Battery cells and electrical devices

Abstract

The present application discloses a battery cell and an electric device. The battery cell comprises a case and a pressure relief assembly, wherein the case has a receiving space and a liquid injection port communicating with the receiving space; the pressure relief assembly covers the liquid injection port, and the pressure relief assembly comprises a switching member, a sealing member, and a pressure relief member, wherein the case, the switching member, the sealing member, and the pressure relief member are sequentially stacked and installed along a first direction, and the switching member comprises a first main body portion and a first weld mark portion, wherein a projection on the switching member along the first direction of the sealing member is a first projection, the first projection is located within the first main body portion, and the first weld mark portion is installed to surround the periphery of the first projection, and furthermore, the first weld mark portion is installed spaced apart from the first projection, and the first weld mark portion is welded to the case. The battery cell provided by the present application has high safety.

Description

Technology Field

[0001] This application claims priority to a Chinese patent application filed with the Chinese Intellectual Property Office on January 29, 2024, with application number 202410121864.2 and title of the invention "battery cell and electric device," the entire contents of which are incorporated by reference into this application.

[0002] This application relates to the field of electric energy storage technology, and in particular to battery cells and electric devices. Background Technology

[0003] A battery cell is a device that converts external energy into electrical energy, stores it internally, and supplies power to external electrical devices (e.g., portable electronic devices) when needed. In the relevant technology, the battery cell includes a case, which is equipped with an injection port. Electrolyte can be injected into the case through this port, and the injection port is then sealed using a pressure release assembly. If the pressure release assembly is damaged during the battery cell assembly process, a large amount of gas is generated inside the battery when the battery cell is in a thermal runaway state. Since the damaged pressure release assembly cannot immediately release pressure against the internal air pressure of the case, it can lead to a battery explosion, thereby affecting user safety. The problem to be solved

[0004] In summary, based on the above, it is necessary to design a battery cell and an electrical device to solve the aforementioned technical problem. means of solving the problem

[0005] Embodiments of the present application provide a battery cell and an electric device, wherein the safety of the battery cell is improved.

[0006] In a first aspect, an embodiment of the present application provides a battery cell, said battery cell, said battery cell,

[0007] A case having a receiving space and a liquid injection hole communicating with the receiving space; and

[0008] The system includes a pressure release assembly covering the above-mentioned injection port, wherein the pressure release assembly includes a switching member, a sealing member, and a pressure release member, and the case, the switching member, the sealing member, and the pressure release member are sequentially stacked along a first direction, and the switching member includes a first main body part and a first weld mark part, and a projection on the switching member along the first direction of the sealing member is a first projection, the first projection is located within the first main body part, and the first weld mark part is installed to surround the periphery of the first projection, and the first weld mark part is installed spaced apart from the first projection, and the first weld mark part is welded to the case.

[0009] In some embodiments, the minimum separation distance between the first projection and the first weld mark is d3, and d3 satisfies 0.02 mm to 0.25 mm.

[0010] In some embodiments, d3 satisfies 0.05 mm to 0.18 mm.

[0011] In some embodiments, the transition member further includes an edge portion, and the first main body portion, the first weld mark portion, and the edge portion are installed sequentially from the inside to the outside.

[0012] In some embodiments, the case includes a case wall and a second weld mark portion, and the second weld mark portion is embedded in the case wall and connected to the first weld mark portion.

[0013] In some embodiments, the first weld mark portion includes a first surface close to the case and a second surface away from the case, and a projection along the first direction of the first surface is located within a projection along the first direction of the second surface.

[0014] In some embodiments, a projection along the first direction of the first surface covers the second weld mark portion.

[0015] In some embodiments, the length along the second direction of the first weld mark is the width of the first weld mark, and the width of the first weld mark gradually decreases along the direction from the pressure release member to the case, and the length along the second direction of the second weld mark is the width of the second weld mark, and the width of the second weld mark gradually decreases along the direction from the pressure release member to the case, and the second direction is perpendicular to the first direction.

[0016] In some embodiments, the width of the second surface is d1, and d1 satisfies 70 µm to 150 µm.

[0017] In some embodiments, the width of the surface facing away from the case of the second weld mark portion is d2, and d2 satisfies 30 µm to 80 µm.

[0018] In some embodiments, the length along the first direction of the second weld mark is H2, and the length along the first direction of the case wall is H3, and H2 and H3 satisfy 30 µm ≤ H2 ≤ 0.8 * H3.

[0019] In some embodiments, the minimum separation distance between the edge of the transition member and the first weld mark portion is d4, and d4 satisfies 0.02 mm to 0.22 mm.

[0020] In some embodiments, the switching member has a first through hole communicating with the injection hole, the sealing member has a second through hole communicating with the injection hole, and the pressure release member covers the second through hole.

[0021] In some embodiments, the projection on the transition member along the first direction of the sealing member partially enters the first through hole.

[0022] In some embodiments, the edge of the sealing member is located outside the projection on the sealing member along the first direction of the pressure release member.

[0023] In some embodiments, the projection on the case along the first direction of the switching member partially enters the injection hole.

[0024] In some embodiments, the outer diameter of the sealing member is 2.5 mm to 3.0 mm, the inner diameter of the sealing member is 0.6 mm to 1.0 mm, and the thickness along the first direction of the sealing member is 0.03 mm to 0.07 mm.

[0025] In some embodiments, the sealing member comprises a first adhesive layer, a second adhesive layer, and a third adhesive layer installed sequentially along a first direction, wherein the melting point of the second adhesive layer is higher than the melting point of the first adhesive layer, and the melting point of the second adhesive layer is higher than the melting point of the third adhesive layer.

[0026] In a second aspect, an embodiment of the present application also provides an electric device, comprising a battery cell according to the first aspect, and the battery cell is used to provide electricity.

[0027] In some embodiments, the electric device includes an outer case, the outer case includes a receiving space and an avoidance space that are in communication with each other, and the battery cell is partially fitted into the receiving space and the recess is fitted into the avoidance space.

[0028] Compared to related technologies, the battery cell and electric device provided by the embodiment of the present application install a first weld mark portion and weld it to the case to stabilize the connection between the case and the switching member, thereby preventing the electrolyte from leaking out of the case from between the case and the first weld mark portion; by installing a sealing member laminated between the first main body portion and the pressure release member, the connection between the switching member and the pressure release member is stabilized, thereby preventing the electrolyte from leaking out of the case from between the switching member and the pressure release member; and by installing the sealing member such that a projection on the switching member along the first direction is located within the first main body portion and is spaced apart from the first weld mark portion, the welding area is spaced apart from the sealing member by a certain distance when welding the first weld mark portion and the case, thereby preventing or reducing the impact of the welding operation on the sealing member connecting the switching member and the pressure release member during welding of the first weld mark portion and the case, thus preventing or reducing damage to the pressure release assembly and improving the safety of use of the manufactured battery unit. Effects of the invention

[0029] It is included in the contents of the present invention. Brief explanation of the drawing

[0030] To more clearly explain the technical methods of the embodiments of the present application, the drawings used in the embodiments of the present application are briefly introduced below. Clearly, the drawings described below are merely some embodiments of the present application, and a person skilled in the art can obtain other drawings based on these drawings without creative effort. FIG. 1 is a schematic diagram of the three-dimensional structure of a battery cell provided by one embodiment of the present application. FIG. 2 is a schematic diagram of the exploded structure of a battery cell provided by one embodiment of the present application. FIG. 3 is a schematic diagram of a partial cross-sectional structure of a battery cell provided by one embodiment of the present application. FIG. 4 is a schematic diagram of a partial cross-sectional structure of a battery cell provided by one embodiment of the present application. FIG. 5 is a schematic diagram of a partial cross-sectional structure of a battery cell provided by one embodiment of the present application. FIG. 6 is an electron microscope image of a partial cross-sectional structure of a sealing member provided by one embodiment of the present application. FIG. 7 is a schematic diagram of the three-dimensional structure of a battery cell provided by one embodiment of the present application. Figure 8 is a schematic diagram of the enlarged structure of part A shown in Figure 7. FIG. 9 is an electron microscope image of a partial cross-sectional structure of a battery cell provided by one embodiment of the present application. Among the drawings: 1: Case; 11: Injection hole; 12: Case wall; 13: Second weld mark; 14: Receiving space; 15: Upper cover; 16: Lower cover; 17: Recess; 2: Pressure release assembly; 21: Switching member; 211: First main body part; 212: First weld mark part; 2121: First surface; 2122: Second surface; 213: Edge part; 214: First through hole; 22: Sealing member; 221: Second through hole; 224: First adhesive layer; 222: Second adhesive layer; 223: Third adhesive layer; 23: Pressure release member; X: 1st direction; Y: 2nd direction; Z: 3rd direction. Specific details for implementing the invention

[0031] Features of each aspect of the present application and exemplary embodiments are described in detail below. In the following detailed description, many specific details are provided to provide a comprehensive understanding of the present application. However, it is obvious to those skilled in the art that the present application can be practiced without some of these specific details. The description of the following embodiments is intended only to provide a better understanding of the present application through examples.

[0032] It is necessary to explain that, provided there is no conflict, the embodiments and features of the embodiments of the present application may be combined with one another. The embodiments are described in detail below in conjunction with the drawings.

[0033] In one aspect, the present application provides a battery cell. To better understand the technical solution and technical effect of the present application, specific embodiments are described in detail below in conjunction with the drawings.

[0034] Referring to FIGS. 1, 2 and 3, the battery cell comprises a case (1) and a pressure release assembly (2), the case (1) has a receiving space (14) and a liquid injection port (11) communicating with the receiving space (14); the pressure release assembly (2) covers the liquid injection port (11), and the pressure release assembly (2) comprises a switching member (21), a sealing member (22), and a pressure release member (23), and the case (1), the switching member (21), the sealing member (22), and the pressure release member (23) are sequentially stacked and installed along a first direction (X). The switching member (21) includes a first main body part (211) and a first weld mark part (212), and a projection on the switching member (21) along the first direction (X) of the sealing member (22) is a first projection, the first projection is located within the first main body part (211), and the first weld mark part (212) is installed to surround the periphery of the first projection, and the first weld mark part (212) is installed spaced apart from the first projection, and the first weld mark part (212) is welded to the case (1).

[0035] The battery cell provided by the present application may specifically be a lithium-ion secondary battery cell, a lithium-ion primary battery cell, a lithium-sulfur battery cell, a sodium lithium-ion battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, and the embodiments of the present application are not limited thereto.

[0036] A case (1) has an upper cover (15) and a lower cover (16), and the upper cover (15) and the lower cover (16) are combined to form a receiving space (14) of the case (1). A battery core may be placed within the receiving space (14), and the battery core includes a positive electrode, a negative electrode, and a separator. The portion of the battery core having an active material constitutes the positive electrode and the negative electrode of the battery core, and the portion not having an active material constitutes a tab. Electrolyte may also be injected into the receiving space (14) through an injection port (11), and the positive electrode, the negative electrode, and the separator are immersed in the electrolyte. In some embodiments, the positive electrode, the negative electrode, and the separator are wound to form a wound structure. In other embodiments, the positive electrode, the separator, and the negative electrode are sequentially stacked to form a stacked structure. A person skilled in the art may select a suitable battery core as needed. During the charging and discharging process of the battery cell, the positive active material and the negative active material react with the electrolyte. The tab is connected to the electrode terminal and used to form a current circuit, and the electrode terminal is drawn out from one end of the case (1).

[0037] The case (1) may include an upper wall and a lower wall arranged along the thickness direction (Z), and a side wall connecting the upper wall and the lower wall, and a liquid injection hole (11) may be installed in the side wall, and the first direction (X) may be the length direction or width direction of the case (1).

[0038] The pressure release assembly (2) is welded to the case (1) through the switching member (21), so that the pressure release assembly (2) seals the injection port (11) to prevent the electrolyte inside the case (1) from leaking out. The sealing member (22) is made of a material having a preset melting point, and the preset melting point may be lower than the melting point of the switching member (21) and / or lower than the melting point of the pressure release member (23). When the battery cell is in a thermal runaway state, if the temperature of the sealing member (22) reaches the preset melting point, the sealing member (22) melts to form a pressure release passage between the switching member (21) and the pressure release member (23), and pressure release is carried out against the air pressure inside the case (1) through the pressure release passage to prevent or reduce the explosion of the battery cell.

[0039] The switching member (21) may be in the form of a metal plate to facilitate welding between the switching member (21) and the case (1). The switching member (21) may be a nickel plate having a passivation layer, and the passivation layer may be chromium oxide. The pressure release member (23) may also be in the form of a metal plate to facilitate connecting the switching member (21) and the pressure release member (23) with the sealing member (22). The pressure release member (23) may be a nickel plate having a passivation layer, and the passivation layer may be chromium oxide. A nickel plate with a cleaned surface may be immersed in a chromate solution to form a passivation layer of chromium oxide on the surface of the nickel plate. Optionally, the thickness of the passivation layer is 10 nm to 150 nm. The passivation layer may reduce or prevent the electrolyte from corroding the switching member (21) and the pressure release member (23). The conversion member (21) and the pressure release member (23) may be manufactured from different materials so that the conversion member (21) and the pressure release member (23) have different physicochemical properties, or the conversion member (21) and the pressure release member (23) may be manufactured from the same material to simplify the manufacturing steps.

[0040] When manufacturing a battery cell, the pressure release assembly (2) can be pre-assembled by sequentially stacking the switching member (21), the sealing member (22), and the pressure release member (23), and then the assembled pressure release assembly (2) can be welded to the case (1) so that the pressure release assembly (2) seals the injection port (11).

[0041] For example, when manufacturing a battery cell, a pressure release assembly (2) is pre-assembled by sequentially stacking a switching member (21), a sealing member (22), and a pressure release member (23); a battery core is placed inside a case (1), and an electrolyte is injected into the case (1) through a liquid injection port (11); an image showing the liquid injection port (11) is obtained, and the liquid injection port (11) in the image is recognized to obtain first coordinate information of the liquid injection port (11), and second coordinate information is obtained based on a preset offset coordinate and the first coordinate information; according to the second coordinate information, the pre-assembled pressure release assembly (2) is positioned on one side of the liquid injection port (11) so that the pressure release assembly (2) covers the liquid injection port (11). An image showing the switching member (21) is obtained, and the switching member (21) in the image is recognized to obtain third coordinate information of the weld; A carrier supporting the case (1) is moved and installed to face the laser galvanometer, and a welding gun is controlled to irradiate a laser to a position corresponding to the first welding mark portion (212) among the switching members (21) according to the third coordinate information, thereby forming a weld on the first welding mark portion (212) that is welded to the case (1).

[0042] In this embodiment, by installing a first weld mark portion (212) and welding it to the case (1), the connection between the case (1) and the switching member (21) is stabilized to prevent the electrolyte from leaking out of the case (1) from between the case (1) and the first weld mark portion (212); and by stacking and installing a sealing member (22) between the first main body portion (211) and the pressure release member (23), the connection between the switching member (21) and the pressure release member (23) is stabilized to prevent the electrolyte from leaking out of the case (1) from between the switching member (21) and the pressure release member (23); By installing the projection of the switching member (21) along the first direction (X) of the sealing member (22) so that it is located within the first main body part (211) and spaced apart from the first welding trace part (212), the welding area is spaced a certain distance from the sealing member (22) when welding the first welding trace part (212) and the case (1), thereby preventing or reducing the impact of the sealing member (22) on the connection between the switching member (21) and the pressure release member (23) during the welding of the first welding trace part (212) and the case (1), thereby preventing or reducing damage to the pressure release assembly (2) and improving the safety of use of the manufactured battery unit.

[0043] In some embodiments, the transition member (21) further includes an edge portion (213), and the first main body portion (211), the first weld mark portion (212), and the edge portion (213) are installed sequentially from the inside to the outside.

[0044] The first weld mark portion (212) can penetrate the transition member (21) along the first direction (X). The first weld mark portion (212) is installed to surround the first main body portion (211), and the edge portion (213) is installed to surround the first weld mark portion (212). The sealing member (22) does not cover the first weld mark portion (212) and the edge portion (213) in the first direction (X), so that when welding the transition member (21) and the case (1), the welding gun can directly act on the area where the first weld mark portion (212) is located, thereby facilitating the welding operation. When performing a welding operation, the welding gun can weld the case (1) and the transition member (21) along the boundary between the first main body part (211) and the edge part (213) to form a first welding mark part (212) at the boundary between the first main body part (211) and the edge part (213).

[0045] An edge portion (213) is installed on the outer side of the first weld mark portion (212) so that the area where the welding gun can operate to form the first weld mark portion (212) is sufficiently wide, thereby preventing the first weld mark portion (212) from not being stably connected to the case (1) due to a welding position error during welding.

[0046] Referring to FIG. 4 in combination, in some embodiments, the case (1) includes a case wall (12) and a second weld mark portion (13), and the second weld mark portion (13) is embedded in the case wall (12) and connected to the first weld mark portion (212).

[0047] When the welding gun acts on the switching member (21), high temperature is transmitted to the case (1) through the switching member (21), causing some of the material of the case (1) to melt and form a second welding mark (13) connected to the first welding mark (212). The second welding mark (13) formed by controlling the parameters of the welding gun is embedded in the case wall (12), and the second welding mark (13) is prevented from penetrating the case wall (12) to prevent over-welding and to prevent the welding operation from affecting the electrolyte, battery core, etc. inside the case (1).

[0048] In some embodiments, the first weld mark portion (212) includes a first surface (2121) close to the case (1) and a second surface (2122) away from the case (1), and the first weld mark portion (212) is located within a projection along the first direction (X) of the first surface (2121) in the projection along the first direction (X) of the second surface (2122).

[0049] The area of ​​the second surface (2122) is larger than the area of ​​the first surface (2121). During the welding operation, the welding gun may act on the surface facing away from the case (1) of the conversion member (21), and the heat generated from the welding gun is conducted from the surface facing away from the case (1) of the conversion member (21) to the surface facing the case (1) of the conversion member (21), so that the projection on the case (1) along the first direction (X) of the first surface (2121) is located within the projection on the case (1) along the first direction (X) of the second surface (2122), that is, the first welding mark portion (212) forms a structure in which one end is large and the other end is small along the first direction (X). The welding gun acts on the second surface (2122) to facilitate the welding operation.

[0050] In some embodiments, a projection along the first direction (X) of the first surface (2121) covers the second weld mark portion (13).

[0051] The first surface (2121) is connected to the second weld mark portion (13), and by increasing the area of ​​the first surface (2121), the connection stability between the conversion member (21) and the case (1) is improved. During the welding operation, the welding gun may act on the second surface (2122), and thermal energy is conducted from the first weld mark portion (212) to the second weld mark portion (13), so that the projection along the first direction (X) of the first surface (2121) covers the second weld mark portion (13) on the case (1), that is, the width of the first weld mark portion (212) is greater than the width of the second weld mark portion (13). By installing the first weld mark portion (212) to have smaller dimensions than the second weld mark portion (13), the process of forming the second weld mark portion (13) is prevented from affecting the electrolyte and the electrode assembly.

[0052] In some embodiments, the length along the second direction (Y) of the first weld mark portion (212) is the width of the first weld mark portion (212), and the width of the first weld mark portion (212) gradually decreases along the direction from the pressure release member (23) to the case (1), and the length along the second direction (Y) of the second weld mark portion (13) is the width of the second weld mark portion (13), and the width of the second weld mark portion (13) gradually decreases along the direction from the pressure release member (23) to the case (1), and the first direction (X) is perpendicular to the second direction (Y).

[0053] If the switching member (21) is annular, the second direction (Y) may be the radial direction of the switching member (21). The width of the first weld mark (212) gradually decreases along the direction from the pressure release member (23) to the case (1), and the width of the second weld mark (13) gradually decreases along the direction from the pressure release member (23) to the case (1), so that the cross-section along the first direction (X) of the first weld mark (212) and the cross-section along the first direction (X) of the second weld mark (13) can form a triangle. In the direction from the first weld mark (212) to the second weld mark (13), the width of the second weld mark (13) of the first weld mark (212) gradually decreases along the direction from the pressure release member (23) to the case (1), thereby reducing the effect of the second weld mark (13) formation process on the electrolyte and battery core.

[0054] Referring to FIG. 5 in combination, in some embodiments, the width of the second surface (2122) is d1, and d1 satisfies 70 µm to 150 µm.

[0055] The width of the second surface (2122) is d1. If d1 is too narrow, it affects the conduction of thermal energy from the first weld mark (212) to the second weld mark (13), thereby affecting the connection area between the first weld mark (212) and the second weld mark (13). If d1 is too wide, it affects the separation distance between the first weld mark (212) and the sealing member (22). By setting d1 to 70 µm to 150 µm, the first weld mark (212) and the second weld mark (13) formed during the welding process are stably connected, and at the same time, the separation distance between the first weld mark (212) and the sealing member (22) is sufficiently large so that the sealing member (22) receives heat and melts during the welding process, thereby ensuring that structural changes in the sealing member (22) can be prevented or reduced. Optionally, d1 is 90 µm to 120 µm.

[0056] In some embodiments, the width of the surface facing the case (1) of the second weld mark portion (13) is d2, and d2 satisfies 30 µm to 80 µm. The thermal effect on the sealing member (22) is relatively small while further ensuring the connection stability between the first weld mark portion (212) and the second weld mark portion (13).

[0057] The width of the surface facing away from the case (1) of the second weld mark portion (13) is d2. If d2 is too narrow, it affects the connection stability between the first weld mark portion (212) and the second weld mark portion (13). If d2 is too wide, the formed second weld mark portion (13) becomes too deep, making it easy to penetrate the case wall (12) and come into contact with the electrolyte, which affects the quality of the battery cell. By setting d1 to 30 µm to 80 µm, the first weld mark portion (212) and the second weld mark portion (13) formed during the welding process are stably connected, and the dimensions of the second weld mark portion (13) are sufficiently small to ensure that the formation of the second weld mark portion (13) can prevent or reduce the impact on the electrolyte and battery core. Optionally, d2 is 40 µm to 70 µm.

[0058] In some embodiments, the length along the first direction (X) of the second weld mark portion (13) is H2, and the length along the first direction (X) of the case wall (12) is H3, and 30 µm ≤ H2 ≤ 0.8 * H3.

[0059] The length along the first direction (X) of the first weld mark portion (212) is H1, and since the first weld mark portion (212) penetrates the first main body portion (211), H1 can be made equal to the length along the first direction (X) of the transition member (21). The second weld mark portion (13) is embedded in the case wall (12) forming the injection hole (11) of the case (1), so that the length H2 along the first direction (X) of the second weld mark portion (13) is smaller than the length H3 along the first direction (X) of the case wall (12). If H2 is too small, it affects the connection stability between the case (1) and the second weld mark portion (13). If H2 is too large, the formed second weld mark portion (13) becomes too deep, causing over-welding. By installing 30um ≤ H2 ≤ 0.8*H3, the first weld mark portion (212) and the second weld mark portion (13) formed during the welding process are stably connected, and the dimensions of the second weld mark portion (13) are sufficiently small to ensure that the formation of the second weld mark portion (13) can be prevented or reduced from affecting the electrolyte and battery core. Optionally, 30um ≤ H2 ≤ 80um.

[0060] In some embodiments, the minimum separation distance d3 between the first projection and the first weld mark portion (212) is 0.02 mm to 0.25 mm.

[0061] If d3 is too narrow, the welding heat generated during the formation of the first welding mark portion (212) may be conducted to the sealing layer, thereby reducing the reliability of the sealing layer. If d3 is too wide, the dimensions of the switching member (21) become too large or the dimensions of the sealing member (22) become too small; if the dimensions of the switching member (21) are too large, it is disadvantageous for miniaturization of the battery cell, and if the dimensions of the sealing member (22) are too small, the pressure release capacity of the pressure release passage formed by the molten sealing member (22) in the event of electrical runaway becomes insufficient. By setting d3 to 0.02 mm to 0.25 mm, the heat generated during the welding process is reduced or prevented from affecting the reliability of the sealing layer, and the dimensions of the switching member (21) and the sealing member (22) are appropriate. Optionally, d3 satisfies 0.05 mm to 0.18 mm.

[0062] In some embodiments, the minimum separation distance d4 between the edge of the transition member (21) and the first weld mark portion (212) is 0.02 mm to 0.22 mm.

[0063] The edge of the switching member (21) may be an edge facing away from the first main body part (211) of the edge part (213). If d4 is too narrow, the positioning requirements for the edge of the switching member (21) during the welding process increase, making it easy for the working position of the welding gun to deviate to the outside of the switching member (21), resulting in incomplete welding between the switching member (21) and the case (1), thereby reducing the welding sealing effect between the switching member (21) and the case (1). If d4 is too wide, the dimensions of the switching member become too large, which is disadvantageous for miniaturizing the battery cell. By setting d4 to 0.02 mm to 0.22 mm, incomplete welding between the switching member (21) and the case (1) is reduced or prevented.

[0064] In some embodiments, the switching member (21) has a first through hole (214) communicating with the injection hole (11), the sealing member (22) has a second through hole (221) communicating with the injection hole (11), and the pressure release member (23) covers the second through hole (221).

[0065] The injection port (11), the first through hole (214), and the second through hole (221) may be installed coaxially. The receiving space (14), the injection port (11), the first through hole (214), and the second through hole (221) are connected sequentially. The diameter of the injection port (11) may be greater than or equal to the diameter of the first through hole (214), and the diameter of the first through hole (214) may be greater than the diameter of the second through hole (221). In the event of thermal runaway occurring in the battery cell, the pressure release passage formed by the melting of the sealing member (22) is connected to the second through hole (221), so that the pressure release passage can perform exhaust for the high-pressure gas within the receiving space (14).

[0066] In some embodiments, the projection on the transition member (21) along the first direction (X) of the sealing member (22) partially enters the first through hole (214).

[0067] The sealing member (22) and the switching member (21) may be toroidal. The outer diameter Φ1 of the switching member (21) is larger than the outer diameter Φ2 of the sealing member (22), that is, the projection on the switching member (21) along the first direction (X) of the outer edge of the sealing member (22) is located inside the outer edge of the switching member (21), so that the first projection of the sealing member (22) stacked on the switching member (21) can be installed spaced apart from the first weld mark portion (212). The inner diameter Ψ1 of the switching member (21) is larger than the inner diameter Ψ2 of the sealing member (22), so that the projection on the switching member (21) along the first direction (X) of the sealing member (22) partially enters the first through hole (214), thereby improving the sealing performance of the sealing member (22) between the switching member (21) and the pressure release member (23).

[0068] In some embodiments, the edge of the sealing member (22) is located outside the projection on the sealing member (22) along the first direction (X) of the pressure release member (23).

[0069] The outer diameter Φ3 of the pressure release member (23) is smaller than the outer diameter Φ2 of the sealing member (22), so that the edge of the sealing member (22) is positioned outside the projection on the sealing member (22) along the first direction (X) of the pressure release member (23), and the pressure release member (23) can be laminated on the sealing member (22) to ensure that the sealing member (22) and the pressure release member (23) effectively form a seal. The outer diameter Φ3 of the pressure release member (23) is larger than the inner diameter Ψ2 of the sealing member (22), so that the pressure release member (23) can cover the second through hole (221) along the first direction (X), thereby realizing the sealing of the injection hole (11).

[0070] In some embodiments, the projection on the case (1) along the first direction (X) of the switching member (21) partially enters the injection hole (11).

[0071] The outer diameter Φ1 of the switching member (21) is larger than the diameter r1 of the injection hole (11), so that the switching member (21) can be covered on one side of the injection hole (11). The inner diameter Ψ1 of the switching member (21) is smaller than the diameter r1 of the injection hole (11), so that the projection on the case (1) along the first direction (X) of the switching member (21) partially enters the injection hole (11), thereby facilitating the injection of liquid into the receiving space (14) through the injection hole (11), reducing the diameter of the first through hole (214), reducing the diameter of the second through hole (221), and reducing the dimensions of the pressure release member (23), thereby improving the sealing performance of the switching member and the sealing member (22), and the sealing member (22) and the pressure release member (23), and the projection on the case (1) along the first direction (X) of the switching member (21) partially entering the injection hole (11) can improve the sealing performance of the pressure release assembly (2) without affecting the liquid injection.

[0072] The diameter D1 of the injection port (11) can be 0.5 to 3 mm, ensuring the efficiency of liquid injection through the injection port (11).

[0073] In some embodiments, the outer diameter Φ1 of the switching member (21) is 3 to 4 mm, the inner diameter Ψ1 of the switching member (21) is 0.5 to 2 mm, and the thickness along the first direction (X) of the switching member (21) is 0.05 to 1.5 mm. The inner diameter Ψ1 of the switching member (21) is the diameter of the first through hole (214), and if the inner diameter Ψ1 of the switching member (21) is too large, the area that the switching member (21) must connect with the case (1) increases, which is disadvantageous for sealing the switching member (21) and the case (1). If the inner diameter Ψ1 of the switching member (21) is too small, the diameter of the first through hole (214) becomes smaller, which is disadvantageous for releasing pressure through the first through hole (214) in the event of thermal runaway.

[0074] In one embodiment, the initial outer diameter of the sealing member (22) that is not bonded to the switching member (21) and the pressure release member (23) is 2 to 4 mm, the initial inner diameter of the sealing member (22) is 0.8 to 1.9 mm, and the initial thickness along the first direction (X) of the sealing member (22) is 0.05 to 1.5 mm. When the sealing member (22) is hot-pressed so that the sealing member (22) connects the switching member (21) and the pressure release member (23), the outer diameter Φ2 of the hot-pressed sealing member (22) is 2.5 to 3.0 mm, the inner diameter Ψ2 of the sealing member (22) is 0.6 to 1.0 mm, and the thickness along the first direction (X) of the sealing member (22) is 0.03 to 0.07 mm. The inner diameter Ψ2 of the sealing member (22) is the diameter of the second through hole (221), and if the inner diameter Ψ2 of the sealing member (22) is too large, the connection area between the sealing member (22) and the pressure release member (23) is reduced, which is disadvantageous for sealing the sealing member (22) and the pressure release member (23); if the inner diameter Ψ2 of the sealing member (22) is too small, the diameter of the second through hole (221) is reduced, making it easy for the molten sealing member (22) to have a Glue Overflow, which is disadvantageous for forming a pressure release passage and for pressure release in the case of thermal runaway.

[0075] In one embodiment, the outer diameter Φ3 of the pressure release member (23) is 2 to 3 mm, and the thickness along the first direction (X) of the pressure release member (23) is 0.1 to 0.2 mm. If the outer diameter Φ3 of the pressure release member (23) is too large, it is disadvantageous for the molten sealing member (22) to form a pressure release passage and disadvantageous for pressure release in the case of thermal runaway; if the outer diameter Φ3 of the pressure release member (23) is too small, the area where the pressure release member (23) can be connected to the sealing member (22) is reduced, which is disadvantageous for sealing the sealing member (22) and the pressure release member (23).

[0076] The outer diameter Φ1 of the switching member (21) is 3.4 mm, the inner diameter Ψ1 of the switching member (21) is 1 mm, and the thickness along the first direction (X) of the switching member (21) is 0.08 mm; the outer diameter Φ2 of the sealing member (22) is 2.2 mm, the inner diameter Ψ2 of the sealing member (22) is 1.2 mm, and the thickness along the first direction (X) of the sealing member (22) is 0.08 mm. The outer diameter Φ3 of the pressure release member (23) is 2.5 mm, and the thickness along the first direction (X) of the pressure release member (23) is 0.08 mm. The diameter D1 of the injection hole (11) is 1 to 2 mm. The initial outer diameter of the sealing member (22) that is not bonded to the switching member (21) and the pressure release member (23) is 2.2 mm, the initial inner diameter of the sealing member (22) is 1.2 mm, and the initial thickness along the first direction (X) of the sealing member (22) is 0.08 mm.

[0077] The sealing member (22) may be single-layer or multi-layer, and a single layer is manufactured by making the sealing member (22) of the same material so that the melting points at each part of the sealing member (22) match. A multi-layer is manufactured by making the sealing member (22) of different materials so that different layer structures have different melting points.

[0078] In some embodiments, the sealing member (22) is a single layer, and the melting point of the sealing member (22) is 123±5℃.

[0079] In some embodiments, the sealing member (22) is double-layered and includes a first adhesive layer (224) and a second adhesive layer (222), the first adhesive layer (224) is located on the side closer to the transition member (21) of the second adhesive layer (222), and the melting point of the first adhesive layer (224) is 123±5℃.

[0080] Referring to FIG. 6, in some embodiments, the sealing member (22) comprises a first adhesive layer (224), a second adhesive layer (222), and a third adhesive layer (223) installed sequentially along a first direction (X), and the melting point of the second adhesive layer (222) is higher than the melting point of the first adhesive layer (224), and the melting point of the second adhesive layer (222) is higher than the melting point of the third adhesive layer (223).

[0081] The first adhesive layer (224) and the third adhesive layer (223) may be made of the same material, and optionally, the melting point of the first adhesive layer (224) and the third adhesive layer (223) is 123±5℃. The melting point of the second adhesive layer (222) is 145±10℃. In the event of thermal runaway, the first adhesive layer (224) and the third adhesive layer (223) melt before the second adhesive layer (222), so that the second adhesive layer (222) can support the first adhesive layer (224) and the third adhesive layer (223). The first adhesive layer (224) melts to form a pressure release passage between the second adhesive layer (222) and the switching member (21); and the third adhesive layer (223) melts to form a pressure release passage between the second adhesive layer (222) and the pressure release member (23).

[0082] Referring to FIG. 7, in some embodiments, the maximum length along the second direction (Y) of the pressure release assembly (2) is greater than the maximum length along the third direction (Z) of the pressure release assembly (2), and the first direction (X), the second direction (Y), and the third direction (Z) are perpendicular to each other.

[0083] The reference plane where the second direction (Y) and the third direction (Z) are located may be parallel to the case wall (12) forming the injection port (11). The pressure release assembly (2) may be rectangular, and the pressure release assembly (2) satisfies that the maximum length along the second direction (Y) is greater than the maximum length along the third direction (Z), and the third direction (Z) may be the thickness direction of the battery cell.

[0084] The contact area between the pressure relief assembly (2) and the case (1) is increased by installing the pressure relief assembly (2) such that its maximum length along its second direction (Y) is greater than its maximum length along its third direction (Z). The length of the switching member (21) in the third direction (Z) may be 1.0 to 6 mm. Optionally, the length of the switching member (21) in the third direction (Z) is 1.0 mm to 3.5 mm. The length of the case (1) along the third direction (Z) may be 1.1 mm to 5 mm, and the thickness of the case wall (12) along the first direction (X) is 0.075 to 0.20 mm.

[0085] Referring to FIG. 8, in some embodiments, the case (1) has a recess (17), the recess (17) is formed concavely toward the direction closer to the battery core relative to the outer surface of the case (1), a liquid injection hole (11) is opened in the recess (17), a pressure release assembly (2) is installed in the recess (17), and the surface facing the switching member of the pressure release member (23) is in the same plane as the outer surface of the case (1), or the surface facing the switching member of the pressure release member (23) is located on the side of the outer surface of the case (1) closer to the battery core.

[0086] FIG. 9 is an electron microscope image of a partial cross-sectional structure of a battery cell. As can be seen in FIG. 9, a first weld mark (212) can be formed on the switching member (21) and a second weld mark (13) can be formed on the case (1) through laser welding.

[0087] In a second aspect, the present application also provides an electric device, the electric device comprising a battery cell provided in the first aspect, and the battery cell is used to provide electric energy.

[0088] The number of battery cells may be multiple, and the multiple battery cells are connected in series, parallel, or in a mixed manner to form a single whole, through which charging and discharging are performed externally; here, a mixed connection means that both series and parallel connections exist among the multiple battery cells.

[0089] Specific product types of electric devices include, but are not limited to, mobile terminals, smart wearables, power tools, electric vehicles, portable power sources, etc.

[0090] Since the battery cell has the aforementioned beneficial effects, the safety reliability of the electrical device is high.

[0091] The aforementioned beneficial effects are further explained through the following examples and comparative examples.

[0092] Battery cells were manufactured using the parameters of Tables 1, 2, and 3. Unless otherwise noted, the switching member, sealing member, and pressure release member of Experimental Examples 1-26 and Comparative Example 1 were installed coaxially. The width of the second surface (2122) is d1, the minimum separation distance between the first projection and the first weld mark (212) is d3, the width of the first surface (2122) is d2, and the minimum separation distance between the edge of the switching member (21) and the first weld mark (212) is d4.

[0093] A bonding strength test was performed on the manufactured battery cell. The case (1) was fixed, and a different thrust F1 was applied to the switching member (21) through the pin using a pin suitable for the injection port (11) to measure and obtain the bonding strength between the switching member (21) and the case (1). The case (1) and the switching member (21) were fixed, and a thrust F2 was applied to the pressure release member (23) through the pin using a pin suitable for the injection port (11) to measure the bonding strength in which the sealing member (22) connects the switching member (21) and the pressure release member (23). One experimental example or one comparative example was repeated by setting up 100 groups, and the average bonding strength of the battery cells of the same group was calculated and the average value was recorded as the bonding strength of the corresponding battery cell experimental example or comparative example.

[0094] High temperature and high humidity tests were performed on the manufactured battery cells. Fully charged battery cells were left in an open circuit for 42 days at (65±2)°C and 90-95% humidity, and the battery cores were removed every 7 days to observe whether leakage was present on the exterior of the battery cores. If there was no leakage on the exterior, it was recorded that the fully charged battery cells had passed the test. One experimental example or one comparative example was repeated by setting up 100 groups, and the probability of passing the test for the battery cells in the same group was calculated and recorded as the high temperature and high humidity test pass rate.

[0095] Table 1

[0096]

[0097] F2 represents the bonding strength of the sealing member (22) connecting the switching member (21) and the pressure release member (23). Through Experimental Examples 1-8, it can be seen that F2 increases as d3 increases while d1 and d4 are kept constant. This implies that the greater the separation distance between the sealing member (22) and the first weld mark (212), the better the bonding strength of the sealing member (22) connecting the switching member (21) and the pressure release member (23), and thus the more stable the structure of the pressure release assembly (2). As d3 increases, the battery cell has a higher leakage test pass rate in a high temperature and high humidity environment, and the safety of the battery cell is better.

[0098] In Comparative Example 1, d3 is 0, which means that the first weld mark portion (212) formed by welding the switching member (21) and the case (1) along the edge of the sealing member (22) is installed along the edge of the sealing member (22). When comparing Comparative Example 1 and Example 1, it can be seen that when the first weld mark portion (212) is installed so as not to be separated from the first projection of the sealing member (22), F2 is relatively small and the leakage test pass rate is low, so the process of forming the first weld mark portion (212) affects the sealing member (22), causing the bonding strength connecting the sealing member (22) to the switching member (21) and the pressure release member (23) to deteriorate and the safety of the battery cell to decrease.

[0099] Comparing Example 1 and Example 9, it can be seen that when d3 is less than 20 µm, F2 decreases, indicating that the welding process affects the structure of the sealing member (22) and that the battery cell has poor safety with a leakage test pass rate of less than 90% in a high temperature and high humidity environment. Comparing Example 8 and Example 10, when d3 is greater than 250 µm, F2 remains constant and the leakage test pass rate of the battery cell remains constant in a high temperature and high humidity environment, meaning that when d3 is greater than 250 µm, an increase in d3 does not affect F2 or the leakage test pass rate. The larger the value of d1+d3+d4, the larger the outer diameter of the switching member (21), which is disadvantageous for miniaturization of the pressure release assembly.

[0100] Table 2

[0101]

[0102] F1 represents the bonding strength between the switching member (21) and the case (1). Through Experimental Examples 4 and 11 to 16, it can be seen that when d3 and d4 are kept constant, F1 increases as d1 increases. This means that the wider the second surface (2122), the better the bonding strength between the switching member (21) and the case (1), and the more stable the connection between the pressure release assembly (2) and the case (1). When d1 increases, the battery cell has a higher leakage test pass rate in a high temperature and high humidity environment, and the safety of the battery cell is better.

[0103] Comparing Example 16 and Example 17, when d1 is greater than 150 µm, F1 continues to increase, but the battery cell's leakage test pass rate in a high temperature and high humidity environment remains constant, meaning that when d1 is greater than 150 µm, an increase in d3 does not significantly affect the leakage test pass rate. The larger the value of d1+d3+d4, the larger the outer diameter of the switching member (21) and the more disadvantageous it is for miniaturization of the pressure release assembly. Comparing Example 11 and Example 18, when d1 is less than 60 µm, F1 decreases, and the battery cell's leakage test pass rate in a high temperature and high humidity environment is less than 90%, indicating poor safety of the battery cell.

[0104] Table 3

[0105]

[0106] Through Experimental Examples 19 to 24, it can be seen that when d2 increases while d1 is kept constant, F1 increases, which means that when the width of the first surface (2122) increases, the bonding strength between the switching member (21) and the case (1) improves, and the connection between the pressure release assembly (2) and the case (1) becomes more stable. Through Experimental Examples 26 and 19 to 22, it can be seen that when d2 increases between 20 µm and 60 µm, the battery cell has a higher leakage test pass rate in a high temperature and high humidity environment and the safety of the battery cell is better. Through Experimental Examples 22 to 25, it can be seen that when d2 increases between 60 µm and 90 µm, the battery cell has a lower leakage test pass rate in a high temperature and high humidity environment, and the safety of the battery cell is worse. This means that when d2 is greater than a certain threshold, the welding process affects the structure of the sealing member (22), which affects the safety of the battery cell in a high temperature and high humidity environment.

[0107] Comparing Example 25 and Example 26, it can be seen that when d3 is less than 250 µm or d3 is greater than 250 µm, the battery cell has a leakage test pass rate of less than 90% in a high temperature and high humidity environment, indicating poor safety of the battery cell.

[0108] Furthermore, in this specification, the term "and / or" describes the association of associated objects and indicates that three types of relationships may exist. For example, A and / or B may represent the three cases where A exists alone, where A and B exist simultaneously, or where B exists alone. Additionally, in this specification, the symbol " / " generally indicates that the preceding and succeeding associated objects are in an "or" relationship.

[0109] It should be understood that, in the embodiments of the present application, "B corresponding to A" indicates that B is associated with A and that B can be determined according to A. However, the fact that B is determined according to A does not mean that B is determined solely by A, but that B may also be determined according to A and / or other information.

[0110] The above is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto, and all various equivalent modifications or substitutions readily conceivable by a person skilled in the art within the scope of the technology disclosed in the present application should be included within the scope of protection of the present application. Accordingly, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

Claim 1 A battery cell comprising: a case having a receiving space and a liquid injection hole communicating with said receiving space; and a pressure release assembly covering said liquid injection hole, wherein the pressure release assembly includes a switching member, a sealing member, and a pressure release member, and the case, said switching member, said sealing member, and said pressure release member are sequentially stacked and installed along a first direction, and the switching member includes a first main body part and a first weld mark part, and the projection of the sealing member on the switching member along the first direction is a first projection, said projection is located within the first main body part, said first weld mark part is installed to surround the periphery of said first projection, said first weld mark part is installed spaced apart from said first projection, and said first weld mark part is welded to said case. Claim 2 A battery cell according to claim 1, characterized in that the minimum separation distance between the first projection and the first weld mark portion is d3, and d3 satisfies 0.02mm to 0.25mm. Claim 3 A battery cell according to paragraph 2, characterized in that d3 satisfies 0.05mm to 0.18mm. Claim 4 A battery cell according to any one of claims 1 to 3, wherein the switching member further includes an edge portion, and the first main body portion, the first weld mark portion, and the edge portion are installed sequentially from the inside to the outside. Claim 5 A battery cell according to any one of claims 1 to 3, wherein the case comprises a case wall and a second weld mark portion, and the second weld mark portion is embedded in the case wall and connected to the first weld mark portion. Claim 6 A battery cell according to claim 5, wherein the first weld mark portion comprises a first surface close to the case and a second surface facing away from the case, and the projection of the first surface along the first direction is located within the projection of the second surface along the first direction. Claim 7 A battery cell according to claim 6, characterized in that the projection along the first direction of the first surface covers the second weld mark portion. Claim 8 A battery cell according to claim 7, wherein the length along the second direction of the first weld mark is the width of the first weld mark, and the width of the first weld mark gradually decreases along the direction from the pressure release member to the case, and the length along the second direction of the second weld mark is the width of the second weld mark, and the width of the second weld mark gradually decreases along the direction from the pressure release member to the case, and the second direction is perpendicular to the first direction. Claim 9 A battery cell according to claim 8, characterized in that the width of the second surface is d1, and d1 satisfies 70 µm to 150 µm. Claim 10 A battery cell according to claim 8, characterized in that the width of the surface facing away from the case of the second weld mark portion is d2, and d2 satisfies 30 µm to 80 µm. Claim 11 A battery cell according to claim 5, characterized in that the length along the first direction of the second weld mark portion is H2, the length along the first direction of the case wall is H3, and H2 and H3 satisfy 30um ≤ H2 ≤ 0.8*H3. Claim 12 A battery cell characterized in that, in any one of claims 1 to 3, the minimum separation distance between the edge of the switching member and the first weld mark portion is d4, and d4 satisfies 0.02mm to 0.22mm. Claim 13 A battery cell according to any one of claims 1 to 3, wherein the switching member has a first through hole communicating with the liquid injection hole, the sealing member has a second through hole communicating with the liquid injection hole, and the pressure release member covers the second through hole. Claim 14 A battery cell according to claim 13, characterized in that the projection on the switching member along the first direction of the sealing member partially enters the first through hole. Claim 15 A battery cell according to any one of claims 1 to 3, characterized in that the edge of the sealing member is located outside the projection on the sealing member along the first direction of the pressure release member. Claim 16 A battery cell characterized in that, in any one of claims 1 to 3, the projection on the case along the first direction of the switching member partially enters the injection hole. Claim 17 A battery cell according to any one of claims 1 to 3, characterized in that the outer diameter of the sealing member is 2.5 mm to 3.0 mm, the inner diameter of the sealing member is 0.6 mm to 1.0 mm, and the thickness of the sealing member along the first direction is 0.03 mm to 0.07 mm. Claim 18 A battery cell according to any one of claims 1 to 3, wherein the sealing member comprises a first adhesive layer, a second adhesive layer, and a third adhesive layer installed sequentially along the first direction, and wherein the melting point of the second adhesive layer is higher than the melting point of the first adhesive layer and the melting point of the second adhesive layer is higher than the melting point of the third adhesive layer. Claim 19 An electric device comprising a battery cell according to any one of claims 1 to 18, wherein the battery cell is used to provide electricity.

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