-notch 1110, and the outer edge 102 may be the sub-outer edge 1002 of any explosion-proof sub-notch 1110.

[0031] As an example, as shown in Figure 4B, some of the explosion-proof sub-notches 1110 are arranged in an annular pattern, while other explosion-proof sub-notches 1110 are located further out from the center point O than the aforementioned some explosion-proof sub-notches 1110, and are also arranged in an annular pattern. In other words, both parts of the explosion-proof sub-notches 1110 are centered on the center point O and located in different annular patterns. In this case, the sub-inner edge 1001 of the explosion-proof sub-notch 1110 closer to the center point O can be referred to as the inner edge 101, and the sub-outer edge 1002 of the explosion-proof sub-notch 1110 further from the center point O can be referred to as the outer edge 102.

[0032] In some examples, multiple explosion-proof sub-notches 1110 may be spaced apart along the direction away from the center point O.

[0033] In some examples, the width of the explosion-proof sub-notch groove 1110 may be 1 mm. The width direction of the explosion-proof sub-notch groove 1110 is perpendicular to the extension direction of the explosion-proof sub-notch groove 1110. If the explosion-proof notch groove 111 contains one explosion-proof sub-notch groove 1110, the width of the explosion-proof sub-notch groove 1110 is also the width of the explosion-proof notch groove 111.

[0034] Tests were conducted on the formation position of the explosion-proof notch groove 111 and the opening pressure (i.e., the pressure inside the battery case when the explosion-proof notch groove 111 is opened). Here, the thickness of the enclosure plate 20 was 0.4 mm, the thickness of the bottom plate 10 was 0.6 mm, the distance between the bottom of the explosion-proof notch groove 111 and the other side surface of the bottom plate 10 was 0.1 mm, the width of the explosion-proof notch groove 111 was 1 mm, and the diameter of the bottom plate 10 was 26 mm. Based on different distances between the inner edge 101 of the explosion-proof notch groove 111 and the center point O, the data in Tables 1 and 2 were obtained.

[0035] [Table 1]

[0036] From the data in Table 1, it can be seen that when the distance L1 between the inner edge 101 of the explosion-proof notch groove 111 and the center point O increases from 4.5 mm to 6.5 mm (i.e., when the ratio of this distance L1 to the radius R of the base plate 10 increases from 9 / 26 to 1 / 2), the valve opening pressure increases significantly. This means that when the inner edge 101 of the explosion-proof notch groove 111 is located within the range of that area, the heat generated by welding the base plate 10 during welding has a greater effect on the explosion-proof notch groove 111, resulting in a larger change in valve opening pressure.

[0037] When the distance L1 between the inner edge 101 and the center point O increases from 6.5 mm to 9 mm (i.e., when the ratio of this distance L1 to the radius R of the bottom plate 10 increases from 1 / 2 to 9 / 13), the trend in the change of valve opening pressure becomes very gradual. This means that when the inner edge 101 of the explosion-proof notch groove 111 is located within the range of that area, the effect of the heat generated by welding the bottom plate 10 on the explosion-proof notch groove 111 during welding becomes smaller, and the change in valve opening pressure becomes smaller.

[0038] [Table 2]

[0039] From the data in Table 2, it can be seen that when the distance L2 between the outer edge 102 of the explosion-proof notch groove 111 and the center point O increases from 6.5 mm to 10.4 mm (i.e., when the ratio of the distance L2 to the radius R of the base plate 10 increases from 1 / 2 to 4 / 5), the trend in the change of valve opening pressure is very gradual. This means that when the outer edge 102 of the explosion-proof notch groove 111 is located within the area, the impact of collisions with the edge of the base plate 10 on the explosion-proof notch groove 111 during subsequent strength safety tests of the battery will be small, and the change in valve opening pressure will be small.

[0040] When the distance L2 between the outer edge 102 and the center point O increases from 10.4 mm to 11.5 mm (i.e., when the ratio of the distance L1 to the radius R of the base plate 10 increases from 4 / 5 to 23 / 26), the valve opening pressure decreases more significantly. This means that if the outer edge 102 of the explosion-proof notch groove 111 is located within the area, the impact of impacts on the edge of the base plate 10 on the explosion-proof notch groove 111 will increase during subsequent strength safety tests of the battery, resulting in a larger change in valve opening pressure.

[0041] Therefore, for the explosion-proof notch groove 111, if the distance L1 between the inner edge 101 and the center point O is 1 / 2 or more of the radius R of the bottom plate 10, and the distance L2 between the outer edge 102 and the center point O is 4 / 5 or less of the radius R of the bottom plate 10, the opening pressure of the explosion-proof notch groove 111 is relatively stable, which is advantageous for ensuring the stable operation of the battery.

[0042] In some embodiments, as shown in Figures 5 and 6, the explosion-proof notch groove 111 is located on one side of the bottom plate 10. The explosion-proof notch groove 111 has a groove bottom, and the distance A1 between the groove bottom and the other side of the bottom plate 10 is 0.03 mm or more and 0.2 mm or less.

[0043] This arrangement facilitates rupture at the location of the explosion-proof notch groove 111, enabling smooth exhaust and pressure release.

[0044] For example, the normal discharge pressure of a battery is between 1.2 MPa and 2.5 MPa, and by setting the distance A1 within this range, pressure release within this range can be easily achieved. For example, if the distance A1 is 0.03 mm, the discharge pressure of the battery corresponds to approximately 1.2 MPa. In other words, when the pressure inside the battery exceeds 1.2 MPa, the explosion-proof notch groove 111 breaks and the pressure is released. If the distance A1 is 0.2 mm, the discharge pressure of the battery corresponds to approximately 2.5 MPa. In other words, when the pressure inside the battery exceeds 2.5 MPa, the explosion-proof notch groove 111 breaks and the pressure is released. Therefore, in the battery case of this application, an appropriate distance A1 can be set according to the actual pressure release demand, and stable pressure release can be achieved.

[0045] In some embodiments, the explosion-proof notch 111 is located on the side of the bottom plate 10 closer to the surrounding plate 20. This arrangement improves the overall aesthetics of the battery because the explosion-proof notch 111 is located inside the battery, and also prevents foreign matter from easily entering the explosion-proof notch 111 during use, which could affect the battery's performance.

[0046] In some embodiments, as shown in Figures 5 and 6, the explosion-proof notch 111 is located on the side of the bottom plate 10 away from the surrounding plate 20. This arrangement is advantageous because it ensures sufficient space for manufacturing the explosion-proof notch 111, as it is located outside the battery, thereby improving the manufacturing efficiency of the battery case.

[0047] In some embodiments, as shown in Figure 5, the ratio of the diameter D of the base plate 10 to the sum of the height h of the enclosure plate 20 and the thickness A2 of the base plate 10 is 0.2 or greater and 0.4 or less. That is, 0.2 ≤ D / (h+A2) ≤ 0.4. Here, the sum of the height h of the enclosure plate 20 and the thickness A2 of the base plate 10 is the height H of the battery case 100. In this case, 0.2 ≤ D / H ≤ 0.4.

[0048] The diameter D of the base plate 10 is matched to the diameter of the core pack in the housing chamber. A larger core pack diameter results in higher energy density, but also generates more heat during operation. Additionally, a higher height H of the battery case 100 increases its heat dissipation area. Therefore, setting the diameter D of the base plate 10 and the height H of the battery case 100 within the above ratio range ensures a good balance between the battery's energy density and heat dissipation capacity, resulting in good battery performance.

[0049] In some examples, the ratio of the diameter D of the base plate 10 to the height H of the battery case 100 is 0.2, 0.25, 0.3, 0.35, 0.4, etc., but this application is not limited thereto.

[0050] In some embodiments, as shown in Figure 5, the ratio of the thickness A2 of the bottom plate 10 to the thickness A3 of the enclosure plate 20 is 1 or greater and 2 or less. That is, 1 ≤ A2 / A3 ≤ 2.

[0051] This arrangement allows the bottom plate 10 to be relatively thick, which is advantageous for manufacturing the explosion-proof notches 111, and also improves the overall strength of the bottom plate 10, thus avoiding damage during battery strength safety testing caused by the manufacturing of the explosion-proof notches.

[0052] In some examples, the ratio of the thickness A2 of the base plate 10 to the thickness A3 of the enclosure plate 20 may be 1, 1.2, 1.4, 1.6, 1.8, 2, etc., but this application is not limited thereto.

[0053] In some embodiments, the material of the base plate 10 and the material of the surrounding plate 20 are the same. This is advantageous in improving the consistency and stability of the battery case 100, as the battery case 100 can withstand some degree of thermal expansion and contraction of the internal core pack, thereby ensuring the battery's operational stability.

[0054] In some examples, the base plate 10 and the surrounding plate 20 may be made of aluminum or steel.

[0055] For example, the materials of the base plate 10 and the surrounding plate 20 may be Al 3003, Al 3004, nickel-plated SPCC steel, or stainless steel. By using the above materials, the battery case 100 can have considerable strength, corrosion resistance, and workability, which is advantageous for the subsequent manufacture of batteries.

[0056] In some embodiments, the base plate 10 and the surrounding plate 20 are integrally molded. This improves the connection stability between the base plate 10 and the surrounding plate 20, ensuring the overall strength of the battery case 100, while also improving the airtightness of the battery case 100 and ensuring the operational stability of the core pack.

[0057] In the specific manufacturing process of the battery case 100, the method for manufacturing the battery case 100 may include the following steps.

[0058] S10: The roll of metal strip material is sent to the extrusion station, where it is extruded and deformed by a die in the extrusion station, then cut to form a cup-shaped initial material.

[0059] S20: The cup-shaped initial material is sent to the drawing station, where it is continuously drawn using upper and lower molds to form a blank case of a predetermined size.

[0060] S30: The case blank is sent to the notching station, pressed by upper and lower dies to form explosion-proof notches on the side of the bottom plate closer to the surrounding plate or on the side of the bottom plate further away from the surrounding plate, thereby forming the case blank into a semi-finished case.

[0061] S40: The semi-finished case is sent to the flattening station, where the bottom plate is flattened by pressing it out with upper and lower dies. This ensures that the products manufactured from the semi-finished case are uniform in size and flat.

[0062] S50: The semi-finished case from step S40 is sent to the cutting station, where the opening of the semi-finished case is cut to form a smooth opening.

[0063] By employing the above manufacturing method, it is possible to integrally mold the bottom plate 10 and the surrounding plate 20, and to form explosion-proof notches, thereby improving the production efficiency of the battery case 100.

[0064] Based on the above considerations, some embodiments of this application further provide a battery comprising the battery case 100 described in any of the above embodiments.

[0065] Since the battery is equipped with a battery case 100, the battery has the technical effects of the battery case 100 described above, but these will not be explained in detail here.

[0066] In some embodiments, the battery further comprises a core pack located within the battery case 100.

[0067] In some examples, the core pack may include a positive electrode sheet, a negative electrode sheet, separators, tabs, etc.

[0068] For example, a core pack may be a wound-type battery cell called a wound core. In the manufacturing process, a positive electrode sheet, a separator, and a negative electrode sheet are stacked in order and wound together to form a core.

[0069] As another example, the core pack may be a stacked core or other battery cell well known to those skilled in the art, and this application is not limited thereto.

[0070] Based on the above considerations, some embodiments of this application further provide a battery pack comprising the battery described in any of the above embodiments.

[0071] Since the battery is equipped with a battery case 100, the battery has the technical effects of the battery case 100 described above, but these will not be explained in detail here. [Explanation of symbols]

[0072] 10 Bottom plate 20 Enclosure boards 100 Battery Case 101 Common-law marriage 102 Outer edge 111 Explosion-proof notched groove 201 Opening 1001 Sub-internal margin 1002 Sub-outer edge 1110 Explosion-proof sub-notch groove.

Claims

1. It is a battery case, The base plate and The base plate is surrounded by an enclosing plate, A battery case characterized in that the surrounding plate and the bottom plate jointly define a housing chamber having an opening, the opening and the bottom plate are arranged opposite each other, the bottom plate has a center point, the bottom plate is provided with an explosion-proof notch groove, the explosion-proof notch groove has an inner edge closest to the center point and an outer edge furthest from the center point, the distance between the inner edge and the center point is 1 / 2 or more of the radius of the bottom plate, and the distance between the outer edge and the center point is 4 / 5 or less of the radius of the bottom plate.

2. The explosion-proof notch groove includes an explosion-proof sub-notch groove, wherein the sub-inner edge of the explosion-proof sub-notch groove closest to the center point O is the inner edge, and the sub-outer edge of the explosion-proof sub-notch groove furthest from the center point O is the outer edge, or The battery case according to claim 1, wherein the explosion-proof notch groove includes a plurality of explosion-proof sub-notches spaced apart from each other, and each explosion-proof sub-notch groove has a sub-inner edge closest to the center point O and a sub-outer edge furthest from the center point O, the sub-inner edge closest to the center point O among the plurality of sub-inner edges is the inner edge, and the sub-outer edge furthest from the center point O among the plurality of sub-outer edges is the outer edge.

3. The battery case according to claim 2, characterized in that, if the explosion-proof notch groove includes a plurality of explosion-proof sub-notches spaced apart from each other, the plurality of explosion-proof sub-notches are arranged around the central point.

4. The battery case according to claim 1, characterized in that the explosion-proof notch groove is located on one side surface of the bottom plate, the explosion-proof notch groove has a groove bottom, and the distance between the groove bottom and the other side surface of the bottom plate is 0.03 mm or more and 0.2 mm or less.

5. The battery case according to claim 4, characterized in that the explosion-proof notch groove is located on the side of the bottom plate closer to the surrounding plate, or the explosion-proof notch groove is located on the side of the bottom plate further away from the surrounding plate.

6. The battery case according to any one of claims 1 to 5, characterized in that the ratio of the diameter of the bottom plate to the sum of the height of the surrounding plate and the thickness of the bottom plate is 0.2 or more and 0.4 or less.

7. The battery case according to any one of claims 1 to 5, characterized in that the ratio of the thickness of the bottom plate to the thickness of the surrounding plate is 1 or more and 2 or less.

8. The battery case according to any one of claims 1 to 5, characterized in that the material of the bottom plate and the material of the surrounding plate are the same.

9. A battery characterized by comprising a battery case according to any one of claims 1 to 8.

10. A battery pack characterized by comprising the battery described in claim 9.

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