Electrochemical device and electric equipment

Abstract

The application discloses an electrochemical device and an electric equipment. The electrochemical device comprises an electrode assembly and a shell. The shell comprises a first side wall and a second side wall oppositely arranged along a first direction, the first direction being a thickness direction of the electrode assembly, and the electrode assembly is arranged between the first side wall and the second side wall. The first side wall comprises a first outer surface and a first inner surface, the first outer surface is away from the electrode assembly relative to the first inner surface, the first outer surface has a first convex part, and the first inner surface has a first concave part at a position opposite to the first convex part. A normal projection of the first convex part on a first plane is located in a first angular position area of a normal projection of the first side wall on the first plane, and the first plane is perpendicular to the first direction. The electrochemical device can reduce the stress on the corner of the shell when the electrode assembly expands, thereby reducing the risk of damage and improving the reliability of the electrochemical device during use.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an electrochemical device and electrical equipment. Background Technology

[0002] Electrochemical devices are widely used in portable electronic devices, electric vehicles, power tools, drones, energy storage devices, and other fields. With the increasing energy density of electrochemical devices and the diversification of their application environments, higher demands are being placed on the reliability of these devices during use. Summary of the Invention

[0003] In view of the above problems, this application provides an electrochemical device and electrical equipment that can improve the reliability of the electrochemical device.

[0004] In a first aspect, this application provides an electrochemical device, which includes an electrode assembly and a housing. The housing includes a first sidewall and a second sidewall disposed opposite to each other along a first direction, the first direction being the thickness direction of the electrode assembly. The electrode assembly is disposed between the first sidewall and the second sidewall. The first sidewall includes a first outer surface and a first inner surface. The first outer surface is farther from the electrode assembly relative to the first inner surface. The first outer surface has a first protrusion, and the first inner surface has a first recess at a position opposite to the first protrusion. The orthographic projection of the first protrusion onto a first plane is located in the first angular region of the orthographic projection of the first sidewall onto the first plane, and the first plane is perpendicular to the first direction.

[0005] In the electrochemical device of this application, by providing a protrusion in the corner area of ​​the first sidewall of the housing, it is less likely to hit the corner of the housing during the expansion of the electrode assembly. At the same time, since there is a height difference between the inner surface of the corner area of ​​the first sidewall and the inner surface of the main body area, the electrode assembly will preferentially contact the main body area of ​​the first sidewall when it expands. This makes the tensile force generated by the expansion of the electrode assembly mainly act on the edge of the main body area, thereby alleviating the pulling on the corner of the housing, reducing the risk of damage to the corner of the housing, and improving the reliability of the electrochemical device during use.

[0006] In any of the above optional embodiments, the first outer surface further has a first base surface. Along the first direction, the first protrusion protrudes from the first base surface by a height of t. The second sidewall includes a second outer surface and a second inner surface. The second outer surface is farther away from the electrode assembly relative to the second inner surface. The distance between the first base surface and the second outer surface is T, satisfying: 0.05T≤t≤0.4T. Thus, while improving the reliability of the electrochemical device, it also enables the electrochemical device to possess a high volumetric energy density.

[0007] In any of the above optional embodiments, along the second direction, which is the length direction of the electrode assembly, the length of the first protrusion is l, and the length of the first sidewall is L, satisfying: 0.05L≤l≤0.4L. Thus, while improving the reliability of the electrochemical device, it also enables the electrochemical device to possess a high volumetric energy density.

[0008] In any of the above optional embodiments, along a third direction, which is the width direction of the electrode assembly, the width of the first protrusion is w, and the width of the first sidewall is W, satisfying: 0.05W ≤ w ≤ 0.4W. Thus, while improving the reliability of the electrochemical device, it also enables the electrochemical device to possess a high volumetric energy density.

[0009] In any of the above optional embodiments, when viewed along the first direction, the first sidewall is L-shaped, and the first corner region is the inner corner region of the orthographic projection of the first sidewall onto the first plane. The inventors of this application have discovered that, for L-shaped electrochemical devices, due to the special nature of their housing structure, the deformation at the inner corner of the housing is more severe when the electrode assembly expands, resulting in a higher risk of corner breakage. By providing a protrusion in the inner corner region of the first sidewall, the risk of damage to the inner corner of the housing caused by the electrode assembly expanding and compressing it can be significantly reduced, thereby improving the reliability of the electrochemical device during use.

[0010] In any of the above optional embodiments, the first sidewall includes a first short side extending along a second direction and a second short side extending along a third direction. The first short side and the second short side are connected to form an inner corner of the first sidewall. The length of the first protrusion coinciding with the first short side is l1, the length of the first protrusion coinciding with the second short side is l2, the length of the first short side is L1, and the length of the second short side is L2, satisfying at least one of the following conditions: (1) 0.05L1≤l1≤0.5L1; (2) 0.05L2≤l2≤0.5L2. In this way, while improving the reliability of the electrochemical device, the electrochemical device can also have a higher volumetric energy density.

[0011] In any of the above optional embodiments, the first sidewall further includes an arc-shaped chamfered edge located between the first short side and the second short side. This facilitates the processing and manufacturing of the housing and also improves the reliability of the connections at the corners within the housing.

[0012] In any of the above optional embodiments, the first outer surface is provided with a plurality of first protrusions, and the orthographic projections of the plurality of first protrusions on the first plane are respectively located in a plurality of first angular regions of the orthographic projection of the first sidewall on the first plane. In this way, the risk of damage to the corners of the housing caused by the expansion of the electrode assembly can be further reduced, thereby improving the reliability of the electrochemical device during use.

[0013] In any of the above optional embodiments, when viewed along the first direction, the first protrusion is any one of a quadrilateral, a sector, an L-shape, or a triangle.

[0014] In any of the above optional embodiments, the second sidewall includes a second outer surface and a second inner surface. The second outer surface is farther from the electrode assembly than the second inner surface. The second outer surface has a second protrusion, and the second inner surface has a second recess opposite to the second protrusion. The orthographic projection of the second protrusion onto the first plane is located in the second angular region of the orthographic projection of the second sidewall onto the first plane. This further reduces the risk of corner damage to the housing caused by the expansion of the electrode assembly, thus improving the reliability of the electrochemical device during use.

[0015] Secondly, this application provides an electrical device that includes the electrochemical device provided in the first aspect. Since the electrochemical device provided in the first aspect has a low risk of corner breakage during use, the electrical device including the aforementioned electrochemical device has high reliability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0017] Figure 1 This is an isometric view of an electrochemical device according to some embodiments of this application;

[0018] Figure 2 This is a cross-sectional view of a partial structure of an electrochemical device according to some embodiments of this application;

[0019] Figure 3 This is a top view of an electrochemical device according to some embodiments of this application;

[0020] Figure 4 This is an isometric view of an electrochemical device according to other embodiments of this application;

[0021] Figure 5 This is a top view of an electrochemical device according to other embodiments of this application;

[0022] Figure 6 This is a cross-sectional view of a partial structure of an electrochemical device according to other embodiments of this application;

[0023] Figure 7 This is a schematic diagram of the structure of an electrochemical device according to some embodiments of this application;

[0024] Figure 8This is a schematic diagram of the structure of an electrochemical device according to other embodiments of this application;

[0025] Figure 9 This is a schematic diagram of the structure of an electrochemical device according to some embodiments of this application.

[0026] The reference numerals in the attached diagram are as follows: 100-Electrochemical device; 10-Shell; 101-First sidewall; 1011-First outer surface; 10111-First protrusion; 10112-First base surface; 10121-First recess; 1012-First inner surface; 1013-First short side; 1014-Second short side; 1015-Edge; 1016-First long side; 1017-Fourth short side; 1018-Second long side; 1019-Third short side Side; 102-Second sidewall; 1021-Second outer surface; 1022-Second inner surface; 20-Electrode assembly; 201-Electrode tab; 202-Electrode assembly; 200-First plane; 30-First packaging part; 301-First peripheral wall; 302-First recess; 303-Second recess; 40-Second packaging part; 10222-Second protrusion; 10221-Second recess; X-First direction; Y-Second direction; Z-Third direction. Detailed Implementation

[0027] The technical solution of this application will now be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the following embodiments are only used to more clearly illustrate the technical solution of this application, and are not intended to limit the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0029] In the description of this application, the terms "first," "second," etc., are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly defined. Those skilled in the art will understand that, without conflict, the features in the embodiments described herein can be combined with other embodiments.

[0030] In the description of this application, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0031] In the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0032] Currently, electrochemical devices are widely used in portable electronic devices, electric vehicles, power tools, drones, energy storage devices, and other fields. To meet the demand for long-lasting power in these devices, the energy density requirements for electrochemical devices are increasingly stringent. To further improve energy density, measures such as increasing the coating weight of active material on the current collector per unit area or using high-specific-capacity active materials (e.g., silicon-based materials for lithium-ion batteries) are commonly employed. However, the inventors of this application have discovered that for such electrochemical devices, the expansion of the electrode plates increases significantly during charge-discharge cycles. This causes the electrode assembly to compress the corners of the casing, increasing the risk of damage at these corners. Simultaneously, during casing expansion, the corners of the casing are subjected to inward pulling forces, further increasing the risk of damage under the pressure of the electrode assembly, thus affecting the reliability of the electrochemical device.

[0033] Therefore, please refer to Figure 1 , Figure 2 and Figure 3This application provides an electrochemical device 100, which includes an electrode assembly 20 and a housing 10. The housing 10 includes a first sidewall 101 and a second sidewall 102 disposed opposite to each other along a first direction X, where the first direction X is the thickness direction of the electrode assembly 20. The electrode assembly 20 is disposed between the first sidewall 101 and the second sidewall 102. The first sidewall 101 includes a first outer surface 1011 and a first inner surface 1012. The first outer surface 1011 is away from the electrode assembly 20 relative to the first inner surface 1012. The first outer surface 1011 has a first protrusion 10111. The first inner surface 1012 has a first recess 10121 at a position opposite to the first protrusion 10111. The orthographic projection of the first protrusion 10111 onto a first plane 200 is located in the first angular region of the orthographic projection of the first sidewall 101 onto the first plane 200. The first plane 200 is perpendicular to the first direction X. In the electrochemical device 100 of this application, by providing a protrusion in the corner region of the first sidewall 101 of the housing 10, the electrode assembly 20 is less likely to hit the corner of the housing 10 during expansion. At the same time, since there is a height difference between the inner surface of the corner region of the first sidewall 101 and the inner surface of the main body region, the electrode assembly 20 preferentially contacts the main body region of the first sidewall 101 when it expands. This makes the tensile force generated by the expansion of the electrode assembly 20 mainly act on the edge 1015 of the main body region, thereby alleviating the tensile force on the corner of the housing 10, reducing the risk of damage to the corner of the housing 10, and improving the reliability of the electrochemical device 100 during use.

[0034] In some embodiments, the electrode assembly 20 includes a tab 201 and an electrode assembly 202. The electrode assembly 202 is housed in a receiving cavity of the housing 10. One end of the tab 201 is electrically connected to the electrode assembly 202, and the other end of the tab 201 extends out of the housing 10. The electrode assembly 202 typically includes a positive electrode, a separator, and a negative electrode, with the separator disposed between the positive and negative electrode. In some embodiments, the positive electrode includes a positive current collector and a positive active material layer coated on the surface of the positive current collector. The tab 201 includes a positive tab connected to the positive current collector. The negative electrode includes a negative current collector and a negative active material layer coated on the surface of the negative current collector. The tab 201 includes a negative tab connected to the negative current collector. Taking a lithium-ion battery as an example, the positive electrode current collector can be aluminum foil, and the positive electrode active material can include at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, ternary lithium, or lithium manganese oxide; the negative electrode current collector can be copper foil, and the negative electrode active material can include at least one of carbon materials or silicon-based materials. In some embodiments, the tab 201 can be integrally formed with the current collector. In other embodiments, the tab 201 can be separately formed from the electrode sheet, and the tab 201 is electrically connected to the current collector of the electrode sheet by riveting or welding. In some embodiments, the structure of the electrode assembly 20 can include, but is not limited to, a wound type or a stacked type.

[0035] In the following text, "outer" refers to the side away from the receiving cavity, and "inner" refers to the side facing the receiving cavity.

[0036] The housing 10 can be made of aluminum-plastic film, steel, aluminum, etc., and this application does not impose specific limitations. The housing 10 generally includes multiple walls that collectively define a receiving cavity. In some embodiments, the housing 10 may include a first part and a second part, which are encapsulated together to form the receiving cavity. Either the first part or the second part may have an opening, or both may have an opening. The structure of the first part may be the same as or different from the structure of the second part. For example, a groove may be provided in the first part, with the groove opening being an opening, through which the electrode assembly 20 can be assembled into the groove. The second part may be flat, and the second part closes the groove opening to form a closed receiving cavity. For example, grooves may also be provided in both the first and second parts, and after the two grooves are engaged and encapsulated in the first and second parts, the two grooves collectively define a closed receiving cavity.

[0037] In some embodiments, please refer to Figure 2A first recess 302 for accommodating the electrode assembly 20 can be located in the first packaging section 30. The wall of the first recess 302 in the first direction X is a first sidewall 101. The second packaging section 40 closes the first recess 302 to form a receiving cavity. The first packaging section 30 also includes a first peripheral wall 301. The first sidewall 101 and the first peripheral wall 301 surround the first recess 302. The second packaging section 40 is flat. The first protrusion 10111 and the first recess 10121 can be formed simultaneously with the formation of the first recess 302, thus achieving high processing efficiency and low cost. Alternatively, the first recess 302 can be processed first, followed by the processing of the first protrusion 10111 and the first recess 10121. In some embodiments, the second packaging section 40 may have a second recess 303 corresponding to the first recess 302.

[0038] Depending on the assembly environment of the electrochemical device 100 in the electrical equipment, the shape of the electrochemical device 100 can be rectangular, square, L-shaped, triangular, trapezoidal, T-shaped, etc.

[0039] Please refer to Figure 2 In this application, the first plane 200 is any plane perpendicular to the first direction X, and can be understood as a reference plane rather than referring to the surface of an entity.

[0040] The orthographic projection of the first protrusion 10111 on the first plane 200 is located in the first angular region of the orthographic projection of the first sidewall 101 on the first plane 200, meaning that the first protrusion 10111 and the first recess 10121 are located at the corner of the housing 10. The corner of the electrode assembly 20 corresponds to the corner of the housing 10. The first angular region can be understood as the area near the intersection of the two sides of the orthographic projection of the first sidewall 101 on the first plane 200. The corner can generally be understood as the position where at least three walls of the housing 10 used to define the receiving cavity intersect in pairs. The shape of the electrode assembly 20 can be understood as a reference body including multiple surfaces. Taking the electrode assembly 20 formed by stacking as an example, the electrode assembly 20 may include a top surface and a bottom surface arranged opposite each other along the electrode stacking direction, and a side surface surrounding the edge of the top surface and connecting to the bottom surface. The corner of the electrode assembly 20 can refer to the corner position of the projection of the top surface of the electrode assembly 20 along its thickness direction. Taking the wound electrode assembly 20 as an example, the electrode assembly 20 may include an outer peripheral surface and a top surface and a bottom surface opposite each other along the winding axis. Both the top surface and the bottom surface are connected to the edge of the outer peripheral surface. The corner position of the electrode assembly 20 may refer to the corner position of the projection of the outer peripheral surface of the electrode assembly 20 along its thickness direction.

[0041] Please see Figure 7 , Figure 8 and Figure 9In some embodiments, one or more first protrusions 10111 may be provided. In embodiments where multiple first protrusions 10111 are provided, the multiple first protrusions 10111 may be provided at any corner of the first sidewall 101.

[0042] According to some embodiments of this application, please refer to Figure 1 and Figure 2 The first outer surface 1011 also has a first base surface 10112. Along the first direction X, the first protrusion 10111 protrudes from the first base surface 10112 by a height of t. The second sidewall 102 includes a second outer surface 1021 and a second inner surface 1022. The second outer surface 1021 is farther away from the electrode assembly 20 relative to the second inner surface 1022. The distance between the first base surface 10112 and the second outer surface 1021 is T, satisfying: 0.05T≤t≤0.4T. Here, the first base surface 10112 refers to the surface of the first outer surface 1011 where the first protrusion 10111 is not provided. Thus, while improving the reliability of the electrochemical device 100, it also enables the electrochemical device 100 to possess a high volumetric energy density. In some embodiments, t can be 0.05T, 0.06T, 0.07T, 0.08T, 0.09T, 0.1T, 0.15T, 0.2T, 0.25T, 0.3T, 0.35T, 0.4T, or a range consisting of any two of the above.

[0043] According to some embodiments of this application, please refer to Figure 1 and Figure 2 Along the second direction Y, which is the length direction of the electrode assembly 20, the length of the first protrusion 10111 is l, and the length of the first sidewall 101 is L, satisfying: 0.05L ≤ l ≤ 0.4L. Here, the length of the first protrusion 10111 refers to its maximum dimension in the second direction Y, and the length of the first sidewall 101 refers to its maximum dimension in the second direction Y. Thus, while improving the reliability of the electrochemical device 100, it also enables the electrochemical device 100 to possess a high volumetric energy density. In some embodiments, l can be 0.05L, 0.06L, 0.07L, 0.08L, 0.09L, 0.1L, 0.15L, 0.2L, 0.25L, 0.3L, 0.35L, 0.4L, or any combination thereof.

[0044] According to some embodiments of this application, please refer to Figure 1 and Figure 3Along the third direction Z, where Z is the width direction of the electrode assembly 20, the width of the first protrusion 10111 is w, and the width of the first sidewall 101 is W, satisfying: 0.05W ≤ w ≤ 0.4W. Here, the width of the first protrusion 10111 refers to its maximum dimension along the third direction Z, and the width of the first sidewall 101 refers to its maximum dimension along the third direction Z. Thus, while improving the reliability of the electrochemical device 100, it also enables the electrochemical device 100 to possess a high volumetric energy density. In some embodiments, w can be 0.05W, 0.06W, 0.07W, 0.08W, 0.09W, 0.1W, 0.15W, 0.2W, 0.25W, 0.3W, 0.35W, 0.4W, or any combination thereof.

[0045] According to some embodiments of this application, please refer to Figure 4 and Figure 5 When viewed along the first direction X, the first sidewall 101 is L-shaped, and the first angular region is the inner corner region of the orthographic projection of the first sidewall 101 onto the first plane 200.

[0046] The inventors of this application have discovered that, for the L-shaped electrochemical device 100, due to the unique structure of its housing 10, the deformation at the corners of the housing 10 is more severe when the electrode assembly 20 expands, resulting in a higher risk of corner breakage. Please refer to... Figure 4 In an electrochemical device 100 where the first sidewall 101 is L-shaped, when the electrode assembly 20 expands, the housing 10 expands along the first direction X, causing the first sidewall 101 to pull on the inner corner of the housing 10. Because the first short side 1013 and the second short side 1014 at the inner corner are relatively short and have low structural strength, the connection between the first short side 1013 and the second short side 1014 is prone to collapse under the pull of the first sidewall 101, thus making the deformation at the inner corner of the housing 10 more severe. For example, in some embodiments, please refer to... Figure 5 The angle between the first short side 1013 and the second short side 1014 is 90°. When the electrode assembly 20 expands, the angle between the first short side 1013 and the second short side 1014 tends to collapse and shrink. In other words, compared with a regular-shaped shell 10, the L-shaped shell 10 has a higher risk of collapse and deformation at the inner corner when the electrode assembly 20 expands, thus making the risk of damage at the inner corner of the L-shaped shell 10 higher than at other corner positions. This application provides a protrusion in the inner corner area of ​​the first sidewall 101. On the one hand, it makes it less likely for the electrode assembly 20 to squeeze the inner corner of the shell 10 when it expands. On the other hand, it can alleviate the pulling of the first sidewall 101 on the inner corner, thereby better suppressing the collapse at the inner corner, reducing the risk of damage at the inner corner of the shell 10, and improving the reliability of the electrochemical device 100 during use.

[0047] Please refer to Figure 4 and Figure 5 The L-shaped first sidewall 101 has a first long side 1016 and a fourth short side 1017 opposite each other along the third direction Z, a second long side 1018 and a third short side 1019 opposite each other along the second direction Y, and a first short side 1013 extending along the second direction Y and a second short side 1014 extending along the third direction Z. The first long side 1016, the second long side 1018, the fourth short side 1017, the second short side 1014, the first short side 1013, and the third short side 1019 are connected end-to-end. The inner corner region can be understood as the area near the connection point of the first short side 1013 and the second short side 1014, which are projected onto the first plane 200.

[0048] The first corner region is the inner corner region of the orthographic projection of the first sidewall 101 onto the first plane 200. This means that the first protrusion 10111 and the first recess 10121 are located at the inner corner of the housing 10.

[0049] In some embodiments, an arc-shaped chamfer is provided at the inner corner of the L-shaped housing 10, that is, the first short side 1013 and the second short side 1014 are not directly connected, but are connected by an arc-shaped edge, which is also the edge of the first sidewall 101. This facilitates the processing and manufacturing of the housing 10, and also improves the reliability of the connection at the inner corner of the housing 10.

[0050] According to some embodiments of this application, the first sidewall 101 includes a first short side 1013 extending along the second direction Y and a second short side 1014 extending along the third direction Z. The first short side 1013 and the second short side 1014 are connected to form an inner corner of the first sidewall 101. The length of the first protrusion 10111 overlapping with the first short side 1013 is l1, and the length of the first protrusion 10111 overlapping with the second short side 1014 is l2. The length of the first short side 1013 is L1, and the length of the second short side 1014 is L2, satisfying at least one of the following conditions: (1) 0.05L1≤l1≤0.5L1; (2) 0.05L2≤l2≤0.5L2. In this way, while improving the reliability of the electrochemical device 100, the electrochemical device 100 can also have a higher volumetric energy density. In some embodiments, l1 can be a range of 0.05L1, 0.06L1, 0.07L1, 0.08L1, 0.09L1, 0.1L1, 0.15L1, 0.2L1, 0.25L1, 0.3L1, 0.35L1, 0.4L1, 0.45L1, 0.5L1, or any combination thereof. In some embodiments, l2 can be a range of 0.05L2, 0.06L2, 0.07L2, 0.08L2, 0.09L2, 0.1L2, 0.15L2, 0.2L2, 0.25L2, 0.3L2, 0.35L2, 0.4L2, 0.45L2, 0.5L2, or any combination thereof.

[0051] According to some embodiments of this application, please refer to Figure 2 , Figures 7-9 The first outer surface 1011 is provided with a plurality of first protrusions 10111, and the orthographic projections of the plurality of first protrusions 10111 on the first plane 200 are respectively located in a plurality of first corner regions of the orthographic projection of the first sidewall 101 on the first plane 200. In this way, the risk of damage to the corners of the housing 10 caused by the expansion of the electrode assembly 20 squeezing the housing 10 can be further reduced, and the reliability of the electrochemical device 100 during use can be improved. The plurality of first protrusions 10111 can be provided at opposite or adjacent corners of the first sidewall 101, and a first protrusion 10111 can be provided at each corner position of the first sidewall 101.

[0052] According to some embodiments of this application, please refer to Figure 4 , Figures 7-9 Viewed along the first direction X, the first convex part 10111 is any one of a quadrilateral, a sector, an L-shape, or a triangle. Please refer to... Figure 7 Each of the four corners of the first sidewall 101 has a triangular first protrusion 10111. Please refer to... Figure 8 A quadrilateral first protrusion 10111 is provided at one of the two diagonal positions of the first sidewall 101. Please refer to... Figure 9A rhomboid first protrusion 10111 is provided at one of the adjacent corner positions of the first sidewall 101. Please refer to... Figure 4 A fan-shaped first protrusion 10111 is provided at the inner corner of the first sidewall 101.

[0053] In the above design, when viewed along the first direction X, the first convex portion 10111 can be any one of a quadrilateral, a sector, an L-shape, or a triangle. This design allows the electrochemical device 100 to be adapted to more electrical devices, improving the adaptability of the electrochemical device 100.

[0054] According to some embodiments of this application, please refer to Figure 6 The second sidewall 102 includes a second outer surface 1021 and a second inner surface 1022. The second outer surface 1021 is farther away from the electrode assembly 20 relative to the second inner surface 1022. The second outer surface 1021 has a second protrusion 10222, and the second inner surface 1022 has a second recess 10221 opposite to the second protrusion 10222. The orthographic projection of the second protrusion 10222 on the first plane 200 is located in the second angular region of the orthographic projection of the second sidewall 102 on the first plane 200. Thus, when the electrode assembly 20 expands, the provision of the second protrusion 10222 makes it less likely that the corners of the two sidewalls of the housing 10 in the first direction X will be squeezed by the electrode assembly 20, further reducing the risk of damage at the corners of the housing 10 and improving the reliability of the electrochemical device 100.

[0055] The orthographic projection of the second protrusion 10222 on the first plane 200 may or may not overlap with the orthographic projection of the first protrusion 10111 on the first plane 200. In other words, the first protrusion 10111 and the second protrusion 10222 may be located at the same corner of the housing 10 or at different corners of the housing 10. One or more second protrusions 10222 may be provided. The second protrusion 10222 and the second recess 10221 may be formed in a single process or in two separate processes.

[0056] Please refer to Figure 6 In an embodiment where two grooves together define a closed receiving cavity, the first sidewall 101 is the bottom wall of one of the grooves, and the second sidewall 102 is the bottom wall of the other groove.

[0057] The electrochemical device 100 of this application includes, but is not limited to, lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries. The shape of the electrochemical device 100 of this application may include, but is not limited to, rectangles, L-shapes, squares, trapezoids, or other shapes, and this application does not impose specific limitations.

[0058] The following section uses lithium-ion batteries as an example to provide a more detailed explanation of the technical solution applied for.

[0059] Example 1

[0060] Preparation of positive electrode sheet: Lithium cobalt oxide, conductive agent Super P, and binder polyvinylidene fluoride are mixed in a weight ratio of 97.5:1:1.5, N-methylpyrrolidone (NMP) is added, and the mixture is stirred evenly under vacuum to obtain positive electrode slurry; the positive electrode slurry is uniformly coated on positive electrode current collector aluminum foil; dried, and then cold-pressed, cut, and slit to obtain positive electrode sheet.

[0061] Preparation of negative electrode sheet: The negative electrode active material graphite, the thickener sodium carboxymethyl cellulose (CMC), and the binder styrene-butadiene rubber (SBR) are mixed in a weight ratio of 96:1.5:2.5, deionized water is added, and the mixture is stirred evenly under the action of a vacuum mixer to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil; dried, and then cold-pressed, cut, and slit to obtain the negative electrode sheet.

[0062] Electrolyte preparation: In a dry argon atmosphere glove box, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 3:5:2, and lithium salt LiPF6 was added. After mixing evenly, the electrolyte was obtained, wherein the mass concentration of LiPF6 was 12.5%.

[0063] Preparation of the separator membrane: Alumina and polyvinylidene fluoride are mixed evenly in deionized water at a weight ratio of 95:5 to form a ceramic coating slurry, and polyvinylidene fluoride is dispersed in deionized water and mixed evenly to form an adhesive coating slurry. Subsequently, the ceramic coating slurry is uniformly coated onto one surface of a polyethylene porous substrate using a microgravure coating method. After drying, the adhesive coating slurry is coated onto the ceramic coating surface and the other surface of the polyethylene porous substrate by spraying. After drying, the desired separator membrane is obtained.

[0064] Lithium-ion battery fabrication: Positive electrode, separator, and negative electrode are stacked sequentially, with the separator acting as a separator between the positive and negative electrodes, resulting in a stacked electrode assembly. After welding tabs 201, the electrode assembly 20 is placed in a single-sided perforated aluminum-plastic film. The bottom wall of the single-sided perforation forms a rectangular first protrusion 10111 and a first recess 10121 at the two corners of the protruding side of the tab 201. After preliminary encapsulation, the prepared electrolyte is injected. Following vacuum sealing, settling, formation, shaping, and capacity testing, a square lithium-ion battery is obtained. The lithium-ion battery has a length L of 87 mm, a width W of 64 mm, and a thickness T of 4.8 mm. The first protrusion 10111 has a length l of 0.1L, a width w of 0.1W, and a height t of 0.1T.

[0065] Examples 2-6: The only difference from Example 1 is that the height t of the first protrusion 10111 is adjusted according to the proportions in Table 1.

[0066] Examples 7-16: The only difference from Example 3 is that the length l and width w of the first protrusion 10111 are adjusted according to the proportions in Table 1.

[0067] Example 17: The difference from Example 3 is that the lithium-ion battery is L-shaped, with the length L of the first long side 1016 being 76.5 mm, the length W of the second long side 1018 being 54 mm, the length L1 of the first short side 1013 being 44 mm, the length L2 of the second short side 1014 being 20 mm, the length of the third short side 1019 being 34 mm, the length of the fourth short side 1017 being 32.5 mm, and the thickness T being 5.1 mm; the first convex part 10111 and the first concave part 10121 in the fan shape are provided on the first sidewall 101 at the outer corner.

[0068] Examples 18-23: The difference from Example 17 is that the first protrusion 10111 and the first concave portion 10121 are provided on the first sidewall 101 at the inner corner and are fan-shaped. The length l1 of the first protrusion 10111 overlapping with the first short side 1013 and the length l2 of the first protrusion 10111 overlapping with the second short side 1014 are shown in Table 2.

[0069] Comparative Example 1: The difference from Example 1 is that the first protrusion 10111 and the first recess 10121 are not provided.

[0070] Comparative Example 2: The difference from Example 17 is that the first protrusion 10111 and the first recess 10121 are not provided.

[0071] Cyclic damage test: 10 lithium-ion batteries were tested in each group at a temperature of 35°C. The lithium-ion batteries were placed in a constant temperature environment at 35°C and left to stand for 60 minutes to reach a constant temperature state. Then, they were charged at a constant current of 1C to 4.48V, and then charged at a constant voltage of 4.48V to a current of 0.05C, and left to stand for 5 minutes. Next, they were discharged at a constant current of 0.7C to 3V, and left to stand for 5 minutes. This is one charge-discharge cycle. The above charge-discharge cycle was repeated 500 times. After the cycle, the corners of the lithium-ion batteries were checked for damage or leakage, and the number of damaged or leaking lithium-ion batteries was counted.

[0072] The specific parameters and cycle failure test results of the square lithium-ion batteries of Examples 1-16 and Comparative Example 1 are shown in Table 1.

[0073] Table 1: Specific parameters and cycle failure test results of the square lithium-ion batteries of Examples 1-16 and Comparative Example 1

[0074]

[0075]

[0076] As can be seen from the comparison of Examples 1-16 and Comparative Example 1 in Table 1, the lithium-ion battery of this application, by providing a first protrusion 10111 and a first recess 10121 at the corner, can effectively reduce the probability of damage at the corner of the casing 10 during lithium-ion battery cycling, thereby improving the reliability of the lithium-ion battery during use. Meanwhile, as can be seen from Examples 1-16, when the first protrusion 10111 satisfies 0.05T≤t≤0.4T, 0.05L≤l≤0.4L, and 0.05W≤w≤0.4W, it can improve the reliability of the lithium-ion battery while also enabling the lithium-ion battery to have a higher volumetric energy density.

[0077] The specific parameters and cycle failure test results of the L-type lithium-ion batteries of Examples 17-23 and Comparative Example 2 are shown in Table 2.

[0078] Table 2: Specific parameters and cycle failure test results of L-type lithium-ion batteries from Examples 17-23 and Comparative Example 2

[0079]

[0080] As shown in Table 2, a comparison between Example 17 and Comparative Example 2 reveals that by providing the first protrusion 10111 and the first recess 10121 at the outer corner, the probability of damage at the inner corner of the casing 10 during lithium-ion battery cycling can be effectively reduced, thereby improving the reliability of the lithium-ion battery during use. Furthermore, a comparison between Examples 18-22 and Example 17 shows that by providing the first protrusion 10111 and the first recess 10121 on the first sidewall 101 at the inner corner, the probability of damage at the inner corner of the casing 10 during lithium-ion battery cycling can be further significantly reduced, thereby further improving the reliability of the lithium-ion battery.

[0081] This application also provides an electrical device including the electrochemical device 100 provided in any one or more of the above embodiments. Since the electrochemical device 100 provided in the first aspect embodiment has a low risk of damage at the corner of the casing during use, the electrical device including the electrochemical device 100 has high reliability.

[0082] The electrical equipment covered by this application includes, but is not limited to: portable electronic devices, electric vehicles, power tools, drones, energy storage devices, VR / AR devices, etc.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way.

Claims

1. An electrochemical device, characterized in that, include: Electrode assembly; The housing includes a first sidewall and a second sidewall disposed opposite to each other along a first direction, the first direction being the thickness direction of the electrode assembly, and the electrode assembly being disposed between the first sidewall and the second sidewall; The first sidewall includes a first outer surface and a first inner surface. The first outer surface is away from the electrode assembly relative to the first inner surface. The first outer surface has a first protrusion. The first inner surface has a first recess at a position opposite to the first protrusion. The orthographic projection of the first protrusion on the first plane is located in the first angular region of the orthographic projection of the first sidewall on the first plane. The first protrusion and the first recess are located at a corner of the housing. The corner is the position where at least three wall portions of the housing intersect in pairs to define the receiving cavity. The first plane is perpendicular to the first direction.

2. The electrochemical device according to claim 1, characterized in that, The first outer surface also has a first base surface. Along the first direction, the first protrusion protrudes from the first base surface by a height of t. The second sidewall includes a second outer surface and a second inner surface. The second outer surface is farther away from the electrode assembly relative to the second inner surface. The distance between the first base surface and the second outer surface is T, which satisfies: 0.05T≤t≤0.4T.

3. The electrochemical device according to claim 1, characterized in that, Along the second direction, which is the length direction of the electrode assembly, the length of the first protrusion is l, and the length of the first sidewall is L, satisfying: 0.05L≤l≤0.4L.

4. The electrochemical device according to claim 1, characterized in that, Along a third direction, which is the width direction of the electrode assembly, the width of the first protrusion is w, and the width of the first sidewall is W, satisfying: 0.05W≤w≤0.4W.

5. The electrochemical device according to claim 1, characterized in that, When viewed along the first direction, the first sidewall is L-shaped, and the first corner region is the inner corner region of the orthographic projection of the first sidewall onto the first plane.

6. The electrochemical device according to claim 5, characterized in that, The first sidewall includes a first short side extending along a second direction and a second short side extending along a third direction. The first short side and the second short side are connected to form an inner corner of the first sidewall. The length of the first protrusion coinciding with the first short side is l1, the length of the first protrusion coinciding with the second short side is l2, the length of the first short side is L1, and the length of the second short side is L2, satisfying at least one of the following conditions: (1) 0.05L1≤l1≤0.5L1; (2) 0.05L2≤l2≤0.5L2.

7. The electrochemical device according to any one of claims 1 to 4, characterized in that, The first outer surface is provided with a plurality of first protrusions, and the orthographic projections of the plurality of first protrusions on the first plane are respectively located in a plurality of first angular regions of the orthographic projections of the first sidewall on the first plane.

8. The electrochemical device according to any one of claims 1 to 6, characterized in that, Viewed along the first direction, the first convex part is any one of quadrilateral, sector, L-shape or triangle.

9. The electrochemical device according to any one of claims 1 to 6, characterized in that, The second sidewall includes a second outer surface and a second inner surface. The second outer surface is away from the electrode assembly relative to the second inner surface. The second outer surface has a second protrusion. The second inner surface has a second recess at a position opposite to the second protrusion. The orthographic projection of the second protrusion on the first plane is located in the second angular region of the orthographic projection of the second sidewall on the first plane.

10. An electrical appliance, characterized in that, Includes the electrochemical device according to any one of claims 1-9.

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