Battery cell casing, electrochemical apparatus and preparation method therefor, and electrical device

Abstract

A battery cell casing (100), an electrochemical apparatus and a preparation method therefor, and an electrical device. The battery cell casing (100) comprises a bottom wall (110), a side wall (120), and a flange portion (130), and, together with the bottom wall (110), encloses to form an accommodating space (101) having an opening (102). The flange portion (130) is provided at an end of the side wall (120) which is away from the bottom wall (110), and at least a portion of the flange portion (130) protrudes from an inner surface and / or an outer surface of the side wall (120); a flange face (131) of the flange portion (130) is approximately perpendicular to the side wall (120) and is connected to a battery cell casing cover (200); a transition surface (132) of the flange portion (130) bends to connect the flange face (131) and the inner surface and / or the outer surface of the side wall (120); the width of the transition surface (132) in the thickness direction of the side wall (120) is W1, the thickness of the side wall (120) is T1, and 0 < W1 ≤ T1 is satisfied, enabling the width of the flange face (131) to be larger; meanwhile, the width of the portion of the flange portion (130) which protrudes from the side wall (120) is smaller, and may enable the thickness of the side wall (120) to be smaller, thereby increasing the volume of the accommodating space (101) and increasing the energy density of the electrochemical apparatus.

Description

Battery cell shell, electrochemical device and preparation method therefor, and electric device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. CN202310870108.5, filed on July 14, 2023, entitled “Battery cell shell, electrochemical device and preparation method therefor, and electric device,” the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a battery cell shell, an electrochemical device, a preparation method therefor, and an electric device. BACKGROUND

[0004] With the rapid development of electronic information technology, various electronic devices are also developing towards intelligence and multifunction, and the energy density requirement of batteries is also becoming higher and higher. Therefore, how to improve the energy density of batteries has become a problem to be solved in the field of batteries.

[0005] SUMMARY

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

[0007] In a first aspect, the present application provides a battery cell shell, comprising a bottom wall, a side wall, and a flange portion, the side wall being arranged around the bottom wall and forming a containing space with an opening together with the bottom wall, the flange portion being arranged at an end of the side wall away from the bottom wall, at least a portion of the flange portion protruding from the inner surface and / or the outer surface of the side wall.

[0008] The flange portion has a flange surface and a transition surface, the flange surface being substantially perpendicular to the side wall and being used to connect with a battery cell shell cover, the transition surface being curvedly connected with the inner surface and / or the outer surface of the side wall, the width of the transition surface in the thickness direction of the side wall being W1, the wall thickness of the side wall being T1, and satisfying 0 < W1 ≤ T1.

[0009] In the technical solution, the shell of the battery cell includes a bottom wall, a side wall and a flange part. The side wall is arranged around the bottom wall and cooperates with the bottom wall to form an accommodating space with an opening, so that the electrode assembly can be accommodated in the accommodating space through the opening. The flange part is arranged at an end of the side wall away from the bottom wall. At least a part of the flange part protrudes from the inner surface and / or the outer surface of the side wall, so that the flange part can be used to connect with the shell cover of the battery cell and increase the connection area with the shell cover of the battery cell. The flange part has a flange surface and a transition surface. The flange surface is substantially perpendicular to the side wall and is used to connect with the shell cover of the battery cell. The transition surface is curvedly connected with the inner surface and / or the outer surface of the side wall and the flange surface. 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. It is satisfied that 0 < W1 ≤ T1. The width of the flange surface is large, and the width of the part of the flange part protruding from the side wall is small, so that the occupied space of the shell of the battery cell is small, the volume of the accommodating space is increased, the energy density of the electrochemical device is increased, and the wall thickness of the side wall is small, so that the volume of the accommodating space is further increased, and the energy density of the electrochemical device is further increased. If W1 is large (for example, greater than T1), the width of the flange surface may be small or the width of the part of the flange part protruding from the side wall is large, which may affect the connection strength of the shell of the battery cell and the shell cover of the battery cell, and the width of the flange surface is small, which may affect the connection strength of the shell of the battery cell and the shell cover of the battery cell.

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

[0011] In the technical solution, by satisfying 0 < W1 ≤ 0.7 * T1, the width of the flange surface is further increased, and the width of the part of the flange part protruding from the side wall is further small, so that the volume of the accommodating space is further increased, the energy density of the electrochemical device is further increased, and the wall thickness of the side wall is further small, so that the volume of the accommodating space is increased, and the energy density of the electrochemical device is increased.

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

[0013] In the technical solution, by satisfying that the width W2 of the flange surface in the thickness direction of the side wall is W2 ≥ 0.7 * T1, the connection area of the flange surface and the shell cover of the battery cell is larger, the connection of the shell of the battery cell and the shell cover of the battery cell is more stable, the sealing performance is better, the electrochemical device is not easy to cause a gap or separation between the shell of the battery cell and the shell cover of the battery cell due to stress or environmental changes, and the reliability of the electrochemical device is higher. If W2 is small (for example, less than 0.7 * T1), the connection strength of the shell of the battery cell and the shell cover of the battery cell may be affected, and then the sealing performance of the electrochemical device is affected.

[0014] In some embodiments of the first aspect, the flange surface is planar, and the transition surface is arc-shaped.

[0015] In the above technical solution, by setting the flange surface as a planar surface, the flange surface can better fit the shell cover of the battery cell, facilitating the connection of the flange surface and the shell cover of the battery cell. By setting the transition surface as an arc-shaped surface, the preparation of the flange portion is facilitated.

[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 the 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 0.05mm≤W3≤0.3mm.

[0017] In the above technical solution, at least a portion of the flange portion protrudes from the outer surface of the side wall. By setting 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 to satisfy 0.05mm≤W3≤0.3mm, on the one hand, the width of the flange surface can be larger, the connection area of the shell of the battery cell and the shell cover of the battery cell is larger, and the connection strength is better. 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 making the volume of the accommodation space larger, the volume of the electrode assembly larger, and the energy density of the electrochemical device larger under the condition that the size of the electrochemical device is constant. If W3 is smaller (e.g., less than 0.05mm), the width of the flange surface is smaller, the connection area of the shell of the battery cell and the shell cover of the battery cell is smaller, and the connection strength is lower. When the electrochemical device is subjected to stress or environmental changes, a gap or separation may occur between the shell of the battery cell and the shell cover of the battery cell, affecting the sealing performance of the electrochemical device. If W3 is larger (e.g., greater than 0.3mm), the space occupied by the portion of the flange portion protruding from the outer surface of the side wall is larger, thereby making the volume of the accommodation space smaller, the volume of the electrode assembly smaller, and the energy density of the electrochemical device smaller under the condition that the size of the electrochemical device is constant.

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

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

[0020] 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 the 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.

[0021] In the technical solution, the thickness T2 of the part of the flange portion protruding from the outer surface of the side wall satisfies 0.7*T1≤T2≤1.1*T1, on the one hand, the strength of the flange portion is large and is not easy to deform, and enough welding depth is reserved for the welding connection of the battery cell shell and the battery cell shell cover, so that the connection strength of the battery cell shell and the battery cell shell cover is large, on the other hand, the width of the transition surface is small, and thus the volume of the accommodation space is increased, and the energy density of the electrochemical device is increased. If T2 is small (for example, less than 0.7*T1), the strength of the flange portion is small, and the flange portion may be deformed due to stress or environmental changes, and the welding depth of the battery cell shell and the battery cell shell cover is limited, which may affect the connection strength of the battery cell shell and the battery cell shell cover. If T2 is large (for example, greater than 1.1*T1), it is not convenient to form a transition surface with a small width, which may affect the volume of the accommodation space, and thus affect the energy density of the electrochemical device.

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

[0023] In the technical solution, the thickness T2 of the part of the flange portion protruding from the outer surface of the side wall satisfies 0.7*T1≤T2≤1.1*T1, on the one hand, the strength of the flange portion is large and is not easy to deform, and enough welding depth is reserved for the welding connection of the battery cell shell and the battery cell shell cover, so that the connection strength of the battery cell shell and the battery cell shell cover is large, on the other hand, the width of the transition surface is small, and thus the volume of the accommodation space is increased, and the energy density of the electrochemical device is increased. If T2 is small (for example, less than 0.7*T1), the strength of the flange portion is small, and the flange portion may be deformed due to stress or environmental changes, and the welding depth of the battery cell shell and the battery cell shell cover is limited, which may affect the connection strength of the battery cell shell and the battery cell shell cover. If T2 is large (for example, greater than 1.1*T1), it is not convenient to form a transition surface with a small width, which may affect the volume of the accommodation space, and thus affect the energy density of the electrochemical device.

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

[0025] In the technical solution, the thickness T2 of the part of the flange portion protruding from the outer surface of the side wall satisfies 0.7*T1≤T2≤1.1*T1, on the one hand, the strength of the flange portion is large and is not easy to deform, and enough welding depth is reserved for the welding connection of the battery cell shell and the battery cell shell cover, so that the connection strength of the battery cell shell and the battery cell shell cover is large, on the other hand, the width of the transition surface is small, and thus the volume of the accommodation space is increased, and the energy density of the electrochemical device is increased. If T2 is small (for example, less than 0.7*T1), the strength of the flange portion is small, and the flange portion may be deformed due to stress or environmental changes, and the welding depth of the battery cell shell and the battery cell shell cover is limited, which may affect the connection strength of the battery cell shell and the battery cell shell cover. If T2 is large (for example, greater than 1.1*T1), it is not convenient to form a transition surface with a small width, which may affect the volume of the accommodation space, and thus affect the energy density of the electrochemical device.

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

[0027] In the technical solution, the thickness T3 of the part of the flange portion corresponding to the transition surface satisfies T3>T1, so that the connection between the flange portion and the side wall is more firm, the flange portion is less likely to separate from the side wall, and the overall structure of the battery cell shell is more stable.

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

[0029] In the technical solution, the thickness T3 of the part of the flange portion corresponding to the transition surface satisfies 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 shell is reduced, and T3 satisfies the above condition to balance the relationship between the firm connection between the flange portion and the side wall in the battery cell shell and the energy density of the battery cell.

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

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

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

[0033] In the technical solution, the thickness T3 of the part of the flange portion corresponding to the transition surface satisfies 0.09mm≤T3≤0.12mm, and the above solution can more greatly ensure the connection strength while reducing the loss of energy density.

[0034] In the second aspect, the application provides an electrochemical device, which comprises the battery cell shell, the battery cell shell cover and the electrode assembly as described above, the electrode assembly is accommodated in the accommodation space, and the battery cell shell cover is arranged on the opening.

[0035] In some embodiments of the second aspect, 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, and D1≤D3 and D2≤D4 are satisfied; the first direction, the second direction and the thickness direction of the battery cell shell cover are perpendicular to each other.

[0036] In the technical solution, the length D1 of the cell shell cover along the first direction, the length D2 of the cell shell cover along the second direction, the length D3 of the cell shell body along the first direction, and the length D4 of the cell shell body along the second direction satisfy D1≤D3 and D2≤D4, which facilitates the connection of the cell shell body and the cell shell cover, makes the connection of the cell shell body and the cell shell cover more stable, and reduces the possibility of the cell shell cover protruding from the cell shell body, thereby improving the energy density of the electrochemical device.

[0037] In some embodiments of the second aspect, the lengths of the two sides of the cell shell body along the first direction beyond the cell shell cover are E1 and E2, respectively, the lengths of the two sides of the cell shell body along the second direction beyond the cell shell cover are E3 and E4, respectively, and the average value of E1, E2, E3, and E4 is E, which satisfies E≤0.05 mm.

[0038] In the technical solution, the lengths of the two sides of the cell shell body along the first direction beyond the cell shell cover are E1 and E2, respectively, the lengths of the two sides of the cell shell body along the second direction beyond the cell shell cover are E3 and E4, respectively, and the average value of E1, E2, E3, and E4 is E, which satisfies E≤0.05 mm. This makes the length of the part of the flange surface that does not exceed the cell shell cover larger, i.e., the length of the part of the flange surface connected to the cell shell cover larger, thereby further facilitating the connection of the cell shell body and the cell shell cover, making the connection of the cell shell body and the cell shell cover more stable, the electrochemical device having better sealing performance, and the electrochemical device less likely to have gaps or separation between the cell shell body and the cell shell cover due to stress or environmental changes, thereby improving the reliability of the electrochemical device. If E is larger (e.g., greater than 0.05 mm), the length of the part of the flange surface that does not exceed the cell shell cover is smaller, i.e., the length of the part of the flange surface connected to the cell shell cover smaller, which may affect the connection strength of the cell shell body and the cell shell cover.

[0039] In some embodiments of the second aspect, the cell shell body and the cell shell cover are connected by welding or adhesion.

[0040] In the technical solution, the cell shell body and the cell shell cover are connected by welding or adhesion, which makes the connection of the cell shell body and the cell shell cover stable, the electrochemical device has good sealing performance, and the electrochemical device is less likely to have gaps or separation between the cell shell body and the cell shell cover due to stress or environmental changes, thereby improving the reliability of the electrochemical device.

[0041] In some embodiments of the second aspect, the cell shell body and the cell shell cover are connected by welding, and a welding portion is formed between the cell shell body and the 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, which satisfy H≥0.5*T1 and W4≥T1.

[0042] In the technical solution, the depth H of the welding portion in the thickness direction of the bottom wall and the width W4 of the welding portion in the thickness direction of the side wall satisfy H≥0.5*T1 and W4≥T1, so that the welding strength of the battery cell shell and the battery cell shell cover is high, the connection between the battery cell shell and the battery cell shell cover is stable, the sealing performance of the electrochemical device is good, the electrochemical device is not prone to have a gap or be separated between the battery cell shell and the battery cell shell cover due to stress 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 of the battery cell shell and the battery cell shell cover is low, the electrochemical device can have a gap or be separated between the battery cell shell and the battery cell shell cover due to stress or environmental changes, and the reliability of the electrochemical device is affected.

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

[0044] In the technical solution, the part of the welding portion protruding from the side of the battery cell shell cover can make the volume of the welding portion large, the connection strength between the battery cell shell and the battery cell shell cover is high, the connection between the battery cell shell and the battery cell shell cover is stable, the sealing performance of the electrochemical device is good, the electrochemical device is not prone to have a gap or be separated between the battery cell shell and the battery cell shell cover due to stress or environmental changes, and the reliability of the electrochemical device is high. The outer surface of the part of the welding portion protruding from the battery cell shell cover is an arc surface, which can reduce the possibility of damage to the welding portion and other devices when the welding portion interferes with the other devices.

[0045] In a third aspect, the present application provides a power utilization device, which comprises the electrochemical device as described above, and the electrochemical device is used to provide electric energy.

[0046] In a fourth aspect, the present application provides a preparation method of an electrochemical device, which comprises:

[0047] The raw material plate is punched to form the battery cell shell;

[0048] In the punching process, the transition surface of the flange portion of the battery cell shell is extruded and formed to the inner side of the battery cell shell by flattening and negative angle extrusion, so that the width W1 of the transition surface 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

[0049] The electrode assembly is installed in the accommodation space of the battery cell shell;

[0050] The battery cell shell cover is arranged on the opening of the battery cell shell, and the battery cell shell cover is fixedly connected with the battery cell shell.

[0051] In the technical solution, 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 through flattening and negative angle extrusion during stamping, so that the width of the flange surface of the battery cell shell is large, the width of the part of the flange of the battery cell shell protruding from the side wall is small, the volume of the accommodation space is increased, the energy density of the electrochemical device is increased, and the wall thickness of the side wall is small, so that the volume of the accommodation space is further increased, and the energy density of the electrochemical device is further increased.

[0052] In some embodiments of the fourth aspect, the method for fixedly connecting the battery cell shell cover and the battery cell shell comprises:

[0053] The battery cell shell cover and the battery cell shell are welded and connected through swing welding.

[0054] In the technical solution, the battery cell shell cover and the battery cell shell are welded and connected through swing welding, so that the welding strength of the battery cell shell and the battery cell shell cover is further increased, the connection between the battery cell shell and the battery cell shell cover is stable, the sealing performance of the electrochemical device is good, the electrochemical device is not prone to have a gap or be separated between the battery cell shell and the battery cell shell cover due to stress or environmental changes, and the reliability of the electrochemical device is high. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0056] Fig. 1 is a perspective structural schematic view of a battery cell shell provided by some embodiments of the present application;

[0057] Fig. 2 is a structural schematic view of one perspective of a battery cell shell provided by some embodiments of the present application;

[0058] Fig. 3 is a sectional view schematic view of the battery cell shell shown in Fig. 2 along the A-A direction;

[0059] Fig. 4 is a partially enlarged structural schematic view of B of the battery cell shell shown in Fig. 3;

[0060] Fig. 5 is a perspective structural schematic view of an electrochemical device provided by some embodiments of the present application;

[0061] Fig. 6 is an exploded structural schematic view of an electrochemical device provided by some embodiments of the present application;

[0062] Fig. 7 is a structural schematic diagram of an electrochemical device according to some embodiments of the present application;

[0063] Fig. 8 is a sectional view of the electrochemical device shown in Fig. 7 along the direction of C-C;

[0064] Fig. 9 is a partially enlarged structural schematic diagram of D of the electrochemical device shown in Fig. 8;

[0065] Fig. 10 is a partially enlarged structural schematic diagram of D of the electrochemical device shown in Fig. 8 in another state;

[0066] Fig. 11 is a flowchart of a method for manufacturing an electrochemical device according to some embodiments of the present application.

[0067] Fig. 12 is a structural schematic diagram of an electrochemical device according to some embodiments of the present application.

[0068] Specific Embodiment Modes

[0069] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0070] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0071] The terms "first", "second", etc. in the specification and claims of the present application or in the above description of drawings are used to distinguish different objects and are not intended to describe a specific order or primary and secondary relationship.

[0072] Reference to an "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another.

[0073] In the description of the application, it is necessary to point out that, unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting", "attaching" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

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

[0075] With the development of new energy industry, the battery gradually develops towards high energy density and high power density. However, the volume of the battery compartment used for accommodating the electrochemical device by the electric equipment is limited, so that the way of increasing the energy density of the electrochemical device by increasing the volume of the electrochemical device is limited. Therefore, the feasibility of increasing the energy density of the electrochemical device by changing the structure of the electrochemical device itself is higher.

[0076] The shell of the battery cell generally comprises a bottom wall and a side wall, the side wall is arranged around the bottom wall and cooperates with the bottom wall to form an accommodating space with an opening, so that the electrode assembly can be accommodated in the accommodating space through the opening. After the electrode assembly is installed, a shell cover of the battery cell needs to be arranged on the shell of the battery cell to cover the opening, so that the accommodating space is isolated from the outside. At present, there are mainly two connection modes of the shell of the battery cell and the shell cover of the battery cell. One is the mode of rotary cutting shell plus top welding, specifically, the shell of the battery cell does not arrange a flange part, the shell cover of the battery cell abuts against the top surface of the side wall of the shell of the battery cell, and the shell cover of the battery cell is welded with the top surface of the side wall. In order to make the top surface of the side wall have sufficient welding area, the side wall needs to have a large thickness, which will cause the shell of the battery cell to occupy a large space, compress the volume of the accommodating space, reduce the volume of the electrode assembly, and affect the energy density of the electrochemical device. The other is the mode of large flange plus top welding, specifically, a flange part with a large width is arranged at one end of the side wall of the shell of the battery cell away from the bottom wall, the flange part protrudes away from the accommodating space, can form a flange surface, and is used for connecting with the shell cover of the battery cell, so that the thickness of the side wall can be reduced, but the flange part will increase the overall size of the shell of the battery cell. In the case that the overall size of the shell of the battery cell is unchanged, the arrangement of the flange part will compress the accommodating space, reduce the volume of the electrode assembly, and affect the energy density of the electrochemical device.

[0077] In order to improve the energy density of the electrochemical device, the shell of the battery cell is provided, which comprises a bottom wall, a side wall and a flange part. The side wall is arranged around the bottom wall and cooperates with the bottom wall to form an accommodating space with an opening. The flange part is arranged at one end of the side wall away from the bottom wall. At least a part of the flange part protrudes from the inner surface and / or the outer surface of the side wall. The flange part has a flange surface and a transition surface. The flange surface is substantially perpendicular to the side wall and is used for connecting with the shell cover of the battery cell. The transition surface is curvedly connected with the inner surface and / or the outer surface of the side wall and the flange surface. The width of the transition surface in the thickness direction of the side wall is W1, the wall thickness of the side wall is T1, and 0 < W1 ≤ T1 is satisfied.

[0078] In the structure of the battery cell shell, the battery cell shell comprises a bottom wall, a side wall and a flange portion. The side wall is arranged around the bottom wall and cooperates with the bottom wall to form an accommodating space with an opening, so that the electrode assembly can be accommodated in the accommodating space through the opening. The flange portion is arranged at an end of the side wall away from the bottom wall. At least a part of the flange portion protrudes from the 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 substantially perpendicular to the side wall and is used to connect with the battery cell shell cover. The transition surface is curvedly connected with 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, which satisfies 0 < W1 < T1. The width of the flange surface is large, and the width of the part of the flange portion protruding from the side wall is small, so that the occupied space of the battery cell shell is small, thereby increasing the volume of the accommodating space, increasing the energy density of the electrochemical device, and reducing the wall thickness of the side wall, thereby further increasing the volume of the accommodating space and increasing the energy density of the electrochemical device. If W1 is large (for example, greater than T1), the width of the flange surface may be small or the width of the part of the flange portion protruding from the side wall may be large, which may affect the connection strength of the battery cell shell and the battery cell shell cover, and the width of the part of the flange portion protruding from the side wall may be large, which may compress the accommodating space and affect the energy density of the electrochemical device.

[0079] The embodiment of the present application provides an electrochemical device comprising a battery cell shell. The electrochemical device can be a secondary battery or a primary battery, for example, a lithium ion battery, a sodium ion battery or a magnesium ion battery, etc. The embodiment of the present application is not limited thereto. The electrochemical device can be in the shape of a cylinder, a flat body, a cuboid or other shapes, etc. The embodiment of the present application is not limited thereto.

[0080] The embodiment of the present application provides a power consumption device using the electrochemical device as a power supply. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc.

[0081] Referring to FIGS. 1-4, FIG. 1 is a perspective view of an electrode shell according to some embodiments of the present application, FIG. 2 is a view of the structure of the electrode shell according to some embodiments of the present application, FIG. 3 is a sectional view of the electrode shell shown in FIG. 2 along the direction of A-A, and FIG. 4 is a partially enlarged view of the structure of the electrode shell at B shown in FIG. 3. An electrode shell 100 according to some embodiments of the present application includes a bottom wall 110, a side wall 120, and a flange portion 130. The side wall 120 is arranged around the bottom wall 110 and, together with the bottom wall 110, encloses a receiving space 101 having an opening 102. The flange portion 130 is arranged at an end of the side wall 120 away from the bottom wall 110, and at least a portion of the flange portion 130 protrudes from the outer surface of the side wall 120. 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 with an electrode shell cover 200. The transition surface 132 is curvedly connected with the inner surface of the side wall 120 and the flange surface 131. 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 included angle between the plane where the flange surface 131 is located and the plane where the outer surface or the inner surface of the side wall 120 is located is within a preset difference range.

[0083] In some embodiments, the electrode shell 100 can be made of a material with high strength, such as a metal material, for example, steel or aluminum alloy, so that the electrode shell 100 has high stress performance, thereby making the electrode shell 100 less likely to deform or break due to stress or environmental changes, and thus making the electrochemical device 10 have higher reliability.

[0084] In other embodiments, the electrode shell 100 can also be made of a non-metallic material with high strength, such as carbon fiber or hard plastic.

[0085] A flange is a part that connects two components to each other and is used for the connection between the ends of the components. Flange connection refers to the detachable connection of a component provided with a flange and another component as a combined sealing structure. Any connection part that is connected by a fixed connection method while being closed around two planes is generally referred to as a "flange".

[0086] In some embodiments, the flange portion 130 is arranged around the side wall 120 and extends away from the receiving space 101, so 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, so that the overall structure of the battery cell shell 100 is stable and less likely to form gaps or separate from each other between the bottom wall 110 and the side wall 120, or between the side wall 120 and the flange portion 130 due to stress or environmental changes, and the sealing performance of the battery cell shell 100 is good.

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

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

[0090] For example, as shown in FIGS. 2 and 4, the width of the transition surface 132 between two opposite portions of the flange portion 130 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 between two opposite portions of the flange portion 130 along the second direction Y is the size of the transition surface 132 along the second direction Y.

[0091] For example, as shown in FIGS. 2 and 4, the thickness of the side wall 120 between two opposite portions 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 thickness of the side wall 120 between two opposite portions 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 shell 100 of the battery cell includes a bottom wall 110, a side wall 120 and a flange portion 130. The side wall 120 is arranged around the bottom wall 110 and cooperates with the bottom wall 110 to define a receiving space 101 having an opening 102, so that the electrode assembly 300 can be accommodated in the receiving space 101 through the opening 102. The flange portion 130 is arranged at an end of the side wall 120 away from the bottom wall 110. At least a portion of the flange portion 130 protrudes from the outer surface of the side wall 120, so that the flange portion 130 can be used to connect with the shell cover 200 and increase the connection area with the shell cover 200. Meanwhile, the area of the opening 102 is large, which 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 with the shell cover 200. The transition surface 132 is curvedly connected with the inner surface of the side wall 120 and the flange surface 131. 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. It is satisfied that 0 < W1 < T1. For example, W1 can be 0.5*T1, 0.8*T1 or T1. In this way, the width of the flange surface 131 is large, and meanwhile, the width of the portion of the flange portion 130 protruding from the side wall 120 is small, so that the volume of the receiving space 101 can be increased, the energy density of the electrochemical device 10 can be increased, and the wall thickness of the side wall 120 can be small, so that the volume of the receiving space 101 can be further increased, and the energy density of the electrochemical device 10 can be further increased. If W1 is large (e.g., greater than T1), it is possible that the width of the flange surface 131 is small or the width of the portion of the flange portion 130 protruding from the side wall 120 is large. The small width of the flange surface 131 can affect the connection strength of the shell 100 and the shell cover 200, and the large width of the portion of the flange portion 130 protruding from the side wall 120 can compress the receiving space 101 and affect the energy density of the electrochemical device 10.

[0093] In some embodiments, the flange portion 130 can protrude from the inner surface of the side wall 120, and the transition surface 132 is curvedly connected between the flange surface 131 and the outer surface of the side wall 120, which can reduce the occupied space of the battery cell shell 100, and facilitate to improve the energy density of the electrochemical device 10. By making the width W1 of the transition surface 132 in the thickness direction of the side wall 120 and the wall thickness T1 of the side wall 120 satisfy 0 < W1 ≤ T1, the width of the flange surface 131 is larger, and the width of the portion of the flange portion 130 protruding from the side wall 120 is smaller, which facilitates the installation of the electrode assembly 300. If W1 is larger (for example, greater than T1), it is possible that the width of the flange surface 131 is smaller or the width of the portion of the flange portion 130 protruding from the side wall 120 is larger. The smaller width of the flange surface 131 can affect the connection strength between the battery cell shell 100 and the battery cell shell cover 200, and the larger width of the portion of the flange portion 130 protruding from the side wall 120 can affect the installation of the electrode assembly 300, thereby causing the volume of the electrode assembly 300 to be smaller, and affecting the energy density of the electrochemical device 10.

[0094] In some embodiments, a portion of the flange portion 130 can protrude from the inner surface of the side wall 120, and a portion can protrude from the outer surface of the side wall 120, and the flange portion 130 forms two transition surfaces 132. One transition surface 132 is curvedly connected between the flange surface 131 and the outer surface of the side wall 120, and the other transition surface 132 is curvedly connected between the flange surface 131 and the inner surface of the side wall 120, which can further increase the width of the flange surface 131 and improve the connection strength between the battery cell shell 100 and the battery cell shell cover 200. By making the width W1 of the transition surface 132 in the thickness direction of the side wall 120 and the wall thickness T1 of the side wall 120 satisfy 0 < W1 ≤ T1, the flange portion 130 occupies a smaller space in the accommodation space 101, which facilitates to improve the energy density of the electrochemical device 10.

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

[0096] By making 0 < W1 ≤ 0.7 * T1, the width of the flange surface 131 can be further increased, and the width of the portion of the flange portion 130 protruding from the side wall 120 is smaller, thereby further increasing the volume of the accommodation space 101, increasing the energy density of the electrochemical device 10, and further reducing the wall thickness of the side wall 120, thereby increasing the volume of the accommodation 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, which satisfies W2 ≥ 0.7 * T1, for example, W2 can be 0.7 * T1, 0.8 * T1, or T1, etc.

[0098] For example, as shown in FIG. 2 and FIG. 4, the width of the flange surface 131 located at two portions of the flange portion 130 opposite along the first direction X is the dimension of the flange surface 131 along the first direction X, and the width of the flange surface 131 located at two portions of the flange portion 130 opposite along the second direction Y is the dimension of the flange surface 131 along the second direction Y.

[0099] By making the width W2 of the flange surface 131 in the thickness direction of the side wall 120 satisfy W2≥0.7*T1, the connection area of the flange surface 131 and the cell shell cover 200 can be made larger, the connection of the cell shell 100 and the cell shell cover 200 is more stable, the sealing performance is better, the electrochemical device 10 is less likely to have a gap or separation between the cell shell 100 and the cell shell cover 200 due to stress or environmental changes, and the reliability of the electrochemical device 10 is higher. If W2 is small (for example, less than 0.7*T1), it may affect the connection strength of the cell shell 100 and the cell shell cover 200, and further affect the sealing performance of the electrochemical device 10.

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

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

[0102] By setting the flange surface 131 as a plane, the flange surface 131 is perpendicular to the inner surface or the outer surface of the side wall 120, that is, the flange surface 131 is parallel to the X-Y direction, so that the flange surface 131 can better fit the cell shell cover 200, so as to facilitate the connection of the flange surface 131 and the cell shell cover 200. The transition surface 132 is set as an arc surface, which is convenient for the preparation of the flange portion 130. The flange portion 130 can be formed by bending the side wall of the cell shell 100.

[0103] In some embodiments, the width of the portion 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, which satisfies 0.05mm≤W3≤0.3mm, for example, W3 can be 0.05mm, 0.1mm or 0.3mm, etc.

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

[0105] By making the width W3 of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 in the thickness direction of the side wall 120 satisfy 0.05mm≤W3≤0.3mm, on the one hand, the width of the flange surface 131 can be made larger, the connection area of the battery cell shell 100 and the battery cell shell cover 200 is larger, and the connection strength is better, on the other hand, the space occupied by the portion of the flange portion 130 protruding from the outer surface of the side wall 120 can be reduced, and thus, under the condition that the size of the electrochemical device 10 is constant, the volume of the accommodation space 101 is larger, the volume of the electrode assembly 300 is larger, and the energy density of the electrochemical device 10 is larger. If W3 is smaller (for example, less than 0.05mm), the width of the flange surface 131 is smaller, the connection area of the battery cell shell 100 and the battery cell shell cover 200 is smaller, and the connection strength is lower, and when the electrochemical device 10 is stressed or the environment changes, a gap or separation between the battery cell shell 100 and the battery cell shell cover 200 can be generated, affecting the sealing of the electrochemical device 10. If W3 is larger (for example, greater than 0.3mm), the space occupied by the portion of the flange portion 130 protruding from the outer surface of the side wall 120 is larger, and thus, under the condition that the size of the electrochemical device 10 is constant, the volume of the accommodation 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, 0.05mm≤W3≤0.15mm, for example, W3 can be 0.05mm, 0.1mm or 0.15mm, etc.

[0107] By making 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, and thus, under the condition that the size of the electrochemical device 10 is constant, the volume of the accommodation space 101 is larger, the volume of the electrode assembly 300 is larger, and the energy density of the electrochemical device 10 is larger.

[0108] In some embodiments, the thickness of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 is T2, which satisfies 0.7*T1≤T2≤1.1*T1, for example, T2 can be 0.7*T1, 0.9*T1 or 1.1*T1, etc.

[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 preparation of the shell 100 is shaped, the width W1 of the transition surface 132 can also be reduced by cutting. For example, cutting the top surface of the shell 100 in the vertical direction (parallel direction of the X-Y plane) along the thickness direction of the bottom wall 110 of the shell 100 can further reduce the width W1 of the transition surface 132, increase the width W2 of the flange surface 131, and at the same time, the thickness T2 of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 can also be reduced.

[0112] In some embodiments, during the preparation of the shell 100, the raw material plate can be extruded away from the end of the bottom wall 110 of the shell 100 to the side wall 120, 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 making the thickness T2 of the portion of the flange portion 130 protruding from the outer surface of the side wall 120 satisfy 0.7*T1≤T2≤1.1*T1, on the one hand, the strength of the flange portion 130 can be greater and less likely to deform, and enough welding depth can be reserved for the welding connection between the shell 100 and the shell cover 200, so that the connection strength between the shell 100 and the shell cover 200 is greater, and on the other hand, the width of the transition surface 132 can be smaller, thereby increasing the volume of the accommodation space 101 and the energy density of the electrochemical device 10. If T2 is smaller (e.g., less than 0.7*T1), the strength of the flange portion 130 can be smaller and can be easily deformed due to stress or environmental changes, and at the same time, the welding depth of the shell 100 and the shell cover 200 is limited, which can affect the connection strength between the shell 100 and the shell cover 200. If T2 is larger (e.g., greater than 1.1*T1), it is not convenient to form a transition surface 132 with a smaller width, which can affect the volume of the accommodation space 101 and in turn affect the energy density of the electrochemical device 10.

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

[0115] By making the wall thickness T1 of the side wall 120 satisfy 0.05mm≤T1≤0.15mm, on the one hand, the strength of the battery cell shell 100 can be made larger, and the battery cell shell 100 is less likely to be deformed or damaged due to stress or environmental changes, and can better play a protective role on the electrode assembly 300 and maintain the normal work of the electrochemical device 10. On the other hand, the space occupied by the battery cell shell 100 can be reduced, and in the case of a certain size of the electrochemical device 10, 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. If T1 is smaller (for example, less than 0.05mm), the strength of the battery cell shell 100 is smaller, and the battery cell shell 100 is likely to be deformed or damaged due to stress or environmental changes, affecting the protection of the electrode assembly 300 and the normal work of the electrochemical device 10. If T1 is larger (for example, greater than 0.15mm), the space occupied by the battery cell shell 100 is larger, and in the case of a certain size of the electrochemical device 10, the accommodation space 101 reserved is smaller, so that the volume of the electrode assembly 300 is smaller, and the energy density of the electrochemical device 10 is smaller.

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

[0117] By making 0.05mm≤T1≤0.1mm, the space occupied by the battery cell shell 100 can be further reduced, and in the case of a certain size of the electrochemical device 10, 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, which satisfies T3>T1.

[0119] The thickness of the portion of the flange portion 130 corresponding to the transition surface 132 is the size of the flange portion 130 in the vertical direction of the transition surface 132. The thickness of a portion of the flange portion 130 corresponding to the transition surface 132 is exemplarily marked in FIG. 4.

[0120] By making the thickness T3 of the portion of the flange portion 130 corresponding to the transition surface 132 satisfy T3>T1, the connection between the flange portion 130 and the side wall 120 can be made more firm, and the flange portion 130 is less likely to separate from the side wall 120, and the overall structure of the battery cell shell 100 is more stable.

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

[0122] The thickness T3 of the portion of the flange part corresponding to the transition surface satisfies T1 < T3 < 1.5 * T1, so that when the thickness of the portion of the transition surface is too large, the energy density of the battery cell shell 100 is reduced, and T3 satisfies the above condition to balance the relationship between the firm connection of the flange part 130 and the side wall 120 in the battery cell shell 100 and the energy density of the battery cell.

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

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

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

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

[0127] Referring to FIGS. 5 and 6, FIG. 5 is a perspective structural schematic diagram of an electrochemical device provided in some embodiments of the present application, and FIG. 6 is an exploded structural schematic diagram of the electrochemical device provided in some embodiments of the present application. The embodiments of the present application provide an electrochemical device 10, which includes the battery cell shell 100, the battery cell shell cover 200, and the electrode assembly 300 of any of the above schemes. The electrode assembly 100 is accommodated in the accommodation space 101, and the battery cell shell cover 200 is arranged on the opening 102.

[0128] In some embodiments, the battery cell shell cover 200 can be made of a material with high strength, such as a metal material, for example, steel, aluminum alloy, etc., so that the battery cell shell 200 has high stress performance, and thus the battery cell shell cover 200 is not easy to deform or break due to stress or environmental changes, and thus the reliability of the electrochemical device 10 is higher.

[0129] In some other embodiments, the battery cell shell cover 200 can also be made of a non-metallic material with high strength, such as carbon fiber or hard plastic.

[0130] The electrochemical device includes a battery shell 100, a battery shell cover 200, an electrode assembly 300, and an electrolyte, and the shell 100 and the battery shell 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 film. 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 current collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode current collector. The part of the positive electrode current collector without the positive electrode active material layer serves as a positive electrode tab to realize the input or output of electric energy of the positive electrode sheet through the positive electrode tab. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary material, or lithium manganate, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector. The part of the negative electrode current collector without the negative electrode active material layer serves as a negative electrode tab to realize the input or output of electric energy of the negative electrode sheet through the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be a carbon material or a silicon material, etc. The material of the separator film can be polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include an organic solvent, an electrolyte lithium salt, etc.

[0131] In some embodiments, the electrode assembly 300 can be a laminated structure formed by the negative electrode sheet, the separator film, and the positive electrode sheet through a laminated arrangement.

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

[0133] In some embodiments, the electrochemical device 10 is arranged in a rectangular cuboid, and the top corner is arranged in a rounded corner, which can better adapt to the rounded battery compartment in the electrical equipment.

[0134] In other embodiments, the top corner of the electrochemical device 10 can also be arranged in a square corner.

[0135] In some embodiments, the thickness direction of the battery shell 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] Referring to FIGS. 1 and 6, in some embodiments, the battery shell 100 is provided with a liquid injection hole 121, which is used to inject electrolyte into the accommodation space 101 through the liquid injection hole 121 after the battery shell 100 and the battery shell cover 200 are assembled, so that the electrolyte can soak the electrode assembly 300.

[0137] In some embodiments, the liquid injection hole 121 can be arranged on the side wall 120 of the battery shell 100, which facilitates the injection of electrolyte into the accommodation space 101 through the liquid injection hole 121.

[0138] In some embodiments, the electrochemical device 10 further comprises a liquid injection plug (not shown in the figure) for plugging the liquid injection hole 121 after injection of the electrolyte, so as to seal the electrochemical device 10 and reduce the possibility of water vapor from the outside entering the accommodation space 101 or the electrolyte leaking from the accommodation space 101.

[0139] In some embodiments, the liquid injection hole 121 can be a circular hole, which facilitates injection of the electrolyte through the liquid injection hole 121 and plugging of the liquid injection hole 121 by the liquid injection plug, thereby reducing the possibility of electrolyte leakage.

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

[0141] In some embodiments, the electrochemical device 10 further comprises a first electrical connection member 310 and a second electrical connection member 320. The battery shell 100 is provided with a pole 140 extending through the battery shell 100. One end of the first electrical connection member 310 is electrically connected to the positive tab on the positive electrode tab, and the other end is electrically connected to the pole 140, so that the external device can be electrically connected to the positive electrode tab through the pole 140 and the first electrical connection member 310. One end of the second electrical connection member 320 is electrically connected to the negative tab on the negative electrode tab, and the other end is electrically connected to the battery shell 100, so that the external device can be electrically connected to the negative electrode tab through the battery shell 100 and the second electrical connection member 320.

[0142] In other embodiments, the electrochemical device 10 further comprises a first electrical connection member 310 and a second electrical connection member 320. The battery shell 100 is provided with two poles 140 extending through the battery shell 100. One end of the first electrical connection member 310 is electrically connected to the positive electrode tab, and the other end is electrically connected to one of the poles 140, so that the external device can be electrically connected to the positive electrode tab through the pole 140 and the first electrical connection member 310. One end of the second electrical connection member 320 is electrically connected to the negative electrode tab, and the other end is electrically connected to the other pole 140, so that the external device can be electrically connected to the negative electrode tab through the pole 140 and the second electrical connection member 320.

[0143] In some embodiments, the first electrical connection member 310 and the positive tab can be a welded connection, and the second electrical connection member 320 and the negative tab can be a welded connection.

[0144] In other embodiments, the first electrical connection member 310 and the positive tab can be integrally formed, and the second electrical connection member 320 and the negative tab can be integrally formed.

[0145] In some embodiments, the first electrical connection member 310 and the second electrical connection member 320 can 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, which can increase the cross-sectional area of the pole 140 (the cross section of the pole 140 in the X-Z plane) in the case that the thickness of the battery cell shell 100 is limited, thereby increasing the connection area of the pole 140 with the second electrical connector 310 and the external device, and improving the connection reliability of the pole 140 with the second electrical connector 310 and the external device.

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

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

[0149] In some embodiments, the pole 140 can be arranged on the side wall 120 of the battery shell 100, which facilitates the electrical connection of the pole 140 with the external device.

[0150] In some embodiments, the projection of the liquid 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 influence of the liquid injection hole 121 on the electrical connection of the first electrical connector 310 with the pole 140 and the electrical connection of the second electrical connector 320 with the battery cell shell 100.

[0151] In some embodiments, the liquid injection hole 121 and the pole 140 can be arranged on the same side of the side wall 120, which facilitates the preparation of the battery cell shell 100.

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

[0153] Referring to FIG. 2 and FIG. 7, FIG. 7 is a structural schematic diagram of an electrochemical device according to some embodiments of the present application. In some embodiments, the length of the battery cell shell cover 200 along the first direction X is D1, the length of the battery cell shell cover 200 along the second direction Y is D2, the length of the battery cell shell 100 along the first direction X is D3, and the length of the battery cell shell 100 along the second direction Y is D4, which satisfy D1≤D3 and D2≤D4.

[0154] In some embodiments, the battery cell shell cover 200 can have a plate-like structure, so that the battery cell shell cover 200 can cover the open side of the battery cell shell 100, and the battery cell shell 100 and the battery cell shell cover 200 together define the accommodation space 101.

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

[0156] Due to the limited accuracy and cost of preparing the cell shell 100 and the cell shell cover 200, the size of the cell shell 100 and the size of the cell shell cover 200 may not be completely matched in production, i.e., D1=D3 and D2=D4. By making the size of the cell shell cover 200 slightly smaller than the size of the cell shell 100, the connection of the cell shell cover 200 and the cell shell 100 can be stable, and 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 can be 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 improve the energy density of the electrochemical device 10.

[0157] Referring to FIGS. 8 and 9, FIG. 8 is a cross-sectional view of the electrochemical device shown in FIG. 7 along the direction C-C, and FIG. 9 is a structure schematic view of a partial enlargement of D of the electrochemical device shown in FIG. 8. In some embodiments, the lengths of the two sides of the cell shell 100 along the first direction X beyond the length of the cell shell cover 200 are E1 and E2, respectively, and the lengths of the two sides of the cell shell 100 along the second direction Y beyond the length of the cell shell cover 200 are E3 and E4, respectively. The average values of E1, E2, E3, and E4 are ˉE, which satisfies ˉE≤0.05 mm, for example, ˉE can be 0.05 mm, 0.04 mm, or 0.03 mm, etc.

[0158] In FIG. 9, the size E1 of one side of the cell shell 100 along the first direction X beyond the cell shell cover 200 is schematically indicated, and other sizes such as E2, E3, and E4 are similar to E1 and are not indicated in the figure.

[0159] The lengths of the two sides of the electric core shell 100 along the first direction X beyond the length of the electric core shell cover 200 are E1 and E2 respectively, and the lengths of the two sides of the electric core shell 100 along the second direction Y beyond the length of the electric core shell cover 200 are E3 and E4 respectively. By making the average value of E1, E2, E3 and E4, i.e. ˉE, satisfy ˉE≤0.05mm, the length of the part of the flange surface 131 not beyond the electric core shell cover 200, i.e. the length of the part of the flange surface 131 connected with the electric core shell cover 200, is larger, thereby further facilitating the connection between the electric core shell 100 and the electric core shell cover 200, making the connection between the electric core shell 100 and the electric core shell cover 200 more stable, the sealing performance of the electrochemical device 10 better, and the electrochemical device 10 less likely to have a gap or be separated between the electric core shell 100 and the electric core shell cover 200 due to stress or environmental changes, and the reliability of the electrochemical device 10 higher. If ˉE is larger (e.g. greater than 0.05mm), the length of the part of the flange surface 131 not beyond the electric core shell cover 200, i.e. the length of the part of the flange surface 131 connected with the electric core shell cover 200, is smaller, which may affect the connection strength between the electric core shell 100 and the electric core shell cover 200.

[0160] In some embodiments, the two sides of the electric core shell 100 along the first direction X and the two sides of the electric core shell 100 along the second direction Y can all beyond the electric core shell cover 200.

[0161] In other embodiments, the side edges of the electric core shell 100 can also be aligned with the electric core shell cover 200, or the side edges of the electric core shell cover 200 can also beyond the electric core shell 100. For example, when one side of the electric core shell cover 200 along the first direction X beyond the electric core shell 100, E1 is negative. However, by making ˉE≤0.05mm, the four side edges of the electric core shell cover 200 do not excessively beyond the electric core shell 100, thereby reducing the overall occupied space of the electric core shell 100 and the electric core shell cover 200, and being beneficial to improve the energy density of the electrochemical device 10.

[0162] For example, E1≤0.05mm, E2≤0.05mm, E3≤0.05mm and E4≤0.05mm, which can make the length of the part of the flange surface 131 connected with the electric core shell 100 larger, and the electric core shell cover 200 connected with the electric core shell 100 more stable, while reducing the possibility that the electric core shell cover 200 protrudes from the electric core shell 100 after the electric core shell cover 200 is assembled with the electric core shell 100, thereby reducing the possibility that the overall size of the electrochemical device 10 is increased due to the assembly of the electric core shell cover 200, and being beneficial to improve the energy density of the electrochemical device 10.

[0163] In some embodiments, the cell shell 100 and the cell shell cover 200 can be connected by welding.

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

[0165] By connecting the cell shell 100 and the cell shell cover 200 by welding, the connection between the cell shell 100 and the cell shell cover 200 is stable, the sealing performance of the electrochemical device 10 is good, and the electrochemical device 10 is less likely to have a gap or separation between the cell shell 100 and the cell shell cover 200 due to stress or environmental changes, and the reliability of the electrochemical device 10 is high.

[0166] In some embodiments, the cell shell 100 and the cell shell cover 200 can be connected by welding.

[0167] Referring to FIG. 10, FIG. 10 is a partially enlarged structural schematic view of D of another state of the electrochemical device shown in FIG. 8. In some embodiments, the cell shell 100 and the cell shell cover 200 are connected by welding, and a welding portion 210 is formed between the cell shell 100 and the cell shell cover 200. The depth of the welding portion 210 in the thickness direction of the bottom 110 is H, and the width of the welding 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.

[0168] In some embodiments, the welding method of the cell shell 100 and the cell shell cover 200 can be laser welding, that is, the laser passes through the cell shell cover 200 to the cell shell 100, melts the connection between the cell shell 100 and the cell shell cover 200, and forms the welding portion 210.

[0169] In some embodiments, the depth of the welding portion 210 is the size of the welding portion 210 in the third direction Z, and the width of the welding portion 210 is the size of the welding portion 210 in the direction perpendicular to the third direction Z (including the first direction X and the second direction Y). For example, as shown in FIGS. 2 and 4, the width of the two parts of the welding portion 210 opposite in the first direction X is the size of the welding portion 210 in the first direction X, and the width of the two parts of the welding portion 210 opposite in the second direction Y is the size of the welding portion 210 in the second direction Y.

[0170] In the top welding mode of the rotary cutting shell, the welding part formed between the shell 100 and the shell cover 200 is formed in the opposite direction of the third direction Z, and the width of the welding part in the opposite direction of the third direction Z gradually decreases. The welding width is the width of the cross section of the welding part on the plane where the top surface (the end surface of the flange part away from the bottom wall 110) of the shell 100 is located, which can reach 1 / 4 of the wall thickness T1 of the side wall of the shell 100. Therefore, the welding width is small, and the welding strength between the shell 100 and the shell cover 200 is small. The electrochemical device 10 can be separated or have a gap between the shell 100 and the shell cover 200 due to stress or environmental changes, which affects the reliability of the electrochemical device 10.

[0171] In the large flange top welding mode, the welding part formed between the shell 100 and the shell cover 200 is formed in the opposite direction of the third direction Z, and the width of the welding part in the opposite direction of the third direction Z gradually decreases. The welding width is the width of the cross section of the welding part on the plane where the top surface (the end surface of the flange part away from the bottom wall 110) of the shell 100 is located, which can reach 1 / 2 of the wall thickness T1 of the side wall of the shell 100. Therefore, the welding width is small, and the welding strength between the shell 100 and the shell cover 200 is small. The electrochemical device 10 can be separated or have a gap between the shell 100 and the shell cover 200 due to stress or environmental changes, which affects the reliability of the electrochemical device 10.

[0172] In the embodiments of the present application, by making the depth H of the welding part 210 in the thickness direction of the bottom wall 110 and the width W4 of the welding part 210 in the thickness direction of the side wall 120 satisfy H≥0.5*T1 and W4≥T1, the welding strength between the shell 100 and the shell cover 200 is high, the connection between the shell 100 and the shell cover 200 is stable, the sealing performance of the electrochemical device 10 is good, the electrochemical device 10 is not easy to have a gap or be separated between the shell 100 and the shell cover 200 due to stress or environmental changes, and the reliability of the electrochemical device 10 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 shell 100 and the shell cover 200 is low, and the electrochemical device 10 can be separated or have a gap between the shell 100 and the shell cover 200 due to stress or environmental changes, which affects the reliability of the electrochemical device 10.

[0173] In some embodiments, part of the welding part 210 protrudes from the side of the shell cover 200, and the outer surface of the protruding part is an arc surface.

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

[0175] In the embodiments of the present application, the welding portion 210 protrudes from the side edge of the cell shell cover 200, so that the welding portion 210 has a large volume, 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 stable, the sealing performance of the electrochemical device 10 is better, the electrochemical device 10 is less likely to have a gap or be separated between the cell shell 100 and the cell shell cover 200 due to stress or environmental changes, and the reliability of the electrochemical device 10 is higher.

[0176] In some embodiments, part of the welding portion 210 can also protrude from the side edges of the cell shell 100 and the cell shell cover 200.

[0177] If the outer surface of the part of the welding portion 210 protruding from the cell shell cover 200 has an edge, when the welding portion 210 interferes with other devices, the welding portion 210 is prone to stress concentration and damage, and other devices are prone to damage. In the embodiments of the present application, the outer surface of the part of the welding portion 210 protruding from the cell shell cover 200 is an arc surface, which can reduce the possibility of damage to the welding portion 210 and other devices when the welding portion 210 interferes with other devices.

[0178] Table 1: Energy density and welding strength of the electrochemical device

[0179] Referring to Table 1, T1 in Table 1 is the wall thickness of the side wall of the cell shell, W1 is the width of the transition surface of the cell shell, W2 is the width of the flange surface of the cell shell, W3 is the width of the part of the flange of the cell shell protruding from the outer surface of the side wall, T2 is the thickness of the part of the flange of the cell shell protruding from the outer surface of the side wall, T3 is the thickness of the cell shell cover, Q1 is the energy density improvement rate of Comparative Example 2 and Examples 1-13 compared with Comparative Example 1, Q2 is the welding strength improvement rate of Comparative Example 2 and Examples 1-13 compared with Comparative Example 1, and Q3 is the welding strength improvement value of Comparative Example 2 and Examples 1-13 compared with Comparative Example 1. The thickness and width of each part are in mm, and the welding strength value is in N / mm. In Comparative Example 1, the cell shell does not have a flange, and the cell shell cover is directly connected to the top surface of the side wall of the cell shell. In Comparative Example 2, the cell shell has a flange, but the flange is not treated.

[0180] The method for measuring the welding strength of the cell case and the cell case is as follows: cutting the cell case and the cell case along the vertical direction of the welding seam to a predetermined width S, folding the sample into a T shape, using a high-iron tension machine to pull apart the metal parts at both ends of the welding seam, and measuring the maximum tension value F. The welding strength is F / S.

[0181] The following conclusions can be drawn from Table 1:

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

[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 case decreases, the wall thickness T1 of the cell case decreases, and the energy density of the electrochemical device can be improved.

[0184] 3. Referring to Examples 1-3, Examples 4-6, and Examples 11-13, 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, the energy density of the electrochemical device can be improved, but the welding strength of the cell case and the cell case decreases.

[0185] 4. Referring to Examples 1-3 and Examples 8-10, as the width W2 of the flange surface of the cell case decreases, 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 welding strength of the cell case and the cell case is less affected.

[0186] 5. Referring to Example 7 and Example 12, as 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 increase, the wall thickness T1 of the cell case can be reduced, and the energy density of the electrochemical device can be improved.

[0187] 6. Referring to Examples 6 and 8, as the width W1 of the transition surface of the cell case remains unchanged, 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, and the width W2 of the flange surface of the cell case increases, but the wall thickness T1 of the cell case decreases, which has a greater impact on the welding strength of the cell case and the cell case.

[0188] Table 2: Welding strength test of electrochemical device

[0189] Referring to Table 2, T1 in Table 2 is the wall thickness of the side wall of the battery cell shell (in the tested comparative examples and embodiments, the wall thickness of the bottom wall of the battery cell shell is equal to the wall thickness of the side wall), T3 is the thickness of the battery cell shell cover, and W3 is the width of the part of the flange of the battery cell shell protruding from the outer surface of the side wall. In Comparative Example 1, the battery cell shell is not provided with a flange, and the battery cell shell cover is directly connected to the top surface of the side wall of the battery cell shell. In Comparative Example 2, the battery cell shell is provided with a flange, but the flange is not treated. Example 4 is the electrochemical device of Example 4 in Table 1.

[0190] As can be seen from Table 2, compared with Comparative Example 1, the width W3 of the part of the flange of the battery cell shell protruding from the outer surface of the side wall is equal, the wall thickness T1 of the side wall of the battery cell shell is smaller, the welding strength of the electrochemical device is greatly improved, specifically, the welding strength is averagely increased by 43.87%, and at the same time, in combination with Table 1, the energy density of the electrochemical device is also increased by 2.26%. Compared with Comparative Example 2, the wall thickness T1 of the side wall of the battery cell shell is equal, the width W3 of the part of the flange of the battery cell shell protruding from the outer surface of the side wall is smaller, the welding strength of the electrochemical device is greatly improved, specifically, the welding strength is averagely increased by 30.15%, and at the same time, in combination with Table 1, the energy density of the electrochemical device is also increased by 2.2%.

[0191] Therefore, 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 the battery cell shell to have a higher welding strength with the battery cell shell.

[0192] The electrochemical device 10 provided in the embodiments of the present application can be used in a variety of fields. For example, the electrochemical device 10 can be used in a variety of electronic devices, such as a mobile phone, a tablet computer, a laptop computer, a wearable device, a smart home device, a smart car, and the like.

[0193] The electronic device can be any of the devices or systems to which the electrochemical device 10 is applied.

[0194] Referring to FIG. 11, FIG. 11 is a flowchart of a method for manufacturing an electrochemical device provided in some embodiments of the present application. The method for manufacturing the electrochemical device includes the following steps.

[0195] S410, stamping the raw material plate to form a battery cell shell.

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

[0197] S420, in the stamping process, the transition surface of the flange of the battery cell shell is extruded and formed to the inner side of the battery cell shell by flattening and negative angle extrusion, so that the width W1 of the transition surface 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.

[0198] In some embodiments, the transition surface of the flange portion of the battery cell shell can be formed by only the flattening method or only the negative angle extrusion method.

[0199] In some embodiments, the transition surface of the flange portion of the battery cell shell can be processed after the stamping, so that the width W1 of the transition surface 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.

[0200] S430, mounting 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 with the pole column of the battery cell shell, and the second electrical connector of the electrode assembly is connected with the battery cell shell, so as to achieve the mounting of the electrode assembly.

[0202] S440, covering the opening of the battery cell shell with the battery cell shell cover and fixedly connecting the battery cell shell cover with the battery cell shell.

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

[0204] In 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 the flattening and negative angle extrusion methods, so that the width of the flange surface of the battery cell shell is large, and the width of the part of the flange portion of the battery cell shell protruding from the side wall is small, thereby increasing the volume of the accommodation space and the energy density of the electrochemical device, and the wall thickness of the side wall is small, thereby further increasing the volume of the accommodation space and the energy density of the electrochemical device. If W1 is large (for example, greater than T1), it is possible that the width of the flange surface is small or the width of the part of the flange portion protruding from the side wall is large. The small width of the flange surface may affect the connection strength of the battery cell shell and the battery cell shell cover, and the large width of the part 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 battery cell shell cover with the battery cell shell includes: fixedly connecting the battery cell shell cover with the battery cell shell by the swing welding method.

[0206] The swing welding method makes the laser swing back and forth to form a welding portion extending along a curve between the battery cell shell and the battery cell shell cover, thereby increasing the area of the welding portion.

[0207] Linear welding is to make the laser move along a straight line to form a welding part extending along a straight line between the battery cell shell and the battery cell shell cover.

[0208] Since the swing welding needs to reserve a certain welding width, the swing welding is not easy to be used in the structure in which the battery cell shell cover and the battery cell shell reserve a narrow welding width, and linear welding or the like is generally used. In the embodiments of the present application, 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, which can make the width of the flange surface of the battery cell shell larger, and facilitate the swing welding.

[0209] The battery cell shell cover and the battery cell shell are welded and connected by the swing welding, which can increase the area of the welding part compared with linear welding or the like, thereby further increasing the welding strength of the battery cell shell and the battery cell shell cover, making the connection of the battery cell shell and the battery cell shell cover stable, the sealing of the electrochemical device good, and the electrochemical device not easy to produce a gap or separate between the battery cell shell and the battery cell shell cover due to stress or environmental changes, and the reliability of the electrochemical device high.

[0210] In other embodiments, the battery cell shell cover and the battery cell shell can also be welded and connected by linear welding or the like.

[0211] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0212] The above is only the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

An electric cell housing characterized by The side wall is arranged around the bottom wall and cooperates with the bottom wall to form a containing space with an opening. 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 with the cell shell cover, and the transition surface is curvedly connected with the flange surface and the inner surface and / or the outer surface of the side wall. The electric cell case according to claim 1, wherein 0 < W1 ≤ 0.7 * T1. The electric cell case according to claim 1, wherein The width of the flange surface in the thickness direction of the side wall is W2, and W2 ≥ 0.7 * T1 is satisfied. The electric cell case according to claim 1, wherein The flange surface is a plane, and the transition surface is an arc surface. The electric cell case according to claim 1, wherein At least a part of the flange portion protrudes from the outer surface of the side wall, the width of the part of the flange portion protruding from the outer surface of the side wall in the thickness direction of the side wall is W3, and 0.05 mm ≤ W3 ≤ 0.3 mm is satisfied. The electric cell case according to claim 5, wherein 0.05 mm ≤ W3 ≤ 0.15 mm. The electric cell case according to claim 1, wherein At least a part of the flange portion protrudes from the outer surface of the side wall, the thickness of the part of the flange portion protruding from the outer surface of the side wall is T2, and 0.7 * T1 ≤ T2 ≤ 1.1 * T1 is satisfied. The electric cell case according to claim 1, wherein 0.05 mm ≤ T1 ≤ 0.15 mm. The electric cell case according to claim 8, wherein 0.05 mm ≤ T1 ≤ 0.1 mm. The electric cell case according to claim 1, wherein The thickness of the part of the flange portion corresponding to the transition surface is T3, and T3 > T1 is satisfied. The electric cell case according to claim 10, wherein The T3 satisfies: T1 < T3 < 1.5 * T1. The electric cell case according to claim 1, wherein The thickness of the part of the flange portion corresponding to the transition surface is T3, and 0.06 mm ≤ T3 ≤ 0.2 mm is satisfied. The electric cell case according to claim 12, wherein The T3 satisfies: 0.09 mm ≤ T3 ≤ 0.12 mm. An electrochemical device characterized by The electrode assembly is accommodated in the containing space, and the cell shell cover covers the opening. The electrochemical device according to claim 14, wherein The length of the cell shell cover along the first direction is D1, the length of the cell shell cover along the second direction is D2, the length of the cell shell along the first direction is D3, the length of the cell shell along the second direction is D4, D1 ≤ D3 and D2 ≤ D4 are satisfied, and the first direction, the second direction and the thickness direction of the cell shell cover are perpendicular to each other. The electrochemical device according to claim 14, wherein The lengths of the two sides of the cell shell along the first direction beyond the length of the cell shell cover are E1 and E2 respectively, the lengths of the two sides of the cell shell along the second direction beyond the length of the cell shell cover are E3 and E4 respectively, the average value of E1, E2, E3 and E4 is ˉE, and ˉE ≤ 0.05 mm is satisfied. The electrochemical device according to claim 14, wherein The cell shell and the cell shell cover are welded or bonded. The electrochemical device according to claim 14, wherein The electric core shell and the electric core shell cover are welded, a welding part is formed between the electric core shell and the electric core shell cover, a depth of the welding part in a thickness direction of the bottom wall is H, a width of the welding part in a thickness direction of the side wall is W4, H is greater than or equal to 0.5*T1, and W4 is greater than or equal to T1. The electrochemical device according to claim 14, wherein The electric core shell and the electric core shell cover are welded, a welding part is formed between the electric core shell and the electric core shell cover, a part of the welding part protrudes from a side edge of the electric core shell cover, and an outer surface of the protruding part is an arc surface. An electric device characterized by comprising: The electrochemical device comprises the electric core shell and the electric core shell cover. A method for producing an electrochemical device, characterized by The electrochemical device comprises the electric core shell and the electric core shell cover. The raw plate is punched to form the electric core shell. During the punching, the transition surface of the flange part of the electric core shell is extruded to the inner side of the electric core shell by flattening and negative angle extrusion to make the width W1 of the transition surface in the thickness direction of the side wall of the electric core shell and the wall thickness T1 of the side wall of the electric core shell satisfy 0 The electrode assembly is installed in the accommodation space of the electric core shell. The electric core shell cover is arranged on the opening of the electric core shell, and the electric core shell cover and the electric core shell are fixedly connected. The method of claim 21, wherein The method for fixedly connecting the electric core shell cover and the electric core shell comprises: The electric core shell cover and the electric core shell are welded by swing welding.

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