Battery

Abstract

The utility model provides a battery which comprises a shell and a battery cell, and the shell covers the outer side of the battery cell; 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 utility model relates to battery technology field, concretely relates to a battery. BACKGROUND

[0002] Lithium ion battery is widely used in electronic equipment such as mobile phone, notebook computer and the like at present due to the advantages of high energy density, long cycle life and environmental protection low pollution.

[0003] Among them, lithium ion battery includes electric core and the shell that is covered in the electric core outside side. Such as in the process of continuously charging and discharging electric core, electric core will expand with time and extrude shell constantly, especially such as when shell is soft package shell, shell is extruded and is easy to break or break. And the shell that breaks or breaks can not effectively block water and oxygen and the like into the electric core inside, and seriously can lead to the leakage of electrolyte, causes the performance failure of electric core and even the unsafe problems such as combustion explosion. SUMMARY

[0004] Therefore, the utility model embodiment is dedicated to providing a battery to improve the problem that the shell of the battery is easy to break or break to some extent.

[0005] The utility model provides a kind of battery, including shell and electric core, the shell is covered in the electric core outside side;

[0006] The shell at least includes first arc-shaped side wall, second arc-shaped side wall and third arc-shaped side wall connected with each other, and the junction of the first arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall forms arc-shaped corner;

[0007] The battery further includes 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 arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall.

[0009] Optionally, the protective layer covering at least one of the first arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall is connected with the protective layer covering the arc-shaped corner.

[0010] Optionally, the shell includes a plurality of side walls, and the plurality of side walls form a recess around the electric core, and the electric core is located in the recess.

[0011] The plurality of side walls comprises a first side wall, a second side wall and a third side wall connected to each other; the first side wall and the second side wall are connected by the first arc-shaped side wall; the second side wall and the third side wall are connected by the second arc-shaped side wall, and the first side wall and the third side wall are connected by the third arc-shaped 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 arranged on a side surface of the shell away from the battery cell.

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

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

[0016] And / or, in the first direction, the ratio of the thickness of the protective layer to the thickness of the shell wall of the shell ranges from 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 cell, 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 the two adjacent arc-shaped corners are both located on a side surface of the shell away from the battery cell or both located on a side surface of the shell facing the battery cell, and the protective layers on the at least two adjacent arc-shaped corners are connected.

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

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

[0023] Optionally, at least part of the protective layer covers the whole side surface of the shell away from the battery cell;

[0024] Optionally, at least part of the protective layer covers the whole side surface of the shell away from the battery cell.

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

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

[0027] The silicon-carbon composite material comprises a porous carbon matrix, silicon grains located in 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] Optionally, the carbon layer is provided with openings corresponding to the pores of the porous carbon matrix.

[0030] Optionally, the specific surface area of the silicon-carbon composite material is 0.5 m 2 / g to 10 m 2 / g.

[0031] Optionally, the median particle size of the silicon-carbon composite material is 6 μm to 15 μm.

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

[0033] The battery provided by the utility model has the advantages that the shell comprises at least a first arc-shaped side wall, a second arc-shaped side wall and a third arc-shaped side wall connected with each other, an arc-shaped corner is formed at the connection intersection of the first arc-shaped side wall, the second arc-shaped side wall and the third arc-shaped side wall, the protective layer is arranged, at least covers the arc-shaped corner, at least protects the arc-shaped corner of the shell by the protective layer, the tensile strength and the structural strength of the shell are improved, for example, when the battery cell is expanded to extrude the shell during the charging and discharging process of the battery cell, or when the battery cell is put into the shell, the battery cell contacts the corner of the shell, and the like, due to the existence of the protective layer, the arc-shaped corner of the shell is at least prevented from being extruded or contacted and collided to be damaged or broken to a certain extent, the shell is effectively protected, the performance of the battery cell is ensured, and the safety of the battery is improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The utility model discloses a battery's structure schematic view of an embodiment of the utility model;

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

[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 protective layers are provided on the corresponding curved corners, first curved side walls, second curved side walls, and third curved side walls of the housing;

[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] Figure 9 This is a partial structural cross-sectional view of the housing and protective layer according to an embodiment of the present utility model;

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

[0044] Figure 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. Arc-shaped corner; 101. First side wall; 102. Second side wall; 103. Third side wall; 104. First arc-shaped side wall; 105. Second arc-shaped side wall; 106. Third arc-shaped side wall; 11. One side surface; 12. Heat-sealing area; 121. Top sealing area; 122. Side sealing area; 2. Battery cell; 21. Tab; 3. Protective layer. DETAILED DESCRIPTION

[0046] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application belong to the scope of protection of the present application.

[0047] The lithium ion battery comprises: an electric core and a shell, and the shell is wrapped on the outer side of the electric core.

[0048] For example, in the process of continuous charging and discharging of the electric core, the electric core will continuously expand and extrude the shell with time, especially when the shell is a soft package shell, the shell is easily damaged or broken under extrusion, such as causing the shell to have an angular crack or angular break.

[0049] For another example, when the electric core is put into the shell, the edges and corners of the electric core are easy to contact with the edges and corners of the shell, which easily causes the shell to be broken or damaged.

[0050] However, the shell which is damaged or broken cannot effectively block the entry of water and oxygen and the like into the inside of the electric core, and seriously can cause the leakage of electrolyte and the like, resulting in performance failure of the electric core and even unsafe problems such as combustion and explosion.

[0051] Therefore, the present application provides a battery, by setting a protective layer, the protective layer covers at least part of the arc-shaped corner of the shell. The protective layer protects at least part of the arc-shaped corner of the shell, thereby improving the tensile strength and structural strength of the shell, at least avoiding the damage or breakage of the corner of the shell under extrusion or contact collision, effectively protecting the shell, and further ensuring the performance of the electric core and improving the safety of the battery.

[0052] The battery provided by the present application will be described in detail below with reference to the accompanying drawings and specific embodiments:

[0053] Referring to Figures 1 to 11 The present embodiment provides a battery, which can be a lithium ion battery, and specifically can be a soft package lithium ion battery.

[0054] The battery can be used as a power supply or an energy storage unit of an electronic device, which can be a mobile phone, a notebook computer, a tablet computer or the like.

[0055] The battery provided by the present embodiment comprises: a shell 1 and an electric core 2, and the shell 1 is wrapped on the outer side of the electric core 2.

[0056] The battery cell 2 may specifically include a positive electrode sheet, a negative electrode sheet, and a separator, with the separator positioned between the positive and negative electrode sheets. Exemplarily, the positive electrode sheet, separator, and negative electrode sheet are stacked and wound to form a wound battery cell. The battery cell 2 has a tab 21 extending outside the housing 1.

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

[0058] It should be noted that Figures 2 to 8 、 Figures 10 to 11 The shell 1 shown is specifically a shell structure corresponding to the shell before the battery cell 2 is encapsulated, 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, Figure 2 The battery cell is placed in the punched hole in the direction of the arrow shown in the figure, and the aluminum-plastic film is folded in half. The subsequent heat sealing, liquid injection, and formation processes are then carried out to form a battery. Among them, heat sealing can specifically include top sealing and side sealing.

[0060] In a 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 together define a cavity for placing the battery cell.

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

[0062] Based on this, in the battery provided in this embodiment, the housing 1 includes at least: 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 , which covers at least the arc-shaped corner 100 .

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

[0066] Since the arc-shaped corner 100 is located at the connection 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 protective layer 3 at least protects the arc-shaped corner 100, thereby not only improving the tensile strength and structural strength of the arc-shaped corner 100, but also improving the tensile strength and structural strength of the first arc-shaped side wall 104, the second arc-shaped side wall 105, and the third arc-shaped 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 being cracked or broken to a certain extent.

[0067] Taking the shell 1 as an aluminum-plastic film shell as an example, referring to Figures 2 to 11 , it is shown that, for example, when a single pit is punched on an aluminum-plastic film, the shell 1 can have four arc-shaped corners 100, which can be the four corner positions of the pit.

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

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

[0070] For example, referring to Figure 7 , Figure 10 , and Figure 11 , the four arc-shaped corners 100 of the shell 1 are all covered with the protective layer 3.

[0071] The battery provided by the embodiment comprises a shell 1, the shell 1 comprises 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 of the first arc-shaped side wall 104, the second arc-shaped side wall 105 and the third arc-shaped side wall 106, and the protective layer 3 is arranged to cover at least the arc-shaped corner 100, so that the protective layer 3 protects at least the arc-shaped corner 100 of the shell 1, improves the tensile strength and structural strength of the shell 1, and avoids the damage or rupture of the arc-shaped corner 100 of the shell 1 caused by extrusion or contact collision, effectively protects the shell 1, ensures the performance of the battery cell 2 and improves the safety of the battery.

[0072] Referring to Figure 6 In some embodiments, the protective layer 3 also covers at least one of the first arc-shaped side wall 104, the second arc-shaped side wall 105 and the third arc-shaped side wall 106.

[0073] For example, the protective layer 3 covers at least part of the arc-shaped corner 100 and at least part of the first arc-shaped side wall 104, or the protective layer 3 covers at least part of the arc-shaped corner 100 and at least part of the second arc-shaped side wall 105, or the protective layer 3 covers at least part of the arc-shaped corner 100 and at least part of the third arc-shaped side wall 106, or the protective layer 3 covers at least part of the arc-shaped corner 100 and at least part of one or two of the first arc-shaped side wall 104, the second arc-shaped side wall 105 and the third arc-shaped side wall 106, or as shown in Figure 6 The protective 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, further improves the tensile strength and structural strength of the shell 1, and further avoids the damage or rupture of the shell 1.

[0075] Referring to Figure 6 In some embodiments, the protective layer 3 covering at least one of the first arc-shaped side wall 104, the second arc-shaped side wall 105 and the third arc-shaped side wall 106 is connected to the protective layer 3 covering the arc-shaped corner 100.

[0076] In this way, the protective layer 3 is not easily detached, improving the stability and protection effect of the protective layer 3. For example, if the connection between the protective layer 3 at the arc-shaped corner 100 and the arc-shaped corner 100 is accidentally loosened, the protective layer 3 located on the first arc-shaped side wall 104, the second arc-shaped side wall 105, and the third arc-shaped side wall 106 can play a certain fixing role on the protective layer 3 located at the arc-shaped corner 100, avoiding the protective layer 3 at the arc-shaped corner 100 from being detached from the arc-shaped corner 100.

[0077] Referring to Figures 2 to 6 In some embodiments, the shell 1 includes a plurality of side walls that form a recess around the battery cell 2, and the battery cell 2 is located in the recess. The plurality of side walls includes a first side wall 101, a second side wall 102, and a third side wall 103 connected to each other.

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

[0079] For example, the first side wall 101 and the second side wall 102 are perpendicular to each other, the second side wall 102 and the third side wall 103 are perpendicular to each other, and the first side wall 101 and the third side wall 103 are perpendicular to each other.

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

[0081] 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 arranged between the two first side walls 101, thereby enclosing the battery cell 2, and the shell 1 forms eight corners, i.e., eight arc-shaped corners 100.

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

[0083] Referring to Figure 8As shown, the protective layer 3 can cover at least part of the first sidewall 101, at least part of the second sidewall 102, and at least part of the third sidewall 103 simultaneously. Of course, the protective layer 3 can also cover only one or two of the first sidewall 101, the second sidewall 102, and the third sidewall 103.

[0084] In this way, the coverage of the protective layer 3 is further increased, and the tensile strength and structural strength of the shell 1 are further improved, and the occurrence of damage or rupture of the shell 1 is further avoided.

[0085] Continuing to refer to Figure 8 As shown, the protective layer 3 covers the arc-shaped corner 100, the first arc-shaped sidewall 104, the second arc-shaped sidewall 105, the third arc-shaped sidewall 106, the first sidewall 101, the second sidewall 102, and the third sidewall 103 simultaneously, thereby further increasing the coverage of the edge and corner of the shell 1 and further improving the protection effect on the shell 1.

[0086] Referring to Figures 5 to 11 As shown, in some embodiments, at least part of the protective layer 3 is arranged on the side surface 11 of the shell 1 away from the battery cell 2.

[0087] That is, at least part of the protective layer 3 is arranged on the outer side surface of the shell 1 and covers at least part of the arc-shaped corner 100 of the shell 1.

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

[0089] By arranging at least part of the protective layer 3 on the outer side surface of the shell 1, not only is the protection of the shell 1 by the protective layer 3 achieved, and the occurrence of rupture or damage of the shell 1 due to expansion and extrusion or contact, collision, etc. is avoided, but also the protective layer 3 can be observed whether it is detached from the arc-shaped corner 100 or the like, so as to further ensure the effective protection of the shell 1 by the protective layer 3, and the arrangement of the protective layer 3 is more convenient and easier to operate.

[0090] Moreover, since the protective layer 3 is located on the outer side 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 accommodation space of the battery cell 2 is larger, and the energy density of the battery cell 2 is improved.

[0091] In some embodiments, at least part of the protective layer 3 can also be arranged on the side surface of the shell 1 facing the battery cell 2.

[0092] That is, at least part of the protective layer 3 is arranged on the inner side surface of the shell 1 and covers at least part of the arc-shaped corner 100 of the shell 1.

[0093] For example, in the case of an aluminum-plastic film shell, after the pits are punched on the aluminum-plastic film and before the battery cell 2 is placed in the shell 1, the protective layer 3 is arranged on the inner side surface of the shell 1, so that the protective layer 3 covers at least part of the arc-shaped corner 100 of the inner side surface of the shell 1.

[0094] By arranging at least part of the protective layer 3 on the inner side surface of the shell 1, the protective layer 3 not only protects the shell 1 from being broken or damaged due to expansion and extrusion, contact, collision, etc., but also effectively hides the protective layer 3 to some extent, thereby improving the appearance of the battery.

[0095] In some embodiments, the protective layer 3 can also be arranged on the side surface of the shell 1 facing the battery cell 2 and the side surface of the shell 1 away from the battery cell 2.

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

[0097] Of course, the protective layer 3 can also be fixed on the shell 1 by other means, and the present embodiment is not limited to the above-mentioned means.

[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] For example, when the protective layer 3 is arranged on the shell 1 by spraying, the protective layer 3 can be selected from a polymer coating, such as polyurethane, polyurea, polyamide, epoxy resin, rubber paint, graphene oxide, graphene coating, silicon dioxide, ceramic coating, chitosan coating, etc.

[0100] By spraying the protective layer 3 on the shell 1, the protective layer 3 is not easy to fall off, thereby improving the stability of the protective layer 3 and further improving the protective effect of the protective layer 3 on the shell 1.

[0101] For example, when the protective layer 3 is arranged on the shell 1 by pasting, 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 selected from a graphene film and a polymer film (such as a polyurethane film and a nylon film).

[0102] By pasting the protective layer 3 on the shell 1, the operation is convenient, and when the protective layer 3 is pasted on the outer side surface of the shell 1, the protective layer 3 can be easily replaced.

[0103] For example, when the protective layer 3 is provided 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. 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 can 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 Figure 9 As shown, the first direction here can be specifically Figure 9 In the up and down direction, the thickness h here is specifically the thickness of the protective layer 3 along Figure 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 effective protection effect of the protective layer 3 on the shell 1 be guaranteed, 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 Figure 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 Figure 9 In the up and down direction, the thickness h here is specifically the thickness of the protective layer 3 along Figure 9 The vertical dimension in the figure is the thickness H of the shell 1 along the wall.Figure 9 the thickness H of the shell wall of the shell 1, i.e. the vertical distance between the inner side of the shell 1 to the outer side of the shell 1 along the first direction.

[0113] It should be noted that the thickness H of the shell wall of the shell 1 here can be the thickness of the region of the shell wall of the shell 1 covered by the protective layer 3, or can be the average thickness of the entire shell wall of the 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 in the above range, not only can the effective protection of the protective layer 3 to the shell 1 be ensured, but also the overall thickness of the battery product can meet the requirements, and the high energy density of the battery is also considered.

[0115] Referring to FIG. 1, Figures 1 to 11 In some embodiments, the shell 1 has at least four arc-shaped corners 100. Among all the arc-shaped corners 100, the protective layer 3 is covered on at least two adjacent arc-shaped corners 100.

[0116] Such a setting can further improve the coverage and protection range of the protective layer 3 to the shell 1, and further improve the protection effect.

[0117] Referring to FIG. 1, Figure 11 Among them, the protective layer 3 on the two adjacent arc-shaped corners 100 can be located on the side surface 11 of the shell 1 away from the battery cell 2 or on the side surface of the shell 1 facing the battery cell 2, and the protective layer 3 on at least two adjacent arc-shaped corners 100 is connected.

[0118] For example, Figure 11 In FIG. 1, the protective layer 3 is covered on the four arc-shaped corners 100, and the protective layer 3 on the two arc-shaped corners 100 on the right side is connected.

[0119] Of course, in other implementations, such as the two protective layers 3 on the left side can also be connected, or the protective layer 3 on the four arc-shaped corners 100 can be connected together, etc.

[0120] Such a setting improves the coverage range of the protective layer 3 on the shell 1, such as covering the two adjacent arc-shaped corners 100 and the region between the two arc-shaped corners 100 at the same time, thereby further improving the protection effect of the protective layer 3 to the shell 1, and improving the stability of the entire protective layer 3 on the shell 1, so that the protective layer 3 is not easy to fall off.

[0121] In combination with FIGS. 1 and 2, Figure 1 and FIG. 3, Figure 10 As shown, in specific implementation, the shell 1 has a heat sealing area 12. Exemplarily, the heat sealing area 12 can specifically include a top sealing area 121, and can also include a side sealing area 122.

[0122] Referring to Figure 10 shown, in some embodiments, the at least partial protective layer 3 is arranged on the side surface of the housing 1 facing the battery cell 2, and the protective layer 3 on the side surface of the housing 1 facing the battery cell 2 has a spacing b from the heat sealing area 12.

[0123] Referring to Figure 10 shown, taking the aluminum plastic film housing as an example, after the battery cell 2 is placed in the pit, the aluminum plastic film is folded along o-o, and then heat sealing treatment is performed at the top sealing area 121 to form a top sealing edge, and heat sealing treatment is performed at the side sealing area 122 to form a side sealing edge. Specifically, the aluminum plastic film can include, from inside to outside, a hot melt layer, an aluminum layer, and a nylon layer in sequence, and after the aluminum plastic film is folded, the two opposite hot melt layers are fused together at the heat sealing area 12, thereby realizing edge sealing.

[0124] When the protective layer 3 is arranged on the side surface of the housing 1 facing the battery cell 2, if the protective layer 3 contacts or covers the heat sealing area 12, it will affect the fusion of the heat sealing area, and thus cause leakage and other situations to occur, therefore, by providing the spacing b between the protective layer 3 and the heat sealing area 12, the sealing effect is ensured, and the safety of the battery is improved.

[0125] For example, the spacing b here can be the vertical distance between the protective layer 3 and the top sealing area 121 in the up-down direction along o-o. Figure 10

[0126] In some embodiments, in 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 can 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, the up-down direction in o-o. Figure 10

[0128] By setting the spacing b between the protective layer 3 and the heat sealing area 12 to be not 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 can also be the side sealing area 122, that is, the protective layer 3 has a spacing from the side sealing area 122, and the spacing here is, for example, the horizontal distance between the side sealing area 122 and the protective layer 3 in the left-right direction along o-o. Figure 10

[0130] In some embodiments, when the protective layer 3 is arranged on the side surface of the housing 1 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] Referring to​​​Figure 1 As shown, the outer edge of the top sealing area 121 here can be specifically the upper edge of the top sealing area 121 along the up-down direction. Figure 1 As shown, the projection of the protective layer 3 on the shell 1 here can be specifically the projection of the protective layer 3 on the plane of the top sealing area 121. Figure 1 As shown, the projection of the protective layer 3 on the shell 1 here can be specifically the projection of the protective layer 3 on the plane of the top sealing area 121.

[0132] In this way, the protective layer 3 effectively protects the shell 1 while avoiding the situation that the protective layer 3 exceeds the outer edge of the top sealing area 121, thus causing the length dimension (for example, the dimension in the up-down direction) of the shell 1 to be too large, and further ensuring the unit volume energy density of the battery to a certain extent. Figure 1

[0133] In some embodiments, at least part of the protective layer 3 covers the side surface 11 of the entire shell 1 away from the battery cell 2.

[0134] That is, the protective layer 3 covers the entire outer side surface of the shell 1, thereby protecting the entire shell 1, further improving the protection effect of the shell 1, and further avoiding the situation that the shell 1 is broken or damaged due to the expansion and extrusion of the battery cell 2 or due to impact.

[0135] In some embodiments, at least part of the protective layer 3 covers the side surface of the entire shell 1 towards the battery cell 2.

[0136] That is, the protective layer 3 covers the entire inner side surface of the shell 1, thereby protecting the entire shell 1, further improving the protection effect of the shell 1, and further avoiding the situation that the shell 1 is broken or damaged due to the expansion and extrusion of the battery cell 2 or due to impact.

[0137] In some embodiments, the negative electrode tab 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 may, for example, be selected from a silicon-based material.

[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, for example, include a silicon-carbon composite material. The silicon-carbon composite material includes a porous carbon matrix, silicon grains located 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 the matrix can uniformly disperse the silicon grains in the porous carbon material, and alleviate the volume expansion of the silicon grains during the lithium intercalation process.

[0141] ​By providing 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 conductive properties of the material, thereby improving the initial performance of the negative electrode active material.

[0142] This arrangement enables the negative electrode sheets and batteries prepared using silicon-carbon composite materials as negative electrode active materials 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 squeezing 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 squeezing.

[0144] In this embodiment, by providing protective layer 3 covering at least the curved corners 100, the housing 1 is particularly suitable for encapsulating negative silicon-doped battery cells 2. When the negative silicon-doped battery cells 2 expand during charging and discharging, the protective layer 3 provided at least partially at the curved corners 100 of the housing 1 enhances the tensile and structural strength of the housing 1, at least to a certain extent preventing damage or cracking at the corners of the housing 1, thereby ensuring the performance of the battery cells 2 and improving battery safety.

[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 breaking, 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 silicon-carbon composite material more structurally 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, 5.25 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, 9 m 2 / g, 10 m 2 / g.

[0148] By setting the specific surface area of the silicon-carbon composite material in the above range, the contact between the negative active material and the electrolyte is reduced, the formation of the solid electrolyte interface film (SEI film) is reduced, and thus the initial efficiency and capacity retention rate of the battery are improved.

[0149] In specific implementation, the specific surface area of the silicon-carbon composite material can be determined 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 can 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 small, it means that it has a higher specific surface area, a larger contact area with the electrolyte, and more active lithium consumed during the first charge process, resulting in a lower initial efficiency of the negative active material. If the particle size of the material is large, the diffusion path of lithium ions in the material is longer, the kinetic performance of the negative active material is poorer, and the gap between large particle size particles is large, making it difficult to obtain a negative plate with a higher compaction density, resulting in a lower volumetric energy density of the battery. Therefore, by setting the particle size of the silicon-carbon composite material in the above range, the initial efficiency performance of the negative active material is improved, while the kinetic performance of the negative active material and the volumetric energy density of the battery are also considered.

[0152] In specific implementation, the particle size distribution of the material can be determined by a laser particle size analyzer: for example, first, the sample to be measured is added to a medium liquid and uniformly dispersed by ultrasonic; then the medium liquid containing the sample to be measured is poured into a measuring chamber; then the laser particle size analyzer is started, the laser beam is irradiated into the sample to scatter, and the intensity and angle of the scattered light are recorded, that is, the particle size and distribution of the sample to be measured 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 can 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 in the above range, it can to some extent avoid the situation that the battery internal resistance is too high and the energy loss is large, thereby ensuring the efficiency of the battery.

[0155] In this document, unless otherwise clearly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of this application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting this application.

[0156] In this document, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action, and do not necessarily require or imply that the entities or actions are in any such actual relationship or order. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a list of elements not only includes those elements, but also includes other elements not explicitly listed, or other elements inherent in such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0157] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

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 curved side wall (104), a second curved side wall (105), and a third curved side wall (106) connected to each other, wherein a curved corner (100) is formed at a junction of the first curved side wall (104), the second curved side wall (105), and the third curved side wall (106); The battery further comprises a protective layer (3), wherein the protective layer (3) covers at least 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 forming a recess around the battery core (2), 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) that are connected to each other; the first side wall (101) and the second side wall (102) are connected via the first curved side wall (104); the second side wall (102) and the third side wall (103) are connected via the second curved side wall (105); and the first side wall (101) and the third side wall (103) are connected via the third curved 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 a portion 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 provided 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 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 the protective layer (3); The protective layers (3) on the two adjacent arc-shaped corners (100) are both located on the surface of the shell (1) facing away from the battery cell (2) or on the surface of the shell (1) 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 core (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 core (2) and the heat-sealing area (12).

10. The battery according to claim 9, characterized in that In 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) 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 includes a negative electrode sheet, and the negative electrode sheet includes 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 includes a porous carbon matrix, silicon 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 0.5m 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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