A winding core and a battery

Abstract

The utility model provides a kind of roll core and battery, including positive sheet, negative sheet and diaphragm;Positive sheet includes positive current collector, positive active material layer;Negative sheet includes negative current collector, negative active material layer;Along the length direction of positive sheet, the side of positive sheet away from negative sheet is equipped with the first empty foil area exposed to positive active material layer, first aerogel layer is equipped on the first empty foil area;And / or, along the length direction of negative sheet, the side of negative sheet away from positive sheet is equipped with the second empty foil area exposed to negative active material layer, second aerogel layer is equipped on the second empty foil area;The utility model can prevent the single surface area of pole piece curling by setting aerogel layer in the empty foil area of pole piece, solve the problem that single surface area of pole piece curls and folds when winding;The compressibility of aerogel layer is strong, aerogel layer shrinks when roll core expands, reduce the internal pressure of roll core, reduce the phenomenon that pole piece breaks in the cycle process of roll core, guarantee battery life.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a winding core and a battery. Background Technology

[0002] The mechanism of electrode breakage in pouch batteries is mainly related to the pressure and mechanical stress experienced by the battery during use. Studies have shown that after multiple charge-discharge cycles, especially under pressure, the expansion of the negative electrode material (such as graphite composite electrode) in pouch lithium-ion batteries can lead to the breakage of the negative electrode sheet and / or the outer positive electrode sheet.

[0003] Specifically, electrode breakage typically occurs at the first bend of the innermost layer of the negative electrode and / or the first bend of the outermost layer of the positive electrode, especially after the copper foil coating the negative electrode material is corroded. This alters the internal structure of the battery, leading to stress concentration and ultimately fracture. Under extrusion conditions, the deformation modes of pouch cells include in-plane fracture and interlaminar shear fracture, which are closely related to the occurrence of internal short circuits. Therefore, overcoming the aforementioned technical problems and defects is a key issue that needs to be addressed. Utility Model Content

[0004] To address the problem that the electrode sheet is prone to bending, folding, and breaking on one side during the winding of existing cores, this utility model provides a core and a battery.

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: This utility model provides a wound core, including a positive electrode sheet, a negative electrode sheet, and a separator; The positive electrode sheet includes a positive current collector and a positive active material layer; The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer; Along the length of the positive electrode sheet, a first empty foil area is provided on the side of the positive electrode sheet opposite to the negative electrode sheet, exposing the positive electrode active material layer. The first empty foil area is located at the starting or ending end of the winding of the positive electrode sheet, and a first aerogel layer is provided on the first empty foil area; and / or, Along the length of the negative electrode sheet, a second empty foil area is provided on the side of the negative electrode sheet opposite to the positive electrode sheet, which is exposed outside the negative electrode active material layer. The second empty foil area is located at the starting end or ending end of the winding of the negative electrode sheet, and a second aerogel layer is provided on the second empty foil area.

[0006] Optionally, the first empty foil area is located at the winding end of the positive electrode sheet; and / or, The second empty foil area is located at the starting end of the winding of the negative electrode sheet.

[0007] Optionally, the thickness of the positive electrode active material layer on the side opposite to the negative electrode sheet is h1, in μm; the thickness of the first aerogel layer is h2, in μm. The first empty foil area is located at the winding end of the positive electrode sheet, and h1 and h2 satisfy the relationship: 1≤h2 / h1≤10.

[0008] Optionally, the thickness of the negative electrode active material layer on the side opposite to the positive electrode sheet is h3, in μm; the thickness of the second aerogel layer is h4, in μm. The second empty foil region is located at the starting end of the winding of the negative electrode sheet, and h3 and h4 satisfy the relationship: 1≤h4 / h3≤3; or, The second empty foil area is located at the winding end of the negative electrode sheet, and h3 and h4 satisfy the relationship: 1≤h4 / h3≤10.

[0009] Optionally, the first aerogel layer may wrap around the outer ring of the core at least once from its starting end to its ending end; and / or, The second aerogel layer extends at least once around the inner ring of the core from its starting end to its ending end.

[0010] Optionally, the core includes a flat region and an arc region, with the starting end of the first aerogel layer located in the arc region and the ending end of the first aerogel layer located in the flat region; and / or, The starting end of the second aerogel layer is located in the flat region, and the ending end of the second aerogel layer is located in the arc region.

[0011] Optionally, the positive electrode sheet may further include a third empty foil region on the side opposite to the negative electrode sheet, the third empty foil region being spaced between the positive electrode active material layer and the first aerogel layer; and / or, The negative electrode sheet is further provided with a fourth empty foil region on the side opposite to the positive electrode sheet, and the fourth empty foil region is separated from the negative electrode active material layer and the second aerogel layer.

[0012] Optionally, along the length of the positive electrode sheet, the width of the third empty foil region is w1, where w1 ranges from 0.1 to 3 mm; and / or, Along the length of the negative electrode sheet, the width of the fourth empty foil region is w2, and the value of w2 ranges from 0.1 to 3 mm.

[0013] Optionally, a protective adhesive layer is also provided, with both ends of the protective adhesive layer bonded to the positive electrode active material layer and the first aerogel layer, respectively; and / or, The two ends of the protective adhesive layer are respectively bonded to the negative electrode active material layer and the second aerogel layer.

[0014] Optionally, the first aerogel layer and the second aerogel layer are each independently selected from one of carbon aerogel layer and graphene aerogel layer.

[0015] Another aspect of this invention provides a battery comprising the winding core as described above.

[0016] According to the core provided by this utility model, by setting a first aerogel layer in the first empty foil area of ​​the positive electrode sheet, the curling of one side of the positive electrode sheet can be prevented, solving the problem of curling and folding of one side of the positive electrode sheet during winding; by setting a second aerogel layer in the second empty foil area of ​​the negative electrode sheet, the curling of one side of the negative electrode sheet can be prevented, solving the problem of curling and folding of one side of the negative electrode sheet during winding; the aerogel layer has strong compressibility, and the aerogel layer contracts when the core expands, reducing the internal pressure of the core, reducing the phenomenon of breakage of the positive electrode sheet and / or negative electrode sheet during the core cycle, and ensuring battery life. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the first structure of the winding core provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the second structure of the winding core provided in one embodiment of the present invention; Figure 3 This is a schematic diagram of the third structure of the winding core provided in one embodiment of the present invention; Figure 4 This is a schematic diagram of the first structure of the positive electrode sheet provided in one embodiment of the present invention; Figure 5 This is a schematic diagram of a second structure of the positive electrode sheet provided in one embodiment of the present invention; Figure 6 This is a schematic diagram of the first structure of the negative electrode sheet provided in one embodiment of the present invention; Figure 7 This is a schematic diagram of the second structure of the negative electrode sheet provided in one embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the winding core provided by existing technology; Figure 9 This is a schematic diagram of the structure of a positive electrode provided by existing technology; Figure 10 This is a schematic diagram of the structure of the negative electrode provided by existing technology; The reference numerals in the accompanying drawings are as follows: 100-Core; 1-Positive electrode sheet; 11-Positive electrode current collector; 12-Positive electrode active material layer; 13-First empty foil region; 14-First aerogel layer; 15-Third empty foil region; 2-Negative electrode sheet; 21-Negative electrode current collector; 22-Negative electrode active material layer; 23-Second empty foil region; 24-Second aerogel layer; 25-Fourth empty foil region; 3-Separator; 4-Protective adhesive layer. Detailed Implementation

[0019] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0020] In the description of this utility model, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0022] like Figure 1 , Figure 4 and Figure 6 As shown, in one embodiment, the present invention provides a core 100, including a positive electrode 1, a negative electrode 2, and a separator 3; The positive electrode 1 includes a positive current collector 11 and a positive active material layer 12; The negative electrode 2 includes a negative electrode current collector 21 and a negative electrode active material layer 22; Along the length of the positive electrode 1, a first empty foil region 13 is provided on the side of the positive electrode 1 facing away from the negative electrode 2, exposed outside the positive electrode active material layer 12. The first empty foil region 13 is located at the starting or ending end of the winding of the positive electrode 1, and a first aerogel layer 14 is provided on the first empty foil region 13; and / or, Along the length of the negative electrode 2, a second empty foil region 23 is provided on the side of the negative electrode 2 away from the positive electrode 1, which is exposed outside the negative electrode active material layer 22. The second empty foil region 23 is located at the starting end or ending end of the winding of the negative electrode 2, and a second aerogel layer 24 is provided on the second empty foil region 23.

[0023] Specifically, the positive electrode 1 has a positive active material layer 12 on the side close to the negative electrode 2, and a positive active material layer 12 and a first empty foil region 13 on the side of the positive electrode 1 away from the negative electrode 2. The first empty foil region 13 is located at the starting end or ending end of the winding of the positive electrode 1. The position of the positive electrode 1 in the first empty foil region 13 is a single-sided region, that is, the area on the positive electrode 1 where the first empty foil region 13 is located is a single-sided region of the positive electrode 1.

[0024] This application provides a first aerogel layer 14 in the first empty foil area 13 of the positive electrode 1 to prevent the single-sided area of ​​the positive electrode 1 from curling, thus solving the problem of curling and folding of the single-sided area of ​​the positive electrode 1 during winding.

[0025] Specifically, the negative electrode 2 has a negative electrode active material layer 22 on the side close to the positive electrode 1, and a negative electrode active material layer 22 and a second empty foil region 23 on the side of the negative electrode 2 away from the positive electrode 1. The second empty foil region 23 is located at the starting end or ending end of the winding of the negative electrode 2. The position of the negative electrode 2 in the second empty foil region 23 is a single-sided region, that is, the area on the negative electrode 2 where the second empty foil region 23 is located is the single-sided region of the negative electrode 2.

[0026] This application provides a second aerogel layer 24 in the second empty foil area 23 of the negative electrode 2 to prevent the single-sided area of ​​the negative electrode 2 from curling, thus solving the problem of curling and folding of the single-sided area of ​​the negative electrode 2 during winding.

[0027] Furthermore, the aerogel layer is highly compressible. When the core 100 expands, the aerogel layer contracts, reducing the internal pressure of the core 100 and reducing the occurrence of breakage of the positive electrode 1 and / or negative electrode 2 during the cycle of the core 100, thus ensuring battery life.

[0028] like Figure 1 , Figure 4 and Figure 6 As shown, in one embodiment, the first empty foil region 13 is located at the winding end of the positive electrode sheet 1; and / or, The second empty foil region 23 is located at the starting end of the winding of the negative electrode 2.

[0029] Specifically, setting the first empty foil area 13 at the winding end of the positive electrode sheet 1 has the technical effect of preventing the positive electrode sheet from curling on one side and reducing the breakage of the electrode sheet during the winding cycle. Specifically, setting the second empty foil area 23 at the starting end of the winding of the negative electrode sheet 2 has the technical effect of preventing the negative electrode sheet from curling on one side and reducing the breakage of the electrode sheet during the winding cycle. In other embodiments, the first empty foil area 13 is set at the starting end of the winding of the positive electrode sheet 1, which has the technical effect of reducing the breakage of the electrode sheet during the winding process. Setting the second empty foil area 23 at the winding end of the negative electrode 2 has the technical effect of reducing electrode breakage during the core circulation process.

[0030] like Figures 4-5 As shown, in one embodiment, the thickness of the positive electrode active material layer 12 on the side opposite to the negative electrode 2 is h1, in μm; the thickness of the first aerogel layer 14 is h2, in μm. The first empty foil region 13 is located at the winding end of the positive electrode 1, and h1 and h2 satisfy the relationship: 1≤h2 / h1≤10.

[0031] Specifically, when the first empty foil region 13 is located at the winding end of the positive electrode 1, the value of h2 / h1 is any one of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 or a range of any two of these values; in a preferred embodiment, the value of h2 / h1 is 1-3.

[0032] When the value of h2 / h1 is between 1 and 10, it can prevent the positive electrode from curling on one side and reduce the breakage of the electrode during the winding process. When the value of h2 / h1 is less than 1, it will lead to greater pressure during the winding process and cause the electrode to break. When the value of h2 / h1 is greater than 10, it will lead to excessive absorption of electrolyte, resulting in waste, and at the same time, the energy density of the cell will decrease.

[0033] In another embodiment, the first empty foil region 13 is located at the starting end of the winding of the positive electrode 1, and h1 and h2 satisfy the relationship: 1≤h2 / h1≤3.

[0034] When the value of h2 / h1 is between 1 and 3, it has the effect of reducing electrode breakage during core winding. When the value of h2 / h1 is less than 1, it will lead to higher pressure during core winding and electrode breakage; when the value of h2 / h1 is greater than 3, it will lead to excessive electrolyte absorption and waste, and at the same time, the cell energy density will decrease.

[0035] like Figures 6-7 As shown, in one embodiment, the thickness of the negative electrode active material layer 22 on the side opposite to the positive electrode 1 is h3, in μm; the thickness of the second aerogel layer 24 is h4, in μm. The second empty foil region 23 is located at the starting end of the winding of the negative electrode 2, and h3 and h4 satisfy the relationship: 1≤h4 / h3≤3; or, The second empty foil region 23 is located at the winding end of the negative electrode 2, and h3 and h4 satisfy the relationship: 1≤h4 / h3≤10.

[0036] Specifically, when the second empty foil region 23 is located at the starting end of the winding of the negative electrode 2, the value of h4 / h3 is any one of 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3, or a range of any two of these values; in a preferred embodiment, the value of h4 / h3 is 1-2.

[0037] When the value of h4 / h3 is between 1 and 3, it can prevent the negative electrode from curling on one side and reduce the breakage of the electrode during the winding process. When the value of h4 / h3 is less than 1, it will lead to greater pressure during the winding process and cause the electrode to break. When the value of h4 / h3 is greater than 3, it will lead to excessive absorption of electrolyte, resulting in waste, and at the same time, the energy density of the cell will decrease.

[0038] Specifically, when the second empty foil region 23 is located at the winding end of the negative electrode sheet 2, the value of h4 / h3 is any one of 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, or a range of any two of these values; in a preferred embodiment, the value of h4 / h3 is 1-3.

[0039] When the value of h4 / h3 is between 1 and 10, it has the effect of reducing electrode breakage during core winding. When the value of h4 / h3 is less than 1, it will lead to higher pressure during core winding and electrode breakage; when the value of h4 / h3 is greater than 10, it will lead to excessive electrolyte absorption and waste, and at the same time, the cell energy density will decrease.

[0040] like Figures 1-3 As shown, in one embodiment, the first aerogel layer 14 at least wraps around the outer perimeter of the core 100 from its starting end to its ending end; and / or, The second aerogel layer 24 extends at least once around the inner circle of the core 100 from the beginning to the end.

[0041] Specifically, the first aerogel layer 14 wraps around the outer ring of the core 100 at least once from the beginning to the end, which has the technical effect of preventing the positive electrode sheet from curling on one side and reducing the breakage of the electrode sheet during the core circulation process. The second aerogel layer 24 surrounds the inner circle of the core 100 at least once from the beginning to the end, which has the technical effect of preventing the negative electrode sheet from curling on one side and reducing the breakage of the electrode sheet during the core circulation process.

[0042] like Figures 1-3As shown, in one embodiment, the core 100 includes a flat region and an arc region, with the starting end of the first aerogel layer 14 located in the arc region and the ending end of the first aerogel layer 14 located in the flat region; and / or, The starting end of the second aerogel layer 24 is located in the flat region, and the ending end of the second aerogel layer 24 is located in the arc region.

[0043] Specifically, the starting end of the first aerogel layer 14 is located in the arc region, and the ending end of the first aerogel layer 14 is located in the straight region, which has the technical effect of reducing the breakage of the electrode sheet during the core circulation process. The starting end of the second aerogel layer 24 is located in the flat region, and the ending end of the second aerogel layer 24 is located in the arc region, which has the technical effect of reducing the breakage of the electrode sheet during the core circulation process. like Figure 2 and Figure 5 As shown, in one embodiment, the positive electrode 1 is further provided with a third empty foil region 15 on the side opposite to the negative electrode 2, and the third empty foil region 15 is spaced between the positive electrode active material layer 12 and the first aerogel layer 14; and / or, like Figure 3 and Figure 7 As shown, the negative electrode 2 is provided with a fourth empty foil region 25 on the side opposite to the positive electrode 1. The fourth empty foil region 25 is separated from the negative electrode active material layer 22 and the second aerogel layer 24.

[0044] Specifically, a third empty foil region 15 is provided between the positive electrode active material layer 12 and the first aerogel layer 14, which has the technical effect of preventing the aerogel layer 14 from covering the positive electrode active material layer 12. A fourth empty foil region 25 is provided between the negative electrode active material layer 22 and the second aerogel layer 24, which has the technical effect of preventing the aerogel layer 24 from covering the negative electrode active material layer 22.

[0045] like Figure 2 , Figure 3 , Figure 5 and Figure 7 As shown, in one embodiment, along the length direction of the positive electrode 1, the width of the third empty foil region 15 is w1, and the value of w1 ranges from 0.1 to 3 mm; and / or, Along the length of the negative electrode 2, the width of the fourth empty foil region 25 is w2, and the value of w2 ranges from 0.1 to 3 mm.

[0046] Specifically, the value of w1 is any point value or any two point values ​​in the range of 0.1-3mm; in a preferred embodiment, the value of w1 is 0.5-2mm.

[0047] When the value of w1 is in the range of 0.1-3mm, it has the effect of preventing the aerogel layer from covering the positive electrode active material layer. When the value of w1 is less than 0.1mm, due to the small processing allowance, the aerogel layer is prone to covering the positive electrode active material layer; when the value of w1 is greater than 3mm, it will cause the empty foil area of ​​w1 to fold during the winding process.

[0048] Specifically, the value of w2 is any point value or any two point values ​​in the range of 0.1-3mm; in a preferred embodiment, the value of w2 is 0.5-2mm.

[0049] When the value of w2 is in the range of 0.1-3mm, it has the effect of preventing the aerogel layer from covering the negative electrode active material layer. When the value of w2 is less than 0.1mm, due to the small processing allowance, the aerogel layer is prone to covering the positive electrode active material layer; when the value of w2 is greater than 3mm, it will cause the empty foil area of ​​w2 to fold during the winding process.

[0050] like Figure 2 , Figure 3 , Figure 5 and Figure 7 As shown, in one embodiment, a protective adhesive layer 4 is also provided, with both ends of the protective adhesive layer 4 bonded to the positive electrode active material layer 12 and the first aerogel layer 14, respectively; and / or, The two ends of the protective adhesive layer 4 are bonded to the negative electrode active material layer 22 and the second aerogel layer 24, respectively.

[0051] By setting a protective adhesive layer 4, the positive electrode active material layer 12 and the first aerogel layer 14 are bonded together, which has the technical effect of preventing the w1 empty foil from breaking; and / or, By setting a protective adhesive layer 4, the negative electrode active material layer 22 and the second aerogel layer 24 are bonded together, which has the technical effect of preventing the empty foil of w2 from breaking.

[0052] like Figures 1-7 As shown, in one embodiment, the first aerogel layer 14 and the second aerogel layer 24 are each independently selected from one of carbon aerogel layer and graphene aerogel layer.

[0053] Specifically, carbon aerogels have extremely high specific surface areas (up to 3000 m²). 2 Porosity is as high as 80% to 99%, and density is extremely low (as low as 0.16 mg / cm³). 3 It can absorb electrolyte, increasing the electrolyte retention of the battery cell. When compressed, the electrolyte is squeezed out, increasing the amount of electrolyte participating in the reaction and improving the kinetic performance of the battery cell. Carbon aerogel also has excellent electrical conductivity and thermal stability, and can remain stable in high-temperature environments.

[0054] The graphene aerogel layer has a three-dimensional continuous porous network structure, inheriting the advantages of graphene and aerogel, such as high specific surface area, high porosity, high electrical conductivity, as well as good thermal conductivity and mechanical strength. It can absorb electrolyte, increase the electrolyte retention of the battery cell, and when compressed, the electrolyte is squeezed out, increasing the amount of electrolyte participating in the reaction and improving the kinetic performance of the battery cell. Carbon aerogel also has excellent electrical conductivity and thermal stability, and can remain stable in high-temperature environments.

[0055] like Figures 1-3 As shown, in one embodiment, the present invention provides a battery comprising the winding core 100 as described above.

[0056] The battery of this application uses the above-mentioned positive electrode 1 and / or negative electrode 2, which can prevent the single-sided area of ​​the electrode from curling and solve the problem of the single-sided area of ​​the electrode curling and folding during winding.

[0057] The battery in this application can be a power source for an electrical device or an energy storage unit for an electrical device. Electrical devices can include, but are not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0058] The following examples further illustrate the beneficial effects of this utility model.

[0059] To make the utility model's objective, technical solution, and beneficial effects clearer, the present invention will be further described in detail below with reference to embodiments. However, it should be understood that the embodiments of the present invention are merely for explaining the present invention and are not intended to limit it, and the embodiments of the present invention are not limited to those given in the specification. Unless otherwise specified in the embodiments, preparations were carried out under conventional conditions or according to the conditions recommended by the material supplier.

[0060] Furthermore, it should be understood that the one or more method steps mentioned in this utility model do not preclude the existence of other method steps before or after the combination steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combination connection relationship between one or more devices / apparatus mentioned in this utility model does not preclude the existence of other devices / apparatus before or after the combination devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this utility model.

[0061] In the following embodiments, the reagents, materials and instruments used, unless otherwise specified, are commercially available or can be obtained through synthesis methods known in the art.

[0062] Table 1 shows the design of the positive and negative current collectors in Examples 1-13 and Comparative Example 1; Example 1 Preparation of positive electrode: Lithium cobalt oxide (CCO), SP (SP), and PVDF (PVDF) binder are mixed in a mass ratio of 97:1.8:1.2. The mixture is thoroughly stirred in NMP solvent to form a uniform CCO slurry. This slurry is then coated onto both sides of the CCO current collector, and after drying, rolling, and die-cutting, a CCO sheet meeting the required specifications is obtained.

[0063] A first empty foil area is provided at the winding end of the positive current collector on the side away from the negative electrode sheet. The first empty foil area is coated with a first aerogel layer. A third empty foil area is provided between the first aerogel layer and the positive electrode active material layer. The third empty foil area w1 is 1 mm. The thickness ratio of the first aerogel layer to the thickness of the positive electrode active material layer is 1. Preparation of negative electrode: The negative electrode active material graphite, conductive agent SP, and binder CMC are mixed in a mass ratio of 98:1:1. The mixture is thoroughly stirred in a deionized water solvent to form a uniform negative electrode slurry. This slurry is coated onto both sides of the negative electrode current collector, and after drying, rolling, and die-cutting, a negative electrode sheet meeting the required specifications is obtained.

[0064] A second empty foil area is provided at the winding start end of the negative electrode current collector on the side opposite to the positive electrode sheet. The second empty foil area is coated with a second aerogel layer. A fourth empty foil area is provided between the second aerogel layer and the negative electrode active material layer. The thickness ratio of the second aerogel layer to the thickness of the negative electrode active material layer is 1. Preparation of the diaphragm: A porous PE polymer film is used as the separator; Electrolyte preparation: Lithium salt LiPF6 was dissolved in organic solvent EC-DMC (1:1 volume ratio) at a concentration of 1M to obtain a liquid electrolyte.

[0065] Battery manufacturing: The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. Then, one end of each of the positive electrode, separator, and negative electrode is wound around the electrolyte separator to form a core. The wound core is then placed in a pre-formed aluminum-plastic film bag. The electrolyte prepared above is injected into the baked and dried cell. After vacuum sealing, settling, and formation processes, a 1Ah battery is obtained.

[0066] Example 2-13 Examples 2-13 illustrate the winding core and battery disclosed in this utility model, including most of the operating steps in Example 1, with the following differences: The design of the positive current collector and negative current collector shown in Table 1 is adopted.

[0067] Comparative Examples 1-3 Comparative Examples 1-3 are used to illustrate the winding core and battery disclosed in this utility model, including most of the operating steps in Example 1, the difference being: The design of the positive current collector and negative current collector shown in Table 1 is adopted.

[0068] Test method: 1. Cyclic performance testing The batteries obtained in Examples 1-13 and Comparative Examples 1-3 were charged at 3C constant current and constant voltage to 4.5V, cut off at 0.05C, and discharged at 0.5C. The initial capacity of the battery was recorded. The number of cycles was counted when the battery capacity retention rate decreased to 80% of the initial capacity. The batteries were disassembled to check the folding of the electrode plates, which were divided into no folding, slight folding, moderate folding, and breakage.

[0069] Test results: See Table 2.

[0070] Table 2 Figure 8 This is a schematic diagram of the core structure in Comparative Example 1; Figure 9 This is a schematic diagram of the positive electrode in Comparative Example 1; Figure 10 This is a schematic diagram of the negative electrode in Comparative Example 1; As shown in Table 2, comparing Examples 1-7 and Comparative Example 1, it can be seen that when a first aerogel layer is provided in the first empty foil area of ​​the positive electrode sheet, the single-sided area of ​​the positive electrode sheet can be prevented from curling, thus solving the problem of curling and folding of the single-sided area of ​​the positive electrode sheet during winding; and / or when a second aerogel layer is provided in the second empty foil area of ​​the negative electrode sheet, the single-sided area of ​​the negative electrode sheet can be prevented from curling, thus solving the problem of curling and folding of the single-sided area of ​​the negative electrode sheet during winding, which is beneficial to improving the cycle life of the battery.

[0071] Comparing Examples 7 and 8, it can be seen that when the value of h2 / h1 is greater than 10, it will lead to excessive absorption of electrolyte, resulting in waste, and at the same time, the energy density of the battery cell will decrease.

[0072] Comparing Examples 10 and 11, it can be seen that when the value of h4 / h3 is greater than 3, it will lead to excessive absorption of electrolyte, resulting in waste, and at the same time, the energy density of the battery cell will decrease.

[0073] Comparing Examples 1 and 12, it can be seen that when the value of w1 is greater than 3mm, it will cause the empty foil of w1 to be folded, affecting the battery cycle life.

[0074] Comparing Example 1 and Example 13, it can be seen that when the value range of w2 is greater than 3mm, it will cause the empty foil of w2 to be folded, affecting the battery cycle life.

[0075] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A winding core, characterized in that: Includes positive electrode, negative electrode, and separator; The positive electrode sheet includes a positive current collector and a positive active material layer; The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer; Along the length of the positive electrode sheet, a first empty foil area is provided on the side of the positive electrode sheet opposite to the negative electrode sheet, exposing the positive electrode active material layer. The first empty foil area is located at the starting or ending end of the winding of the positive electrode sheet, and a first aerogel layer is provided on the first empty foil area; and / or, Along the length of the negative electrode sheet, a second empty foil area is provided on the side of the negative electrode sheet opposite to the positive electrode sheet, which is exposed outside the negative electrode active material layer. The second empty foil area is located at the starting end or ending end of the winding of the negative electrode sheet, and a second aerogel layer is provided on the second empty foil area.

2. The winding core according to claim 1, characterized in that: The first empty foil area is located at the winding end of the positive electrode sheet; and / or, The second empty foil area is located at the starting end of the winding of the negative electrode sheet.

3. The winding core according to claim 2, characterized in that: The thickness of the positive electrode active material layer on the side opposite to the negative electrode sheet is h1, in μm; the thickness of the first aerogel layer is h2, in μm. The first empty foil area is located at the winding end of the positive electrode sheet, and h1 and h2 satisfy the relationship: 1≤h2 / h1≤10.

4. The winding core according to claim 2, characterized in that: The thickness of the negative electrode active material layer on the side opposite to the positive electrode sheet is h3, in μm; the thickness of the second aerogel layer is h4, in μm. The second empty foil region is located at the starting end of the winding of the negative electrode sheet, and h3 and h4 satisfy the relationship: 1≤h4 / h3≤3; or, The second empty foil area is located at the winding end of the negative electrode sheet, and h3 and h4 satisfy the relationship: 1≤h4 / h3≤10.

5. The winding core according to claim 2, characterized in that: The first aerogel layer wraps around the outer ring of the core at least once from its starting end to its ending end; and / or, The second aerogel layer extends at least once around the inner ring of the core from its starting end to its ending end.

6. The winding core according to claim 5, characterized in that: The core includes a flat region and a curved region, with the starting end of the first aerogel layer located in the curved region and the ending end of the first aerogel layer located in the flat region; and / or The starting end of the second aerogel layer is located in the flat region, and the ending end of the second aerogel layer is located in the arc region.

7. The winding core according to claim 1, characterized in that: The positive electrode sheet also has a third empty foil region on the side opposite to the negative electrode sheet, and the third empty foil region is spaced between the positive electrode active material layer and the first aerogel layer; and / or, The negative electrode sheet is further provided with a fourth empty foil region on the side opposite to the positive electrode sheet, and the fourth empty foil region is separated from the negative electrode active material layer and the second aerogel layer.

8. The winding core according to claim 7, characterized in that: Along the length of the positive electrode sheet, the width of the third empty foil region is w1, where w1 ranges from 0.1 to 3 mm; and / or, Along the length of the negative electrode sheet, the width of the fourth empty foil region is w2, and the value of w2 ranges from 0.1 to 3 mm.

9. The winding core according to claim 6, characterized in that: It also protects the protective adhesive layer, the two ends of which are respectively bonded to the positive electrode active material layer and the first aerogel layer; and / or, The two ends of the protective adhesive layer are respectively bonded to the negative electrode active material layer and the second aerogel layer.

10. The winding core according to claim 1, characterized in that: The first aerogel layer and the second aerogel layer are each independently selected from one of carbon aerogel layer and graphene aerogel layer.

11. A battery, characterized in that: Includes the core as described in any one of claims 1-10.

Images