Battery

Abstract

The invention relates to the technical field of batteries, in particular to a battery. The battery comprises a shell and a battery cell, the shell comprises a main body part and a sealing part, and the weight ratio of element silicon in a negative active layer is 5-70%; the main body part comprises a first extension part and a second extension part, and the first extension part and the second extension part are connected to the corner part; the main body part comprises a first wall surface, a second wall surface and an outer arc wall surface; the outer arc wall surface is positioned on one side, deviating from the battery cell, of the intersection of the first wall surface and the second wall surface; and the main body part further comprises a third wall surface, a fifth wall surface and a fourth wall surface, so that the battery meets the following relational expressions: L1 > Max (L4, L5 and L6) or L3 > Max (L4, L5 and L6), 0.3 mm < = L1 < = 2mm, and 0.3 mm < = L3 < = 2mm. According to the battery disclosed by the invention, the risk of electrochemical corrosion of the shell can be reduced when the battery cell at the arc corner is sunken towards the direction close to the shell, and the safety performance of the battery is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a battery. Background Technology

[0002] In recent years, with the rapid development of new energy technologies, batteries have been widely used in electronic devices, electric vehicles, electric two-wheelers, power tools, and other electrical terminals. As the integration of these terminals increases, the space reserved for battery compartments is shrinking to facilitate the placement of various components, while the energy density requirements for batteries are simultaneously rising. Therefore, improving battery energy density within limited space has become a pressing issue.

[0003] With the rapid development of electronic technology, various electronic devices are evolving towards greater intelligence, multifunctionality, and diverse forms. To further improve battery energy density and effectively increase the space utilization of the battery compartment, irregularly shaped stacked batteries, such as L-shaped batteries, U-shaped batteries, and stepped batteries, are gradually becoming the mainstream development. For irregularly shaped cells with arc-shaped corner structures, significant stress will be generated on both sides of the arc-shaped corner during battery cycling. Under this significant stress, the arc-shaped corner is prone to concave towards the side closer to the cell. Consequently, the two sides of the electrode at the arc-shaped corner will move towards the casing, reducing the distance between the casing and the cell. This increases the risk of electrochemical corrosion of the casing and reduces the safety performance of the battery. Summary of the Invention

[0004] To address the issue of reduced battery safety caused by the inward indentation of irregularly shaped battery cells with rounded corners during battery cycling, this invention provides a battery. The battery of this invention ensures that an appropriate distance is maintained between the battery cell and the casing even when the cell at the rounded corner indents towards the casing. This reduces the risk of contact between the negative electrode and the casing, lowers the risk of electrochemical corrosion of the casing, and improves battery safety.

[0005] To achieve the above objectives, the present invention provides a battery comprising a housing and a battery cell located in a receiving space within the housing, the housing comprising a main body portion for receiving the battery cell and a sealing portion extending outward from the edge of the main body portion; The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the negative electrode includes a negative current collector and a negative active layer located on at least one side surface of the negative current collector, the negative active layer comprising a silicon-based material, wherein the weight percentage of elemental silicon in the negative active layer is 5%-70%; The main body includes a first extension extending along the X direction and a second extension extending along the Y direction, the first extension and the second extension being connected at a corner, the Y direction intersecting the X direction; the main body includes a first wall surface located on the first extension, a second wall surface located on the second extension, and an outer arc wall surface connecting the first wall surface and the second wall surface, the outer arc wall surface being located on the side opposite to the battery cell at the intersection of the first wall surface and the second wall surface; the main body also includes a third wall surface and a fifth wall surface disposed opposite to each other along the Y direction, and a fourth wall surface disposed opposite to the second wall surface along the X direction; In the Y direction, the distance between the first wall surface and the edge of the negative electrode is L. 1 The distance between the third wall surface and the edge of the negative electrode is L. 6 The distance between the fifth wall surface and the edge of the negative electrode is L. 4 In the X direction, the distance between the second wall surface and the edge of the negative electrode is L. 3 The distance between the fourth wall surface and the edge of the negative electrode is L. 5 Then the battery satisfies the following relationship: L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm.

[0006] By employing the above technical solution, the present invention has at least the following advantages compared with the prior art: Studies have found that once the negative electrode comes into contact with the casing, a galvanic cell can easily form between the negative electrode, the metal layer inside the casing, and the electrolyte, leading to electrochemical corrosion of the casing. Furthermore, in silicon-based negative electrodes, the volume expansion of the silicon material during battery cycling causes the negative electrode to extend in both length and width directions, thus shortening the distance between the negative electrode and the casing. In addition, the rounded corners of irregularly shaped battery cells are concave towards the side closer to the cell, causing the two sides of the negative electrode at the rounded corners to move closer to the casing, further shortening the distance between the negative electrode and the casing, increasing the risk of contact between the negative electrode and the casing, further exacerbating the risk of electrochemical corrosion of the casing, and deteriorating the battery's safety performance.

[0007] The battery of the present invention controls the distance between the negative electrode plates on both sides of the arc corner of the cell and the inner wall of the casing to be greater than the distance between the negative electrode plates and the inner wall of the casing at other locations, that is, controls the battery to satisfy the following relationship: L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm, on the one hand, control 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm ensures that during battery cycling, the arc corners are recessed towards the cell side, and the two sides of the negative electrode at the arc corners move towards the casing. This still ensures that the two sides of the negative electrode at the arc corners maintain an appropriate distance from the casing, thereby reducing the risk of contact between the negative electrode and the casing, reducing the risk of electrochemical corrosion of the casing, and improving the safety performance of the battery. On the other hand, during battery cycling, the distance between the two sides of the negative electrode at the arc corner and the casing decreases much more than the distance between the negative electrode and the casing at other locations, thus controlling L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L 6 This invention ensures that at least one side of the negative electrode at the arc-shaped corner maintains an appropriate distance from the casing, while preventing excessive distance between the negative electrode and the casing at other locations, thus improving energy density. Therefore, the battery of this invention not only improves the problem of irregularly shaped cells with arc-shaped corner structures, especially those with silicon-containing negative electrodes, where the arc-shaped corners tend to cave inwards during battery cycling, increasing the risk of electrochemical corrosion of the casing, but also avoids excessive waste of space within the casing due to excessive spacing between the negative electrode and the casing, thereby improving the battery's energy density.

[0008] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0010] Figure 1 The image shown is a top view of the housing structure in one embodiment of the present invention.

[0011] Figure 2 The image shown is a top view of the battery structure in one embodiment of the present invention.

[0012] Figure 3 The image shown is a structural perspective view of a battery according to one embodiment of the present invention.

[0013] Figure 4 The diagram shown is a cross-sectional view of the first positive electrode sheet in another embodiment of the present invention.

[0014] Figure 5 The figure shown is a cross-sectional view of the second positive electrode sheet in one embodiment of the present invention.

[0015] Figure 6 The diagram shown is a structural perspective view of a battery according to another embodiment of the present invention. Detailed Implementation

[0016] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention. Unless otherwise specified herein, data ranges include endpoints.

[0017] It should be noted that the numerical designations such as "first" and "second" in this invention are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0018] With the rapid development of electronic technology, various electronic devices are developing towards greater intelligence, multi-functionality, and multi-form. In order to further improve battery energy density and effectively improve the space utilization of the cabin, irregularly shaped stacked batteries are gradually becoming the mainstream of development, such as L-shaped batteries, U-shaped batteries, and stepped batteries. For irregularly shaped battery cells with rounded corners, significant inward stress is generated on both sides of the rounded corners during battery cycling. Under this stress, the membrane at the rounded corner tends to concave towards the side closer to the cell. Consequently, the two sides of the electrode at the rounded corner also move towards the arc-shaped end between the two sides, reducing the distance between the membrane and the sides of the electrode. This can easily lead to the side of the negative electrode contacting the inner wall of the membrane, potentially causing a galvanic cell to form between the negative electrode, the metal layer inside the membrane, and the electrolyte. This results in electrochemical corrosion. First, the membrane at the rounded corner corrodes, potentially causing it to rupture after long-term charge-discharge cycles. Second, aluminum dendrites may form during corrosion, which can grow and penetrate the separator, bridging directly between the positive and negative electrodes and ultimately causing a short circuit, significantly reducing battery safety.

[0019] Furthermore, when the negative electrode of the irregularly shaped battery cell with a rounded corner structure is a silicon-based negative electrode, the expansion of the silicon-based negative electrode is relatively large, which will further increase the stress on both sides of the rounded corner, exacerbate the degree to which the electrode at the rounded corner is concave towards the side of the battery cell, further shorten the distance between the casing and the battery cell, increase the risk of electrochemical corrosion of the casing, and thus further deteriorate the safety performance of the battery.

[0020] To address the aforementioned problems, one embodiment of this application provides a battery, such as... Figures 1-6 As shown, the battery 1 includes a housing 11 and a battery cell 12 located in the housing's accommodating space. The housing 11 includes a main body portion 111 that accommodates the battery cell and a sealing portion that extends outward from the edge of the main body portion.

[0021] In one specific example, the casing may be a steel-plastic film or an aluminum-plastic film. In a further example, the casing includes a fused layer, a conductive layer, and a resin layer, wherein the fused layer is disposed close to the battery cell, the conductive layer is located on the side of the fused layer facing away from the battery cell, and the resin layer is sleeved on the outside of the conductive layer. In one specific example, the fused layer may be, for example, a polypropylene or polyethylene layer; the conductive layer may be, for example, an aluminum layer, a titanium alloy layer, a stainless steel layer, or a copper layer; and the resin layer may be, for example, a nylon layer and / or a polyethylene terephthalate layer. In a specific example where the casing is an aluminum-plastic film, after punching one or two indentations in the aluminum-plastic film, the battery cell is placed into the indentations, and then the battery cell is covered with the aluminum-plastic film. Subsequently, the resin layers of the upper and lower aluminum-plastic films are melted and bonded together by heat fusion, thereby completing the encapsulation. The location where the resin layers of the upper and lower aluminum-plastic films melt and bond together is the sealing part.

[0022] In this embodiment, the battery cell includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the negative electrode includes a negative current collector and a negative active layer located on at least one side surface of the negative current collector, the negative active layer includes a silicon-based material, and the weight percentage of elemental silicon in the negative active layer is 5%-70% (e.g., 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%).

[0023] In some examples, the battery cell may be a wound core formed by stacking and winding positive electrode sheets, separators, and negative electrode sheets; in other examples, the battery cell may be a stacked core formed by stacking positive electrode sheets, separators, and negative electrode sheets. In a further example, the stacked core includes a top layer and a bottom layer of first positive electrode sheets along the thickness direction. The top layer and / or bottom layer of first positive electrode sheets may be single-sided positive electrode sheets, each including a positive current collector and a positive active layer on one side surface of the positive current collector near the center of the battery cell. In other examples, the thickness of the positive current collector of the top layer of first positive electrode sheet is greater than the thickness of the positive current collector of the second positive electrode sheet in the middle of the stacked core, to prevent the top layer of first positive electrode sheet from warping due to uneven stress during charging and discharging caused by the presence of an active layer on one side.

[0024] In some examples, the positive electrode current collector may comprise aluminum foil, aluminum alloy foil, or a composite current collector (e.g., an aluminum-carbon composite current collector). The composite current collector can be formed by coating a metallic material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) onto a polymer substrate. In some examples, the thickness of the positive electrode current collector is 4μm-12μm, for example, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, or 12μm.

[0025] In some examples, the positive active material of the positive active layer may include lithium nickel cobalt manganese oxide (LiNi). 0.90 Co 0.05 Mn 0.05 At least one of the following: O2 (NCM955), NCM811, NCM622, NCM523, NCM111; lithium nickel cobalt aluminum oxide; lithium iron phosphate; lithium vanadium phosphate; lithium cobalt phosphate; lithium manganese phosphate; lithium manganese iron phosphate; lithium-rich manganese-based materials; lithium cobalt oxide (LiCoO2); lithium iron silicate; lithium vanadium silicate; lithium cobalt silicate; lithium manganese silicate; spinel-type lithium manganese oxide; spinel-type lithium nickel manganese oxide; and lithium titanate. In some examples, the thickness of the positive electrode active layer is 30 μm-110 μm, for example, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or 110 μm.

[0026] In some examples, the negative electrode current collector may include, but is not limited to, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collectors (e.g., carbon-copper composite current collectors, nickel-copper composite current collectors, titanium-copper composite current collectors, etc.). In some embodiments, the thickness of the negative electrode current collector is 3μm-12μm, for example, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, or 12μm.

[0027] In one specific example, the silicon-based material of the negative electrode active layer may include at least one of silicon, silicon-carbon composite, silicon-oxygen composite, spherical silicon-carbon, and bulk silicon-carbon. The silicon content comprises 5%-70% by mass (e.g., 5%, 5.5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 65%, 70%).

[0028] In one specific example, the separator includes a base membrane and adhesive layers on both sides of the base membrane. In a further embodiment, a ceramic layer and an adhesive layer are sequentially formed on a first side of the base membrane, and an adhesive layer is formed on a second side. The first side surface of the base membrane is disposed opposite to the positive electrode, and the second side surface of the base membrane is disposed opposite to the negative electrode. In some embodiments, the thickness of the separator is 5 μm-20 μm (e.g., 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, or 20 μm).

[0029] In one specific example, the battery also includes an electrolyte comprising a lithium salt and a solvent, wherein the solvent comprises at least one selected from ethylene carbonate, diethyl carbonate, or fluoroethylene carbonate. In another embodiment, the electrolyte further includes a nitrile additive. The nitrile additive comprises a C3 percentage based on the total mass of the electrolyte. C3 is 0.5%-8%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, or 8%. In some embodiments, the nitrile additive comprises, for example, at least one selected from butadionitrile, adiponitrile, and 1,3,6-hexanetrionitrile.

[0030] The main body 111 includes a first extension 1111 extending in the X direction and a second extension 1112 extending in the Y direction. The first extension 1111 and the second extension 1112 are connected at a corner, and the Y direction intersects the X direction. The main body 111 includes a first wall surface 110 located in the first extension 1111, a second wall surface 130 located in the second extension 1112, and an outer arc wall surface 120 connecting the first wall surface 110 and the second wall surface 130. The outer arc wall surface 120 is located on the side away from the battery cell at the intersection of the first wall surface 110 and the second wall surface 130. That is, by extending the plane of the first wall surface and the plane of the second wall surface towards the battery cell, the extended planes of the first wall surface and the extended planes of the second wall surface intersect at a line, and the outer arc wall surface is located on the outside of this line away from the battery cell, thereby expanding the housing space corresponding to the outer arc wall surface. The outer arc wall surface and the corner are correspondingly provided.

[0031] The main body also includes a third wall surface 160 and a fifth wall surface 140 disposed opposite each other along the Y direction, and a fourth wall surface 150 disposed opposite to the second wall surface 130 along the X direction.

[0032] like Figure 2 As shown, in the Y direction, the distance between the first wall surface 110 and the edge of the negative electrode is L. 1 The distance between the third wall surface 160 and the edge of the negative electrode is L. 6 The distance between the fifth wall surface 140 and the edge of the negative electrode is L. 4 ,like Figure 2 As shown, in the X direction, the distance between the second wall surface 130 and the edge of the negative electrode is L. 3 The distance between the fourth wall surface 150 and the edge of the negative electrode is L. 5 Then the battery satisfies the following relationship: L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L6 ), that is, L 1 Or L 3 Exceeding L 5 L 4 L 6 In other words, the distance between the first wall 110 or the second wall 130 near the outer arc wall 120 and the edge of the negative electrode is greater than the distance between other walls (such as the third wall 160, the fourth wall 150 or the fifth wall 140) and the edge of the negative electrode.

[0033] It should be noted that, in the Y direction, the distance between the first wall surface 110 and the edge of the negative electrode sheet can be detected, for example, by the following test method: Take a 50% SOC battery and use optical instruments / microscopes to collect test images; A straight line is drawn along the Y direction using a ruler / optical instrument. This line crosses the edge of the first wall and the negative electrode plate. The linear distance between the point on the first wall and the point on the negative electrode plate is L. 1 Similarly, it can also be used to measure the distance L between the second wall surface 130 and the edge of the negative electrode in the X direction. 3 The distance L between the fourth wall surface 150 and the edge of the negative electrode plate 5 It can also be used to measure the distance L between the fifth wall surface 140 and the edge of the negative electrode in the Y direction. 4 The distance L between the third wall surface 160 and the edge of the negative electrode plate 6 .

[0034] Where 0.3mm≤L 1 ≤2mm (e.g., 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, or 2mm), 0.3mm≤L 3 ≤2mm, for example, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm or 2mm); thereby preventing L 1 Or L 3 If it is too small, it is easy to come into contact with the casing, causing electrochemical corrosion. At the same time, it is necessary to prevent L... 1 Or L 3 Too large an amount will affect the battery's energy density.

[0035] In some specific instances, the distance L between the fourth wall surface 150 and the edge of the negative electrode plate 5 The distance is 0.05mm-1.5mm (e.g., 0.05mm, 0.08mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, or 1.5mm); in other specific examples, the distance L between the fifth wall surface 140 and the edge of the negative electrode sheet is...4 The distance is 0.05mm-1.5mm (e.g., 0.05mm, 0.08mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, or 1.5mm); in some other specific examples, the distance L between the third wall surface 160 and the edge of the negative electrode is... 6 The thickness is 0.05mm-1.5mm (e.g., 0.05mm, 0.08mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm or 1.5mm).

[0036] In some specific instances, the X direction may be, for example, the extension direction of the tab, and the Y direction may be, for example, the direction perpendicular to the extension direction of the tab; in other specific instances, the Y direction may be, for example, the extension direction of the tab, and the X direction may be, for example, the direction perpendicular to the extension direction of the tab.

[0037] The battery of the present invention controls the distance between the negative electrode plates on both sides of the arc corner of the cell and the inner wall of the casing to be greater than the distance between the negative electrode plates and the inner wall of the casing at other locations, that is, controls the battery to satisfy the following relationship: L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm, on the one hand, control 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm means that by providing space for movement and expansion of the two sides of the negative electrode corresponding to the arc corner in advance, it can be ensured that during the cycle, the arc corner is recessed towards the cell and the two sides of the negative electrode at the arc corner move towards the casing, while still maintaining an appropriate distance between the two sides of the negative electrode at the arc corner and the casing. This reduces the risk of the negative electrode contacting the casing, reduces the risk of electrochemical corrosion of the casing, and improves the safety performance of the battery. On the other hand, during battery cycling, the distance between the two sides of the negative electrode at the arc corner and the casing decreases much more than the distance between the negative electrode and the casing at other locations, thus controlling L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5L 6 This technology not only improves the problem of irregularly shaped battery cells with rounded corners, especially those with silicon-containing negative electrodes, where the rounded corners tend to cave inwards during battery cycling, increasing the risk of electrochemical corrosion of the casing, but also avoids excessive waste of space inside the casing due to excessive spacing between the negative electrode and the casing, thereby increasing the energy density of the battery.

[0038] In one possible implementation, the battery is controlled to satisfy the following relationship: Min(L) 1 L 3 )>Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm, on the one hand, control 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm. The battery satisfies the following relationship: Min(L) 1 L 3 )>Max(L 4 L 5 L 6 ), that is, L 1 Or L 3 Always exceeding L 5 L 4 L 6 In other words, the distance between the first wall 110 or the second wall 130 near the outer arc wall 120 and the edge of the negative electrode must always be greater than the distance between other walls (e.g., the third wall 160, the fourth wall 150, or the fifth wall 140) and the edge of the negative electrode. The battery is controlled to satisfy the following relationship: Min(L 1 L 3 )>Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm, on the one hand, control 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 With a diameter of ≤2mm, it can ensure that the two sides of the negative electrode at the rounded corner maintain an appropriate distance from the shell, while avoiding excessive distance between the negative electrode and the shell at other locations, thereby improving energy density.

[0039] In one possible implementation, the sealing portion includes a first sealing portion 1101 corresponding to the first extension portion and a second sealing portion 1301 corresponding to the second extension portion, with the first sealing portion 1101 and the second sealing portion 1301 connected by an outer arc sealing portion 1201; the sealing portion also includes a third sealing portion 1601 and a fifth sealing portion 1401 disposed opposite each other along the Y direction, and a fourth sealing portion 1501 disposed opposite to the second sealing portion along the X direction. In a specific example, the third sealing portion 1601 and the fifth sealing portion 1401 are bent towards the main body portion to reduce the overall width of the battery cell.

[0040] In one possible implementation, the negative electrode 20 includes a negative electrode arc 206 corresponding to the outer arc wall 120, and the positive electrode 10 includes a positive electrode arc 112 corresponding to the outer arc wall 120. In one specific example, the positive electrode arc 112 and the negative electrode arc 206 are concentrically arranged. In another specific example, the diaphragm includes a diaphragm arc corresponding to the outer arc wall, wherein the edge of the diaphragm arc extends beyond the negative electrode arc, and the edge of the negative electrode arc 206 extends beyond the edge of the positive electrode arc 112. The distance between the negative electrode arc and the outer arc wall is L. 2 The distance W that the negative electrode arc extends beyond the positive electrode arc is... 2 The battery meets the following requirements: L 2 >W 2 In embodiments including a diaphragm arc, a negative electrode arc, and a positive electrode arc, the diaphragm arc, the negative electrode arc, and the positive electrode arc are concentric. Therefore, the distance L between the negative electrode arc and the outer arc wall is... 2 This refers to the difference between the radius of the negative electrode arc and the radius of the outer arc wall, and the distance W that the negative electrode arc extends beyond the positive electrode arc. 2 This refers to the difference between the radius of the negative arc and the radius of the positive arc.

[0041] In a specific example, the distance L between the negative electrode arc and the outer arc wall is... 2 For example, the following testing methods can be used: (1) Take a 50% SOC battery and use an optical instrument / microscope to test the image; (2) Use a circle to match the outer arc wall. After the circle overlaps with the outer arc wall, the radius of the circle can be displayed, denoted as R1. (3) Use a circle to match the negative arc. After the circle and the negative arc overlap, the radius of the circle can be displayed, which is denoted as R2. (4) The distance L between the negative arc and the outer arc wall 2 That is, R1-R2.

[0042] Similarly, the distance W that the negative electrode arc extends beyond the positive electrode arc... 2 For example, it can be detected using the following testing methods: (1) Take a 50% SOC battery and use an optical instrument / microscope to test the image; (2) Use a circle to match the negative arc. After the circle and the negative arc overlap, the radius of the circle can be displayed, which is denoted as R2. (3) Use a circle to match the positive electrode arc. After the circle and the positive electrode arc overlap, the radius of the circle can be displayed, which is denoted as R3. (4) The distance W between the negative arc and the outer arc wall 2 That is, R2-R3.

[0043] In another specific example, three parallel straight lines can be drawn that are tangent to the outer arc wall, the positive arc, and the negative arc, respectively. The distance between the negative arc and the outer arc wall is the distance between the straight lines tangent to the negative arc and the outer arc wall. Similarly, the distance between the negative arc and the positive arc is the distance between the straight lines tangent to the negative arc and the positive arc.

[0044] By controlling L 2 >W 2 That is, reducing the distance W between the negative electrode arc and the positive electrode arc. 2 This means that the overlap area between the positive and negative electrodes is larger. Therefore, during charging and discharging, the larger overlap area of ​​the positive electrode will bring greater frictional resistance to the expanding negative electrode, effectively suppressing the elongation of the negative electrode. Furthermore, L... 2 >W 2 This provides further expansion space for the silicon-doped negative electrode, preventing the negative electrode from contacting the casing. Finally, during the cell drop test, shear stress concentrates on the outer wall surface. By increasing the overlap area of ​​the positive and negative electrodes, relative slippage between them during the drop test can be prevented, reducing the impact of relative displacement.

[0045] In one possible implementation, L 2 The thickness is 0.4mm-5mm (e.g., 0.4mm, 0.5mm, 1mm, 2mm, 3mm, 4mm or 5mm).

[0046] In one possible implementation, W 2 The thickness is 0.2mm-1.5mm (e.g., 0.2mm, 0.5mm, 0.8mm, 1mm, 1.3mm or 1.5mm).

[0047] In one possible implementation, the negative electrode 20 further includes a first negative electrode segment 201 corresponding to the first seal 1101, a second negative electrode segment 202 corresponding to the second seal 1301, a third negative electrode segment 203 corresponding to the third seal (1601), a fourth negative electrode segment 204 corresponding to the fourth seal 1501, and a fifth negative electrode segment 205 corresponding to the fifth seal 1401. The positive electrode 10 further includes a first positive electrode segment 105 corresponding to the first seal 1101, a second positive electrode segment 106 corresponding to the second seal 1301, a third positive electrode segment 107 corresponding to the third seal 1601, a fourth positive electrode segment 108 corresponding to the fourth seal 1501, and a fifth positive electrode segment 109 corresponding to the fifth seal 1401. In the Y direction, the distance by which the first segment 201 of the negative electrode exceeds the first segment 105 of the positive electrode is W. 1 The distance W between the third sub-segment 203 of the negative electrode and the third sub-segment 107 of the positive electrode is... 6 The distance W between the fifth sub-segment 105 of the negative electrode and the fifth sub-segment 109 of the positive electrode is... 4 In the X direction, the distance W that the second segment 202 of the negative electrode exceeds the second segment 106 of the positive electrode is... 3 The distance W between the fourth sub-segment 204 of the negative electrode and the fourth sub-segment 108 of the positive electrode is... 5 Then the battery satisfies the following relationship: Min(W) 1 W 2 )>Max(W 3 W 4 W 5 W 6 By differentiating the positive and negative electrode designs, the distance between the positive and negative electrode plates on the outer arc wall can be reduced, increasing the size of the positive electrode plate and thus improving the energy density of the cell. In a further preferred embodiment, W 1 >W 2 This further increases the size of the positive electrode within the space on the outer wall, thereby improving the energy density of the battery.

[0048] In one possible implementation, W 1 The thickness is 0.3mm-2mm (e.g., 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm or 2mm).

[0049] In one possible implementation, W 4 The thickness is 0.1mm-1mm (e.g., 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm).

[0050] In one possible implementation, W3 The thickness is 0.1mm-1mm (e.g., 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm).

[0051] In one possible implementation, W 5 The thickness is 0.1mm-1mm (e.g., 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm).

[0052] In one possible implementation, the positive electrode 10 includes a first positive electrode 1001 located on the outermost side of the cell along a third direction and a second positive electrode 1002 located in the middle region of the cell. The second positive electrode includes a positive current collector and positive active layers on both sides of the current collector. The first positive electrode 1001 includes a positive current collector 102, a positive active layer 104 on the side of the current collector 102 closest to the cell center, and a safety coating 103 on the side of the current collector 102 furthest from the cell center. By using the safety coating on the side of the current collector furthest from the cell center, both sides of the current collector are coated. This ensures that during the rolling process, both sides of the current collector are stressed, preventing the first positive electrode from warping due to uneven stress on the side of the current collector furthest from the cell center, which is uncoated during cycling. Furthermore, the safety coating also prevents the silicon-doped negative electrode from expanding during charging and discharging, causing the first positive electrode on the top surface to fold outward and collide with the casing, resulting in cracks in the resin layer of the casing. The safety coating blocks the collision between the first positive electrode and the casing. In one example, the third direction can be the thickness direction of the battery cell.

[0053] In one possible implementation, the safety coating comprises ceramic particles and a first binder. The ceramic particles are composed of one or more of alumina, silica, zirconium oxide, and titanium dioxide. The first binder comprises one or more of polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide, carboxymethyl cellulose, polyvinylidene fluoride, and polyethylene oxide. In a specific example, the safety coating comprises ceramic particles and a first binder, wherein the weight percentage of the ceramic particles is 80%-99% (e.g., 80%, 83%, 85%, 88%, 90%, 93%, 95%, 98%, or 99%), and the weight percentage of the first binder is 0.5%-20% (e.g., 0.5%, 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, or 20%), based on the total weight of the safety coating.

[0054] In one specific example, the safety coating also includes a conductive agent to improve the electrical performance of the positive current collector in the thicker first positive electrode. In another specific example, the thickness of the safety coating is 0.5 μm-5 μm (e.g., 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm) to avoid affecting the overall energy density of the cell.

[0055] In one possible implementation, the first positive electrode 1001 also includes a first positive electrode tab 10011 extending from one side of the positive current collector 102. In a specific example, the first positive electrode tab and the positive current collector are integrally formed. The safety coating 103 also includes a first coating segment 1031 extending beyond the positive current collector 102 in the X direction. The first coating segment 1031 is located on the surface of the first positive electrode tab 10011 on the side away from the center of the cell in the thickness direction / third direction. In the X direction, the edge of the first coating segment 1031 does not extend beyond the edge of the separator 30. That is, the safety coating extends to the first positive electrode tab. The first positive electrode tab is, for example, bent and connected to the positive hard electrode tab. The bending direction of the first positive electrode tab is towards the bottom of the shell. By forming a safety coating on the first positive electrode tab, it is possible to prevent the first positive electrode tab from shaking during charging and discharging due to the expansion force of the silicon-doped negative electrode sheet. It is also possible for the first positive electrode tab to come into contact with the tab of the negative electrode sheet or the shell and cause a collision. The safety coating can effectively block the first positive electrode tab from the negative electrode tab or the first positive electrode tab from the shell. Furthermore, in the X direction, the edge of the first coating segment does not extend beyond the edge of the diaphragm to prevent the conductive safety coating from bending along with the first positive electrode tab after the first coating segment extends beyond the diaphragm, which could easily lead to powder shedding after the safety coating is bent.

[0056] In one possible implementation, a first insulating layer is included at the interface between the first positive electrode tab and the positive current collector on the first positive electrode sheet. The first insulating layer is located on the first positive electrode tab on the side of the first positive electrode sheet facing away from the casing in the thickness direction / third direction. The first insulating layer prevents the first positive electrode tab from contacting the negative active layer of the corresponding negative electrode sheet, thus preventing short circuits or fires. The thickness of the safety coating is less than the thickness of the first insulating layer. In the thickness direction, the safety coating and the first insulating layer overlap. By controlling the thickness of the safety coating to be less than the thickness of the first insulating layer, the thickness overlap at the safety coating location is reduced, avoiding impact on the overall energy density of the battery cell.

[0057] In one possible implementation, the battery cell 12 includes a body portion, which includes a first surface and a second surface disposed opposite to each other along a third direction, and a side surface connecting the first surface and the second surface. The battery cell also includes a first adhesive member 40, which is respectively bonded to the first surface, the side surface, and the second surface. In a specific example, the first adhesive member may be, for example, a wrapping adhesive, which may be formed on one side surface or the bottom surface of the battery cell. The ratio of the thickness of the safety coating to the thickness of the first adhesive member is 0.03-0.5 (e.g., 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5). This serves to fix the battery cell and prevent misalignment during drop tests, while reducing the impact of the safety coating thickness on the cross-sectional flatness of the battery cell.

[0058] In one possible implementation, the positive electrode includes a first positive electrode located on the outermost side of the cell along a third direction, and the first positive electrode also includes a first positive electrode tab extending from the side of the positive current collector; the cell also includes a second adhesive member located along the X direction on the side of the positive current collector close to the first positive electrode tab, the edge of the second adhesive member extending beyond the edge of the positive current collector along the X direction, and the second adhesive member is bonded to both the safety coating and the separator, the edge of the second adhesive member not exceeding the edge of the separator, wherein the ratio of the thickness of the safety coating to the thickness of the second adhesive member is 0.03-0.5 (e.g., 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5), which serves to fix the cell and prevent cell misalignment during drop tests, while reducing the impact of the thickness of the safety coating on the cross-sectional flatness of the cell.

[0059] In one possible implementation, the cell further includes a third adhesive 50, which is disposed on the surface of the safety coating away from the positive current collector along the thickness direction / third direction. The third adhesive is bonded to both the safety coating and the inner wall of the casing. The adhesive force between the third adhesive and the safety coating is greater than the adhesive force between the third adhesive and the casing, thereby preventing excessive adhesion between the third adhesive and the casing. In the drop test of the cell, the third adhesive and the casing cannot separate, thus generating a pulling force on the electrode, which may lead to delamination or tearing of the electrode.

[0060] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0061] The following examples illustrate the battery of the present invention.

[0062] Example 1 (1) Preparation of positive electrode sheet Lithium cobalt oxide, positive electrode conductive agent (conductive carbon black and carbon nanotubes mixed at a mass ratio of 2:1) and positive electrode binder (polyvinylidene fluoride) were mixed at a mass ratio of 97:1.5:1.5. N-methylpyrrolidone (NMP) was added and stirred evenly to prepare a positive electrode slurry. Ceramic particles (alumina) and the first binder (polyacrylic acid) are mixed at a mass ratio of 90%:10%, added to water, and stirred evenly to prepare a safe coating slurry; The positive electrode slurry is coated on one side of an aluminum foil, and the safety coating slurry is coated on the other side of the aluminum foil. After drying and rolling, a first positive electrode sheet is obtained. The safety coating includes a first coating section extending beyond the positive electrode current collector along the X direction, and the edge of the first coating section extends beyond the edge of the separator in the X direction.

[0063] The positive electrode slurry is coated on both sides of the aluminum foil, and then dried and rolled to obtain the second positive electrode sheet.

[0064] (2) Preparation of negative electrode sheet Artificial graphite, silicon-carbon materials (including a porous carbon matrix and silicon materials located in the pores of the porous carbon matrix), carbon nanotubes, lithium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid are mixed in a mass ratio of 57.5:42:2.5:1.5:1:0.5, and deionized water is added to prepare a negative electrode slurry. The above negative electrode slurry is coated on both sides of a copper foil, and then dried and rolled to obtain a negative electrode sheet. The elemental silicon content in the negative electrode active coating is 20%.

[0065] The surface of the negative electrode active coating includes several parallel linear grooves. The width L2 of the linear grooves is 0.1 mm, the depth L3 of the linear grooves is 15 μm, the spacing L1 between adjacent linear grooves is 1.5 mm, and the linear grooves do not connect with the first arc.

[0066] (3) Preparation of electrolyte In an argon-filled glove box (moisture <1ppm, oxygen <1ppm), EP and PP are mixed evenly at a mass ratio of 1:2. Based on the total mass of the electrolyte, 20% ethylene carbonate and 10% diethyl carbonate are added and mixed evenly. Then, 13% fluoroethylene carbonate, 0.5% vinylene carbonate, 5.2% nitrile additives (butadienenitrile, adiponitrile, and 1,3,6-hexanetrionitrile mixed at a mass ratio of 4:3:3), 3.5% 1,3-propanesulfonate lactone, and 0.1% lithium difluorophosphate are added. Finally, 12.5% ​​lithium hexafluorophosphate based on the total mass of the electrolyte is added to obtain the electrolyte.

[0067] (4) Battery preparation The positive electrode sheet and separator (a 5 μm thick polyethylene film) prepared in step (1) and the negative electrode sheet prepared in step (2) are stacked together and then die-cut. Subsequently, the stacked core is encapsulated, baked, injected with electrolyte, formed, resealed, sorted, and subjected to OCV (Optical Characterization) to obtain a battery. In this battery, L... 1 L 2 L 3 L 4 L 5 L 6 See Table 1-1, W 1 W 2 W 3 W 4 W 5 W 6 See Table 1-2. The battery cell includes a first adhesive component, a second adhesive component, and a third adhesive component. The first adhesive component is bonded to the first surface, the side surface, and the second surface (e.g., ...). Figure 6 As shown, the second adhesive component is located on the side of the positive current collector closer to the first positive electrode tab, and the edge of the second adhesive component extends beyond the edge of the positive current collector. The third adhesive component is disposed along the X direction on the surface of the safety coating on the side away from the positive current collector. The adhesive force between the third adhesive component and the safety coating is greater than the adhesive force between the third adhesive component and the housing. The ratio of the thickness of the safety coating to the thickness of the first adhesive component is 0.1, and the ratio of the thickness of the safety coating to the thickness of the second adhesive component is 0.1.

[0068] Example 2 Example 2a The same procedure was followed as in Example 1, except that the weight percentage of elemental silicon in the negative electrode active layer was 5.3%.

[0069] Example 2b The same procedure was carried out as in Example 1, except that the weight percentage of elemental silicon in the negative electrode active layer was 68.2%.

[0070] Example 3 Group This embodiment group is carried out with reference to Embodiment 1, except that L is changed. 1 L 2 L 3 L 4 L 5 L 6 One or more of them, see Table 1-1 for details.

[0071] Table 1-1 Example 4 group This embodiment group is carried out with reference to Embodiment 1, except that W is changed. 1 W 2 W3 W 4 W 5 W 6 One or more of them, see Table 1-2 for details.

[0072] Table 1-2 Comparative Examples 1 to 4 The procedure was carried out in accordance with Example 1, except that L was changed. 1 L 2 L 3 L 4 L 5 L 6 One or more of them, see Table 1-3 for details.

[0073] Table 1-3 Comparative Example 5 The same procedure was followed as in Example 1, except that the weight percentage of elemental silicon in the negative electrode active layer was 74.6%.

[0074] Test case The lithium-ion batteries prepared by the examples and comparative examples were tested as follows.

[0075] 1. Leakage test The lithium-ion battery was placed in an environment of 25℃±2℃ and left to stand for 4 hours. Then it was discharged at 0.2C to 3.0V. After standing for 10 minutes, it was charged at a constant current of 1.5C to the upper limit voltage (4.53V). Then it was charged at a constant voltage of 4.53V to 0.05C. Then it was discharged at a constant current of 1C to 2.5V and left to stand for 10 minutes. This is one charge-discharge cycle. 300 charge-discharge cycles were performed.

[0076] The aluminum-plastic film is disassembled and inspected repeatedly. After high-temperature cycling, the batteries were fully charged to 4.53V at 1C, and then charged at a constant voltage of 4.53V to 0.05C. Twenty batteries from each embodiment and comparative example were then disassembled. If no leakage was observed, the test was passed; if leakage was observed, the test failed. The result was expressed as "number of batteries that failed the test / 20". For example, "20 / 20" means all 20 batteries failed the test, and "5 / 20" means 5 out of 20 batteries failed the test.

[0077] 2. Volumetric energy density The battery was left to stand for 1 hour at (25±2)℃. It was then charged at a constant current of 0.5C to 4.53V, and then charged at a constant voltage of 4.53V to a current of 0.05C, and left to stand for 10 minutes. Next, it was discharged at a constant current of 0.2C to 3.0V and left to stand for 10 minutes. The discharge capacity was recorded as C, the average discharge plateau voltage as V, the lithium-ion battery thickness as X, the lithium-ion battery length as Y, the lithium-ion battery width as Z, and the volumetric energy density as (C×V) / (X×Y×Z), in Wh / L.

[0078] The results are recorded in Table 2.

[0079] Table 2 As can be seen from Table 2, the comparison between the comparative examples and the embodiments shows that the batteries prepared in the embodiments have significantly lower leakage rates and higher volumetric energy density, indicating that by controlling the battery to satisfy the following relationship: L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 With a thickness of ≤2mm, the battery reduces the risk of electrochemical corrosion of the casing while ensuring high energy density, thus improving the battery's safety performance.

[0080] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A battery, characterized in that, The battery includes a housing and a battery cell located in a receiving space within the housing. The housing includes a main body portion that receives the battery cell and a sealing portion that extends outward from the edge of the main body portion. The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; the negative electrode includes a negative current collector and a negative active layer located on at least one side surface of the negative current collector, the negative active layer comprising a silicon-based material, wherein the weight percentage of elemental silicon in the negative active layer is 5%-70%; The main body includes a first extension extending along the X direction and a second extension extending along the Y direction, the first extension and the second extension being connected at a corner, the Y direction intersecting the X direction; The main body includes a first wall surface located in the first extension, a second wall surface located in the second extension, and an outer arc wall surface connecting the first wall surface and the second wall surface. The outer arc wall surface is located on the side away from the battery cell at the intersection of the first wall surface and the second wall surface. The main body also includes a third wall and a fifth wall that are disposed opposite to each other along the Y direction, and a fourth wall that is disposed opposite to the second wall along the X direction; In the Y direction, the distance between the first wall surface and the edge of the negative electrode is L. 1 The distance between the third wall surface and the edge of the negative electrode is L. 6 The distance between the fifth wall surface and the edge of the negative electrode is L. 4 In the X direction, the distance between the second wall surface and the edge of the negative electrode is L. 3 The distance between the fourth wall surface and the edge of the negative electrode is L. 5 Then the battery satisfies the following relationship: L 1 >Max(L 4 L 5 L 6 ) or L 3 >Max(L 4 L 5 L 6 ), 0.3mm≤L 1 ≤2mm, 0.3mm≤L 3 ≤2mm.

2. The battery according to claim 1, characterized in that, The sealing portion includes a first sealing portion corresponding to the first extension portion and a second sealing portion corresponding to the second extension portion, the first sealing portion and the second sealing portion being connected by an outer arc sealing portion; the sealing portion also includes a third sealing portion and a fifth sealing portion disposed opposite to each other along the Y direction, and a fourth sealing portion disposed opposite to the second sealing portion along the X direction; And / or, the negative electrode includes a negative electrode arc corresponding to the outer arc wall, the positive electrode includes a positive electrode arc corresponding to the outer arc wall, and the distance between the negative electrode arc and the outer arc wall is L. 2 The distance by which the negative electrode arc extends beyond the positive electrode arc is W. 2 The battery satisfies: L 2 >W 2 .

3. The battery according to claim 1, characterized in that, The distance L between the fourth wall surface and the edge of the negative electrode sheet 5 The thickness ranges from 0.05mm to 1.5mm. And / or, the distance L between the fifth wall surface and the edge of the negative electrode plate 4 The thickness ranges from 0.05mm to 1.5mm. And / or, the distance L between the third wall surface and the edge of the negative electrode sheet 6 The thickness ranges from 0.05mm to 1.5mm.

4. The battery according to claim 2, characterized in that, The negative electrode sheet further includes a first negative electrode sub-segment corresponding to the first sealing portion, a second negative electrode sub-segment corresponding to the second sealing portion, a third negative electrode sub-segment corresponding to the third sealing portion, a fourth negative electrode sub-segment corresponding to the fourth sealing portion, and a fifth negative electrode sub-segment corresponding to the fifth sealing portion; The positive electrode sheet further includes a first positive electrode sub-segment corresponding to the first sealing portion, a second positive electrode sub-segment corresponding to the second sealing portion, a third positive electrode sub-segment corresponding to the third sealing portion, a fourth positive electrode sub-segment corresponding to the fourth sealing portion, and a fifth positive electrode sub-segment corresponding to the fifth sealing portion; In the Y direction, the distance by which the first segment of the negative electrode extends beyond the first segment of the positive electrode is W. 1 The distance W between the third segment of the negative electrode and the third segment of the positive electrode is... 6 The distance W between the fifth sub-segment of the negative electrode and the fifth sub-segment of the positive electrode is... 4 In the X direction, the distance by which the second segment of the negative electrode extends beyond the second segment of the positive electrode is W. 3 The distance W between the fourth sub-segment of the negative electrode and the fourth sub-segment of the positive electrode is... 5 Then the battery satisfies the following relationship: Min(W) 1 W 2 )>Max(W 3 W 4 W 5 W 6 ).

5. The battery according to claim 4, characterized in that, IN 1 >W 2 ; And / or, W 1 The thickness is 0.3mm-2mm; And / or, W 2 The thickness is 0.2mm-1.5mm; And / or, W 4 It is 0.1mm-1mm; And / or, W 3 It is 0.1mm-1mm; And / or, W 5 It is 0.1mm-1mm.

6. The battery according to claim 1, characterized in that, The positive electrode includes a first positive electrode located on the outermost side of the cell along a third direction and a second positive electrode located in the middle region of the cell. The first positive electrode sheet includes a positive current collector, a positive active layer located on the side surface of the positive current collector near the center of the cell, and a safety coating located on the side surface of the positive current collector away from the center of the cell.

7. The battery according to claim 6, characterized in that: The safety coating comprises ceramic particles and a first binder. The ceramic particles are composed of one or more of alumina, silicon dioxide, zirconium oxide, and titanium dioxide. The first binder comprises one or more of polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide, carboxymethyl cellulose, polyvinylidene fluoride, and polyethylene oxide. And / or, the safety coating comprises ceramic particles and a first binder, wherein, based on the total weight of the safety coating, the ceramic particles account for 80%-99% by weight and the first binder accounts for 0.5%-20% by weight; And / or, the thickness of the safety coating is 0.5μm-5μm.

8. The battery according to claim 5 or 6, characterized in that, The first positive electrode sheet also includes a first positive electrode tab extending from one side of the positive current collector, and the safety coating also includes a first coating segment extending beyond the positive current collector in the X direction. The first coating segment is located on the side surface of the first positive electrode tab away from the center of the cell; in the X direction, the edge of the first coating segment does not extend beyond the edge of the separator.

9. The battery according to claim 6, characterized in that, On the first positive electrode sheet, a first insulating layer is included at the junction of the first positive electrode tab and the positive current collector, and the thickness of the safety coating is less than the thickness of the first insulating layer; And / or, the cell further includes a third adhesive member disposed along the X direction on the surface of the safety coating on the side away from the positive current collector; The adhesive force between the third adhesive and the safety coating is greater than the adhesive force between the third adhesive and the housing.

10. The battery according to claim 6, characterized in that, The battery cell includes a body portion, the body portion including a first surface and a second surface disposed opposite to each other along the third direction, and a side surface connecting the first surface and the second surface; The battery cell also includes a first adhesive component, which is respectively bonded to the first surface, the side surface, and the second surface; The ratio of the thickness of the safety coating to the thickness of the first adhesive component is 0.03-0.5; And / or, the positive electrode includes a first positive electrode located on the outermost side of the cell along a third direction, and the first positive electrode also includes a first positive electrode tab extending from the side of the positive current collector; The battery cell also includes a second adhesive member located on the side of the positive current collector near the first positive electrode tab, and the edge of the second adhesive member extends beyond the edge of the positive current collector along the X direction; the ratio of the thickness of the safety coating to the thickness of the second adhesive member is 0.03-0.5.

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