Battery

Abstract

The invention provides a battery which comprises a shell and a battery cell, and the outer side of the battery cell is coated with the shell; the shell at least comprises a first arc-shaped side wall, a second arc-shaped side wall and a third arc-shaped side wall which are connected with one another, and an arc-shaped corner is formed at the junction of the first arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall; the battery further comprises a protective layer which at least covers the arc-shaped corners, so that the shell is effectively protected, the tensile strength and the structural strength of the shell are improved, the situation that the corners of the shell are damaged or broken is at least avoided to a certain extent, the performance of the battery cell is ensured, and the safety of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery. Background Art

[0002] Lithium-ion batteries are currently widely used in electronic devices such as mobile phones and laptops due to their advantages such as high energy density, long cycle life, and low environmental pollution.

[0003] Among them, lithium-ion batteries include a battery cell and a shell covering the outside of the battery cell. For example, during the continuous charging and discharging process of the battery cell, the battery cell will continue to expand over time and squeeze the shell. Especially when the shell is a soft-pack shell, the shell is easily damaged or cracked due to compression. The damaged or cracked shell cannot effectively prevent moisture and oxygen from entering the battery cell. In severe cases, it will cause leakage of the electrolyte, resulting in performance failure of the battery cell and even unsafe problems such as combustion and explosion. Summary of the invention

[0004] In view of this, the embodiments of the present invention are directed to providing a battery, so as to improve the problem that the battery shell is easily damaged or cracked to a certain extent.

[0005] The present invention provides a battery, comprising a shell and a battery core, wherein the shell is coated on the outside of the battery core;

[0006] The housing at least comprises a first arc-shaped side wall, a second arc-shaped side wall and a third arc-shaped side wall connected to each other, wherein an arc-shaped corner is formed at the connection and intersection of the first arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall;

[0007] The battery further comprises a protective layer, and the protective layer covers at least the arc-shaped corner.

[0008] Optionally, the protective layer also covers at least one of the first curved side wall, the second curved side wall and the third curved side wall.

[0009] Optionally, the protective layer covering at least one of the first curved side wall, the second curved side wall and the third curved side wall is connected to the protective layer covering the curved corner.

[0010] Optionally, the housing includes a plurality of side walls, the plurality of side walls surround the battery core to form a recess, and the battery core is located in the recess;

[0011] The multiple side walls include a first side wall, a second side wall and a third side wall that are connected to each other; the first side wall and the second side wall are connected through the first curved side wall; the second side wall and the third side wall are connected through the second curved side wall, and the first side wall and the third side wall are connected through the third curved side wall.

[0012] Optionally, the protective layer also covers at least one of the first side wall, the second side wall and the third side wall.

[0013] Optionally, at least part of the protective layer is disposed on a surface of the housing that is away from the battery core;

[0014] And / or, at least part of the protective layer is arranged on a surface of the shell facing the battery core.

[0015] Optionally, along the first direction, the thickness of the protective layer ranges from 0.5 μm to 1000 μm;

[0016] And / or, along the first direction, the ratio of the thickness of the protective layer to the thickness of the shell wall of the shell is in the range of 0.01 to 10;

[0017] And / or, the material of the protective layer is selected from at least one of polyurethane, polyurea, polyamide, epoxy resin, rubber paint, silicon dioxide, graphene, copper and aluminum;

[0018] And / or, the shell has a top sealing area, at least part of the protective layer is arranged on a side surface of the shell away from the battery core, and the projection of the protective layer on the shell does not exceed the outer edge of the top sealing area.

[0019] Optionally, the shell has at least four arc-shaped corners; among all the arc-shaped corners, at least two adjacent arc-shaped corners are covered with the protective layer;

[0020] The protective layers on two adjacent arc-shaped corners are both located on a surface of the shell facing away from the battery cell or on a surface of the shell facing the battery cell, and the protective layers on at least two adjacent arc-shaped corners are connected.

[0021] Optionally, at least part of the protective layer is arranged on the side surface of the shell facing the battery cell, the edge of the shell has a heat sealing area, and there is a distance between the protective layer on the side surface of the shell facing the battery cell and the heat sealing area.

[0022] Optionally, along the second direction, the distance between the protective layer and the heat-sealing area is not less than 0.5 mm.

[0023] Optionally, at least a portion of the protective layer covers a surface of the entire shell on a side away from the battery core;

[0024] And / or, at least a portion of the protective layer covers the entire surface of the shell on one side facing the battery core.

[0025] Optionally, the battery cell includes a negative electrode sheet, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on the negative electrode current collector;

[0026] The negative electrode active material of the negative electrode active layer includes a silicon-carbon composite material;

[0027] The silicon-carbon composite material comprises a porous carbon matrix, silicon crystal grains located in the pores of the porous carbon matrix, and a carbon layer coated on the surface of the porous carbon matrix.

[0028] Optionally, the mass percentage of silicon in the negative electrode active material is 3% to 30%;

[0029] and / or, the carbon layer is provided with openings corresponding to the pores of the porous carbon matrix;

[0030] And / or, the specific surface area of ​​the silicon-carbon composite material is 0.5 m 2 / g~10m 2 / g;

[0031] And / or, the median particle size of the silicon-carbon composite material is 6 μm to 15 μm;

[0032] And / or, the powder resistivity of the silicon-carbon composite material is 0.1 Ω·cm to 1000 Ω·cm.

[0033] The battery provided by the present invention has a shell that includes at least a first curved side wall, a second curved side wall and a third curved side wall that are connected to each other, and a curved corner is formed at the connection and intersection of the first curved side wall, the second curved side wall and the third curved side wall. A protective layer is provided so that the protective layer at least covers the curved corner, so that at least part of the curved corner of the shell is protected by the protective layer, thereby improving the tensile strength and structural strength of the shell. For example, when the battery cell expands and squeezes the shell during charging and discharging, or when the battery cell is put into the shell and the battery cell contacts the corner of the shell, the presence of the protective layer can at least avoid the curved corner of the shell from being damaged or broken due to squeezing or contact collision to a certain extent, thereby effectively protecting the shell, thereby ensuring the performance of the battery cell and improving the safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the structure of a battery according to an embodiment of the present invention;

[0035] Figure 2 It is a structural schematic diagram of a battery cell and a shell (the shell before the battery cell is packaged) according to an embodiment of the present invention when no protective layer is provided on the shell;

[0036] Figure 3 for Figure 2 Schematic diagram of the structure of the corresponding shell;

[0037] Figure 4 for Figure 3 A magnified view of the structure at position I in the middle;

[0038] Figure 5 for Figure 4 A schematic diagram of the structure when a protective layer is provided on the arc-shaped corner of the corresponding shell;

[0039] Figure 6 for Figure 4 A schematic diagram of the structure when a protective layer is provided on the arc-shaped corner, the first arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall of the corresponding shell;

[0040] Figure 7 for Figure 3 Schematic diagram of the structure when a protective layer is provided on the corresponding shell Figure 1 ;

[0041] Figure 8 for Figure 7 A magnified view of the structure at position I in the middle;

[0042] Fig. 9 A partial structural cross-sectional view of a shell and a protective layer according to an embodiment of the present invention;

[0043] Fig.10 It is a schematic diagram of the main structure of the housing (the housing before the battery cell is packaged) according to an embodiment of the present invention;

[0044] Fig.11 for Figure 3 Schematic diagram of the structure when a protective layer is provided on the corresponding shell Figure 2 .

[0045] Among them, 1. shell; 100, curved corner; 101, first side wall; 102, second side wall; 103, third side wall; 104, first curved side wall; 105, second curved side wall; 106, third curved side wall; 11, one side surface; 12, heat sealing area; 121, top sealing area; 122, side sealing area; 2, battery cell; 21, pole ear; 3, protective layer. DETAILED DESCRIPTION

[0046] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0047] The lithium-ion battery includes: a battery cell and a shell, wherein the shell is coated on the outside of the battery cell.

[0048] For example, during the continuous charging and discharging process of the battery cell, the battery cell will continue to expand and squeeze the shell over time. In particular, when the shell is a soft-pack shell, the shell is easily damaged or cracked due to squeezing, such as causing corner cracks or breaks in the shell.

[0049] For another example, when the battery cell is put into the shell, the corners of the battery cell are likely to come into contact with the corners of the shell, which may easily cause the shell to crack or break.

[0050] However, a damaged or cracked shell cannot effectively prevent moisture and oxygen from entering the battery cell. In severe cases, it may cause leakage of the electrolyte, resulting in performance failure of the battery cell and even unsafe problems such as combustion and explosion.

[0051] Based on this, the present invention provides a battery, which is provided with a protective layer so that the protective layer covers at least a portion of the arc-shaped corners of the shell. The protective layer protects at least a portion of the arc-shaped corners of the shell, thereby improving the tensile strength and structural strength of the shell, and at least avoiding the corners of the shell from being damaged or cracked due to compression or contact collision to a certain extent, effectively protecting the shell, thereby ensuring the performance of the battery cell and improving the safety of the battery.

[0052] The battery provided by the present invention is described in detail below with reference to the accompanying drawings through specific embodiments:

[0053] Reference Figures 1 to 11 As shown, this embodiment provides a battery, which may be, for example, a lithium-ion battery, and specifically, may be a soft-pack lithium-ion battery.

[0054] Batteries can be used as power sources or energy storage units for electronic devices, which may be, but are not limited to, mobile phones, laptops, tablet computers, etc.

[0055] The battery provided in this embodiment includes: a shell 1 and a battery cell 2 , wherein the shell 1 is coated on the outside of the battery cell 2 .

[0056] The battery cell 2 may specifically include a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet. Exemplarily, the positive electrode sheet, the separator and the negative electrode sheet are stacked and wound to form a wound battery cell. The battery cell 2 has a tab 21, and the tab 21 extends out of the housing 1.

[0057] Exemplarily, the housing 1 may be an aluminum-plastic film housing, for example. Of course, the housing 1 may also be made of other materials.

[0058] It should be noted that Figures 2 to 8 , Figure 10 to Figure 11 The shell 1 shown is specifically a shell structure corresponding to the shell before the battery cell 2 is packaged, such as an aluminum-plastic film.

[0059] Take the aluminum-plastic film shell as an example: Figure 2 As shown, during the specific production, a recess (such as a pit) capable of placing the battery cell is punched out on the aluminum-plastic film through a mold, and then, for example, along Figure 2 The battery cell is placed in the punched pit in the direction of the arrow shown in the figure, and then the aluminum-plastic film is folded in half, and then subsequent heat sealing, liquid injection, formation and other processes are performed to form a battery. Among them, heat sealing can specifically include top sealing, side sealing and the like.

[0060] In specific implementation, when the battery cell is thin, one hole can be punched on the aluminum-plastic film. When the battery cell is thick, two holes can be punched. After the aluminum-plastic film is folded in half, the two holes face each other and jointly define a cavity for placing the battery cell.

[0061] After punching the pit, the thickness at the corners of the pit may be thinner than other positions of the shell. When the tensile strength at the corners of the shell is lower than the extrusion stress of the battery cell, the corresponding position of the shell will be damaged or cracked.

[0062] Based on this, in the battery provided in this embodiment, the shell 1 at least includes: a first curved side wall 104, a second curved side wall 105, a third curved side wall 106 and a curved corner 100. The first curved side wall 104, the second curved side wall 105 and the third curved side wall 106 are connected to each other, and the curved corner 100 is located at the connection and intersection of the first curved side wall 104, the second curved side wall 105 and the third curved side wall 106.

[0063] Reference Figure 4 As shown, it can be understood that one end of the first curved side wall 104 , one end of the second curved side wall 105 , and one end of the third curved side wall 106 extend toward each other, and form a curved corner 100 at the intersection of the three.

[0064] Reference Figures 1 to 11 As shown, the battery further includes a protective layer 3 , and the protective layer 3 at least covers the arc-shaped corner 100 .

[0065] The arc-shaped corner 100 here can be understood as, for example, a corner formed on the shell 1 after the shell 1 encapsulates the battery cell 2 .

[0066] Since the arc corner 100 is located at the connection and intersection of the first arc side wall 104, the second arc side wall 105 and the third arc side wall 106, the protective layer 3 is used to protect at least the arc corner 100, thereby not only improving the tensile strength and structural strength of the arc corner 100, but also improving the tensile strength and structural strength of the first arc side wall 104, the second arc side wall 105 and the third arc side wall 106 as a whole to a certain extent, thereby improving the tensile strength and structural strength of the shell 1, and preventing the shell 1 from cracking or breaking at the corners to a certain extent.

[0067] Take the case 1 as an aluminum-plastic film case as an example, refer to Figures 2 to 11 As shown, for example, when a single hole is punched on an aluminum-plastic film, the housing 1 may have four arc-shaped corners 100 , and the four arc-shaped corners 100 may be, for example, the four corners of the hole.

[0068] For another example, when double pits are punched on the aluminum-plastic film, each pit has four corners, and the housing 1 can have eight arc-shaped corners 100. It should be noted that the number of the specific corners of the housing 1 is not limited to this, and can be set according to actual conditions.

[0069] The above-mentioned protective layer 3 at least covers the arc corner 100, which can be understood as: the protective layer 3 covers all the arc corners 100 of the shell 1; or, the protective layer 3 covers part of the arc corners 100 of the shell 1 (it can be a part of all the arc corners 100, or it can be, for example, for a certain arc corner 100, covering a part of the arc corner 100); or, the protective layer 3 covers part of the arc corner 100 or all of the arc corners 100, and also covers part or all of other areas outside the arc corner 100 of the shell 1.

[0070] For example, refer to Figure 7 , Fig.10 and Fig.11 As shown, the four arc-shaped corners 100 of the housing 1 are all covered with a protective layer 3 .

[0071] The battery provided in this embodiment has a shell 1 that includes at least a first curved side wall 104, a second curved side wall 105 and a third curved side wall 106 that are connected to each other. A curved corner 100 is formed at the connection and intersection of the first curved side wall 104, the second curved side wall 105 and the third curved side wall 106. By providing a protective layer 3, the protective layer 3 at least covers the curved corner 100, so that at least part of the curved corner 100 of the shell 1 is protected by the protective layer 3, thereby improving the tensile strength and structural strength of the shell 1. For example, when the battery cell 2 expands and squeezes the shell 1 during charging and discharging, or when the battery cell 2 is put into the shell and the battery cell 2 contacts the corner of the shell 1, due to the presence of the protective layer 3, it is possible to at least avoid the curved corner 100 of the shell 1 from being damaged or broken due to squeezing or contact collision to a certain extent, thereby effectively protecting the shell 1, ensuring the performance of the battery cell 2, and improving the safety of the battery.

[0072] Reference Figure 6 As shown, in some embodiments, the protection layer 3 also covers at least one of the first curved side wall 104 , the second curved side wall 105 and the third curved side wall 106 .

[0073] Exemplarily, specifically, the protective layer 3 may cover at least a portion of the curved corner 100 and at least a portion of the first curved side wall 104, or the protective layer 3 may cover at least a portion of the curved corner 100 and at least a portion of the second curved side wall 105, or the protective layer 3 may cover at least a portion of the curved corner 100 and at least a portion of the third curved side wall 106, or the protective layer 3 may cover at least a portion of the curved corner 100 and at least a portion of the first curved side wall 104, at least a portion of the second curved side wall 105, and at least a portion of the third curved side wall 106, or, as Figure 6 As shown, the protection layer 3 covers the arc-shaped corner 100 , and covers the first arc-shaped side wall 104 , the second arc-shaped side wall 105 and the third arc-shaped side wall 106 .

[0074] Such an arrangement further improves the coverage of the protective layer 3 , thereby further improving the tensile strength and structural strength of the shell 1 , and further preventing the shell 1 from being damaged or broken.

[0075] Continue to refer to Figure 6 As shown, in some embodiments, the protection layer 3 covering at least one of the first curved side wall 104 , the second curved side wall 105 and the third curved side wall 106 is connected to the protection layer 3 covering the curved corner 100 .

[0076] This arrangement makes it difficult for the protective layer 3 to fall off, thereby improving the stability and protective effect of the protective layer 3. For example, if the connection between the protective layer 3 at the arc corner 100 and the arc corner 100 is accidentally loosened, the protective layer 3 located on the first arc side wall 104, the second arc side wall 105 and the third arc side wall 106 can play a certain role in fixing the protective layer 3 at the arc corner 100, thereby preventing the protective layer 3 at the arc corner 100 from falling off from the arc corner 100.

[0077] Reference Figures 2 to 6 As shown, in some embodiments, the housing 1 includes a plurality of side walls, which surround the battery cell 2 to form a recess, and the battery cell 2 is located in the recess. The plurality of side walls include a first side wall 101, a second side wall 102, and a third side wall 103 which are connected to each other.

[0078] The first side wall 101 and the second side wall 102 are connected via the first arc-shaped side wall 104 , the second side wall 102 and the third side wall 103 are connected via the second arc-shaped side wall 105 , and the first side wall 101 and the third side wall 103 are connected via the third arc-shaped side wall 106 .

[0079] Exemplarily, for example, the first side wall 101 is perpendicular to the second side wall 102 , the second side wall 102 is perpendicular to the third side wall 103 , and the first side wall 101 is perpendicular to the third side wall 103 .

[0080] In this way, the connection between the two adjacent side walls is achieved through the arc-shaped side wall, which can reduce the connection stress between the two adjacent side walls to a certain extent, thereby avoiding the occurrence of excessive stress at the connection between the two adjacent side walls and rupture, further improving the structural strength and tensile strength of the shell 1, and further preventing the shell 1 from rupture.

[0081] Exemplarily, for example, the shell 1 has two first side walls 101, two second side walls 102 and two third side walls 103, the two first side walls 101 are oppositely arranged, the two second side walls 102 are oppositely arranged, the two third side walls 103 are oppositely arranged, the second side wall 102 and the third side wall 103 are connected, and the second side wall 102 and the third side wall 103 are surrounded between the two first side walls 101, so as to enclose the battery cell 2. At this time, the shell 1 forms eight corners, that is, eight arc-shaped corners 100 are formed.

[0082] Further, in some embodiments, referring to Figure 7 and Figure 8 As shown, the protection layer 3 may also cover at least one of the first side wall 101 , the second side wall 102 and the third side wall 103 .

[0083] Reference Figure 8As shown, illustratively, the protective layer 3 can simultaneously cover at least a portion of the first side wall 101, at least a portion of the second side wall 102, and at least a portion of the third side wall 103. Of course, the protective layer 3 can also only cover one or both of the first side wall 101, the second side wall 102, and the third side wall 103.

[0084] Such an arrangement further increases the coverage of the protective layer 3 , thereby further improving the tensile strength and structural strength of the shell 1 , and further preventing the shell 1 from being damaged or broken.

[0085] Continue to refer to Figure 8 As shown, the protective layer 3 simultaneously covers the arc corner 100, the first arc side wall 104, the second arc side wall 105, the third arc side wall 106, the first side wall 101, the second side wall 102 and the third side wall 103, thereby further increasing the coverage of the corners of the shell 1 and further improving the protective effect of the shell 1.

[0086] Reference Figures 5 to 11 As shown, in some embodiments, at least a portion of the protection layer 3 is disposed on a side surface 11 of the housing 1 that faces away from the battery cell 2 .

[0087] That is, at least a portion of the protection layer 3 is disposed on the outer surface of the housing 1 , and at least covers at least a portion of the arc-shaped corner 100 of the housing 1 .

[0088] Taking the aluminum-plastic film shell as an example, in the specific implementation, after the aluminum-plastic film packaging, or double sealing, or side folding process is completed, a protective layer 3 can be set on the outer surface of the aluminum-plastic film, so that the protective layer 3 at least covers the outer surface of at least part of the arc corner 100 of the shell 1.

[0089] By setting at least part of the protective layer 3 on the outer surface of the shell 1, not only is the protective layer 3 able to protect the shell 1, at least preventing the shell 1 from being cracked or damaged due to expansion, compression, contact, collision, etc., but it is also easy to observe whether the protective layer 3 falls off from the arc corner 100 and other positions, so as to further ensure the effective protection of the shell 1 by the protective layer 3, and this makes the setting of the protective layer 3 more convenient and easier to operate.

[0090] Moreover, since the protective layer 3 is located on the outer surface of the shell 1 , the protective layer 3 does not occupy the space in the inner cavity of the shell 1 , so that the accommodating space of the battery cell 2 is larger, which is beneficial to improving the energy density of the battery cell 2 .

[0091] In some embodiments, at least a portion of the protection layer 3 may also be disposed on a surface of the housing 1 facing the battery cell 2 .

[0092] That is to say, at least a portion of the protection layer 3 is disposed on the inner surface of the housing 1 , and at least covers at least a portion of the arc-shaped corner 100 of the housing 1 .

[0093] Taking the aluminum-plastic film shell as an example, in a specific implementation, after the holes are punched in the aluminum-plastic film and before the battery cell 2 is placed, a protective layer 3 is provided on the inner surface of the shell 1, so that the protective layer 3 at least covers at least part of the arc-shaped corner 100 of the inner surface of the shell 1.

[0094] By arranging at least part of the protective layer 3 on the inner surface of the shell 1, not only the protective layer 3 protects the shell 1, at least preventing the shell 1 from being cracked or damaged due to expansion, compression, contact, collision, etc., but also the protective layer 3 is effectively hidden to a certain extent, which can improve the aesthetic appearance of the battery.

[0095] In some embodiments, the protective layer 3 may also be provided on both the surface of the housing 1 facing the battery cell 2 and the surface of the housing 1 facing away from the battery cell 2 .

[0096] In some embodiments, the protective layer 3 is disposed on the housing 1 by spraying, pasting or electroplating, which is convenient to manufacture and has reliable connection.

[0097] Of course, the protective layer 3 may also be fixed on the housing 1 in other ways, and this embodiment is not limited to the above-listed ways.

[0098] In some embodiments, the material of the protective layer 3 can be selected from at least one of polyurethane, polyurea, polyamide (also known as nylon), epoxy resin, rubber paint, silicon dioxide, graphene, copper, and aluminum.

[0099] Exemplarily, when the protective layer 3 is disposed on the shell 1 by spraying, the protective layer 3 can be, for example, a polymer coating, such as polyurethane, polyurea, polyamide, epoxy resin, rubber paint, graphene oxide, graphene coating, silica, ceramic coating, chitosan coating, etc.

[0100] The protective layer 3 is coated on the shell 1 by spraying, and the protective layer 3 is not easy to fall off, which improves the stability of the protective layer 3 and further improves the protective effect of the protective layer 3 on the shell 1.

[0101] Exemplarily, when the protective layer 3 is set on the shell 1 by pasting, for example, the protective layer 3 can be attached to the shell 1 by an adhesive (such as double-sided tape), and the protective layer 3 can be made of, for example, graphene film, polymer film (such as polyurethane film, nylon film), etc.

[0102] The protective layer 3 is attached to the shell 1 by pasting, which is easy to operate. When the protective layer 3 is pasted on the outer surface of the shell 1, it is also convenient to replace the protective layer 3.

[0103] Exemplarily, when the protective layer 3 is disposed on the housing 1 by electroplating, the protective layer 3 may be made of metal materials such as copper and aluminum, or non-metallic materials.

[0104] The protective layer 3 is plated on the housing 1 by electroplating, and the protective layer 3 is not easy to fall off, which improves the stability of the protective layer 3 and further improves the protective effect of the protective layer 3 on the housing 1.

[0105] In specific implementation, if the protective layer 3 is too thin, the protective effect of the protective layer 3 on the shell 1 will be reduced, but if the protective layer 3 is too thick, the thickness of the battery will be too thick, and the product thickness will not meet the requirements. If the protective layer 3 is too thick, the energy density per unit volume of the battery will be reduced, and the consumables of the protective layer 3 will increase, thereby increasing the production cost.

[0106] Based on this, in some embodiments, along the first direction, the thickness h of the protection layer 3 can be set between 0.5 μm and 1000 μm.

[0107] For example, the specific thickness may be 0.5 μm, 1 μm, 10 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, or 1000 μm.

[0108] Reference Fig. 9 As shown, the first direction here can be specifically Fig. 9 In the up and down direction, the thickness h here is specifically the protective layer 3 along Fig. 9 The dimensions in the up and down directions.

[0109] By setting the thickness h of the protective layer 3 within the above range, not only can the protective layer 3 effectively protect the shell 1, but it can also ensure that the thickness of the battery product can meet the requirements, taking into account the higher energy density of the battery, and avoiding excessive consumables and resulting in increased costs.

[0110] Continue to refer to Fig. 9 As shown, in some embodiments, along the first direction, the ratio of the thickness h of the protective layer 3 to the thickness H of the shell wall of the shell 1 ranges from 0.01 to 10.

[0111] Exemplarily, the above ratio can be set to 0.01, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0112] The first direction here can be specifically Fig. 9 In the up and down direction, the thickness h here is specifically the protective layer 3 along Fig. 9 The dimension in the vertical direction in the figure, where the thickness H is specifically the thickness of the shell wall of the shell 1 along the Fig. 9 The dimension in the up-down direction, that is, the vertical distance between the inner side surface of the shell 1 and the outer side surface of the shell 1 along the first direction.

[0113] It should be noted that the shell wall thickness H of the shell 1 here may be, for example, the thickness of the shell wall area covered by the protective layer 3 of the shell 1, or may be the average thickness of the shell wall of the entire shell 1, such as the average thickness of the aluminum-plastic film itself.

[0114] By setting the thickness h of the protective layer 3 and the thickness H of the shell 1 within the above range, not only can the protective layer 3 effectively protect the shell 1, but it can also ensure that the entire thickness of the battery product can meet the requirements while taking into account the higher energy density of the battery.

[0115] Reference Figures 1 to 11 As shown, in some embodiments, the housing 1 has at least four arc-shaped corners 100. Among all the arc-shaped corners 100, at least two adjacent arc-shaped corners 100 are covered with a protective layer 3.

[0116] Such an arrangement can further increase the coverage and protection range of the protective layer 3 on the shell 1, thereby further improving the protection effect.

[0117] Reference Fig.11 As shown, the protective layers 3 on two adjacent arc corners 100 can be both located on the side surface 11 of the shell 1 facing away from the battery cell 2 or both located on the side surface of the shell 1 facing the battery cell 2, and the protective layers 3 on at least two adjacent arc corners 100 are connected.

[0118] for example Fig.11 In the figure, the four arc-shaped corners 100 are all covered with the protective layer 3, wherein the protective layers 3 on the two arc-shaped corners 100 on the right are connected.

[0119] Of course, in other implementations, for example, the two protection layers 3 on the left side may be connected, or the protection layers 3 on the four arc-shaped corners 100 may be connected together, and so on.

[0120] This arrangement improves the coverage of the protective layer 3 on the shell 1, for example, it covers two adjacent arc corners 100 and the area between the two arc corners 100 at the same time, thereby further improving the protective effect of the protective layer 3 on the shell 1, and improving the stability of the entire protective layer 3 on the shell 1, making it difficult for the protective layer 3 to fall off.

[0121] Combination Figure 1 and Fig.10 As shown, in a specific implementation, the housing 1 has a heat sealing area 12. Exemplarily, the heat sealing area 12 may specifically include a top sealing area 121, and may also include a side sealing area 122.

[0122] Reference Fig.10 As shown, in some embodiments, at least part of the protective layer 3 is disposed on the surface of the shell 1 facing the battery cell 2 , and there is a distance b between the protective layer 3 on the surface of the shell 1 facing the battery cell 2 and the heat sealing area 12 .

[0123] Reference Fig.10 As shown, taking the aluminum-plastic film housing as an example, after the battery cell 2 is placed in the punching pit, the aluminum-plastic film is folded in half along the oo direction, and then heat-sealed at the top sealing area 121 to form a top sealing edge, and heat-sealed at the side sealing area 122 to form a side sealing edge. Specifically, the aluminum-plastic film may include a hot melt layer, an aluminum layer, and a nylon layer in sequence from the inside to the outside. After the aluminum-plastic film is folded in half, the two opposite hot melt layers are melted together at the heat sealing area 12, thereby achieving edge sealing.

[0124] When the protective layer 3 is arranged on the surface of the shell 1 facing the battery cell 2, if the protective layer 3 contacts the heat-sealing area 12 or covers the heat-sealing area 12, it will affect the melting of the heat-sealing area, and then cause leakage, etc. Therefore, by providing a spacing b between the protective layer 3 and the heat-sealing area 12, the sealing effect is ensured to improve the safety of the battery.

[0125] For example, the spacing b here can be specifically the distance between the protective layer 3 and the top sealing area 121 along the Fig.10 The vertical distance in the up and down directions.

[0126] In some embodiments, along the second direction, the spacing b between the protective layer 3 and the heat-sealing area 12 is not less than 0.5 mm. For example, the spacing b may be 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, or 0.7 mm.

[0127] The second direction here can be, for example, Fig.10 The up and down directions in .

[0128] By setting the distance b between the protective layer 3 and the heat-sealing area 12 to be no greater than 0.5 mm, the sealing effect of the heat-sealing area 12 is further ensured.

[0129] In other implementations, the heat-sealing area 12 may also be a side-sealing area 122, that is, there is a distance between the protective layer 3 and the side-sealing area 122, and the distance in this case is, for example, Fig.10 The horizontal distance between the side sealing area 122 and the protective layer 3 in the left-right direction of the middle edge.

[0130] In some embodiments, when the protective layer 3 is disposed on the surface of the housing 1 facing away from the battery cell 2 , the projection of the protective layer 3 on the housing 1 does not exceed the outer edge of the top sealing area 121 .

[0131] Reference Figure 1 As shown, the outer edge of the top sealing area 121 can be specifically Figure 1 In the vertical direction of the middle edge, the upper edge of the top sealing area 121. The projection of the protective layer 3 on the shell 1 can be specifically Figure 1 Projection onto the plane shown.

[0132] In this way, the protective layer 3 can effectively protect the shell 1, while preventing the protective layer 3 from exceeding the outer edge of the top sealing area 121, which will cause the length of the shell 1 (for example, Figure 1 The situation where the dimensions in the upper and lower directions are too large occurs, thereby ensuring the energy density per unit volume of the battery to a certain extent.

[0133] In some embodiments, at least a portion of the protection layer 3 covers a surface 11 of the entire housing 1 that faces away from the battery cell 2 .

[0134] That is to say, the protective layer 3 covers the outer surface of the entire shell 1, thereby protecting the entire shell 1, further improving the protective effect of the shell 1, and further preventing the shell 1 from being cracked or damaged due to expansion, compression or collision of the battery cell 2.

[0135] In some embodiments, at least a portion of the protection layer 3 covers the entire surface of the housing 1 on one side facing the battery core 2 .

[0136] That is to say, the protective layer 3 covers the inner surface of the entire shell 1, thereby protecting the entire shell 1, further improving the protective effect of the shell 1, and further preventing the shell 1 from being cracked or damaged due to expansion, compression or collision of the battery cell 2.

[0137] In some embodiments, the negative electrode sheet of the battery cell 2 includes: a negative electrode current collector and a negative electrode active layer disposed on the negative electrode current collector. The negative electrode active material of the negative electrode active layer can be selected from silicon-based materials.

[0138] In some embodiments, the mass percentage of silicon in the negative electrode active material is 3% to 30%.

[0139] Specifically, in some embodiments, the silicon-based material may include a silicon-carbon composite material, which includes a porous carbon matrix, silicon grains in the pores of the porous carbon matrix, and a carbon layer coated on the surface of the porous carbon matrix.

[0140] The porous carbon material as a matrix can make the silicon grains evenly dispersed in the porous carbon material, alleviating the volume expansion of the silicon particles caused by lithium insertion during the charging process.

[0141] By setting a carbon layer on the surface of the porous carbon matrix, the carbon layer can reduce the direct contact between silicon particles and the electrolyte to a certain extent, reduce the occurrence of side reactions, improve the structural stability of the silicon-carbon composite material, and thus improve the structural stability of the negative electrode active material. At the same time, the carbon layer also plays a certain degree of isolation role, inhibiting the agglomeration tendency of silicon particles, avoiding material failure caused by stress concentration, and improving the cycle stability of the negative electrode active material. In addition, since silicon is a semiconductor, the conductivity of the porous carbon material is significantly reduced after being composited with silicon. The surface coating of the carbon layer helps to improve the conductivity of the material, thereby improving the initial performance of the negative electrode active material.

[0142] This arrangement enables the silicon-carbon composite material to be used as the negative electrode active material in the preparation of negative electrode sheets and batteries, and to exhibit advantages such as high initial efficiency, small cycle expansion, and high cycle stability.

[0143] Since the negative electrode sheet prepared by the above negative electrode active material has a smaller cyclic expansion, the extrusion force of the electrode sheet on the shell 1 due to expansion is further reduced, thereby further avoiding the shell 1 from being cracked or damaged due to being squeezed.

[0144] In this embodiment, the protective layer 3 is covered at least at the arc-shaped corner 100, so that the shell 1 is particularly suitable for packaging the negative electrode silicon-doped battery cell 2. When the negative electrode silicon-doped battery cell 2 expands during charging and discharging, since the protective layer 3 is arranged at at least part of the arc-shaped corner 100 of the shell 1, the tensile strength and structural strength of the shell 1 are improved, and at least the corners of the shell 1 are prevented from being damaged or broken to a certain extent, the performance of the battery cell 2 is guaranteed, and the safety of the battery is improved.

[0145] In some embodiments, the carbon layer is provided with openings corresponding to the pores of the porous carbon matrix.

[0146] This setting can alleviate volume changes, that is, the presence of pores allows silicon to expand and contract during charging and discharging, thereby reducing the pressure on the carbon layer and preventing the carbon layer from rupturing, thereby improving the stability of the negative electrode active material; moreover, the presence of open pores increases the specific surface area of ​​the material, which is beneficial to the penetration of the electrolyte and improves the conductivity of the material; in addition, the open pore design makes the structure of the silicon-carbon composite material more stable during the cycle, thereby extending the cycle life of the battery.

[0147] In some embodiments, the specific surface area of ​​the silicon-carbon composite material is 0.5 m 2 / g~10m 2 / g. For example, the specific surface area can be 0.5m 2 / g, 1m 2 / g, 2m 2 / g, 3m 2 / g, 4m 2 / g, 5m2 / g, 5.25m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g, 9m 2 / g, 10m 2 / g.

[0148] By setting the specific surface area of ​​the silicon-carbon composite material within the above range, it is beneficial to reduce the contact between the negative electrode active material and the electrolyte, reduce the formation of the solid electrolyte interface membrane (Solid Electrolyte Interface membrane, referred to as SEI membrane), thereby improving the initial efficiency and capacity retention rate of the battery.

[0149] In specific implementation, the specific surface area of ​​the silicon-carbon composite material can be measured by N2 constant temperature adsorption and desorption, and calculated by the BET method.

[0150] In some embodiments, the median particle size Dv50 of the silicon-carbon composite material is 6 μm to 15 μm. For example, the median particle size may be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm.

[0151] Specifically, if the particle size of the material is smaller, it means that it has a higher specific surface area and a larger contact area with the electrolyte. More active lithium is consumed during the first week of charging, resulting in a low first efficiency of the negative electrode active material. If the particle size of the material is larger, the diffusion path of lithium ions inside the material is longer, the kinetic properties of the negative electrode active material are poor, and the gaps between large-size particles are large, making it difficult to obtain a negative electrode sheet with a higher compaction density, resulting in a low volume energy density of the battery. Therefore, by setting the particle size of the silicon-carbon composite material within the above range, while improving the first efficiency performance of the negative electrode active material, it is possible to take into account both the higher kinetic properties of the negative electrode active material and the volume energy density of the battery.

[0152] In specific implementation, the particle size distribution of the material can be measured by a laser particle size analyzer: for example, the sample to be tested is first added to the medium liquid and ultrasonically dispersed evenly; then the medium liquid containing the sample to be tested is poured into the measuring chamber; then the laser particle size analyzer is started, the laser beam is irradiated into the sample to cause scattering, and the intensity and angle of the scattered light are recorded, so that the particle size and distribution of the sample to be tested can be analyzed.

[0153] In some embodiments, the powder resistivity of the silicon-carbon composite material is 0.1 Ω·cm to 1000 Ω·cm. For example, it may be 0.1 Ω·cm, 1 Ω·cm, 100 Ω·cm, 200 Ω·cm, 300 Ω·cm, 400 Ω·cm, 500 Ω·cm, 600 Ω·cm, 700 Ω·cm, 800 Ω·cm, 900 Ω·cm, or 1000 Ω·cm.

[0154] By setting the powder resistivity of the silicon-carbon composite material within the above range, it is possible to avoid, to a certain extent, the situation in which the internal resistance of the battery is too high and thus resulting in large energy losses, thereby ensuring the efficiency of the battery.

[0155] In this article, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does 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 present application.

[0156] In this article, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0157] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery, characterized in that: It comprises a shell (1) and a battery core (2), wherein the shell (1) is wrapped around the outside of the battery core (2); The shell (1) comprises at least a first arc-shaped side wall (104), a second arc-shaped side wall (105) and a third arc-shaped side wall (106) which are connected to each other, and an arc-shaped corner (100) is formed at the connection and intersection of the first arc-shaped side wall (104), the second arc-shaped side wall (105) and the third arc-shaped side wall (106); The battery further comprises a protective layer (3), wherein the protective layer (3) at least covers the arc-shaped corner (100).

2. The battery according to claim 1, characterized in that The protective layer (3) also covers at least one of the first curved side wall (104), the second curved side wall (105) and the third curved side wall (106).

3. The battery according to claim 2, characterized in that The protective layer (3) covering at least one of the first curved side wall (104), the second curved side wall (105) and the third curved side wall (106) is connected to the protective layer (3) covering the curved corner (100).

4. The battery according to claim 1, characterized in that The housing (1) comprises a plurality of side walls, the plurality of side walls surround the battery core (2) to form a recess, and the battery core (2) is located in the recess; The multiple side walls include a first side wall (101), a second side wall (102) and a third side wall (103) which are connected to each other; the first side wall (101) and the second side wall (102) are connected via the first arc-shaped side wall (104); the second side wall (102) and the third side wall (103) are connected via the second arc-shaped side wall (105), and the first side wall (101) and the third side wall (103) are connected via the third arc-shaped side wall (106).

5. The battery according to claim 4, characterized in that The protective layer (3) also covers at least one of the first side wall (101), the second side wall (102) and the third side wall (103).

6. The battery according to any one of claims 1 to 5, characterized in that: At least part of the protective layer (3) is arranged on a side surface (11) of the housing (1) facing away from the battery core (2); And / or, at least a portion of the protective layer (3) is arranged on a surface of the housing (1) facing the battery core (2).

7. The battery according to any one of claims 1 to 5, characterized in that: In the first direction, the thickness of the protective layer (3) ranges from 0.5 μm to 1000 μm; And / or, along the first direction, the ratio of the thickness of the protective layer (3) to the thickness of the shell wall of the shell (1) is in the range of 0.01 to 10; And / or, the material of the protective layer (3) is selected from at least one of polyurethane, polyurea, polyamide, epoxy resin, rubber paint, silicon dioxide, graphene, copper and aluminum; And / or, the shell (1) has a top sealing area (121), at least part of the protective layer (3) is arranged on a side surface of the shell (1) facing away from the battery cell (2), and the projection of the protective layer (3) on the shell (1) does not exceed the outer edge of the top sealing area (121).

8. The battery according to any one of claims 1 to 5, characterized in that: The shell (1) has at least four arc-shaped corners (100); among all the arc-shaped corners (100), at least two adjacent arc-shaped corners (100) are covered with the protective layer (3); The protective layers (3) on two adjacent arc-shaped corners (100) are both located on a surface of the shell (1) on a side facing away from the battery cell (2) or on a surface of the shell (1) on a side facing the battery cell (2), and the protective layers (3) on at least two adjacent arc-shaped corners (100) are connected.

9. The battery according to any one of claims 1 to 5, characterized in that: At least part of the protective layer (3) is arranged on a side surface of the shell (1) facing the battery cell (2), the edge of the shell (1) has a heat-sealing area (12), and there is a distance between the protective layer (3) located on the side surface of the shell (1) facing the battery cell (2) and the heat-sealing area (12).

10. The battery according to claim 9, characterized in that Along the second direction, the distance between the protective layer (3) and the heat-sealing area (12) is not less than 0.5 mm.

11. The battery according to any one of claims 1 to 5, characterized in that: At least a portion of the protective layer (3) covers a surface (11) on one side of the entire housing (1) that faces away from the battery core (2); And / or, at least a portion of the protective layer (3) covers the entire surface of the housing (1) on one side facing the battery core (2).

12. The battery according to any one of claims 1 to 5, characterized in that: The battery cell comprises a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on the negative electrode current collector; The negative electrode active material of the negative electrode active layer includes a silicon-carbon composite material; The silicon-carbon composite material comprises a porous carbon matrix, silicon crystal grains located in the pores of the porous carbon matrix, and a carbon layer coated on the surface of the porous carbon matrix.

13. The battery according to claim 12, characterized in that The mass percentage of silicon in the negative electrode active material is 3% to 30%; and / or, the carbon layer is provided with openings corresponding to the pores of the porous carbon matrix; And / or, the specific surface area of ​​the silicon-carbon composite material is 0.5 m 2 / g~10m 2 / g; And / or, the median particle size of the silicon-carbon composite material is 6 μm to 15 μm; And / or, the powder resistivity of the silicon-carbon composite material is 0.1 Ω·cm to 1000 Ω·cm.

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