Battery case, energy storage apparatus, and electric device

Abstract

The present application provides a battery case, an energy storage apparatus, and an electric device. The battery case comprises a bottom case and a top cover. The bottom case comprises a main case and a reinforcing rib. The main case is provided with an accommodating cavity and an opening, wherein the accommodating cavity is formed inside the main case, and the opening is located on the outer surface of the main case and is communicated with the accommodating cavity. The reinforcing rib is fixedly connected to cavity side wall surfaces of the accommodating cavity, is spaced apart from the opening and a cavity bottom wall surface of the accommodating cavity, and extends in the circumferential direction of the main case; first sub-reinforcing portions of the reinforcing rib each comprise a step surface facing the opening; second sub-reinforcing portions of the reinforcing rib are located on the sides of the first sub-reinforcing portions facing away from the step surfaces, and are fixedly connected to the first sub-reinforcing portions; and in the direction from the opening to the cavity bottom wall surface, the thickness of the second sub-reinforcing portions gradually decreases. The top cover is located on the accommodating cavity, is welded to the cavity side wall surfaces, abuts against the step surfaces, and also closes the opening.

Description

Battery housings, energy storage devices, and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 29, 2024, with application number 202420644942.2 and application name “Battery housing, energy storage device and electrical equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of energy storage technology, and in particular to a battery housing, an energy storage device, and an electrical device. Background Art

[0003] In existing energy storage devices, the top cover and shell are often assembled by welding. This creates significant notch stress and a heat-affected zone near the weld seam between the top cover and shell, reducing the shell's strength. This can lead to cracking of the shell after repeated charge and discharge cycles, compromising the device's reliability.

[0004] Application Contents

[0005] The present application provides a battery housing, an energy storage device, and an electrical device, which are used to improve the stress concentration problem at the weld position between the top cover and the housing, improve the strength of the housing, extend the charge and discharge cycle life of the housing, and ensure the reliability of the energy storage device.

[0006] In a first aspect, the present application provides a battery housing, the battery housing comprising a bottom shell and a top cover, the bottom shell comprising a main shell and reinforcing ribs;

[0007] The main shell is provided with a receiving cavity and an opening, wherein the receiving cavity is located on the inner side of the main shell, and the opening is located on the outer surface of the main shell and communicates with the receiving cavity;

[0008] The reinforcing rib is fixedly connected to the side wall of the receiving cavity, and is spaced apart from the opening and the bottom wall of the receiving cavity, and extends along the circumference of the main shell. The reinforcing rib includes a first sub-reinforcing portion and a second sub-reinforcing portion. The first sub-reinforcing portion includes a stepped surface facing the opening. The second sub-reinforcing portion is located on a side of the first sub-reinforcing portion away from the stepped surface and is fixedly connected to the first sub-reinforcing portion. The thickness of the second sub-reinforcing portion gradually decreases along the direction from the opening to the bottom wall of the receiving cavity.

[0009] The top cover is located in the receiving cavity, welded to the side wall surface of the receiving cavity, abutted against the step surface, and also closes the opening.

[0010] In a second aspect, the present application provides an energy storage device comprising any of the above-mentioned battery housings and an electrode assembly, wherein the electrode assembly is located in the receiving cavity.

[0011] In a third aspect, the present application provides an electrical device comprising any of the above-mentioned energy storage devices, wherein the energy storage device supplies power to the electrical device.

[0012] In the energy storage device described in this application, the reinforcing ribs are designed on the inner side of the main shell to separate the position of the bottom shell supporting the top cover from the position welded to the top cover. This separates the stress concentration area of ​​the bottom shell from the heat-affected zone of the weld, improving the stress concentration problem at the weld between the bottom shell and the top cover, increasing the strength of the bottom shell, extending the charge-discharge cycle life of the bottom shell, and ensuring the reliability of the energy storage device. In addition, the thickness of the second sub-reinforcement portion gradually decreases from the opening to the bottom wall of the receiving cavity, which can reduce the stress concentration at the groove of the bottom shell caused by the sudden change in size, thereby ensuring the reliability of the bottom shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be described below.

[0014] FIG1 is a schematic structural diagram of an energy storage system used in an energy storage device according to an embodiment of the present application;

[0015] FIG2 is a schematic structural diagram of an energy storage device provided in an embodiment of the present application;

[0016] FIG3 is a schematic diagram of the exploded structure of the energy storage device shown in FIG2 ;

[0017] FIG4 is a schematic structural diagram of the bottom shell of the energy storage device shown in FIG3 ;

[0018] FIG5 is a schematic structural diagram of the bottom shell shown in FIG4 after being cut open along position II;

[0019] FIG6 is a schematic cross-sectional view of the bottom shell shown in FIG4 taken along line II;

[0020] FIG7 is a schematic structural diagram of the energy storage device shown in FIG2 after being cut along II-II;

[0021] FIG8 is a cross-sectional schematic diagram of the energy storage device shown in FIG2 taken along line II-II;

[0022] FIG9 is a stress simulation diagram of the bottom shell of a conventional energy storage device;

[0023] FIG10 is a stress simulation diagram of the bottom shell of the energy storage device shown in this application.

[0024] The names corresponding to the various figure marks in the figure are: photovoltaic panel 2000, wind turbine 3000, power grid 4000, energy storage device 1000, battery shell 5000, bottom shell 100, top cover 200, accommodating cavity 101, opening 102, main shell 110, reinforcing rib 120, cavity bottom wall 111, cavity side wall 112, first sub-reinforcement part 122, second sub-reinforcement part 123, step surface 121, inner side surface 124, main cover 210 and flange part 220. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0026] Because the energy people need is highly temporal and spatially dependent, rational energy utilization and improved efficiency require a medium or device that can store one form of energy in the same form or convert it into another, allowing it to be released in a specific form based on future application needs. As we all know, the primary method for generating green electricity currently is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels. Currently, green electricity generation generally relies on photovoltaics, wind power, and hydropower. However, wind and solar power suffer from significant intermittent and fluctuating output, leading to grid instability, insufficient peak power consumption, and excessive off-peak power consumption. Unstable voltage can also damage power supply. Consequently, insufficient electricity demand or insufficient grid capacity can lead to "wind and solar curtailment." Addressing these issues requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing them, converting the energy back into electricity when needed. Simply put, energy storage is like a large "power bank," storing electricity when photovoltaic and wind power are plentiful and releasing it when needed.

[0027] Taking electrochemical energy storage as an example, this solution provides an energy storage device with a group of chemical batteries inside. The energy storage device mainly uses the chemical elements in the chemical batteries as energy storage media. The charging and discharging process is accompanied by chemical reactions or changes in the energy storage medium. Simply put, the electricity generated by wind and solar energy is stored in the chemical batteries. When the use of external electricity reaches its peak, the stored electricity is released for use, or transferred to places where electricity is scarce for use.

[0028] Currently, energy storage (i.e., energy storage) has a wide range of application scenarios, including (wind and solar) power generation-side energy storage, grid-side energy storage, base station-side energy storage, and user-side energy storage. The corresponding energy storage device types include:

[0029] (1) Large energy storage containers used in grid-side energy storage scenarios can serve as high-quality active and reactive power regulation power sources in the grid, achieving load matching of electricity in time and space, enhancing the ability to absorb renewable energy, and are of great significance in grid system backup, alleviating peak load power supply pressure, and peak and frequency regulation.

[0030] (2) Small and medium-sized energy storage cabinets used in industrial and commercial energy storage scenarios (banks, shopping malls, etc.) on the user side mainly operate in the "peak shaving and valley filling" mode. Since there is a large price difference in electricity prices at peak and valley locations according to electricity demand, after users have energy storage equipment, in order to reduce costs, they usually charge the energy storage cabinets / boxes during the low electricity price period; during the peak electricity price period, they release the electricity in the energy storage equipment for use, thereby saving electricity costs.

[0031] Please refer to FIG1 , which is a schematic structural diagram of an energy storage system applied to an energy storage device provided in an embodiment of the present application.

[0032] The energy storage device provided in the embodiment of the present application is applied to an energy storage system, which includes an electric energy conversion device (photovoltaic panel 2000), a wind energy conversion device (wind turbine 3000), a power grid 4000 and an energy storage device 1000. The energy storage device 1000 can be used as an energy storage cabinet and can be installed outdoors. Specifically, the photovoltaic panel 2000 can convert solar energy into electric energy during the period of low electricity prices. The energy storage device 1000 is used to store the electric energy and supply it to the power grid 4000 during peak electricity consumption, or to supply power when the power grid 4000 is out of power / outage. The wind energy conversion device (wind turbine 3000) can convert wind energy into electric energy. The energy storage device 1000 is used to store the electric energy and supply it to the power grid 4000 during peak electricity consumption, or to supply power when the power grid 4000 is out of power / outage. Among them, the transmission of electric energy can be carried out using high-voltage cables.

[0033] There may be multiple energy storage devices 1000, each connected in series or in parallel. These devices 1000 are supported and electrically connected using an isolation plate (not shown). In this embodiment, "multiple" refers to two or more. An energy storage box may also be provided externally to the energy storage device 1000 to house the energy storage device 1000.

[0034] It is understood that the energy storage device 1000 may include, but is not limited to, single cells, battery modules, battery packs, and battery systems. The energy storage device provided in the embodiments of this application may be, but is not limited to, the products listed above, or may be implemented in other forms. The embodiments of this application do not impose strict limitations on the application of the energy storage device 1000. The embodiments of this application illustrate the energy storage device 1000 as a multi-cell battery.

[0035] The embodiment of the present application is described by taking the energy storage device 1000 as a single battery as an example.

[0036] 2 and 3 , FIG2 is a schematic diagram of the structure of the energy storage device 1000 provided in an embodiment of the present application, and FIG3 is a schematic diagram of the exploded structure of the energy storage device 1000 shown in FIG2 .

[0037] In this embodiment, the energy storage device 1000 is a square battery. The energy storage device 1000 includes a battery shell 5000 and an electrode assembly. The battery shell 5000 includes a bottom shell 100 and a top cover 200. The bottom shell 100 has a receiving cavity 101 and an opening 102. The receiving cavity 101 is located on the inner side of the bottom shell 100 and contains an electrolyte. The opening 102 is located on the top side of the receiving cavity 101 and is connected to the receiving cavity 101. The electrode assembly is located on the inner side of the bottom shell 100. The electrode assembly is accommodated in the receiving cavity 101 and is immersed in the electrolyte. The top cover 200 is located in the receiving cavity 101, closes the opening 102, and is electrically connected to the electrode assembly.

[0038] Please refer to Figures 4 to 6. Figure 4 is a schematic structural diagram of the bottom case 100 in the energy storage device 1000 shown in Figure 3. Figure 5 is a schematic structural diagram of the bottom case 100 shown in Figure 4 after being cut along line II. Figure 6 is a schematic cross-sectional diagram of the bottom case 100 shown in Figure 4 after being cut along line II. The term "cut along line II" refers to cutting along the plane corresponding to line II, and similar descriptions hereinbelow shall be understood in the same manner.

[0039] The bottom shell 100 includes a main shell 110 and a reinforcing rib 120, and the reinforcing rib 120 is fixedly connected to the main shell 110. Exemplarily, the main shell 110 and the reinforcing rib 120 are integrally formed. The main shell 110 is provided with a receiving cavity 101 and an opening 102. The receiving cavity 101 is located on the inner side of the main shell 110. The receiving cavity 101 has a cavity bottom wall 111 and a cavity side wall 112, and the cavity side wall 112 is connected to the cavity bottom wall 111 and is arranged around the cavity bottom wall 111. The opening 102 is located on the outer surface of the main shell 110, and is connected to the receiving cavity 101, and is arranged opposite to the cavity bottom wall 111. The thickness of the main shell 110 is L1. That is, the thickness of the cavity side wall of the receiving cavity 101 is L1.

[0040] The reinforcing rib 120 is located in the receiving cavity 101 and is fixedly connected to the cavity side wall 112 of the receiving cavity 101. It is located between the opening 102 and the cavity bottom wall 111 of the receiving cavity 101, and is also spaced apart from the opening 102 and the cavity bottom wall 111 of the receiving cavity 101. The distance between the reinforcing rib 120 and the opening 102 is smaller than the distance between the reinforcing rib 120 and the cavity bottom wall 111 of the receiving cavity 101. That is, the reinforcing rib 120 is arranged at a position close to the opening 102. Specifically, the reinforcing rib 120 is located on the side of the electrode assembly facing the opening 102 and extends along the circumference of the main shell 110. The distance between the reinforcing rib 120 and the opening 102 is H1, and the maximum thickness of the reinforcing rib 120 is L2. That is, the height of the portion of the main shell 110 located on the top side of the reinforcing rib 120 is H1, and the maximum distance between the surface of the reinforcing rib 120 away from the cavity side wall 112 of the accommodating cavity 101 and the cavity side wall 112 of the accommodating cavity 101 is L2.

[0041] It can be understood that the provision of the reinforcing ribs 120 can not only increase the thickness of the bottom shell 100, but also increase the cross-sectional area of ​​the stress concentration area in the bottom shell 100, thereby reducing the stress borne by the stress concentration area in the bottom shell 100, thereby improving the strength of the bottom shell 100 and ensuring the reliability of the energy storage device 1000. Moreover, since the reinforcing ribs 120 are provided near the opening 102, they will not affect the space for accommodating the electrode assembly in the bottom shell 100, and can also improve the volume utilization rate of the bottom shell 100, thereby ensuring the energy density per unit volume of the energy storage device 1000.

[0042] In this embodiment, the reinforcing rib 120 is in a continuous ring shape. The shape of the reinforcing rib 120 matches the shape of the main shell 110. For example, the main shell 110 is square, and the reinforcing rib 120 is in a square ring shape. In other embodiments, the reinforcing rib 120 may also be in a discontinuous ring shape. For example, the reinforcing rib 120 may include multiple sub-reinforcing ribs spaced apart along the circumference of the main shell 110. This application does not impose any specific limitations on the structure of the reinforcing rib 120.

[0043] The reinforcing rib 120 includes a first sub-reinforcement portion 122 and a second sub-reinforcement portion 123. The first sub-reinforcement portion 122 and the second sub-reinforcement portion 123 are both fixedly connected to the cavity side wall surface 112 of the accommodating cavity 101, and the second sub-reinforcement portion 123 is fixedly connected to the first sub-reinforcement portion 122. The first sub-reinforcement portion 122 includes a step surface 121 facing the opening 102. The step surface 121 extends along the circumference of the main shell 110 and is used to support the top cover 200. The distance between the step surface 121 and the opening 102 is H1. That is, the distance between the first sub-reinforcement portion 122 and the opening 102 is H1. The step surface 121 of the first sub-reinforcement portion 122 can support the top cover 200, ensure the consistency of the top cover 200 being pressed into the shell, and improve the consistency of the fusion depth and appearance of the welding between the bottom shell 100 and the top cover 200.

[0044] In addition, the thickness of the first sub-reinforcement 122 is L2, and the height of the first sub-reinforcement 122 is H2. That is, the distance between the surface of the first sub-reinforcement 122 facing away from the sidewall 112 of the receiving cavity 101 and the sidewall 112 of the receiving cavity 101 is L2, and the distance between the surface of the first sub-reinforcement 122 facing the opening 102 and the surface of the first sub-reinforcement 122 facing away from the opening 102 is H2. The design of the first sub-reinforcement 122 not only supports the top cover 200, but also increases the thickness of the bottom shell 100, improves the strength of the bottom shell 100, reduces the stress concentration effect of the bottom shell 100, helps to increase the service life of the bottom shell 100, and ensures the reliability of the energy storage device 1000.

[0045] The ratio of the thickness L2 of the first sub-reinforcement portion 122 to the thickness L1 of the main shell 110 is greater than or equal to 0.7 and less than or equal to 1. This ensures that the first sub-reinforcement portion 122 provides sufficient support strength for the top cover 200 while not occupying a large amount of space inside the bottom shell 100, thereby helping to reduce the impact of the first sub-reinforcement portion 122 on the energy density of the energy storage device 1000. For example, the ratio of the thickness L2 of the first sub-reinforcement portion 122 to the thickness L1 of the main shell 110 is equal to 0.8, in which case L1+L2=1.8*L1. Alternatively, the ratio of the thickness L2 of the first sub-reinforcement portion 122 to the thickness L1 of the main shell 110 is equal to 1, in which case L2=L1.

[0046] The second sub-reinforcement 123 is located on the side of the first sub-reinforcement 122 facing the electrode assembly. That is, the second sub-reinforcement 123 is located on the side of the first sub-reinforcement 122 facing away from the opening 102. Specifically, the second sub-reinforcement 123 is fixedly connected to the surface of the first sub-reinforcement 122 facing away from the opening 102. Along the direction from the opening 102 to the cavity bottom wall 111 of the accommodating cavity 101 (i.e., the negative direction of the Z axis in the figure), the thickness of the second sub-reinforcement 123 gradually decreases to reduce the stress concentration on the groove caused by the sudden change in size of the bottom shell 100 and ensure the reliability of the bottom shell 100. Exemplarily, the maximum thickness of the second sub-reinforcement 123 is equal to the thickness L2 of the end of the first sub-reinforcement 122 facing the second sub-reinforcement 123, and the minimum thickness of the second sub-reinforcement 123 is 0 to achieve a smooth transition between the first sub-reinforcement 122 and the main shell 110, so as to reduce the stress concentration on the groove caused by the sudden change in size of the bottom shell 100 and ensure the reliability of the bottom shell 100.

[0047] The second sub-reinforcement portion 123 includes an inner side surface 124 facing away from the side wall 112 of the receiving cavity 101. The distance between the inner side surface 124 and the side wall 112 of the receiving cavity 101 gradually decreases along the direction from the opening 102 to the bottom wall 111 of the receiving cavity 101. The angle θ between the inner side surface 124 and the side wall 112 of the receiving cavity 101 is greater than 20 degrees and less than 40 degrees. This ensures a smooth transition between the first sub-reinforcement portion 122 and the main shell 110, reduces stress concentration at the groove caused by the sudden change in size of the bottom shell 100, and ensures the reliability of the bottom shell 100. Exemplarily, the inner side surface 124 is an inclined surface, and the angle θ between the inner side surface 124 and the side wall 112 of the receiving cavity 101 is 21 degrees.

[0048] Furthermore, the height of the second sub-reinforcement portion 123 is H3. That is, the distance between the surface of the second sub-reinforcement portion 123 facing the first sub-reinforcement portion 122 and the surface of the second sub-reinforcement portion 123 facing away from the first sub-reinforcement portion 122 is H3. The ratio of the height H3 of the second sub-reinforcement portion 123 to the height H2 of the first sub-reinforcement portion 122 is greater than or equal to 0.9 and less than or equal to 1.1. This ensures that the second sub-reinforcement portion 123 effectively supports the first sub-reinforcement portion 122, thereby improving the strength of the bottom case 100. For example, the ratio of the height H3 of the second sub-reinforcement portion 123 to the height H2 of the first sub-reinforcement portion 122 is equal to 1, in which case H3 = H2.

[0049] Please refer to FIG. 7 and FIG. 8 . FIG. 7 is a schematic structural diagram of the energy storage device 1000 shown in FIG. 2 cut along line II-II. FIG. 8 is a schematic cross-sectional diagram of the energy storage device 1000 shown in FIG. 2 cut along line II-II.

[0050] The top cover 200 is welded to the sidewall 112 of the accommodating cavity 101 and abuts the stepped surface 121 of the first sub-reinforcement portion 122. In this embodiment, by designing reinforcing ribs 120 on the inner side of the main shell 110, utilizing the stepped surface 121 of the reinforcing ribs 120 to support the top cover 200, and welding the main shell 110 to the top cover 200, the welding position of the bottom shell 100 to the top cover 200 and the position supporting the top cover 200 can be separated, thereby separating the stress concentration area of ​​the bottom shell 100 from the welding heat-affected zone, improving the stress concentration problem at the weld between the bottom shell 100 and the top cover 200, and enhancing the strength of the bottom shell 100, thereby ensuring the reliability of the energy storage device 1000.

[0051] The thickness of the top cover 200 is H4. The ratio of the thickness H4 of the top cover 200 to the distance H1 between the first sub-reinforcement portion 122 and the opening 102 is greater than or equal to 2 and less than or equal to 4. The ratio of the thickness H2 + H3 of the reinforcing rib 120 to the thickness H4 of the top cover 200 is greater than or equal to 1 and less than or equal to 2, to ensure that the stepped surface 121 of the reinforcing rib 120 effectively supports the top cover 200. For example, the ratio of the thickness H4 of the top cover 200 to the distance H1 between the first sub-reinforcement portion 122 and the opening 102 is 3, and the ratio of the thickness H2 + H3 of the reinforcing rib 120 to the thickness H4 of the top cover 200 is 1.5. In this case, H4 = 3*H1, and H2+H3 = 1.5*H4.

[0052] In this embodiment, the top cover 200 includes a main cover 210 and a flange 220. The flange 220 is fixedly connected to the circumference of the main cover 210 and surrounds the main cover 210. Exemplarily, the main cover 210 and the flange 220 are integrally formed. Specifically, the main cover 210 is inserted into the inner side of the reinforcing rib 120, and the flange 220 abuts the stepped surface 121 of the first sub-reinforcement portion 122.

[0053] Please refer to Figures 9 and 10. Figure 9 is a stress simulation diagram of the shell in a conventional energy storage device, and Figure 10 is a stress simulation diagram of the shell in the energy storage device shown in an embodiment of the present application.

[0054] As can be seen from Figures 9 and 10, compared with the shell of the existing energy storage device, the area of ​​the stress concentration region with a stress greater than 132 MPa in the bottom shell 100 of the energy storage device 1000 shown in the embodiment of the present application is smaller. Therefore, the design of the reinforcing rib 120 in the present application can effectively improve the problem of low strength at the weld position between the bottom shell 100 and the top cover 200 due to the overlap of the heat-affected zone and the stress concentration zone in the bottom shell 100.

[0055] In the energy storage device 1000 shown in this application, reinforcing ribs 120 are designed on the inner side of the main shell 110 to separate the position of the bottom shell 100 supporting the top cover 200 from the position welded to the top cover 200. This separates the stress concentration area of ​​the bottom shell 100 from the heat-affected zone of the weld, improving the stress concentration problem at the weld between the bottom shell 100 and the top cover 200, increasing the strength of the bottom shell 100, extending the charge-discharge cycle life of the bottom shell 100, and ensuring the reliability of the energy storage device 1000. In addition, the thickness of the second sub-reinforcement portion 123 gradually decreases from the opening 102 toward the bottom wall 111 of the receiving cavity 101, which can reduce the stress concentration at the groove of the bottom shell 100 caused by the sudden change in size, thereby ensuring the reliability of the bottom shell 100.

[0056] The present application also provides an electric device, which includes the energy storage device 1000, and the energy storage device 1000 supplies power to the electric device. The electric device may be a new energy vehicle, a power storage station, a server, or other equipment requiring electricity.

[0057] The above description is only a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application; the embodiments of this application and the features of the embodiments can be combined with each other unless there is a conflict. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A battery housing, characterized in that: The battery housing includes a bottom shell and a top cover, and the bottom shell includes a main shell and reinforcing ribs; The main shell is provided with a receiving cavity and an opening, wherein the receiving cavity is located on the inner side of the main shell, and the opening is located on the outer surface of the main shell and communicates with the receiving cavity; The reinforcing rib is fixedly connected to the side wall of the receiving cavity, and is spaced apart from the opening and the bottom wall of the receiving cavity, and extends along the circumference of the main shell. The reinforcing rib includes a first sub-reinforcing portion and a second sub-reinforcing portion. The first sub-reinforcing portion includes a stepped surface facing the opening. The second sub-reinforcing portion is located on a side of the first sub-reinforcing portion away from the stepped surface and is fixedly connected to the first sub-reinforcing portion. The thickness of the second sub-reinforcing portion gradually decreases along the direction from the opening to the bottom wall of the receiving cavity. The top cover is located in the receiving cavity, welded to the side wall surface of the receiving cavity, abutted against the step surface, and also closes the opening.

2. The battery case according to claim 1, wherein: A ratio of a thickness of the first sub-reinforcement portion to a thickness of the main shell is greater than or equal to 0.7 and less than or equal to 1.

3. The battery case according to claim 1 or 2, characterized in that: The maximum thickness of the second sub-reinforcement portion is equal to the thickness of the end portion of the first sub-reinforcement portion toward the second sub-reinforcement portion.

4. The battery case according to claim 1 or 2, characterized in that: A ratio of a height of the second sub-reinforcement portion to a height of the first sub-reinforcement portion is greater than or equal to 0.9 and less than or equal to 1.

1.

5. The battery case according to claim 1 or 2, characterized in that: The second sub-reinforcement portion includes an inner side surface facing away from the side wall surface of the receiving cavity, and an angle between the inner side surface and the side wall surface of the receiving cavity is greater than 20 degrees and less than 40 degrees.

6. The battery case according to claim 1, wherein: A ratio of a thickness of the top cover to a distance between the first sub-reinforcement portion and the opening is greater than or equal to 2 and less than or equal to 4.

7. The battery case according to claim 1, characterized in that The ratio of the height of the reinforcing rib to the thickness of the top cover is greater than or equal to 1 and less than or equal to 2.

8. An energy storage device, characterized in that: It comprises a battery casing and an electrode assembly as described in any one of claims 1 to 7, wherein the electrode assembly is located in the receiving cavity.

9. The energy storage device according to claim 8, characterized in that The electrode assembly is located on a side of the second sub-reinforcement portion away from the first sub-reinforcement portion.

10. An electrical device, characterized in that: It comprises the energy storage device as described in claim 8 or 9, and the energy storage device supplies power to the electrical equipment.

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