Electrochemical apparatus and electric device

Abstract

The present application discloses an electrochemical apparatus and an electric device. The electrochemical apparatus comprises an electrode assembly and a housing; the housing has a first side wall and a second side wall which are oppositely arranged in a first direction; the first direction is the thickness direction of the electrode assembly; the electrode assembly is arranged between the first side wall and the second side wall; the first side wall has a first outer surface and a first inner surface; the first outer surface is distant from the electrode assembly relative to the first inner surface; the first outer surface is provided with a first protrusion; the first inner surface is provided with a first recess at a position opposite to the first protrusion; the orthographic projection of the first protrusion on a first plane is located in a first angular region of the orthographic projection of the first side wall on the first plane; and the first plane is perpendicular to the first direction. According to the electrochemical apparatus of the present application, by providing the protrusion in the angular region of the first side wall, the stress borne by corners of the housing can be reduced when the electrode assembly expands, thereby reducing the risk of damage to the corners, and improving the reliability of the electrochemical apparatus during use.

Description

Electrochemical devices and electrical equipment Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrochemical device and electrical equipment. Background Art

[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 requirements are placed on the reliability of electrochemical devices during use.

[0003] Summary of the Invention

[0004] In view of the above problems, the present application provides an electrochemical device and an electrical equipment, which can improve the reliability of the electrochemical device.

[0005] In a first aspect, the present application provides an electrochemical device, comprising an electrode assembly and a housing, the housing comprising a first sidewall and a second sidewall disposed opposite 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 comprises a first outer surface and a first inner surface, the first outer surface being farther from the electrode assembly than the first inner surface, the first outer surface having a first protrusion, the first inner surface having a first concave portion at a position opposite the first protrusion, the orthographic projection of the first protrusion on a first plane being located within a first angular region of the orthographic projection of the first sidewall on the first plane, and the first plane being perpendicular to the first direction.

[0006] In the electrochemical device of the present application, by providing a protrusion in the corner area of ​​the first side wall of the shell, it is less likely to hit the corner of the shell during the expansion of the electrode assembly. At the same time, due to the height difference between the inner surface of the corner area of ​​the first side wall and the inner surface of the main body area, when the electrode assembly expands, it preferentially contacts the main body area of ​​the first side wall, so that the tension generated by the expansion of the electrode assembly mainly acts on the edges of the main body area, thereby alleviating the pulling on the corners of the shell, reducing the risk of damage to the corners of the shell, and improving the reliability of the electrochemical device during use.

[0007] In any of the above optional embodiments, the first outer surface further includes a first base surface, the first protrusion protrudes from the first base surface by a height t along the first direction, 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, and the distance between the first base surface and the second outer surface is T, satisfying the following: 0.05T≤t≤0.4T. In this manner, while improving the reliability of the electrochemical device, the electrochemical device can also have a higher volumetric energy density.

[0008] In any of the above optional embodiments, along the second direction (the second direction being 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 the following relationship: 0.05L≤l≤0.4L. This improves the reliability of the electrochemical device while also enabling the electrochemical device to have a higher volumetric energy density.

[0009] In any of the above optional embodiments, along the third direction (the third direction being 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 the following relationship: 0.05W≤w≤0.4W. In this manner, while improving the reliability of the electrochemical device, the electrochemical device can also have a higher volumetric energy density.

[0010] In any of the above optional embodiments, when viewed along the first direction, the first side wall is L-shaped, and the first corner area is the inner corner area of ​​the orthographic projection of the first side wall on the first plane. The inventors of the present application have found that for L-shaped electrochemical devices, due to the particularity of their shell structure, when the electrode assembly expands, the deformation of the inner corners of the shell is more serious, and the risk of corner damage is higher. By providing a protrusion in the inner corner area of ​​the first side wall, the risk of the inner corners of the shell being squeezed when the electrode assembly expands, causing damage to the inner corners of the shell, can be significantly reduced, thereby improving the reliability of the electrochemical device during use.

[0011] In any of the above optional embodiments, the first sidewall includes a first short side extending along the second direction and a second short side extending along the 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 overlapping with the first short side is l1, the length of the first protrusion overlapping 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 volume energy density.

[0012] In any of the above optional embodiments, the first side wall further includes an arc-shaped chamfered edge between the first short side and the second short side, which can facilitate the processing and manufacturing of the housing and improve the reliability of the connection at the corner inside the housing.

[0013] 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 corner regions of the orthographic projection of the first side wall on the first plane. This further reduces the risk of damage to the corners of the casing due to compression caused by expansion of the electrode assembly, thereby improving the reliability of the electrochemical device during use.

[0014] In any of the above optional embodiments, when viewed along the first direction, the first protrusion is any one of a quadrilateral, a fan-shaped, an L-shaped or a triangle.

[0015] In any of the above optional embodiments, the second sidewall includes a second outer surface and a second inner surface, the second outer surface being farther away from the electrode assembly than the second inner surface, the second outer surface having a second protrusion, and the second inner surface having a second concave portion opposite the second protrusion, wherein the orthographic projection of the second protrusion on the first plane is located in a second corner region of the orthographic projection of the second sidewall on the first plane. This further reduces the risk of damage to the corners of the casing due to compression by the electrode assembly during expansion, thereby improving the reliability of the electrochemical device during use.

[0016] In a second aspect, the present application provides an electrical device comprising the electrochemical device provided in the first aspect. Since the electrochemical device provided in the first aspect has a low risk of damage to the corners of the housing during use, the electrical device comprising the electrochemical device has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings.

[0018] FIG1 is an axonometric view of an electrochemical device according to some embodiments of the present application;

[0019] FIG2 is a cross-sectional view of a portion of an electrochemical device according to some embodiments of the present application;

[0020] FIG3 is a top view of an electrochemical device according to some embodiments of the present application;

[0021] FIG4 is an axonometric view of electrochemical devices according to other embodiments of the present application;

[0022] FIG5 is a top view of an electrochemical device according to some other embodiments of the present application;

[0023] FIG6 is a cross-sectional view of a portion of the structure of an electrochemical device according to some other embodiments of the present application;

[0024] FIG7 is a schematic structural diagram of an electrochemical device according to some embodiments of the present application;

[0025] FIG8 is a schematic structural diagram of an electrochemical device according to some other embodiments of the present application;

[0026] FIG9 is a schematic structural diagram of an electrochemical device according to some other embodiments of the present application.

[0027] The accompanying drawings are numeraled as follows: 100 - electrochemical device; 10 - housing; 101 - first side wall; 1011 - first outer surface; 10111 - first convex portion; 10112 - first base surface; 10121 - first concave portion; 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 Edge; 102-second side wall; 1021-second outer surface; 1022-second inner surface; 20-electrode assembly; 201-ear; 202-electrode piece assembly; 200-first plane; 30-first packaging portion; 301-first peripheral wall; 302-first pit; 303-second pit; 40-second packaging portion; 10222-second convex portion; 10221-second concave portion; X-first direction; Y-second direction; Z-third direction. DETAILED DESCRIPTION

[0028] The technical solution of the present application will be described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the following embodiments are only used to more clearly illustrate the technical solution of the present application, and are not intended to limit the scope of protection of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusions.

[0030] In the description of this application, the terms "first" and "second" are only used to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined. It will be understood by those skilled in the art that the features in the embodiments described herein can be combined with other embodiments in the absence of conflict.

[0031] In the description of this application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of this application.

[0032] In the description of this application, unless otherwise specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; they can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0033] At present, electrochemical devices are widely used in portable electronic devices, electric vehicles, electric tools, drones, energy storage devices and other fields. In order to meet the demand for long-term battery life of electrical equipment, the energy density of electrochemical devices is required to be higher and higher. In order to further improve the energy density, measures such as increasing the coating weight of active materials on the current collector per unit area or using active materials with high specific capacity (for example, for lithium-ion batteries, silicon-based materials) are usually adopted. However, the inventors of this application have found that for such electrochemical devices, the expansion of the electrode sheets will increase significantly during the charge and discharge cycle, causing the electrode assembly to squeeze the corners of the shell, increasing the risk of damage to the corners of the shell. At the same time, when the shell expands, the corners of the shell are subjected to an inward pulling force. Under the squeezing of the electrode assembly, the risk of damage to the corners of the shell is further increased, thereby affecting the reliability of the electrochemical device.

[0034] In view of this, referring to FIG1 , FIG2 , and FIG3 , the present application provides an electrochemical device 100 . The electrochemical device 100 includes an electrode assembly 20 and a housing 10 . The housing 10 includes a first sidewall 101 and a second sidewall 102 , which are arranged opposite each other along a first direction X. 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 farther away from the electrode assembly 20 than 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 the first protrusion 10111 . The orthographic projection of the first protrusion 10111 on a first plane 200 is located in a first angular region of the orthographic projection of the first sidewall 101 on the first plane 200 . The first plane 200 is perpendicular to the first direction X. In the electrochemical device 100 of the present application, by providing a protrusion in the corner area of ​​the first side wall 101 of the shell 10, it is less likely to hit the corner of the shell 10 during the expansion process of the electrode assembly 20. At the same time, due to the height difference between the inner surface of the corner area of ​​the first side wall 101 and the inner surface of the main body area, when the electrode assembly 20 expands, it preferentially contacts the main body area of ​​the first side wall 101, so that the pulling force generated by the expansion of the electrode assembly 20 mainly acts on the edge 1015 of the main body area, thereby alleviating the pulling on the corner of the shell 10, reducing the risk of damage to the corner of the shell 10, and improving the reliability of the electrochemical device 100 during use.

[0035] In some embodiments, the electrode assembly 20 includes a tab 201 and a plate assembly 202. The plate assembly 202 is accommodated in the accommodating cavity of the housing 10. One end of the tab 201 is electrically connected to the plate assembly 202, and the other end of the tab 201 extends out of the housing 10. The plate assembly 202 generally includes a positive electrode sheet, a separator, and a negative electrode sheet, and the separator is disposed between the positive electrode sheet and the negative electrode sheet. In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, the tab 201 includes a positive tab, and the positive tab is connected to the positive electrode current collector. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, the tab 201 includes a negative tab, and the negative tab is connected to the negative electrode current collector. Taking lithium-ion batteries 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 iron manganese 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 processed and formed from the pole piece, and the tab 201 is electrically connected to the current collector of the pole piece 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 laminated type.

[0036] Hereinafter, the outer side refers to the side facing away from the accommodating cavity, and the inner side refers to the side facing the accommodating cavity.

[0037] The material of the shell 10 can be aluminum-plastic film, steel shell, aluminum shell, etc., and this application does not impose specific restrictions. The shell 10 generally includes a plurality of wall portions, and the plurality of wall portions together define a accommodating cavity. In some embodiments, the shell 10 may include a first part and a second part, and the first part and the second part are packaged together to form a accommodating cavity. One of the first part and 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, and the notch of the groove is an opening, and the electrode assembly 20 may be assembled into the groove through the notch. The second part may be flat, and the second part closes the notch to form a closed accommodating cavity. For example, grooves may also be provided in both the first part and the second part. After the two grooves are relatively buckled and the first part and the second part are packaged, the two grooves together define a closed accommodating cavity.

[0038] In some embodiments, referring to FIG. 2 , a first recess 302 for accommodating the electrode assembly 20 may be provided in the first packaging portion 30 . The wall portion of the first recess 302 in the first direction X is the first sidewall 101 . The second packaging portion 40 encloses the first recess 302 to form a receiving cavity. The first packaging portion 30 further includes a first peripheral wall 301 . The first sidewall 101 and the first peripheral wall 301 enclose the first recess 302 . The second packaging portion 40 is flat. The first protrusion 10111 and the first recess 10121 may be formed by machining at the same time as the first recess 302 is formed. This results in high machining efficiency and low cost. The first recess 302 may also be machined first, followed by the first protrusion 10111 and the first recess 10121. In other embodiments, the second packaging portion 40 may have a second recess 303 corresponding to the first recess 302 .

[0039] Depending on the assembly environment of the electrochemical device 100 in the electrical equipment, the outer shape of the electrochemical device 100 may be rectangular, square, L-shaped, triangular, trapezoidal, T-shaped, etc.

[0040] Please refer to FIG. 2 . The first plane 200 in the present application is any plane perpendicular to the first direction X, and can be understood as a reference plane rather than referring to a physical surface.

[0041] 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 side wall 101 on the first plane 200, which means that the first protrusion 10111 and the first recess 10121 are located at the corner of the shell 10. The angular position of the electrode assembly 20 corresponds to the corner of the shell 10. The first angular region can be understood as the area near the position where the two sides of the orthographic projection of the first side wall 101 on the first plane 200 intersect. The corner can generally be understood as the position where at least three walls of the shell 10 used to define the accommodating cavity intersect with each other. 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 can include a top surface and a bottom surface arranged opposite to each other along the stacking direction of the electrode sheets, and a side surface arranged around the edge of the top surface and connected to the bottom surface. The angular position 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 that are opposite to each other along the winding axis. The top surface and the bottom surface are both 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 outer peripheral surface of the electrode assembly 20 projected along its thickness direction.

[0042] Please refer to Figures 7, 8 and 9. In some embodiments, one or more first protrusions 10111 can be provided. In embodiments where multiple first protrusions 10111 are provided, multiple first protrusions 10111 can be provided at any corner position of the first side wall 101.

[0043] According to some embodiments of the present application, referring to FIG1 and FIG2 , the first outer surface 1011 further includes a first base surface 10112. Along the first direction X, the first protrusion 10111 protrudes from the first base surface 10112 by a height 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 than the second inner surface 1022. The distance between the first base surface 10112 and the second outer surface 1021 is T, satisfying the following: 0.05T≤t≤0.4T. The first base surface 10112 refers to the portion of the first outer surface 1011 where the first protrusion 10111 is not provided. In this manner, while improving the reliability of the electrochemical device 100, the electrochemical device 100 can also have a higher volumetric energy density. In some embodiments, t may 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.

[0044] According to some embodiments of the present application, referring to Figures 1 and 2 , along the second direction Y, which is the length 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 the following: 0.05L ≤ l ≤ 0.4L. The length of the first protrusion 10111 refers to the maximum dimension of the first protrusion 10111 in the second direction Y, and the length of the first sidewall 101 refers to the maximum dimension of the first sidewall 101 in the second direction Y. This improves the reliability of the electrochemical device 100 while also enabling the electrochemical device 100 to have a higher 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 a range consisting of any two of the foregoing.

[0045] According to some embodiments of the present application, referring to Figures 1 and 3 , along the third direction Z, which is the width 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 the following: 0.05W ≤ w ≤ 0.4W. The width of the first protrusion 10111 refers to the maximum dimension of the first protrusion 10111 in the third direction Z, and the width of the first sidewall 101 refers to the maximum dimension of the first sidewall 101 in the third direction Z. This improves the reliability of the electrochemical device 100 while also enabling the electrochemical device 100 to have a higher 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 a range consisting of any two of the foregoing.

[0046] According to some embodiments of the present application, referring to FIG. 4 and FIG. 5 , when viewed along the first direction X, the first side wall 101 is L-shaped, and the first corner area is the inner corner area of ​​the orthographic projection of the first side wall 101 on the first plane 200 .

[0047] The inventors of this application have discovered that, for an L-shaped electrochemical device 100, due to the unique structure of its housing 10, when the electrode assembly 20 expands, deformation at the inner corners of the housing 10 becomes more severe, increasing the risk of corner damage. Referring to FIG4 , in an electrochemical device 100 with an L-shaped first sidewall 101, when the electrode assembly 20 expands, the housing 10 expands along a first direction X, causing the first sidewall 101 to pull on the inner corners of the housing 10. Because the first short side 1013 and the second short side 1014 at the inner corners are shorter and have lower structural strength, the pull of the first sidewall 101 can easily cause the junction of the first short side 1013 and the second short side 1014 to collapse, thereby further exacerbating deformation at the inner corners of the housing 10. For example, in some embodiments, referring to FIG5 , 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, the L-shaped shell 10 has a higher risk of collapse and deformation at the inner corner when the electrode assembly 20 expands than the shell 10 with a regular shape, so that the risk of damage at the inner corner of the L-shaped shell 10 is higher than that at other corners. The present application provides a protrusion in the inner corner area of ​​the first side wall 101. On the one hand, the electrode assembly 20 is less likely to squeeze the inner corner of the shell 10 when it expands. At the same time, it can alleviate the pulling of the first side wall 101 on the inner corner, thereby better suppressing the collapse of the inner corner, thereby reducing the risk of damage to the inner corner of the shell 10 and improving the reliability of the electrochemical device 100 during use.

[0048] 4 and 5 , the L-shaped first sidewall 101 has a first long side 1016 and a fourth short side 1017 that are opposite each other along a third direction Z, a second long side 1018 and a third short side 1019 that are opposite each other along a second direction Y, and a first short side 1013 that extends along the second direction Y and a second short side 1014 that extends 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 between the first short side 1013 and the second short side 1014, where the orthographic projection of the first sidewall 101 on the first plane 200 is located.

[0049] The first corner region is an inner corner region of the orthographic projection of the first side wall 101 on the first plane 200 , which means that the first protrusion 10111 and the first recess 10121 are located at the inner corner of the housing 10 .

[0050] In some embodiments, the inner corners of the L-shaped housing 10 are provided with curved chamfers, that is, the first short side 1013 and the second short side 1014 are not directly connected, but are connected via a curved side, which is also the edge of the first side wall 101. This facilitates the processing and manufacturing of the housing 10 and also improves the reliability of the connection at the inner corners of the housing 10.

[0051] According to some embodiments of the present application, the first side wall 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 side wall 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, which satisfies 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 volume energy density. In some embodiments, l1 can be 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 a range consisting of any two of the above. In some embodiments, l2 can be 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 a range consisting of any two of the above.

[0052] According to some embodiments of the present application, referring to Figures 2, 7, and 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 compression of the housing 10 during expansion of the electrode assembly 20 can be further reduced, thereby improving the reliability of the electrochemical device 100 during use. The plurality of first protrusions 10111 can be provided at diagonally 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.

[0053] According to some embodiments of the present application, referring to Figures 4 and 7 to 9, when viewed along the first direction X, the first protrusion 10111 is any one of a quadrilateral, a fan-shaped, an L-shaped, or a triangle. Referring to Figure 7, the four corners of the first side wall 101 are provided with triangular first protrusions 10111. Referring to Figure 8, a quadrilateral first protrusion 10111 is provided at a pair of diagonal positions of the first side wall 101. Referring to Figure 9, a diamond-shaped first protrusion 10111 is provided at a pair of adjacent corner positions of the first side wall 101. Referring to Figure 4, a fan-shaped first protrusion 10111 is provided at the inner corner of the first side wall 101.

[0054] In the above solution, the first protrusion 10111 is any one of a quadrilateral, a sector, an L-shape, or a triangle when viewed along the first direction X. This design allows the electrochemical device 100 to be compatible with more electrical devices, thereby improving the adaptability of the electrochemical device 100.

[0055] According to some embodiments of the present application, referring to FIG. 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 than the second inner surface 1022. The second outer surface 1021 has a second protrusion 10222. The second inner surface 1022 has a second recess 10221 at a position opposite the second protrusion 10222. The orthographic projection of the second protrusion 10222 on the first plane 200 is located in the second corner 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 can prevent the corners of the two side walls of the housing 10 in the first direction X from being 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.

[0056] The orthographic projection of the second convex portion 10222 on the first plane 200 may or may not overlap with the orthographic projection of the first convex portion 10111 on the first plane 200. In other words, the first convex portion 10111 and the second convex portion 10222 may be located at the same corner of the housing 10 or at different corners of the housing 10. One or more second convex portions 10222 may be provided. The second convex portion 10222 and the second concave portion 10221 may be formed in a single process or in two separate processes.

[0057] 6 , in an embodiment where two grooves jointly define a closed accommodating cavity, the first side wall 101 is the bottom wall of one of the grooves, and the second side wall 102 is the bottom wall of the other groove.

[0058] The electrochemical device 100 of the present 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 the present application may include but is not limited to rectangular, L-shaped, square, trapezoidal, or other shapes, and the present application does not impose specific limitations.

[0059] The following takes lithium-ion batteries as an example to further explain the technical solution of the application.

[0060] Example 1

[0061] Preparation of positive electrode sheet: The positive electrode active material lithium cobalt oxide, the conductive agent Super P, and the 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 the action of a vacuum mixer to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil; and the mixture is dried, and then cold pressed, cut into pieces, and slit to obtain a positive electrode sheet.

[0062] Preparation of the 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; and the mixture is dried, and then cold pressed, cut, and slit to obtain a negative electrode sheet.

[0063] Preparation of electrolyte: 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, an electrolyte was obtained, wherein the mass concentration of LiPF6 was 12.5%.

[0064] Preparation of the isolation membrane: Alumina and polyvinylidene fluoride are mixed evenly in deionized water in 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 a bonding coating slurry; the ceramic coating slurry is then evenly coated on one surface of the polyethylene porous substrate by a micro-concave coating method, and after drying, the bonding coating slurry is sprayed on the ceramic coating surface and the other side surface of the polyethylene porous substrate, and the desired isolation membrane is obtained after drying.

[0065] Preparation of a lithium-ion battery: The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrode sheets to provide isolation, thereby obtaining a laminated electrode assembly. After welding the tabs 201, the electrode assembly 20 is placed in an outer packaging aluminum-plastic film with a single-sided trough, wherein the bottom wall of the single-sided trough 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 packaging, the prepared electrolyte is injected. After vacuum packaging, standing, 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 length l of the first protrusion 10111 is 0.1L, the width w is 0.1W, and the height t is 0.1T.

[0066] Example 2-6: The only difference from Example 1 is that the height t of the first protrusion 10111 is adjusted according to the ratio in Table 1.

[0067] Example 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 ratio in Table 1.

[0068] 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 fan-shaped first protrusion 10111 and the first recess 10121 are arranged on the first side wall 101 at the outer corner.

[0069] Examples 18-23: The difference from Example 17 is that the first protrusion 10111 and the first recess 10121 are arranged on the first side wall 101 at the inner corner and are fan-shaped, wherein 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 as shown in Table 2.

[0070] Comparative Example 1: The difference from Example 1 is that the first convex portion 10111 and the first concave portion 10121 are not provided.

[0071] Comparative Example 2: The difference from Example 17 is that the first convex portion 10111 and the first concave portion 10121 are not provided.

[0072] Cyclic damage test: 10 lithium-ion batteries were tested in each group at a test temperature of 35°C. The lithium-ion batteries were placed in a constant temperature environment at 35°C and allowed to stand for 60 minutes to allow the lithium-ion batteries to reach a constant temperature state. They were then 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 allowed to stand for 5 minutes. Next, they were discharged at a constant current of 0.7C to 3V and allowed to stand for 5 minutes. This constituted one charge and discharge cycle. The above charge and discharge cycles were repeated 500 times. After the cycles were completed, the lithium-ion batteries were inspected for damage or leakage at the corners, and the number of lithium-ion batteries with damage or leakage was counted.

[0073] The specific parameters and cycle damage test results of the square lithium-ion batteries of Examples 1-16 and Comparative Example 1 are shown in Table 1.

[0074] Table 1: Specific parameters and cycle damage test results of the square lithium-ion batteries of Examples 1-16 and Comparative Example 1

[0075] A comparison of Examples 1-16 and Comparative Example 1 in Table 1 shows that the lithium-ion batteries of the present invention, by providing first protrusions 10111 and first recesses 10121 at the corners, can effectively reduce the probability of damage to the corners of the housing 10 during cycling, thereby improving the reliability of the lithium-ion battery during use. Furthermore, as shown in Examples 1-16, when first protrusions 10111 meet the requirements of 0.05T ≤ t ≤ 0.4T, 0.05L ≤ l ≤ 0.4L, and 0.05W ≤ w ≤ 0.4W, the lithium-ion battery not only improves its reliability but also achieves a higher volumetric energy density.

[0076] The specific parameters and cycle damage test results of the L-type lithium-ion batteries of Examples 17-23 and Comparative Example 2 are shown in Table 2.

[0077] Table 2: Specific parameters and cycle damage test results of L-type lithium-ion batteries of Examples 17-23 and Comparative Example 2

[0078] As shown in Table 2, a comparison of Example 17 with Comparative Example 2 shows that the provision of first protrusions 10111 and first recesses 10121 at the outer corners effectively reduces the probability of damage at the inner corners of the housing 10 during lithium-ion battery cycling, thereby improving the reliability of the lithium-ion battery during use. Further, a comparison of Examples 18-22 with Example 17 shows that the provision of first protrusions 10111 and first recesses 10121 on the first sidewall 101 at the inner corners further significantly reduces the probability of damage at the inner corners of the housing 10 during lithium-ion battery cycling, thereby further improving the reliability of the lithium-ion battery during use.

[0079] The present application also provides an electrical device comprising the electrochemical device 100 provided by any one or more of the above embodiments. Since the electrochemical device 100 provided by the first embodiment has a low risk of damage to the corners of the housing 10 during use, the electrical device comprising the electrochemical device 100 has a high reliability.

[0080] The electrical equipment of this application includes, but is not limited to: portable electronic devices, electric vehicles, electric tools, drones, energy storage devices, VR / AR equipment, etc.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of this application, and they should all be included in the scope of the claims and description 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, comprising: an electrode assembly; a housing including a first side wall and a second side wall oppositely arranged along a first direction, the first direction being the thickness direction of the electrode assembly, and the electrode assembly being disposed between the first side wall and the second side wall; wherein, the first side wall includes a first outer surface and a first inner surface, the first outer surface is farther from the electrode assembly than the first inner surface, the first outer surface has a first convex portion, and a position on the first inner surface opposite to the first convex portion has a first concave portion, a positive projection of the first convex portion on a first plane is located in a first angular position region of a positive projection of the first side wall on the first plane, and the first plane is perpendicular to the first direction.

2. The electrochemical device according to claim 1, characterized in that, the first outer surface further has a first base surface, along the first direction, a height by which the first convex portion protrudes from the first base surface is t, the second side wall 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, and a distance between the first base surface and the second outer surface is T, satisfying: 0.05T ≤ t ≤ 0.4T.

3. The electrochemical device according to claim 1, characterized in that, along a second direction, the second direction being the length direction of the electrode assembly, a length of the first convex portion is l, and a length of the first side wall is L, satisfying: 0.05L ≤ l ≤ 0.4L.

4. The electrochemical device according to claim 1, characterized in that, along a third direction, the third direction being the width direction of the electrode assembly, a width of the first convex portion is w, and a width of the first side wall is W, satisfying: 0.05W ≤ w ≤ 0.4W.

5. The electrochemical device according to claim 1, characterized in that, when observed along the first direction, the first side wall is L-shaped, and the first angular position region is an inner corner region of a positive projection of the first side wall on the first plane.

6. The electrochemical device according to claim 5, characterized in that, The first side wall includes a first short side extending in the second direction and a second short side extending in the third direction. The first short side and the second short side are connected to form an inner corner of the first side wall. The length of the first convex portion overlapping with the first short side is l 1 , and the length of the first convex portion overlapping with the second short side is l 2 , the length of the first short side is L 1 , the length of the second short side is L 2 , satisfying at least one of the following conditions: (1) 0.05L 1 ≤ l 1 ≤ 0.5L 1 ; (2) 0.05L 2 ≤ l 2 ≤ 0.5L 2 。 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 the first convex portions, and positive projections of the plurality of first convex portions on the first plane are respectively located in a plurality of first angular position regions of a positive projection of the first side wall on the first plane.

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

9. The electrochemical device according to any one of claims 1 to 6, characterized in that, The second side wall 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 convex portion, and a second concave portion is provided at a position of the second inner surface opposite to the second convex portion. The orthographic projection of the second convex portion on the first plane is located in a second angular position area of the orthographic projection of the second side wall on the first plane.

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

Images