BATTERY CELL CASINGS, ELECTROCHEMICAL DEVICES AND THEIR MANUFACTURING METHODS, AND ELECTRICAL DEVICES CONTAINING THEM

Abstract

The invention proposes a battery cell enclosure (100) consisting of a bottom wall (110), a side wall (120), and a flange (130), the flange (130) being positioned at one end of the side wall (120) away from the bottom wall (110), at least part of the flange (130) protruding from the inner and / or outer surface of the side wall (120), the flange surface (131) of the flange (130) being essentially perpendicular to the side wall (120) and designed to connect with the battery cell enclosure cover (200); the transition surface (132) of the flange (130) is curved between the flange surface (131) and the inner and / or outer surface of the side wall (120), the width of the transition surface (132) is W1, and the thickness of the side wall (120) is T1, satisfying 0 < W1 ≤ T1.

Description

Battery cell shell, electrochemical device and preparation method thereof, and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application CN202310870108.5, entitled “Battery cell shell, electrochemical device, preparation method thereof, and electrical equipment,” filed on July 14, 2023. The entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and more specifically, to a battery cell shell, an electrochemical device, a preparation method thereof, and electrical equipment. Background Art

[0004] With the rapid development of electronic information technology, various electronic devices are also developing towards intelligence and multi-functionality, and the energy density of batteries is becoming increasingly demanding. Therefore, how to improve the energy density of batteries has become an urgent problem to be solved in the battery field.

[0005] Summary of the Invention

[0006] The present application provides a battery cell shell, an electrochemical device and a preparation method thereof, and an electrical device, which can effectively improve the energy density of the electrochemical device.

[0007] In a first aspect, the present application provides a battery cell casing, comprising a bottom wall, a side wall, and a flange portion, wherein the side wall is disposed around the bottom wall and, together with the bottom wall, forms a receiving space having an opening, the flange portion is disposed at an end of the side wall away from the bottom wall, and at least a portion of the flange portion protrudes from an inner surface and / or an outer surface of the side wall;

[0008] Among them, the flange part has a flange surface and a transition surface, the flange surface is roughly perpendicular to the side wall and is used to connect with the battery cell shell cover; the transition surface is curved to connect the flange surface and the inner surface and / or outer surface of the side wall, the width of the transition surface in the thickness direction of the side wall is W1, and the wall thickness of the side wall is T1, satisfying 0<W1≤T1.

[0009] In the above technical solution, the battery cell shell includes a bottom wall, a side wall and a flange portion. The side wall is arranged around the bottom wall and together with the bottom wall, forms a receiving space with an opening, so that the electrode assembly can be received in the receiving space through the opening; the flange portion is arranged at one end of the side wall away from the bottom wall, and at least a part of the flange portion protrudes from the inner surface and / or outer surface of the side wall, so that the flange portion can be used to connect with the battery cell shell cover and increase the connection area with the battery shell cover; the flange portion has a flange surface and a transition surface, the flange surface is roughly perpendicular to the side wall, and is used to connect with the battery cell shell cover. The transition surface is curved to connect the flange surface and the inner and / or outer surface of the side wall. The width of the transition surface in the thickness direction of the side wall is W1, and the wall thickness of the side wall is T1, satisfying 0<W1≤T1. This makes the width of the flange surface larger, while the width of the portion of the flange protruding from the side wall is smaller. This can reduce the space occupied by the battery cell housing, thereby increasing the volume of the accommodation space and the energy density of the electrochemical device. It can also reduce the wall thickness of the side wall, thereby further increasing the volume of the accommodation space and the energy density of the electrochemical device. If W1 is larger (for example, greater than T1), the width of the flange surface may be smaller or the width of the portion of the flange protruding from the side wall may be larger. A smaller width of the flange surface may affect the connection strength between the battery cell housing and the battery cell cover. A larger width of the portion of the flange protruding from the side wall may compress the accommodation space and affect the energy density of the electrochemical device.

[0010] In some embodiments of the first aspect, 0<W1≤0.7*T1.

[0011] In the above technical solution, by making 0<W1≤0.7*T1, the width of the flange surface can be further made larger, and at the same time, the width of the portion of the flange protruding from the side wall can be made smaller, thereby further increasing the volume of the accommodating space and increasing the energy density of the electrochemical device, and the wall thickness of the side wall can be further made smaller, thereby increasing the volume of the accommodating space and increasing the energy density of the electrochemical device.

[0012] In some embodiments of the first aspect, a width of the flange surface in a thickness direction of the side wall is W2, satisfying W2≥0.7*T1.

[0013] In the above technical solution, by ensuring that the width W2 of the flange surface in the thickness direction of the side wall satisfies W2 ≥ 0.7 * T1, the connection area between the flange surface and the cell shell cover can be increased, the connection between the cell shell and the cell shell cover is more stable, the sealing is improved, and the electrochemical device is less likely to have a gap or separation between the cell shell and the cell shell cover due to force or environmental changes, thereby improving the reliability of the electrochemical device. If W2 is smaller (for example, less than 0.7 * T1), the connection strength between the cell shell and the cell shell cover may be affected, thereby affecting the sealing of the electrochemical device.

[0014] In some embodiments of the first aspect, the flange surface is a plane and the transition surface is an arcuate surface.

[0015] In the above technical solution, by setting the flange surface as a plane, the flange surface can be better fitted with the cell cover, so as to facilitate the connection between the flange surface and the cell cover. Setting the transition surface as an arc surface facilitates the preparation of the flange part.

[0016] In some embodiments of the first aspect, at least a portion of the flange portion protrudes from the outer surface of the side wall, and a width of the portion of the flange portion protruding from the outer surface of the side wall in the thickness direction of the side wall is W3, satisfying 0.05 mm ≤ W3 ≤ 0.3 mm.

[0017] In the above technical solution, at least a portion of the flange portion protrudes from the outer surface of the side wall. By ensuring that the width W3 of the portion of the flange portion protruding from the outer surface of the side wall in the thickness direction of the side wall satisfies 0.05mm≤W3≤0.3mm, on the one hand, the width of the flange surface can be made larger, the connection area between the battery cell housing and the battery cell cover is larger, and the connection strength is improved. On the other hand, the space occupied by the portion of the flange portion protruding from the outer surface of the side wall can be reduced, thereby increasing the volume of the accommodation space, increasing the volume of the electrode assembly, and increasing the energy density of the electrochemical device under certain dimensions. If W3 is smaller (for example, less than 0.05mm), the width of the flange surface is smaller, the connection area between the battery cell housing and the battery cell cover is smaller, and the connection strength is lower. When the electrochemical device is subjected to force or the environment changes, a gap or separation may occur between the battery cell housing and the battery cell cover, affecting the sealing of the electrochemical device. If W3 is larger (for example, greater than 0.3 mm), the portion of the flange protruding from the outer surface of the side wall occupies a larger space, so that when the size of the electrochemical device is constant, the volume of the accommodating space is smaller, the volume of the electrode assembly is smaller, and the energy density of the electrochemical device is also smaller.

[0018] In some embodiments of the first aspect, 0.05 mm ≤ W3 ≤ 0.15 mm.

[0019] In the above technical solution, by ensuring that 0.05mm≤W3≤0.15mm, the space occupied by the portion of the flange protruding from the outer surface of the side wall can be further reduced, thereby making the volume of the accommodating space larger, the volume of the electrode assembly larger, and the energy density of the electrochemical device higher when the size of the electrochemical device is constant.

[0020] In some embodiments of the first aspect, at least a portion of the flange protrudes from the outer surface of the sidewall, and a thickness of the portion of the flange protruding from the outer surface of the sidewall is T2, satisfying 0.7*T1≤T2≤1.1*T1.

[0021] In the above technical solution, by ensuring that the thickness T2 of the portion of the flange protruding from the outer surface of the side wall satisfies 0.7*T1≤T2≤1.1*T1, on the one hand, the flange portion can be made stronger and less prone to deformation, and sufficient welding depth can be reserved for the welding connection between the battery cell housing and the battery cell cover, thereby increasing the connection strength between the battery cell housing and the battery cell cover. On the other hand, the width of the transition surface can be made smaller, thereby increasing the volume of the accommodation space and increasing the energy density of the electrochemical device. If T2 is small (for example, less than 0.7*T1), the strength of the flange portion is small and may be easily deformed due to force or environmental changes. At the same time, the welding depth between the battery cell housing and the battery cell cover is limited, which may affect the connection strength between the battery cell housing and the battery cell cover. If T2 is large (for example, greater than 1.1*T1), it is not convenient to form a transition surface with a smaller width, which may affect the volume of the accommodation space and thus the energy density of the electrochemical device.

[0022] In some embodiments of the first aspect, 0.05 mm ≤ T1 ≤ 0.15 mm.

[0023] In the above technical solution, by ensuring that the wall thickness T1 of the side wall satisfies 0.05mm≤T1≤0.15mm, on the one hand, the strength of the battery cell housing can be increased, and it is not easy to deform or break due to force or environmental changes, which can better protect the electrode assembly and maintain the normal operation of the electrochemical device. On the other hand, it can reduce the space occupied by the battery cell housing. When the size of the electrochemical device is constant, more storage space is reserved, making the volume of the electrode assembly larger and the energy density of the electrochemical device higher. If T1 is small (for example, less than 0.05mm), the strength of the battery cell housing is small, and it may be deformed or broken due to force or environmental changes, affecting the protection of the electrode assembly and the normal operation of the electrochemical device. If T1 is large (for example, greater than 0.15mm), the space occupied by the battery cell housing will be larger. When the size of the electrochemical device is constant, the reserved storage space will be smaller, making the volume of the electrode assembly smaller and the energy density of the electrochemical device lower.

[0024] In some embodiments of the first aspect, 0.05 mm ≤ T1 ≤ 0.1 mm.

[0025] In the above technical solution, by ensuring that 0.05mm≤T1≤0.1mm, the space occupied by the battery cell shell can be further reduced. When the size of the electrochemical device is constant, a larger accommodation space is reserved, so that the volume of the electrode assembly is larger and the energy density of the electrochemical device is higher.

[0026] In some embodiments of the first aspect, a thickness of a portion of the flange portion corresponding to the transition surface is T3, satisfying T3>T1.

[0027] In the above technical solution, by making the thickness T3 of the part of the flange corresponding to the transition surface satisfy T3 > T1, the connection between the flange and the side wall can be made more firm, the flange is not easily separated from the side wall, and the overall structure of the battery cell housing is more stable.

[0028] In some embodiments of the first aspect, T3 satisfies: T1 < T3 < 1.5 * T1.

[0029] In the above technical solution, making the thickness T3 of the part of the flange corresponding to the transition surface satisfy T1 < T3 < 1.5 * T1. When the thickness of the part of the transition surface is too large, the energy density of the battery cell housing will be reduced. T3 satisfies the above conditions to balance the relationship between the firm connection of the flange and the side wall in the battery cell housing and the energy density of the battery cell.

[0030] In some embodiments of the first aspect, the thickness of the part of the flange corresponding to the transition surface is T3, and satisfies 0.06 mm ≤ T3 ≤ 0.2 mm.

[0031] In the above technical solution, the thickness T3 of the part of the flange corresponding to the transition surface satisfies 0.06 mm ≤ T3 ≤ 0.2 mm. If the thickness of the part of the transition surface is too small, it will affect the connection strength of the flange. If the thickness is too large, it will affect the energy density of the battery cell. Adopting the above solution can ensure the connection strength while reducing the energy density loss.

[0032] In some embodiments of the first aspect, the thickness of the part of the flange corresponding to the transition surface is T3, and satisfies 0.09 mm ≤ T3 ≤ 0.12 mm.

[0033] In the above technical solution, the thickness T3 of the part of the flange corresponding to the transition surface satisfies 0.09 mm ≤ T3 ≤ 0.12 mm. Adopting the above solution can better ensure the connection strength while reducing the energy density loss to a greater extent.

[0034] In a second aspect, the present application provides an electrochemical device, including the battery cell housing, the battery cell cover, and the electrode assembly as described above. The electrode assembly is accommodated in the accommodation space, and the battery cell cover is disposed on the opening.

[0035] In some embodiments of the second aspect, the length of the battery cell cover along its first direction is D1, the length of the battery cell cover along the second direction is D2, the length of the battery cell housing along the first direction is D3, and the length of the battery cell housing along the second direction is D4, satisfying D1 ≤ D3, D2 ≤ D4; the first direction, the second direction, and the thickness direction of the battery cell cover are perpendicular to each other pairwise.

[0036] In the above technical solution, by making the length D1 of the battery cell shell cover along the first direction, the length D2 of the battery cell shell cover along the second direction, the length D3 of the battery cell shell along the first direction, and the length D4 of the battery cell shell along the second direction satisfy D1≤D3, D2≤D4, the connection between the battery cell shell and the battery cell shell cover can be facilitated, the connection between the battery cell shell and the battery cell shell cover is more stable, and the possibility of the battery cell shell cover protruding from the battery cell shell can be reduced, which is conducive to improving the energy density of the electrochemical device.

[0037] In some embodiments of the second aspect, the lengths of the battery cell shell extending beyond the battery cell shell cover on both sides along the first direction are E1 and E2 respectively, the lengths of the battery cell shell extending beyond the battery cell shell cover on both sides along the second direction are E3 and E4 respectively, and the average value of E1, E2, E3, and E4 is ˉE, satisfying ˉE≤0.05mm.

[0038] In the above technical solution, the lengths of the cell housing extending beyond the cell cover along the first direction are E1 and E2 respectively, and the lengths of the cell housing extending beyond the cell cover along the second direction are E3 and E4 respectively. By ensuring that the average value of E1, E2, E3, and E4, ˉE, satisfies ˉE≤0.05mm, the length of the portion of the flange surface that does not extend beyond the cell cover, i.e., the length of the portion where the flange surface is connected to the cell cover, is made longer. This further facilitates the connection between the cell housing and the cell cover, making the connection between the cell housing and the cell cover more stable, improving the sealing of the electrochemical device, and making it less likely that a gap or separation will occur between the cell housing and the cell cover due to force or environmental changes, thereby increasing the reliability of the electrochemical device. If ˉE is larger (for example, greater than 0.05mm), the length of the portion of the flange surface that does not extend beyond the cell cover, i.e., the length of the portion where the flange surface is connected to the cell cover, is smaller, which may affect the connection strength between the cell housing and the cell cover.

[0039] In some embodiments of the second aspect, the battery cell housing and the battery cell cover are welded or adhesively connected.

[0040] In the above technical solution, the battery cell shell and the battery cell shell cover are connected by welding or bonding, which can make the connection between the battery cell shell and the battery cell shell cover stable, the sealing of the electrochemical device is better, and the electrochemical device is not prone to gaps or separation between the battery cell shell and the battery cell shell cover due to force or environmental changes, and the electrochemical device has high reliability.

[0041] In some embodiments of the second aspect, the battery cell shell and the battery cell shell cover are welded to form a welding portion between the battery cell shell and the battery cell shell cover. The depth of the welding portion in the thickness direction of the bottom wall is H, and the width of the welding portion in the thickness direction of the side wall is W4, satisfying H≥0.5*T1, W4≥T1.

[0042] In the above technical solution, by making the depth H of the weld in the thickness direction of the bottom wall and the width W4 of the weld in the thickness direction of the side wall satisfy H≥0.5*T1 and W4≥T1, the welding strength between the battery cell housing and the battery cell shell cover can be high, the connection between the battery cell housing and the battery cell shell cover is stable, the sealing of the electrochemical device is good, the electrochemical device is not prone to gaps or separation between the battery cell housing and the battery cell shell cover due to force or environmental changes, and the reliability of the electrochemical device is high. If H and W4 are small (for example, H is less than 0.5*T1 and W4 is less than T1), the welding strength between the battery cell housing and the battery cell shell cover is low, and the electrochemical device may cause gaps or separation between the battery cell housing and the battery cell shell cover due to force or environmental changes, affecting the reliability of the electrochemical device.

[0043] In some embodiments of the second aspect, the battery cell shell and the battery cell shell cover are welded to form a welding portion between the battery cell shell and the battery cell shell cover. Part of the welding portion protrudes from the side of the battery cell shell cover, and the outer surface of the protruding portion is an arc-shaped surface.

[0044] In the above technical solution, the weld portion is partially protruded from the side of the cell cover, which can increase the volume of the weld portion, increase the connection strength between the cell housing and the cell cover, and stabilize the connection between the cell housing and the cell cover. This improves the sealing performance of the electrochemical device, and makes it less likely that a gap or separation will occur between the cell housing and the cell cover due to stress or environmental changes, thereby increasing the reliability of the electrochemical device. The outer surface of the weld portion protruding from the cell cover is an arcuate surface, which can reduce the possibility of damage to the weld portion and other devices when the weld portion interferes with other devices.

[0045] In a third aspect, the present application provides an electrical device, comprising the electrochemical device as described above, and the electrochemical device is used to provide electrical energy.

[0046] In a fourth aspect, the present application provides a method for preparing an electrochemical device, comprising:

[0047] Stamping the raw material plate to form the battery cell shell;

[0048] During the stamping process, the transition surface of the flange portion of the cell shell is extruded toward the inner side of the cell shell by flattening and squeezing a negative angle, so that the width W1 of the transition surface in the thickness direction of the side wall of the cell shell and the wall thickness T1 of the side wall of the cell shell satisfy 0<W1≤T1;

[0049] Installing the electrode assembly in the accommodation space of the battery cell shell;

[0050] The cell shell cover is placed on the opening of the cell shell, and the cell shell cover is fixedly connected to the cell shell.

[0051] In the above technical solution, during the stamping process, the width W1 of the transition surface of the battery cell shell in the thickness direction of the side wall of the battery cell shell and the wall thickness T1 of the side wall of the battery cell shell satisfy 0<W1≤T1 by flattening and squeezing negative angles, so that the width of the flange surface of the battery cell shell is larger, and at the same time, the width of the part of the flange portion of the battery cell shell protruding from the side wall is smaller, thereby increasing the volume of the accommodating space and increasing the energy density of the electrochemical device, and the wall thickness of the side wall can be smaller, thereby further increasing the volume of the accommodating space and increasing the energy density of the electrochemical device.

[0052] In some embodiments of the fourth aspect, a method for fixedly connecting the cell cover to the cell housing includes:

[0053] The battery cell cover is welded to the battery cell shell by means of oscillating welding.

[0054] In the above technical solution, the cell shell cover and the cell shell are welded together by oscillating welding, which can further increase the welding strength of the cell shell and the cell shell cover, so that the connection between the cell shell and the cell shell cover is stable, the sealing of the electrochemical device is better, and the electrochemical device is not prone to gaps or separation between the cell shell and the cell shell cover due to force or environmental changes, and the reliability of the electrochemical device is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0056] FIG1 is a schematic diagram of the three-dimensional structure of a battery cell housing provided in some embodiments of the present application;

[0057] FIG2 is a schematic structural diagram of a battery cell housing according to some embodiments of the present application from one perspective;

[0058] FIG3 is a schematic cross-sectional view of the battery cell housing shown in FIG2 along the AA direction;

[0059] FIG4 is a partially enlarged structural schematic diagram of a portion B of the battery cell housing shown in FIG3 ;

[0060] FIG5 is a schematic diagram of the three-dimensional structure of an electrochemical device provided in some embodiments of the present application;

[0061] FIG6 is a schematic diagram of an exploded structure of an electrochemical device provided in some embodiments of the present application;

[0062] FIG7 is a schematic structural diagram of an electrochemical device according to some embodiments of the present application from one perspective;

[0063] FIG8 is a schematic cross-sectional view of the electrochemical device shown in FIG7 along the CC direction;

[0064] FIG9 is a partially enlarged schematic structural diagram of a portion D of the electrochemical device shown in FIG8 ;

[0065] FIG10 is a partially enlarged schematic structural diagram of a portion D of the electrochemical device shown in FIG8 in another state;

[0066] FIG11 is a schematic flow chart of a method for preparing an electrochemical device according to some embodiments of the present application.

[0067] Icons: 10-electrochemical device; 100-cell shell; 101-accommodation space; 102-opening; 110-bottom wall; 120-side wall; 121-liquid injection hole; 130-flange; 140-pole; 200-cell shell cover; 210-welding part; 211-bottom surface; 300-electrode assembly; 310-first electrical connector; 320-second electrical connector; X-first direction; Y-second direction; Z-third direction.

[0068] Specific embodiment

[0069] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0070] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0071] The terms "first", "second" and the like in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0072] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0073] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0074] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0075] With the development of the new energy industry, batteries are gradually moving towards higher energy density and higher power density. However, the volume of battery compartments used to house electrochemical devices in electrical equipment is limited, which limits the method of increasing the energy density of electrochemical devices by increasing their volume. Therefore, it is more feasible to improve the energy density of electrochemical devices by changing their structure.

[0076] The battery cell shell generally includes a bottom wall and a side wall. The side wall is arranged around the bottom wall and together with the bottom wall, forms a storage space with an opening, so that the electrode assembly can be accommodated in the storage space through the opening. After the electrode assembly is installed, a battery cell cover needs to be provided on the battery cell shell to cover the opening so that the storage space is isolated from the outside. At present, there are two main ways to connect the battery cell shell and the battery cell cover. One is a method of rotary cutting the shell and top welding. Specifically, the battery cell shell is not provided with a flange part, the battery cell cover is in contact with the top surface of the side wall of the battery cell shell, and the battery cell cover is welded to the top surface of the side wall. In order to ensure that the top surface of the side wall has sufficient welding area, the side wall needs to have a larger thickness, which will cause the battery cell shell to occupy a larger space, compress the volume of the storage space, reduce the volume of the electrode assembly, and affect the energy density of the electrochemical device. The other is a large flange plus top welding method, specifically, a flange portion with a larger width is provided at one end of the side wall of the battery cell shell away from the bottom wall. The flange portion protrudes in the direction away from the accommodation space to form a flange surface for connection with the battery cell shell cover, which can reduce the thickness of the side wall. However, the flange portion will increase the overall size of the battery cell shell. When the overall size of the battery cell shell remains unchanged, the provision of the flange portion will compress the accommodation space, thereby reducing the volume of the electrode assembly and affecting the energy density of the electrochemical device.

[0077] In order to improve the energy density of an electrochemical device, the present application provides a battery cell shell, which includes a bottom wall, a side wall and a flange portion. The side wall is arranged around the bottom wall and together with the bottom wall forms a accommodating space with an opening. The flange portion is arranged at one end of the side wall away from the bottom wall, and at least a portion of the flange portion protrudes from the inner surface and / or outer surface of the side wall; wherein the flange portion has a flange surface and a transition surface, the flange surface is roughly perpendicular to the side wall and is used to be connected to the battery cell shell cover; the transition surface is curved to connect the flange surface and the inner surface and / or outer surface of the side wall, the width of the transition surface in the thickness direction of the side wall is W1, and the wall thickness of the side wall is T1, satisfying 0<W1≤T1.

[0078] In a battery cell case of this structure, the battery cell case includes a bottom wall, a side wall, and a flange portion. The side wall is arranged around the bottom wall and, together with the bottom wall, defines a storage space having an opening, so that the electrode assembly can be stored in the storage space through the opening. The flange portion is arranged at an end of the side wall away from the bottom wall, and at least a portion of the flange portion protrudes from the outer surface of the side wall, so that the flange portion can be used to connect to the battery cell case cover and increase the connection area with the battery case cover. The flange portion has a flange surface and a transition surface, the flange surface is substantially perpendicular to the side wall and is used to connect to the battery cell case cover. The transition surface is curved to connect the flange surface and the inner surface of the side wall. The width of the transition surface in the thickness direction of the side wall is W1, and the wall thickness of the side wall is T1, satisfying 0<W1≤T1. This makes the width of the flange surface larger, while the width of the portion of the flange portion protruding from the side wall is smaller, which can reduce the space occupied by the battery cell case, thereby increasing the volume of the storage space and increasing the energy density of the electrochemical device. The wall thickness of the side wall can also be reduced, thereby further increasing the volume of the storage space and increasing the energy density of the electrochemical device. If W1 is larger (for example, larger than T1), the width of the flange surface may be smaller or the width of the portion of the flange protruding from the side wall may be larger. The smaller width of the flange surface may affect the connection strength between the battery cell shell and the battery cell shell cover. The larger width of the portion of the flange protruding from the side wall may compress the accommodation space and affect the energy density of the electrochemical device.

[0079] The present invention provides an electrochemical device including a cell housing. The electrochemical device may be a secondary battery or a primary battery, such as a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, although this embodiment is not limited thereto. The electrochemical device may be cylindrical, flat, rectangular, or have other shapes, although this embodiment is not limited thereto.

[0080] The embodiments of the present application provide an electrical device that uses an electrochemical device as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like.

[0081] Referring to Figures 1 to 4, Figure 1 is a schematic diagram of the three-dimensional structure of a battery cell casing provided in some embodiments of the present application, Figure 2 is a schematic diagram of the structure of a battery cell casing provided in some embodiments of the present application from one perspective, Figure 3 is a schematic cross-sectional view of the battery cell casing shown in Figure 2 along the AA direction, and Figure 4 is a schematic diagram of the structure of a part of the battery cell casing shown in Figure 3 that is partially enlarged. The present application provides a battery cell casing 100, which includes a bottom wall 110, a side wall 120, and a flange portion 130. The side wall 120 is disposed around the bottom wall 110 and, together with the bottom wall 110, defines a receiving space 101 having an opening 102. The flange portion 130 is disposed at an end of the side wall 120 away from the bottom wall 110, with at least a portion of the flange portion 130 protruding from the outer surface of the side wall 120. Among them, the flange portion 130 has a flange surface 131 and a transition surface 132. The flange surface 131 is roughly perpendicular to the side wall 120 and is used to connect with the battery cell shell cover 200; the transition surface 132 is curved to connect the flange surface 131 and the inner surface of the side wall 120. The width of the transition surface 132 in the thickness direction of the side wall 120 is W1, and the wall thickness of the side wall 120 is T1, satisfying 0<W1≤T1.

[0082] The flange surface 131 is substantially perpendicular to the side wall 120 , that is, the difference between the angle between the plane where the flange surface 131 is located and the plane where the outer surface or inner surface of the side wall 120 is located and 90° is within a preset difference range.

[0083] In some embodiments, the cell housing 100 may be made of a relatively high-strength material, such as steel, aluminum alloy, or other metal material, so that the cell housing 100 has a relatively high stress-bearing capacity, thereby making the cell housing 100 less susceptible to deformation or damage due to stress or environmental changes, thereby making the electrochemical device 10 more reliable.

[0084] In other embodiments, the battery cell casing 100 may also be made of non-metallic materials with relatively high strength, such as carbon fiber, hard plastic, etc.

[0085] A flange is a part that connects two components, used to connect the ends of the components. A flange connection refers to a removable connection between a component with a flange and another component, forming a combined sealing structure. Any connection that connects and seals two flat surfaces through a fixed connection is generally referred to as a "flange."

[0086] In some embodiments, the flange portion 130 is disposed around the side wall 120 and extends away from the accommodating space 101 , such that at least a portion of the flange portion 130 protrudes from the outer surface of the side wall 120 .

[0087] In some embodiments, the bottom wall 110, the side wall 120 and the flange portion 130 are integrally formed, which can make the overall structure of the battery cell housing 100 stable and prevent gaps from forming or separation between the bottom wall 110 and the side wall 120, or between the side wall 120 and the flange portion 130 due to force or environmental changes. The battery cell housing 100 has good sealing performance.

[0088] In other embodiments, the bottom wall 110 , the side wall 120 and the flange portion 130 may also be separately prepared and formed, and then fixedly connected by welding or bonding.

[0089] In some embodiments, a thickness direction of the sidewall 120 is perpendicular to the third direction Z, and the thickness direction of the sidewall 120 includes a first direction X and a second direction Y.

[0090] For example, as shown in Figures 2 and 4, the width of the transition surface 132 of the two parts of the flange portion 130 that are opposite to each other along the first direction X is the size of the transition surface 132 along the first direction X, and the width of the transition surface 132 of the two parts of the flange portion 130 that are opposite to each other along the second direction Y is the size of the transition surface 132 along the second direction Y.

[0091] For example, as shown in Figures 2 and 4, the wall thickness of the two opposite parts of the side wall 120 along the first direction X is the size of the side wall 120 along the first direction X, and the wall thickness of the two opposite parts of the side wall 120 along the second direction Y is the size of the side wall 120 along the second direction Y.

[0092] The cell casing 100 includes a bottom wall 110, a side wall 120, and a flange 130. The side wall 120 surrounds the bottom wall 110 and, together with the bottom wall 110, defines a receiving space 101 having an opening 102, allowing the electrode assembly 300 to be received in the receiving space 101 through the opening 102. The flange 130 is disposed at an end of the side wall 120 away from the bottom wall 110. At least a portion of the flange 130 protrudes from the outer surface of the side wall 120, enabling the flange 130 to be connected to the cell casing cover 200 and increasing the connection area with the battery casing cover 200. At the same time, the large area of ​​the opening 102 facilitates the installation of the electrode assembly 300. The flange portion 130 has a flange surface 131 and a transition surface 132. The flange surface 131 is substantially perpendicular to the side wall 120 and is used to connect to the cell case cover 200. The transition surface 132 is curved to connect the flange surface 131 and the inner surface of the side wall 120. The width of the transition surface 132 in the thickness direction of the side wall 120 is W1, and the wall thickness of the side wall 120 is T1, satisfying 0<W1≤T1. For example, W1 can be 0.5*T1, 0.8*T1 or T1, so that the width of the flange surface 131 is larger, and at the same time, the width of the portion of the flange portion 130 protruding from the side wall 120 is smaller, thereby increasing the volume of the accommodating space 101 and increasing the energy density of the electrochemical device 10. In addition, the wall thickness of the side wall 120 can be smaller, thereby further increasing the volume of the accommodating space 101 and increasing the energy density of the electrochemical device 10. If W1 is larger (for example, larger than T1), the width of the flange surface 131 may be smaller or the width of the portion of the flange portion 130 protruding from the side wall 120 may be larger. The smaller width of the flange surface 131 may affect the connection strength between the cell housing 100 and the cell cover 200. The larger width of the portion of the flange portion 130 protruding from the side wall 120 may compress the accommodation space 101, thereby affecting the energy density of the electrochemical device 10.

[0093] In other embodiments, a portion of the flange portion 130 may protrude from the inner surface of the sidewall 120 , with the transition surface 132 curved to connect the flange surface 131 and the outer surface of the sidewall 120 . This can reduce the space occupied by the cell housing 100 and facilitate improving the energy density of the electrochemical device 10 . Furthermore, by ensuring that the width W1 of the transition surface 132 in the thickness direction of the sidewall 120 and the wall thickness T1 of the sidewall 120 satisfy 0<W1≤T1, the width of the flange surface 131 is increased, while the width of the portion of the flange portion 130 protruding from the sidewall 120 is reduced, facilitating installation of the electrode assembly 300 . If W1 is larger (for example, larger than T1), the width of the flange surface 131 may be smaller or the width of the portion of the flange portion 130 protruding from the side wall 120 may be larger. The smaller width of the flange surface 131 may affect the connection strength between the battery cell shell 100 and the battery cell shell cover 200. The larger width of the portion of the flange portion 130 protruding from the side wall 120 may affect the installation of the electrode assembly 300, thereby causing the volume of the electrode assembly 300 to be smaller, affecting the energy density of the electrochemical device 10.

[0094] In other embodiments, a portion of the flange portion 130 may be provided protruding from the inner surface of the sidewall 120, while a portion may be provided protruding from the outer surface of the sidewall 120. The flange portion 130 forms two transition surfaces 132: one transition surface 132 curvedly connects the flange surface 131 and the outer surface of the sidewall 120, and the other transition surface 132 curvedly connects the flange surface 131 and the inner surface of the sidewall 120. This can further increase the width of the flange surface 131 and improve the connection strength between the cell casing 100 and the cell casing 200. Furthermore, by ensuring that the width W1 of the transition surface 132 in the thickness direction of the sidewall 120 and the wall thickness T1 of the sidewall 120 satisfy 0<W1≤T1, the flange portion 130 occupies a smaller portion of the accommodation space 101, thereby facilitating an increase in the energy density of the electrochemical device 10.

[0095] In some embodiments, 0<W1≤0.7*T1, for example, W1 may be 0.7*T1, 0.6*T1, or 0.4*T1.

[0096] By ensuring that 0<W1≤0.7*T1, the width of the flange surface 131 can be further increased, while the width of the portion of the flange portion 130 protruding from the side wall 120 can be reduced, thereby further increasing the volume of the accommodating space 101 and increasing the energy density of the electrochemical device 10. In addition, the wall thickness of the side wall 120 can be further reduced, thereby increasing the volume of the accommodating space 101 and increasing the energy density of the electrochemical device 10.

[0097] In some embodiments, the width of the flange surface 131 in the thickness direction of the side wall 120 is W2, satisfying W2≥0.7*T1. For example, W2 can be 0.7*T1, 0.8*T1, or T1.

[0098] For example, as shown in Figures 2 and 4, the width of the flange surface 131 of the two parts of the flange portion 130 that are opposite to each other along the first direction X is the size of the flange surface 131 along the first direction X, and the width of the flange surface 131 of the two parts of the flange portion 130 that are opposite to each other along the second direction Y is the size of the flange surface 131 along the second direction Y.

[0099] By ensuring that the width W2 of the flange surface 131 in the thickness direction of the side wall 120 satisfies W2 ≥ 0.7 * T1, the connection area between the flange surface 131 and the cell case cover 200 can be increased, the connection between the cell case 100 and the cell case cover 200 is more stable, and the sealing is improved. The electrochemical device 10 is less likely to have a gap or separation between the cell case 100 and the cell case cover 200 due to force or environmental changes, and the reliability of the electrochemical device 10 is higher. If W2 is too small (for example, less than 0.7 * T1), the connection strength between the cell case 100 and the cell case cover 200 may be affected, thereby affecting the sealing of the electrochemical device 10.

[0100] In some embodiments, the flange surface 131 is a plane, and the transition surface 132 is an arc-shaped surface.

[0101] In some embodiments, the flange surface 131 is perpendicular to the side wall 120 , that is, the flange surface 131 is perpendicular to the inner surface or outer surface of the side wall 120 , and the inner surface or outer surface of the side wall 120 is parallel to the third direction Z.

[0102] By setting the flange surface 131 as a plane and perpendicular to the inner or outer surface of the sidewall 120, that is, the flange surface 131 is parallel to the XY direction, the flange surface 131 can better fit the cell housing cover 200, thereby facilitating the connection between the flange surface 131 and the cell housing cover 200. Setting the transition surface 132 as an arcuate surface facilitates the preparation of the flange portion 130. The flange portion 130 can be formed by bending the sidewall of the cell housing 100.

[0103] In some embodiments, the width of the flange portion 130 protruding from the outer surface of the side wall 120 in the thickness direction of the side wall 120 is W3, satisfying 0.05mm≤W3≤0.3mm. For example, W3 can be 0.05mm, 0.1mm or 0.3mm.

[0104] For example, as shown in Figures 2 and 4, the width of the portion of the flange portion 130 protruding from the side wall 120 at the two portions opposite to each other along the first direction X of the flange portion 130 is the size of the portion of the flange portion 130 protruding from the side wall 120 along the first direction X, and the width of the portion of the flange portion 130 protruding from the side wall 120 at the two portions opposite to each other along the second direction Y of the flange portion 130 is the size of the portion of the flange portion 130 protruding from the side wall 120 along the second direction Y.

[0105] By ensuring that the width W3 of the portion of the flange 130 protruding from the outer surface of the side wall 120 in the thickness direction of the side wall 120 satisfies 0.05 mm ≤ W3 ≤ 0.3 mm, the width of the flange surface 131 can be increased, thereby increasing the connection area between the cell case 100 and the cell cover 200 and improving the connection strength. Furthermore, the space occupied by the portion of the flange 130 protruding from the outer surface of the side wall 120 can be reduced. Consequently, for a given size of the electrochemical device 10, the volume of the accommodating space 101 is increased, the volume of the electrode assembly 300 is increased, and the energy density of the electrochemical device 10 is increased. If W3 is smaller (e.g., less than 0.05 mm), the width of the flange surface 131 is smaller, the connection area between the cell case 100 and the cell cover 200 is smaller, and the connection strength is lower. When the electrochemical device 10 is subjected to force or the environment changes, a gap or separation may occur between the cell case 100 and the cell cover 200, affecting the sealing performance of the electrochemical device 10. If W3 is larger (for example, greater than 0.3 mm), the portion of the flange portion 130 protruding from the outer surface of the side wall 120 occupies a larger space, so that when the size of the electrochemical device 10 is constant, the volume of the accommodating space 101 is smaller, the volume of the electrode assembly 300 is smaller, and the energy density of the electrochemical device 10 is also smaller.

[0106] In some embodiments, 0.05 mm ≤ W3 ≤ 0.15 mm, for example, W3 may be 0.05 mm, 0.1 mm, or 0.15 mm.

[0107] By ensuring that 0.05mm≤W3≤0.15mm, the space occupied by the portion of the flange portion 130 protruding from the outer surface of the side wall 120 can be further reduced, thereby making it possible to increase the volume of the accommodating space 101, increase the volume of the electrode assembly 300, and increase the energy density of the electrochemical device 10 while maintaining the size of the electrochemical device 10.

[0108] In some embodiments, the thickness of the flange portion 130 protruding from the outer surface of the sidewall 120 is T2, satisfying 0.7*T1≤T2≤1.1*T1. For example, T2 can be 0.7*T1, 0.9*T1, or 1.1*T1.

[0109] In some embodiments, the thickness of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 is the dimension of the flange portion 130 in the thickness direction (third direction Z) of the bottom wall 110 .

[0110] In some embodiments, the thickness direction of the bottom wall 110 is perpendicular to the thickness direction of the side wall 120 .

[0111] In some embodiments, after the cell housing 100 is formed, the width W1 of the transition surface 132 can be reduced by cutting. For example, cutting the top surface of the cell housing 100 in a direction perpendicular to the thickness of the bottom wall 110 of the cell housing 100 (parallel to the XY plane) can further reduce the width W1 of the transition surface 132, increase the width W2 of the flange surface 131, and simultaneously reduce the thickness T2 of the portion of the flange portion 130 protruding from the outer surface of the side wall 120.

[0112] In some embodiments, during the preparation of the battery cell shell 100 , the raw material plate can be squeezed toward the end of the side wall 120 of the battery cell shell 100 away from the bottom wall 110 , so that the thickness T2 of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 can be greater than the wall thickness T1 of the side wall 120 .

[0113] By ensuring that the thickness T2 of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 satisfies 0.7*T1≤T2≤1.1*T1, the flange portion 130 can be made stronger and less prone to deformation. A sufficient welding depth can also be reserved for the welding connection between the cell housing 100 and the cell housing cover 200, thereby increasing the connection strength between the cell housing 100 and the cell housing cover 200. Furthermore, the width of the transition surface 132 can be reduced, thereby increasing the volume of the accommodation space 101 and the energy density of the electrochemical device 10. If T2 is smaller (e.g., smaller than 0.7*T1), the flange portion 130 is weaker and may be easily deformed due to stress or environmental changes. Furthermore, the welding depth between the cell housing 100 and the cell housing cover 200 is limited, which may affect the connection strength between the cell housing 100 and the cell housing cover 200. If T2 is large (eg, greater than 1.1*T1), it is difficult to form a transition surface 132 with a smaller width, which may affect the volume of the accommodation space 101 and further affect the energy density of the electrochemical device 10 .

[0114] In some embodiments, 0.05 mm ≤ T1 ≤ 0.15 mm, for example, T1 may be 0.05 mm, 0.09 mm, or 0.15 mm.

[0115] By ensuring that the wall thickness T1 of the side wall 120 satisfies 0.05 mm ≤ T1 ≤ 0.15 mm, the cell housing 100 can be made stronger and less susceptible to deformation or damage due to stress or environmental changes, thereby better protecting the electrode assembly 300 and maintaining the normal operation of the electrochemical device 10. Furthermore, the space occupied by the cell housing 100 can be reduced. Given a given size of the electrochemical device 10, a larger accommodation space 101 can be reserved, resulting in a larger volume for the electrode assembly 300 and a higher energy density for the electrochemical device 10. If T1 is smaller (e.g., less than 0.05 mm), the cell housing 100 is weaker and may be deformed or damaged due to stress or environmental changes, affecting the protection of the electrode assembly 300 and the normal operation of the electrochemical device 10. If T1 is larger (for example, greater than 0.15 mm), the space occupied by the cell housing 100 will be larger. When the size of the electrochemical device 10 is constant, the reserved accommodation space 101 will be smaller, resulting in a smaller volume of the electrode assembly 300 and a lower energy density of the electrochemical device 10.

[0116] In some embodiments, 0.05 mm ≤ T1 ≤ 0.1 mm, for example, T1 may be 0.05 mm, 0.07 mm, or 0.1 mm.

[0117] By ensuring that 0.05 mm ≤ T1 ≤ 0.1 mm, the space occupied by the cell housing 100 can be further reduced. When the size of the electrochemical device 10 is constant, a larger accommodation space 101 is reserved, so that the volume of the electrode assembly 300 is larger and the energy density of the electrochemical device 10 is higher.

[0118] In some embodiments, the thickness of the portion of the flange portion 130 corresponding to the transition surface 132 is T3, satisfying T3>T1.

[0119] The thickness of the portion of the flange portion 130 corresponding to the transition surface 132 is the dimension of the flange portion 130 in the direction perpendicular to the transition surface 132. The thickness of a portion of the flange portion 130 corresponding to the transition surface 132 is exemplarily indicated in FIG4 .

[0120] By ensuring that the thickness T3 of the portion of the flange 130 corresponding to the transition surface 132 satisfies T3>T1, the connection between the flange 130 and the side wall 120 can be made more secure, the flange 130 is not easily separated from the side wall 120, and the overall structure of the cell housing 100 is more stable.

[0121] In some other embodiments, T3 satisfies: T1 <T3<1.5*T1。

[0122] By making the thickness T3 of the part of the flange portion 130 corresponding to the transition surface 132 satisfy T1 < T3 < 1.5*T1, when the thickness of the part of the transition surface 132 is too large, it will cause a decrease in the energy density of the battery cell housing 100. T3 satisfies the above conditions to balance the relationship between the firm connection of the flange portion 130 and the side wall 120 in the battery cell housing 100 and the energy density of the battery cell.

[0123] In some embodiments, the thickness of the part of the flange portion corresponding to the transition surface is T3, satisfying 0.06 mm ≤ T3 ≤ 0.2 mm.

[0124] By designing the thickness T3 of the part of the flange portion corresponding to the transition surface to satisfy 0.06 mm ≤ T3 ≤ 0.2 mm, if the thickness of the part of the transition surface is too small, it will affect the connection strength of the flange portion, and if the thickness is too large, it will affect the energy density of the battery cell. Adopting the above solution can ensure the connection strength while reducing the energy density loss.

[0125] In some other embodiments, the thickness of the part of the flange portion corresponding to the transition surface is T3, satisfying 0.09 mm ≤ T3 ≤ 0.12 mm.

[0126] By designing the thickness T3 of the part of the flange portion corresponding to the transition surface to satisfy 0.09 mm ≤ T3 ≤ 0.12 mm, it can ensure the connection strength to a greater extent while reducing the energy density loss, where the value of T3 can be within the range of any two values among 0.09 mm, 0.1 mm, 0.11 mm, and 0.12 mm.

[0127] Referring to FIGS. 5 and 6, FIG. 5 is a schematic three-dimensional structure diagram of an electrochemical device provided by some embodiments of the present application, and FIG. 6 is an exploded structure diagram of the electrochemical device provided by some embodiments of the present application. An embodiment of the present application provides an electrochemical device 10, including the battery cell housing 100, the battery cell cover 200, and the electrode assembly 300 of any of the above solutions. The electrode assembly 100 is accommodated in the accommodation space 101, and the battery cell cover 200 is covered on the opening 102.

[0128] In some embodiments, the battery cell cover 200 can be made of a material with relatively high strength, such as metal materials such as steel and aluminum alloy, so that the battery cell housing 200 has relatively high mechanical properties, and further can make the battery cell cover 200 not easily deformed or damaged due to force or environmental changes, and further can make the electrochemical device 10 more reliable.

[0129] In some other embodiments, the battery cell cover 200 can also be a non-metal material with relatively high strength, such as carbon fiber and hard plastic.

[0130] The electrochemical device includes a battery case 100, a battery case cover 200, an electrode assembly 300 and an electrolyte. The case 100 and the battery case cover 200 are used to accommodate the electrode assembly 300 and the electrolyte. The electrode assembly 300 is composed of a positive electrode sheet, a negative electrode sheet and a separator. The electrochemical device mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The part of the positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab to realize the input or output of electrical energy of the positive electrode sheet through the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary material or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The portion of the negative electrode current collector not coated with the negative electrode active material layer serves as the negative electrode tab, through which electrical energy is input or output from the negative electrode sheet. The negative electrode current collector can be made of copper, and the negative electrode active material can be made of carbon or silicon. The separator can be made of polypropylene (PP) or polyethylene (PE). The electrolyte can include organic solvents, electrolyte lithium salts, etc.

[0131] In some embodiments, the electrode assembly 300 may be a laminated structure formed by stacking a negative electrode sheet, a separator, and a positive electrode sheet.

[0132] In other embodiments, the electrode assembly 300 may also be a wound structure formed by winding a negative electrode sheet, a separator, and a positive electrode sheet.

[0133] In some embodiments, the electrochemical device 10 is configured as a rectangular parallelepiped with rounded top corners, which can better adapt to the rounded battery compartment in the electrical equipment.

[0134] In other embodiments, the top corners of the electrochemical device 10 may also be square corners.

[0135] In some embodiments, the thickness direction of the cell housing cover 200 is parallel to the third direction Z, and the first direction X, the second direction Y and the third direction Z are perpendicular to each other.

[0136] 1 and 6 , in some embodiments, a liquid injection hole 121 is provided on the battery housing 100 , which is used to inject electrolyte into the accommodating space 101 through the liquid injection hole 121 after the battery housing 100 and the cell shell cover 200 are assembled, so that the electrolyte can infiltrate the electrode assembly 300 .

[0137] In some embodiments, the injection hole 121 may be provided on the side wall 120 of the battery housing 100 , so as to facilitate injection of electrolyte into the accommodation space 101 through the injection hole 121 .

[0138] In some embodiments, the electrochemical device 10 further includes an injection plug (not shown in the figure), which is used to seal the injection hole 121 after the electrolyte is injected to achieve sealing of the electrochemical device 10 and reduce the possibility of external water vapor entering the accommodation space 101 or the electrolyte leaking from the accommodation space 101.

[0139] In some embodiments, the injection hole 121 may be a circular hole, which facilitates the injection of electrolyte through the injection hole 121 and also facilitates the injection plug to seal the injection hole 121, thereby reducing the possibility of electrolyte leakage.

[0140] In other embodiments, the injection hole 121 may also be a square hole, a special-shaped hole, etc.

[0141] In some embodiments, the electrochemical device 10 further includes a first electrical connector 310 and a second electrical connector 320. The battery housing 100 is provided with a post 140 that passes through the battery housing 100. One end of the first electrical connector 310 is electrically connected to the positive electrode tab on the positive electrode sheet, and the other end is electrically connected to the post 140, allowing an external device to be electrically connected to the positive electrode sheet through the post 140 and the first electrical connector 310. One end of the second electrical connector 320 is electrically connected to the negative electrode tab on the negative electrode sheet, and the other end is electrically connected to the battery cell housing 100, allowing an external device to be electrically connected to the negative electrode sheet through the housing 100 and the second electrical connector 320.

[0142] In other embodiments, the electrochemical device 10 further includes a first electrical connector 310 and a second electrical connector 320. The battery housing 100 is provided with two posts 140 that pass through the battery housing 100. One end of the first electrical connector 310 is electrically connected to the positive electrode tab, and the other end is electrically connected to one of the posts 140, so that an external device can be electrically connected to the positive electrode tab through the post 140 and the first electrical connector 310. One end of the second electrical connector 320 is electrically connected to the negative electrode tab, and the other end is electrically connected to the other post 140, so that an external device can be electrically connected to the negative electrode tab through the post 140 and the second electrical connector 320.

[0143] In some embodiments, the first electrical connector 310 and the positive electrode tab may be connected by welding, and the second electrical connector 320 and the negative electrode tab may be connected by welding.

[0144] In other embodiments, the first electrical connector 310 and the positive electrode tab may be integrally formed, and the second electrical connector 320 and the negative electrode tab may be integrally formed.

[0145] In some embodiments, the first electrical connector 310 and the second electrical connector 320 may be made of a material with good electrical conductivity, such as a metal material such as lead or copper.

[0146] In some embodiments, the pole 140 is arranged in an elliptical shape, and when the thickness of the battery cell shell 100 is limited, the cross-sectional area of ​​the pole 140 (the cross-sectional area of ​​the pole 140 on the XZ plane) can be increased, thereby increasing the connection area between the pole 140 and the second electrical connector 310 and the external device, and improving the connection reliability between the pole 140 and the second electrical connector 310 and the external device.

[0147] In other embodiments, the pole 140 may also be arranged in a circular or square shape.

[0148] In some embodiments, the pole 140 may be made of a material with good electrical conductivity, such as a metal material such as lead or copper.

[0149] In some embodiments, the terminal post 140 may be disposed on the side wall 120 of the battery housing 100 to facilitate electrical connection of the terminal post 140 to an external device.

[0150] In some embodiments, the projection of the injection hole 121 along the second direction Y does not overlap with the projection of the first electrical connector 310 and the second electrical connector 320 along the second direction Y, which can reduce the impact of the injection hole 121 on the electrical connection between the first electrical connector 310 and the pole 140 and the electrical connection between the second electrical connector 320 and the battery cell shell 100.

[0151] In some embodiments, the injection hole 121 and the pole 140 can be disposed on the same side of the side wall 120 to facilitate the preparation of the battery cell housing 100 .

[0152] In other embodiments, the liquid injection hole 121 and the pole 140 may be disposed on different sides of the side wall 120 .

[0153] Referring to Figures 2 and 7, Figure 7 is a schematic structural diagram of an electrochemical device according to some embodiments of the present application from one perspective. In some embodiments, the cell cover 200 has a length D1 along a first direction X, a length D2 along a second direction Y, and a length D3 along the first direction X and a length D4 along the second direction Y of the cell housing 100, satisfying D1 ≤ D3 and D2 ≤ D4.

[0154] In some embodiments, the cell cover 200 may be a plate-shaped structure, so that the cell cover 200 can cover the open side of the cell casing 100 , and the cell casing 100 and the cell cover 200 together define an accommodating space 101 .

[0155] By ensuring that the length D1 of the cell shell cover 200 along the first direction X, the length D2 of the cell shell cover 200 along the second direction Y, the length D3 of the cell housing 100 along the first direction X, and the length D4 of the cell housing 100 along the second direction Y satisfy D1≤D3, D2≤D4, the connection between the cell housing 100 and the cell shell cover 200 can be facilitated, making the connection between the cell housing 100 and the cell shell cover 200 more stable, and reducing the possibility of the cell shell cover 200 protruding from the cell housing 100, which is beneficial to improving the energy density of the electrochemical device 10.

[0156] Due to the limited precision and cost of preparing the battery cell shell 100 and the battery cell shell cover 200, it may not be possible to completely match the size of the battery cell shell 100 with the size of the battery cell shell cover 200 during production, that is, D1=D3, D2=D4. By making the size of the battery cell shell cover 200 slightly smaller than the size of the battery cell shell 100, the battery cell shell cover 200 can be firmly connected to the battery cell shell 100 while reducing the possibility that the battery cell shell cover 200 protrudes from the battery cell shell 100 after the battery cell shell cover 200 and the battery cell shell 100 are assembled, thereby reducing the possibility of increasing the overall size of the electrochemical device 10 due to the assembly of the battery cell shell cover 200, which is beneficial to improving the energy density of the electrochemical device 10.

[0157] Referring to Figures 8 and 9 , Figure 8 is a schematic cross-sectional view of the electrochemical device shown in Figure 7 along the CC direction, and Figure 9 is a partially enlarged structural schematic view of a portion D of the electrochemical device shown in Figure 8 . In some embodiments, the lengths of the cell casing 100 extending beyond the cell cover 200 on both sides along the first direction X are E1 and E2, respectively. The lengths of the cell casing 100 extending beyond the cell cover 200 on both sides along the second direction Y are E3 and E4, respectively. The average value of E1, E2, E3, and E4 is ˉE, satisfying ˉE ≤ 0.05 mm. For example, ˉE can be 0.05 mm, 0.04 mm, or 0.03 mm.

[0158] In FIG9 , a dimension E1 of one side of the cell casing 100 extending beyond the cell casing cover 200 along the first direction X is schematically indicated. Other dimensions such as E2 , E3 , and E4 are similar to E1 and are not indicated in the figure.

[0159] The lengths of the cell casing 100 extending beyond the cell cover 200 on both sides along the first direction X are E1 and E2 respectively, and the lengths of the cell casing 100 extending beyond the cell cover 200 on both sides along the second direction Y are E3 and E4 respectively. By making the average value ˉE of E1, E2, E3, and E4 satisfy ˉE≤0.05mm, the length of the portion where the flange surface 131 does not extend beyond the cell cover 200 can be made longer, that is, the length of the portion where the flange surface 131 is connected to the cell cover 200 is made longer, thereby further facilitating the connection between the cell casing 100 and the cell cover 200, making the connection between the cell casing 100 and the cell cover 200 more stable, and improving the sealing performance of the electrochemical device 10. The electrochemical device 10 is not easily susceptible to gaps or separation between the cell casing 100 and the cell cover 200 due to force or environmental changes, and the electrochemical device 10 has higher reliability. If ˉE is large (for example, greater than 0.05 mm), the length of the portion of the flange surface 131 that does not extend beyond the cell cover 200 is small, that is, the length of the portion where the flange surface 131 is connected to the cell cover 200 is small, which may affect the connection strength between the cell housing 100 and the cell cover 200.

[0160] In some embodiments, both sides of the cell casing 100 along the first direction X and both sides along the second direction Y may extend beyond the cell casing cover 200 .

[0161] In other embodiments, the sides of the cell case 100 may be aligned with the cell cover 200, or the sides of the cell cover 200 may extend beyond the cell case 100. For example, when one side of the cell cover 200 extends beyond the cell case 100 along the first direction X, E1 is a negative number. However, by ensuring that ˉE ≤ 0.05 mm, the four sides of the cell cover 200 do not extend beyond the cell case 100, thereby reducing the overall footprint of the cell case 100 and the cell cover 200, which is beneficial for improving the energy density of the electrochemical device 10.

[0162] For example, E1≤0.05mm, E2≤0.05mm, E3≤0.05mm, and E4≤0.05mm can make the length of the portion where the flange surface 131 is connected to the cell shell 100 larger, and the cell shell cover 200 is firmly connected to the cell shell 100. At the same time, the possibility of the cell shell cover 200 protruding from the cell shell 100 after the cell shell cover 200 and the cell shell 100 are assembled is reduced, thereby reducing the possibility of increasing the overall size of the electrochemical device 10 due to the assembly of the cell shell cover 200, which is beneficial to improving the energy density of the electrochemical device 10.

[0163] In other embodiments, the cell cover 200 may also be a hollow structure with an opening on one side, and the open side of the cell cover 200 covers the open side of the cell housing 100 to form the accommodation space 101. The cell cover 200 may also be provided with a flange portion (not shown in the figure). The structure of the flange portion of the cell cover 200 is similar to that of the flange portion 130 of the cell housing 100 and will not be repeated here. The flange portion of the cell cover 200 can cooperate with the flange portion 130 of the cell housing 100 to achieve connection.

[0164] In some embodiments, the cell casing 100 and the cell cover 200 may be connected by welding.

[0165] By welding the cell housing 100 and the cell cover 200, the connection between the cell housing 100 and the cell cover 200 can be made stable, the sealing performance of the electrochemical device 10 is improved, and the electrochemical device 10 is not likely to have a gap or separation between the cell housing 100 and the cell cover 200 due to force or environmental changes, thereby increasing the reliability of the electrochemical device 10.

[0166] In other embodiments, the cell casing 100 and the cell casing cover 200 may also be connected by adhesive bonding.

[0167] Referring to Figure 10 , Figure 10 is a partially enlarged structural schematic diagram of a position D of another state of the electrochemical device shown in Figure 8 . In some embodiments, the cell housing 100 and the cell cover 200 are welded, forming a weld portion 210 between the cell housing 100 and the cell cover 200 . The depth of the weld portion 210 in the thickness direction of the bottom 110 wall is H, and the width of the weld portion 210 in the thickness direction of the side wall 120 is W4, satisfying H ≥ 0.5 * T1 and W4 ≥ T1. For example, H can be 0.5 * T1, 0.8 * T1, or T1, and W4 can be T1, 1.2 * T1, or 1.4 * T1, etc.

[0168] In some embodiments, the cell housing 100 and the cell cover 200 may be welded by laser welding, that is, the laser penetrates the cell cover 200 to reach the cell housing 100 , melting the connection between the cell housing 100 and the cell cover 200 to form a weld 210 .

[0169] In some embodiments, the depth of the weld portion 210 is the dimension of the weld portion 210 in the third direction Z, and the width of the weld portion 210 is the dimension of the weld portion 210 in a direction perpendicular to the third direction Z (including the first direction X and the second direction Y). For example, as shown in Figures 2 and 4 , the width of two portions of the weld portion 210 that are opposite to each other along the first direction X is the dimension of the weld portion 210 in the first direction X, and the width of two portions of the weld portion 210 that are opposite to each other along the second direction Y is the dimension of the weld portion 210 in the second direction Y.

[0170] In the method of rotary cutting the shell and adding top welding, the weld portion formed between the battery cell shell 100 and the battery cell shell cover 200 is formed in the opposite direction of the third direction Z, and the width of the weld portion in the opposite direction of the third direction Z gradually decreases. The weld width is the width of the cross section of the weld portion on the plane where the top surface of the battery cell shell 100 (the end surface of the side wall 120 or the flange portion away from the bottom wall 110) is located, which can reach 1 / 4 of the wall thickness T1 of the side wall of the battery cell shell 100. Therefore, the weld width is small, resulting in a small welding strength between the battery cell shell 100 and the battery cell shell cover 200. The electrochemical device 10 may cause a gap or separation between the battery cell shell 100 and the battery cell shell cover 200 due to force or environmental changes, affecting the reliability of the electrochemical device 10.

[0171] In the large flange plus top welding method, the weld formed between the cell shell 100 and the cell shell cover 200 is formed in the opposite direction of the third direction Z, and the width of the weld gradually decreases in the opposite direction of the third direction Z. The weld width is the width of the cross section of the weld on the plane where the top surface of the cell shell 100 (the end surface of the side wall 120 or the flange portion away from the bottom wall 110) is located, which can reach 1 / 2 of the wall thickness T1 of the side wall of the cell shell 100. The smaller the weld width, the smaller the weld strength between the cell shell 100 and the cell shell cover 200. The electrochemical device 10 may generate a gap or separation between the cell shell 100 and the cell shell cover 200 due to force or environmental changes, thereby affecting the reliability of the electrochemical device 10.

[0172] In the embodiment of the present application, by ensuring that the depth H of the weld portion 210 in the thickness direction of the bottom wall 110 and the width W4 of the weld portion 210 in the thickness direction of the side wall 120 satisfy H ≥ 0.5 * T1 and W4 ≥ T1, the weld strength between the cell housing 100 and the cell cover 200 can be increased, the connection between the cell housing 100 and the cell cover 200 is stable, the sealing of the electrochemical device 10 is improved, and the electrochemical device 10 is not easily subject to force or environmental changes causing a gap or separation between the cell housing 100 and the cell cover 200, resulting in a high reliability of the electrochemical device 10. If H and W4 are small (for example, H is less than 0.5 * T1 and W4 is less than T1), the weld strength between the cell housing 100 and the cell cover 200 is low, and the electrochemical device 10 may cause a gap or separation between the cell housing 100 and the cell cover 200 due to force or environmental changes, thereby affecting the reliability of the electrochemical device 10.

[0173] In some embodiments, a portion of the welding portion 210 protrudes from a side of the cell housing cover 200 , and an outer surface of the protruding portion is an arc-shaped surface.

[0174] In the current welding method, the welding portion 210 is formed between the battery cell case 100 and the battery cell cover 200, and is located inside the battery cell case 100 and the battery cell cover 200, that is, spaced from the side edges of the battery cell case 100 and the battery cell cover 200. The volume of the welding portion 210 is small, so that the connection strength between the battery cell case 100 and the battery cell cover 200 is low.

[0175] In the embodiment of the present application, part of the welding portion 210 is protruded from the side of the cell shell cover 200, so that the volume of the welding portion 210 can be larger, the connection strength between the cell shell 100 and the cell shell cover 200 is higher, the connection between the cell shell 100 and the cell shell cover 200 is firm, the sealing of the electrochemical device 10 is better, and the electrochemical device 10 is not likely to generate a gap or separation between the cell shell 100 and the cell shell cover 200 due to force or environmental changes, and the reliability of the electrochemical device 10 is higher.

[0176] In some embodiments, portions of the welding portion 210 may also protrude from the sides of both the cell casing 100 and the cell cover 200 .

[0177] If the outer surface of the weld portion 210 protruding from the cell cover 200 has sharp corners, then when the weld portion 210 interferes with other devices, stress concentration may occur on the weld portion 210, causing damage and easily damaging other devices. In the embodiment of the present application, the outer surface of the weld portion 210 protruding from the cell cover 200 is a curved surface, which can reduce the possibility of damage to the weld portion 210 and other devices when the weld portion 210 interferes with other devices.

[0178] Table 1 Improvement in energy density and welding strength of electrochemical devices

[0179] See Table 1, where T1 is the thickness of the sidewall of the cell case, W1 is the width of the transition surface of the cell case, W2 is the width of the flange surface of the cell case, W3 is the width of the portion of the flange portion of the cell case protruding from the outer surface of the sidewall, T2 is the thickness of the portion of the flange portion of the cell case protruding from the outer surface of the sidewall, T3 is the thickness of the cell case cover, Q1 is the energy density improvement rate of Comparative Example 2 and Examples 1-13 compared to Comparative Example 1, Q2 is the welding strength improvement rate of Comparative Example 2 and Examples 1-13 compared to Comparative Example 1, and Q3 is the welding strength improvement value of Comparative Example 2 and Examples 1-13 compared to Comparative Example 1. The units of thickness and width of each part are mm, and the unit of welding strength value is N / mm. In Comparative Example 1, the cell case is not provided with a flange, and the cell case cover is directly connected to the top surface of the sidewall of the cell case. In Comparative Example 2, the cell case is provided with a flange, but the flange is not processed.

[0180] The method for measuring the welding strength of battery cell shells is as follows: cut the welded battery cell shells into a predetermined width S in the vertical direction of the weld, fold the sample into a T shape, and use a high-speed rail tensile testing machine to pull the metal parts at both ends of the weld apart. The maximum tensile force measured is F, and the welding strength is: F / S.

[0181] According to Table 1, the following conclusions can be drawn:

[0182] 1. Referring to Comparative Examples 1 and 2, by providing a flange portion on the cell housing, the wall thickness T1 of the cell housing can be reduced, thereby improving the energy density of the electrochemical device and the welding strength between the cell housings.

[0183] 2. Referring to Comparative Example 2, Example 1, Example 4, and Example 11, as the width W1 of the transition surface of the cell shell decreases, the wall thickness T1 of the cell shell decreases, thereby increasing the energy density of the electrochemical device.

[0184] 3. Referring to Examples 1-3, 4-6, and 11-13, respectively, as the width W2 of the flange surface of the cell case decreases, the width W3 of the portion of the flange portion of the cell case protruding from the outer surface of the side wall also decreases, which can increase the energy density of the electrochemical device, but reduces the welding strength between the cell cases.

[0185] 4. Referring to Examples 1-3 and 8-10, when the width W2 of the flange surface of the cell case is reduced but the thickness T2 of the portion of the flange portion of the cell case protruding from the outer surface of the side wall remains unchanged, the energy density of the electrochemical device can be improved, but the effect on the welding strength between the cell cases is small.

[0186] 5. Referring to Examples 7 and 12, the width W1 of the transition surface of the cell case remains unchanged, the width W2 of the flange surface of the cell case, and the width W3 of the portion of the flange portion of the cell case protruding from the outer surface of the side wall are increased, which can reduce the wall thickness T1 of the cell case, thereby improving the energy density of the electrochemical device.

[0187] 6. Referring to Examples 6 and 8, the width W1 of the transition surface of the cell casing remains unchanged, the thickness T2 of the portion of the flange portion of the cell casing protruding from the outer surface of the side wall remains unchanged, the width W2 of the flange surface of the cell casing increases, but the wall thickness T1 of the cell casing decreases, which will have a greater impact on the welding strength between the cell casings.

[0188] Table 2 Welding strength test of electrochemical device

[0189] See Table 2, where T1 represents the thickness of the cell case's sidewalls (in the comparative examples and examples tested, the thickness of the cell case's bottom wall is equal to the sidewall thickness), T3 represents the thickness of the cell case lid, and W3 represents the width of the cell case's flange protruding from the outer surface of the sidewall. Comparative Example 1 shows a cell case without a flange, with the lid directly attached to the top surface of the cell case's sidewalls. Comparative Example 2 shows a cell case with a flange but no treatment. Example 4 is the electrochemical device of Example 4 in Table 1.

[0190] As shown in Table 2, compared to Comparative Example 1, Example 4 has the same width W3 of the portion of the cell case flange protruding from the outer surface of the side wall, and a smaller wall thickness T1 of the cell case side wall. This significantly improves the weld strength of the electrochemical device. Specifically, the weld strength increases by an average of 43.87%. Furthermore, in conjunction with Table 1, the energy density of the electrochemical device also increases by 2.26%. Compared to Comparative Example 2, Example 4 has the same wall thickness T1 of the cell case side wall, and a smaller width W3 of the portion of the cell case flange protruding from the outer surface of the side wall. This significantly improves the weld strength of the electrochemical device. Specifically, the weld strength increases by an average of 30.15%. Furthermore, in conjunction with Table 1, the energy density of the electrochemical device also increases by 2.2%.

[0191] It can be seen from this that the embodiments provided in the present application can increase the volume of the accommodation space, increase the energy density of the electrochemical device, and also enable higher welding strength between the battery cell shells.

[0192] An embodiment of the present application provides an electrical device, including the electrochemical device 10 of any of the above solutions, and the electrochemical device 10 is used to provide electrical energy to the electrical device.

[0193] The electrical equipment may be any of the aforementioned equipment or systems using the electrochemical device 10 .

[0194] Referring to FIG11 , FIG11 is a schematic flow diagram of a method for preparing an electrochemical device according to some embodiments of the present application. The method for preparing an electrochemical device includes:

[0195] S410: Punch the raw material plate to form a cell shell.

[0196] In some embodiments, the raw material plate may be a steel plate or other metal plates.

[0197] S420. During the stamping process, the transition surface of the flange portion of the cell shell is extruded toward the inner side of the cell shell by flattening and squeezing a negative angle, so that the width W1 of the transition surface in the thickness direction of the side wall of the cell shell and the wall thickness T1 of the side wall of the cell shell satisfy 0<W1≤T1.

[0198] In other embodiments, the transition surface of the flange portion of the cell shell may be extruded toward the inner side of the cell shell only by flattening it, or by extruding it toward the inner side of the cell shell only by forming a negative angle.

[0199] In other embodiments, the flange portion of the cell housing may be processed after stamping so that the width W1 of the transition surface in the thickness direction of the side wall of the cell housing and the wall thickness T1 of the side wall of the cell housing satisfy 0<W1≤T1.

[0200] S430: Install the electrode assembly in the accommodation space of the battery cell shell.

[0201] In some embodiments, after the electrode assembly is placed in the accommodation space, the first electrical connector of the electrode assembly is connected to the pole of the battery cell shell, and the second electrical connector of the electrode assembly is connected to the battery cell shell to achieve installation of the electrode assembly.

[0202] S440: Place the cell shell cover on the opening of the cell shell, and securely connect the cell shell cover to the cell shell.

[0203] In some embodiments, after the cell shell cover is fixedly connected to the cell shell, electrolyte needs to be injected into the accommodating space of the cell shell through the injection hole of the cell shell, and the injection hole is sealed. After the electrolyte infiltrates the electrode assembly, the electrochemical device can work normally.

[0204] During the stamping process, by flattening and squeezing negative angles, the width W1 of the transition surface of the cell shell in the thickness direction of the side wall of the cell shell and the wall thickness T1 of the side wall of the cell shell satisfy 0<W1≤T1, so that the width of the flange surface of the cell shell is larger, and at the same time, the width of the portion of the flange portion of the cell shell protruding from the side wall is smaller, thereby increasing the volume of the accommodation space and increasing the energy density of the electrochemical device, and the wall thickness of the side wall can be reduced, thereby further increasing the volume of the accommodation space and increasing the energy density of the electrochemical device. If W1 is larger (for example, larger than T1), it is possible that the width of the flange surface is smaller or the width of the portion of the flange portion protruding from the side wall is larger. The smaller width of the flange surface may affect the connection strength between the cell shell and the cell shell cover, and the larger width of the portion of the flange portion protruding from the side wall may compress the accommodation space and affect the energy density of the electrochemical device.

[0205] In some embodiments, the method of fixedly connecting the cell cover to the cell housing includes: welding the cell cover to the cell housing by oscillating welding.

[0206] Oscillating welding is to make the laser swing back and forth to form a weld extending along a curve between the battery cell shell and the battery cell cover, which can increase the area of ​​the weld.

[0207] Line welding is to move the laser in a straight line to form a weld extending in a straight line between the cell casing and the cell cover.

[0208] Because oscillating welding requires a certain welding width, it is not easy to use oscillating welding in structures where the reserved welding width between the cell cover and the cell shell is narrow. Line welding and other methods are generally used. However, in the embodiments of the present application, the width W1 of the transition surface of the cell shell in the thickness direction of the cell shell side wall and the wall thickness T1 of the cell shell side wall satisfy 0<W1≤T1, which can make the width of the flange surface of the cell shell larger, making it easier to use oscillating welding.

[0209] The cell shell cover and the cell shell are welded together by oscillating welding. Compared with methods such as wire welding, the area of ​​the welding part can be increased, thereby further increasing the welding strength between the cell shell and the cell shell cover, making the connection between the cell shell and the cell shell cover stable, and the sealing of the electrochemical device is better. The electrochemical device is not prone to gaps or separation between the cell shell and the cell shell cover due to force or environmental changes, and the reliability of the electrochemical device is higher.

[0210] In other embodiments, the cell cover and the cell shell may be welded together by wire welding or other methods.

[0211] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0212] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell casing, characterized in that: The container comprises a bottom wall, a side wall and a flange portion, wherein the side wall is arranged around the bottom wall and together with the bottom wall, forms a receiving space having an opening, the flange portion is arranged at one end of the side wall away from the bottom wall, and at least a part of the flange portion protrudes from the inner surface and / or outer surface of the side wall; Among them, the flange part has a flange surface and a transition surface, the flange surface is roughly perpendicular to the side wall and is used to connect with the battery cell shell cover; the transition surface is curved to connect the flange surface and the inner surface and / or outer surface of the side wall, the width of the transition surface in the thickness direction of the side wall is W1, and the wall thickness of the side wall is T1, satisfying 0<W1≤T1.

2. The battery cell casing according to claim 1, characterized in that: 0<W1≤0.7*T1.

3. The battery cell casing according to claim 1, characterized in that: The width of the flange surface in the thickness direction of the side wall is W2, satisfying W2≥0.7*T1.

4. The battery cell casing according to claim 1, characterized in that: The flange surface is a plane, and the transition surface is an arc-shaped surface.

5. The battery cell casing according to claim 1, characterized in that: At least a portion of the flange portion protrudes from the outer surface of the side wall, and a width of the portion of the flange portion protruding from the outer surface of the side wall in a thickness direction of the side wall is W3, satisfying 0.05 mm ≤ W3 ≤ 0.3 mm.

6. The battery cell casing according to claim 5, characterized in that: 0.05mm≤W3≤0.15mm.

7. The battery cell casing according to claim 1, characterized in that: At least a portion of the flange portion protrudes from the outer surface of the side wall, and a thickness of the portion of the flange portion protruding from the outer surface of the side wall is T2, satisfying 0.7*T1≤T2≤1.1*T1.

8. The battery cell casing according to claim 1, characterized in that: 0.05mm≤T1≤0.15mm.

9. The battery cell casing according to claim 8, characterized in that: 0.05mm≤T1≤0.1mm.

10. The battery cell casing according to claim 1, characterized in that: The thickness of the portion of the flange portion corresponding to the transition surface is T3, satisfying T3>T1.

11. The battery cell casing according to claim 10, characterized in that: The T3 meets: T1 <T3<1.5*T1。 12. The battery cell casing according to claim 1, characterized in that: The thickness of the portion of the flange portion corresponding to the transition surface is T3, satisfying 0.06 mm ≤ T3 ≤ 0.2 mm.

13. The battery cell casing according to claim 12, characterized in that: The T3 satisfies: 0.09mm≤T3≤0.12mm.

14. An electrochemical device, characterized in that: It comprises the battery cell shell, battery cell shell cover, and electrode assembly as described in any one of claims 1 to 13, wherein the electrode assembly is accommodated in the accommodating space, and the battery cell shell cover is covered on the opening.

15. The electrochemical device according to claim 14, characterized in that The length of the battery cell shell cover along the first direction is D1, the length of the battery cell shell cover along the second direction is D2, the length of the battery cell shell along the first direction is D3, and the length of the battery cell shell along the second direction is D4, satisfying D1≤D3, D2≤D4; the first direction, the second direction and the thickness direction of the battery cell shell cover are perpendicular to each other.

16. The electrochemical device according to claim 14, characterized in that The lengths of the battery cell shell on both sides along the first direction that extend beyond the battery cell shell cover are E1 and E2 respectively, the lengths of the battery cell shell on both sides along the second direction that extend beyond the battery cell shell cover are E3 and E4 respectively, and the average value of E1, E2, E3, and E4 is ˉE, satisfying ˉE≤0.05mm.

17. The electrochemical device according to claim 14, characterized in that The battery cell shell and the battery cell shell cover are connected by welding or bonding.

18. The electrochemical device according to claim 14, characterized in that The battery cell shell and the battery cell shell cover are welded to form a welding portion between the battery cell shell and the battery cell shell cover, the depth of the welding portion in the thickness direction of the bottom wall is H, the width of the welding portion in the thickness direction of the side wall is W4, and H≥0.5*T1, W4≥T1 is satisfied.

19. The electrochemical device according to claim 14, characterized in that The battery cell shell and the battery cell shell cover are connected by welding, and a welding portion is formed between the battery cell shell and the battery cell shell cover. Part of the welding portion protrudes from the side of the battery cell shell cover, and the outer surface of the protruding portion is an arc surface.

20. An electrical equipment, characterized in that: The electrochemical device according to any one of claims 14 to 19 is used to provide electrical energy.

21. A method for preparing an electrochemical device, characterized in that: include: Punching the raw material plate to form a cell shell; During the stamping process, the transition surface of the flange portion of the cell housing is extruded toward the inner side of the cell housing by flattening and squeezing a negative angle, so that the width W1 of the transition surface in the thickness direction of the side wall of the cell housing and the wall thickness T1 of the side wall of the cell housing satisfy 0<W1≤T1; Installing the electrode assembly in the accommodation space of the battery cell shell; The cell shell cover is arranged on the opening of the cell shell, and the cell shell cover is fixedly connected to the cell shell.

22. The method according to claim 21, characterized in that The method for fixedly connecting the battery cell cover to the battery cell shell comprises: The battery cell cover is welded to the battery cell shell by means of oscillating welding.

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