Battery, battery assembly and electric device

Abstract

The invention relates to the technical field of batteries, and particularly discloses a battery, a battery assembly and an electric device, the battery comprises an electrode, a diaphragm and a bonding layer, the bonding layer is located between the adjacent electrode and diaphragm, and the porosity of the bonding layer is 38%-76%. The cell in the battery is high in uniformity, the shaping process is convenient, the short circuit rate is low, and the cycle performance is relatively good.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to batteries, battery assemblies and electrical devices. Background Art

[0002] Lithium-ion batteries have been widely used in various fields, and cycle life is one of the important indicators for measuring the performance of lithium-ion batteries. However, in related technologies, battery-related performance still needs to be improved.

[0003] Application Contents

[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present application proposes a battery and an electrical device with a low short-circuit rate or a long cycle life.

[0005] The first aspect of the present application provides a battery. According to an embodiment of the present application, the battery includes electrodes, a separator, and an adhesive layer. The adhesive layer is located between adjacent electrodes and separators, and the porosity of the adhesive layer is 38% to 76%. By providing the adhesive layer, the uniformity of the battery cell can be improved, the shaping process can be facilitated, and the short-circuit rate can be reduced. At the same time, the adhesive layer having the above porosity can have better liquid retention, thereby improving the battery's cycle performance.

[0006] According to an embodiment of the present application, the porosity of the adhesive layer is 50% to 65%, thereby further improving the liquid retention rate and thus the cycle performance of the battery.

[0007] According to an embodiment of the present application, the adhesive layer is located at the edge of the surface of the electrode facing the separator (i.e., the adhesive layer is located at the edge of the surface perpendicular to the thickness direction of the electrode). In this way, the adhesive effect can be effectively exerted without substantially affecting the capacity of the electrode active material.

[0008] According to an embodiment of the present application, the electrode includes a current collector and an active material layer located on the surface of the current collector. The current collector has a hollow foil region where the active material layer is not located. The adhesive layer contacts the hollow foil region of the current collector. This provides strong adhesion while minimizing the impact on the active material layer. Furthermore, the electrode facilitates production, does not increase production cycle time, and is easy to operate.

[0009] According to an embodiment of the present application, the current collector includes a coating area and an adhesive area. The orthographic projection of the active material layer on the current collector is located in the coating area, and the orthographic projection of the adhesive layer on the current collector is located in the adhesive area. The adhesive area is closer to the edge of the current collector than the coating area. As a result, the adhesive layer has a good adhesive fixation effect while covering the edge of the current collector, which can reduce the short circuit rate of the battery. The adhesive layer does not cover the active material layer and will not negatively affect the capacity and energy density of the battery.

[0010] According to an embodiment of the present application, the peel strength between the electrode and the adhesive layer is 10 N / m to 20 N / m. According to an embodiment of the present application, the peel strength between the electrode and the adhesive layer is 12 N / m to 18 N / m.

[0011] According to an embodiment of the present application, the peel strength between the separator and the adhesive layer is 10 N / m to 20 N / m. According to an embodiment of the present application, the peel strength between the separator and the adhesive layer is 12 N / m to 18 N / m.

[0012] According to an embodiment of the present application, the adhesive layer and the current collector together constitute an adhesive structure, and the bending moment of the adhesive structure in the stacking direction of the adhesive layer and the current collector is 10,000 N·m to 20,000 N·m. According to an embodiment of the present application, the bending moment of the adhesive structure in the stacking direction of the adhesive layer and the current collector is 12,000 N·m to 14,000 N·m.

[0013] According to an embodiment of the present application, the electrode includes a tab, the tab is connected to the current collector, and the adhesive layer is provided on the edge of the current collector on the side connected to the tab.

[0014] According to an embodiment of the present application, the battery is a wound battery, and the adhesive layer is provided on two opposite edges of the electrode in a height direction perpendicular to the winding direction.

[0015] According to an embodiment of the present application, the battery is a laminated battery, and the adhesive layer is provided on each edge of the surface of the electrode facing the separator.

[0016] According to an embodiment of the present application, the adhesive layer includes one or more of polymethyl methacrylate, polyethyl methacrylate, polystyrene, polyvinyl chloride, polyethylene-vinyl acetate copolymer, polyethylene oxide, polyethylene succinate, polyethylene wax, polyvinylidene fluoride and its copolymer, polyurethane, polyimide, polyacrylonitrile, polyacrylic acid, styrene-butadiene rubber, carboxylic acid cellulose, polyethylene glycol, acrylamide, cyanate ester and silicone rubber.

[0017] According to an embodiment of the present application, the electrode may be in a sheet shape.

[0018] According to an embodiment of the present application, the electrode may include a positive electrode and a negative electrode, and the separator is stacked between the positive electrode and the negative electrode.

[0019] In a second aspect of the present application, a battery assembly is provided, comprising one or more of the above-mentioned batteries. The battery assembly has all the features and advantages of the above-mentioned batteries, which will not be described in detail here.

[0020] In a third aspect, the present application provides an electrical device. According to an embodiment of the present application, the electrical device includes the aforementioned battery or battery assembly. The electrical device has all the features and advantages of the aforementioned battery, which will not be further elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a partial cross-sectional structure of a battery according to an embodiment of the present application.

[0022] Figure 2 It is a schematic diagram of a partial cross-sectional structure of a battery according to another embodiment of the present application.

[0023] Figure 3 It is a schematic diagram of the cross-sectional structure of an electrode according to an embodiment of the present application.

[0024] Figure 4 It is a schematic diagram of the planar structure of an electrode according to an embodiment of the present application.

[0025] Figure 5 It is a schematic diagram of the planar structure of an electrode according to another embodiment of the present application.

[0026] Figure 6 It is a schematic diagram of the planar structure of an electrode according to another embodiment of the present application.

[0027] Figure 7 It is a schematic diagram of the planar structure of an electrode according to another embodiment of the present application.

[0028] Figure 8 It is a schematic diagram of the planar structure of an electrode according to another embodiment of the present application.

[0029] Figure 9 It is a schematic diagram of a partial cross-sectional structure of a battery according to an embodiment of the present application.

[0030] Figure 10 It is a schematic diagram of the peel strength test of this application. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0032] The first aspect of the present application provides a battery. According to the embodiment of the present application, referring to Figure 1 The battery 1 includes an electrode 10, a separator 20 and an adhesive layer 30. The adhesive layer 30 is located between the adjacent electrodes 10 and the separator 20. The porosity of the adhesive layer 30 is 38% to 76% (specifically 38%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 76%, etc.). By providing an adhesive layer, the internal layer of the battery cell can be prevented from being misplaced, which facilitates transportation and production in the battery production process and reduces the safety risk of the battery during application; and the neatness of the battery cell can be ensured, which facilitates the shaping process and reduces the short circuit rate; in addition, the adhesive layer having the above-mentioned porosity can have better liquid retention, which is beneficial to improving the cycle performance of the battery. In some embodiments of the present application, the electrode 10 can be in the form of a sheet, and the electrode 10 and the separator 20 are stacked.

[0033] According to an embodiment of the present application, the porosity of the adhesive layer is 50% to 65%, specifically 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, etc. This can further improve the liquid retention rate of the adhesive layer, thereby improving the cycle performance of the battery.

[0034] In this article, the porosity of the bonding layer can be tested using the mercury intrusion method defined in GB / T 21650.1-2008 “Determination of pore size distribution and porosity of solid materials by mercury intrusion and gas adsorption method Part 1: Mercury intrusion method”.

[0035] According to the embodiments of this application, referring to Figure 1 The adhesive layer 30 is located at the edge of the surface of the electrode 10 in contact with the adhesive layer 30. Thus, the adhesive layer can effectively exert its adhesive effect without substantially affecting the capacity of the electrode active material, thereby maintaining the energy density of the battery. It also substantially does not block the ion transmission channel, thereby reducing the battery impedance. Furthermore, the introduction of the adhesive layer substantially does not introduce safety risks such as deterioration of electrical performance such as low temperature, rate, and cycle performance, or short circuits caused by lithium plating.

[0036] It is understood that the specific shape of the adhesive layer is not particularly limited and can be flexibly adjusted and selected according to actual needs, including but not limited to strips or special shapes.

[0037] According to the embodiments of this application, referring to Figure 2The electrode 10 includes a current collector 101 and an active material layer 102 located on the surface of the current collector 101. The current collector 101 has a hollow foil region without the active material layer. The adhesive layer 30 contacts the hollow foil region of the current collector 101. This ensures strong adhesion while minimizing the impact on the active material layer. Furthermore, the process is easy to manufacture, does not increase production cycle time, and is simple to operate.

[0038] According to the embodiments of this application, referring to Figure 3 and Figure 4 The current collector 101 includes a coating area 101A and an adhesive area 101B. The orthographic projection of the active material layer 102 on the current collector 101 is located in the coating area 101A, and the orthographic projection of the adhesive layer 30 on the current collector 101 is located in the adhesive area 101B. The adhesive area 101B is closer to the edge of the current collector 101 than the coating area 101A. As a result, the adhesive layer provides a good adhesive fixation effect while covering the edge of the current collector, thereby reducing the short-circuit rate of the battery. Furthermore, the adhesive layer does not cover the active material layer, ensuring smooth and consistent ion channels in the battery, without increasing the battery impedance, achieving good electrical performance, and substantially no negative impact on the battery's capacity and energy density.

[0039] According to an embodiment of the present application, the peel strength between the electrode and the adhesive layer is 10N / m to 20N / m. According to an embodiment of the present application, the peel strength between the electrode and the adhesive layer is 12N / m to 18N / m. As an example, the peel strength between the electrode and the adhesive layer is 12N / m, 13N / m, 14N / m, 15N / m, 16N / m, 17N / m, 18N / m, etc. Within the above-mentioned peel strength range, the internal layer dislocation of the battery cell can be further prevented, which facilitates transportation and production in the battery production process and reduces the safety risk of the battery during application; and it can ensure the neatness of the battery cell, facilitate the shaping process, effectively prevent foreign matter from entering the battery, and significantly reduce the short circuit rate.

[0040] According to an embodiment of the present application, the peel strength between the separator and the adhesive layer is 10 N / m to 20 N / m. According to an embodiment of the present application, the peel strength between the separator and the adhesive layer is 12 N / m to 18 N / m. As an example, the peel strength between the separator and the adhesive layer is 12 N / m, 13 N / m, 14 N / m, 15 N / m, 16 N / m, 17 N / m, 18 N / m, etc.

[0041] This peel strength can further prevent internal misalignment of battery cells, facilitate handling and fabrication during battery production, and reduce safety risks during use. It also ensures the neatness of the battery cells, facilitates the shaping process, effectively prevents foreign matter from entering, and significantly reduces short-circuit rates. The above peel strength can be tested in accordance with GB / 2792-2014, "Test Method for Peel Strength of Adhesive Tapes."

[0042] According to an embodiment of the present application, the adhesive layer and the current collector together constitute an adhesive structure, and the bending moment of the adhesive structure in the direction of stacking the adhesive layer and the current collector is 10,000 N·m to 20,000 N·m. According to an embodiment of the present application, the bending moment of the adhesive structure in the direction of stacking the adhesive layer and the current collector is 12,000 N·m to 14,000 N·m. As an example, the bending moment of the adhesive structure in the direction of stacking the adhesive layer and the current collector is 12,000 N·m, 12,500 N·m, 13,000 N·m, 13,500 N·m, 14,000 N·m, etc.

[0043] Specifically, a higher bending moment ensures the adhesive structure's resistance to bending deformation within the battery, facilitating cell shaping and increasing the molding rate. It also improves the cell manufacturing cycle and yield rate. Bending moment can be measured in accordance with GB / T 9341-2008, "Testing for Flexural Properties of Plastics."

[0044] It is understood that the specific setting area of ​​the adhesive layer is not particularly limited, and the adhesive layer can be set only at the edge of part of the electrode (see Figure 5 and Figure 7 ), or an adhesive layer may be provided on all edges of the electrode (refer to Figure 6 and Figure 8 ).

[0045] According to the embodiments of this application, referring to Figure 5 and Figure 7 The electrode 10 includes a tab 13, and the tab 13 is connected to the current collector 101. In order to obtain a better bonding effect so that the electrode 10 does not slip, the edge of the current collector 101 connected to the tab 13 is provided with the bonding layer 30 (refer to Figure 5 and Figure 7 Specifically, the side of the electrode where the tab is led out generally needs to be welded, bent, and connected to the external circuit. This is very susceptible to external forces, and the electrode is prone to dislocation and slippage. Providing an adhesive layer on the side where the current collector leads out the tab can better bond the electrode, ensuring the neatness of the battery cell, facilitating the shaping process, and reducing the short-circuit rate.

[0046] It can be understood that in actual use, the position where the tabs are led out can be adjusted according to the actual application needs. For example, taking the electrode as a rectangular sheet, the tabs can be led out on the long side of the electrode, or on the short side of the electrode; and there is no special restriction on the number of tabs. For example, there can be multiple tabs or full tabs (that is, the part of the entire current collector in the electrode that is not coated with the active material layer is used as the tab).

[0047] According to the embodiments of this application, referring to Figure 8 The battery is a wound battery, and in the height direction perpendicular to the winding direction, the adhesive layer 30 is provided on both sides of the opposite edges of the electrode 10. This can further improve the neatness of the battery cell and reduce the short circuit rate.

[0048] In this article, wound battery is a common form of battery manufacturing process, which forms the battery cell structure by winding the battery electrodes and separators together in a certain way.

[0049] According to the embodiments of this application, referring to Figure 6 The battery is a laminated battery, and each edge of the surface of the electrode 10 facing the separator is provided with the adhesive layer 30. This can further improve the neatness of the battery cell and reduce the short circuit rate.

[0050] In this article, a laminated battery refers to a battery in which electrodes and separators are stacked layer by layer in a certain order to form a battery cell structure.

[0051] According to the embodiment of the present application, the electrode can be in sheet form. The structural diagram of the sheet electrode can be referred to Figure 7 and Figure 8 In some embodiments, the specific shape of the sheet electrodes is not particularly limited and can be selected according to actual use needs, including but not limited to rectangular, square, etc. This facilitates the preparation and assembly of the battery.

[0052] According to an embodiment of the present application, the electrode may include a positive electrode and a negative electrode, the separator is arranged between the positive electrode and the negative electrode, and the adhesive layer may be arranged between the positive electrode and the separator; may be arranged between the negative electrode and the separator; or may be arranged between the positive electrode and the separator and between the negative electrode and the separator at the same time.

[0053] As an example, see Figure 9The battery includes a positive electrode 11, a negative electrode 12, a separator 20 and an adhesive layer 30. The separator 20 is located between the adjacent positive electrodes 11 and negative electrodes 12. The positive electrode includes a positive electrode collector 111 and a positive electrode active material layer 112 located on both sides of the positive electrode collector. The negative electrode includes a negative electrode collector 121 and a negative electrode active material layer 122 located on both sides of the negative electrode collector. The adhesive layer is arranged at the edge of the positive electrode collector and the negative electrode collector, and is located between adjacent positive electrodes and separators and / or between adjacent negative electrodes and separators.

[0054] According to an embodiment of the present application, the adhesive layer includes one or more of polymethyl methacrylate, polyethyl methacrylate, polystyrene, polyvinyl chloride, polyethylene-vinyl acetate copolymer, polyethylene oxide, polyethylene succinate, polyethylene wax, polyvinylidene fluoride and its copolymers, polyurethane, polyimide, polyacrylonitrile, polyacrylic acid, styrene-butadiene rubber, carboxylic acid cellulose, polyethylene glycol, acrylamide, cyanate ester, and silicone rubber. Therefore, the material is widely available and easily accessible, and the adhesive effect is strong.

[0055] Furthermore, the adhesive layer of the above material can be directly applied during battery production without adding special processes such as winding, and without increasing the production rhythm. It can achieve self-crosslinking or further curing to achieve adhesion during the battery production process; and there is no need to consider the adverse effects of inconsistent thickness, the operation is convenient, and the effect is excellent; it avoids the problem of uneven membrane surface caused by coating the adhesive layer on the diaphragm, and the problem of the membrane surface being aggravated by unevenness after winding, transportation and storage, resulting in unusable problem.

[0056] According to the embodiments of the present application, the specific method for preparing the adhesive layer is not particularly limited. Specifically, the raw materials for the adhesive layer can be made into a solid tape and then bonded to the current collector by hot pressing, cold pressing, etc.; alternatively, the raw materials for the adhesive layer can be prepared into a slurry, coated on the current collector, and then formed into the adhesive layer by curing, chemical crosslinking, etc.

[0057] It can be understood that there is no special restriction on the specific type of the battery, which can be a primary battery, a secondary battery (including but not limited to lithium-ion batteries, sodium-ion batteries, etc.); the shape of the battery can be a cylindrical battery, a square battery, and according to the outer packaging classification, the battery can be a hard-shell battery, a soft-pack battery, etc.

[0058] It is understood that the battery can be used to assemble battery modules, which are then assembled into battery packs, or the battery can be directly assembled into a battery pack. The battery can be suitable for VDA structure battery packs or blade structure battery packs, and the specific choice can be flexible according to actual conditions.

[0059] In a second aspect of the present application, a battery assembly is provided, comprising one or more of the aforementioned batteries. The battery assembly may be, for example, a battery pack, a battery module, or the like.

[0060] In a third aspect, the present application provides an electrical device. According to an embodiment of the present application, the electrical device includes the aforementioned battery. The electrical device has all the features and advantages of the aforementioned battery, which will not be detailed here.

[0061] According to an embodiment of the present application, the battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, energy storage systems, etc.

[0062] It can be understood that in addition to the battery mentioned above, the above-mentioned electrical device also includes the necessary structures and components of a conventional electrical device. Taking a car as an example, it can also include a body, chassis, tires, seats, windows and other control systems, etc., which will not be repeated here.

[0063] The embodiments of the present application are described in detail below.

[0064] Example 1

[0065] Preparation of the adhesive layer:

[0066] Ethylene-vinyl acetate (EVA) resin with a 20wt% vinyl acetate (VA) content, boehmite, a crosslinker (TMCH) (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and a coupling agent (KH-560) (glycidoxypropyltrimethoxysilane)) were added to an open mill in a mass ratio of 84:10:2:4 and processed for 10 minutes at a temperature of 93±3°C. After the open mill, the sample was placed in a mold frame and then placed in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes to form a rubber strip with a thickness of 105.6 microns and a width of 4.5 mm.

[0067] Preparation of positive electrode:

[0068] Lithium iron phosphate (LiFePO4), conductive carbon (Super-P) and polyvinylidene fluoride (PVDF) were mixed in a solvent at a mass ratio of 95:2:3 and stirred evenly to obtain a positive electrode slurry. The slurry was coated on an 8μm aluminum foil, dried, and cold pressed to obtain a compaction density of 2.5g / cm 3The electrode piece is then cut and the ear is welded to obtain the positive electrode.

[0069] Preparation of negative electrode:

[0070] Natural graphite, conductive carbon (Super-P) and sodium carboxymethyl cellulose (CMC) were mixed in a solvent at a mass ratio of 95:2:3 and stirred evenly to obtain a negative electrode slurry. The slurry was coated on an 8μm copper foil, dried, and cold pressed to obtain a compacted density of 1.7g / cm 3 The electrode piece is then cut and the ear is welded to obtain the negative electrode.

[0071] Diaphragm: Use polyethylene ceramic diaphragm with a thickness of 20 microns.

[0072] Preparation of lithium-ion batteries:

[0073] The obtained positive electrode, negative electrode and separator are stacked in order, and the adhesive layer strips are placed on both sides of the edges of each layer of negative electrode and positive electrode during stacking (refer to Figure 8 ). After the battery cells are stacked, the corresponding positions of the adhesive layer strips are hot-pressed at 90°C / 1Mpa on a hot pressing plate to achieve the shaping and bonding effect of the internal electrodes and diaphragms of the battery cells. The shaped battery cells are assembled into an aluminum shell. Then, the electrolyte is poured from the injection port. The electrolyte composition includes 1mol / L LiPF6 and ethylene carbonate (EC), propylene carbonate (PC), and diethylene carbonate (DEC) with a mass ratio of 1:1:1. After the formation and capacity separation processes, the lithium-ion battery is obtained.

[0074] Example 2

[0075] The lithium-ion battery preparation method of Example 2 is substantially the same as that of Example 1, except that the porosity of the bonding layer is adjusted to 75.5% by changing the bonding layer formulation and process adjustments. The main differences are:

[0076] Preparation of the adhesive layer:

[0077] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 90:10:3:5. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0078] Example 3

[0079] The preparation method of the lithium ion battery of Example 3 is substantially the same as that of Example 1, except that the porosity of the bonding layer is adjusted to 48.4% by changing the formulation of the bonding layer and adjusting the process.

[0080] Preparation of the adhesive layer:

[0081] Ethylene-vinyl acetate (EVA) resin with 18 wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 86:10:2.5:4.5. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 93°C for 10 minutes. After the heat preservation period, the sample was placed in a flat plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0082] Example 4

[0083] The preparation method of the lithium ion battery of Example 4 is substantially the same as that of Example 1, except that the porosity of the bonding layer is adjusted to 66.7% by changing the formulation of the bonding layer and adjusting the process.

[0084] Preparation of the adhesive layer:

[0085] Ethylene-vinyl acetate (EVA) resin with a 14wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 88:10:3:5. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 93°C for 10 minutes. After the heat treatment, the sample was pressed in a flat-plate vulcanizer at a pressure of 10 MPa for 10 minutes.

[0086] Example 5

[0087] The preparation method of the lithium ion battery of Example 5 is substantially the same as that of Example 1, except that the porosity of the bonding layer is adjusted to 56% by changing the formulation of the bonding layer and adjusting the process.

[0088] Preparation of the adhesive layer:

[0089] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0090] Example 6

[0091] The preparation method of the lithium-ion battery of Example 6 is substantially the same as that of Example 5, except that the peel strength is adjusted to 10.13 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0092] Preparation of the adhesive layer:

[0093] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 80±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 80°C for 10 minutes. After the heat treatment, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0094] Example 7

[0095] The preparation method of the lithium-ion battery of Example 7 is substantially the same as that of Example 5, except that the peel strength is adjusted to 19.72 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0096] Preparation of the adhesive layer:

[0097] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 105±3°C. After the milling, the sample was placed in a mold frame and then held in an oven at 105°C for 10 minutes. After the heat was complete, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0098] Example 8

[0099] The preparation method of the lithium-ion battery of Example 8 is substantially the same as that of Example 5, except that the peel strength is adjusted to 12.06 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0100] Preparation of the adhesive layer:

[0101] Ethylene-vinyl acetate (EVA) resin (15wt% vinyl acetate (VA) content), boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 85±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 85°C for 10 minutes. After the heat was complete, the sample was pressed in a flat vulcanizer at a pressure of 10 MPa for 10 minutes.

[0102] Example 9

[0103] The preparation method of the lithium-ion battery of Example 9 is substantially the same as that of Example 5, except that the peel strength is adjusted to 18.15 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0104] Preparation of the adhesive layer:

[0105] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, a crosslinker (TMCH) (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and a coupling agent (KH-560) (glycidoxypropyltrimethoxysilane)) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 100±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 100°C for 10 minutes. After the heat treatment, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0106] Example 10

[0107] The preparation method of the lithium ion battery of Example 10 is substantially the same as that of Example 5, except that the peel strength is adjusted to 8.27 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0108] Preparation of the adhesive layer:

[0109] Ethylene-vinyl acetate (EVA) resin containing 15 wt% vinyl acetate (VA), boehmite, a crosslinker (TMCH) (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and a coupling agent (KH-560) (glycidoxypropyltrimethoxysilane)) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was processed for 10 minutes at a temperature of 75±3°C (the temperature increases with increasing filler content). After the open mill, the sample was placed in a mold frame and then incubated in an oven at 75°C for 10 minutes. After the incubation period, the sample was pressed in a flat-plate vulcanizer at a pressure of 10 MPa for 10 minutes.

[0110] Example 11

[0111] The preparation method of the lithium ion battery of Example 11 is substantially the same as that of Example 5, except that the peel strength is adjusted to 22.03 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0112] Preparation of the adhesive layer:

[0113] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:10:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 110±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 110°C for 10 minutes. After the heat treatment, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0114] Example 12

[0115] The preparation method of the lithium-ion battery of Example 12 is substantially the same as that of Example 5, except that the bending moment is adjusted to 10011.6 N·m by changing the formulation of the adhesive layer and adjusting the process.

[0116] Preparation of the adhesive layer:

[0117] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:4:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0118] Example 13

[0119] The preparation method of the lithium-ion battery of Example 13 is substantially the same as that of Example 5, except that the bending moment is adjusted to 15008.5 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0120] Preparation of the adhesive layer:

[0121] Ethylene-vinyl acetate (EVA) resin (15wt% vinyl acetate (VA) content), boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:14:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 93°C for 10 minutes. After the heat preservation period, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0122] Example 14

[0123] The preparation method of the lithium-ion battery of Example 14 is substantially the same as that of Example 5, except that the bending moment is adjusted to 11917.8 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0124] Preparation of the adhesive layer:

[0125] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:8:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0126] Example 15

[0127] The preparation method of the lithium-ion battery of Example 15 is substantially the same as that of Example 5, except that the bending moment is adjusted to 14006.5 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0128] Preparation of the adhesive layer:

[0129] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:12:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0130] Example 16

[0131] The preparation method of the lithium-ion battery of Example 16 is substantially the same as that of Example 5, except that the bending moment is adjusted to 18012.7 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0132] Preparation of the adhesive layer:

[0133] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, a crosslinker (TMCH) (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and a coupling agent (KH-560) (glycidoxypropyltrimethoxysilane)) were added to an open mill in a mass ratio of 87:20:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat-plate vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0134] Example 17

[0135] The preparation method of the lithium-ion battery of Example 17 is substantially the same as that of Example 5, except that the bending moment is adjusted to 17020.5 N / m by changing the formulation of the adhesive layer and adjusting the process.

[0136] Ethylene-vinyl acetate (EVA) resin with a 15wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 87:18:2.75:4.75. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then kept in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0137] Example 18

[0138] Preparation of the adhesive layer:

[0139] Methyl methacrylate (MMA): butyl acrylate (BA): hydroxyethyl methacrylate (HEMA): N-acetoxymethyl acrylamide: AIBN: alumina are mixed in NMP solvent in a mass ratio of 4:4:1:1:0.05:1.5. When coating the electrode, the mixture is applied to a 5 mm wide area around the edge of the current collector. The adhesive layer is self-crosslinked during the cell drying process.

[0140] The preparation method of the lithium ion battery is the same as that in Example 1.

[0141] Comparative Example 1

[0142] The preparation method of the lithium ion battery of Comparative Example 1 is substantially the same as that of Example 1, except that the porosity of the adhesive layer is adjusted to 29.8% by changing the formulation of the adhesive layer and adjusting the process.

[0143] Ethylene-vinyl acetate (EVA) resin (22 wt% vinyl acetate (VA) content), boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 82:10:1.6:3.6. The mixture was milled for 10 minutes at a temperature of 80±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 80°C for 10 minutes. After the heat was maintained, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0144] Comparative Example 2

[0145] The preparation method of the lithium ion battery of Example 2 is substantially the same as that of Example 1, except that the porosity of the bonding layer is adjusted to 79.6% by changing the formulation of the bonding layer and adjusting the process.

[0146] Ethylene-vinyl acetate (EVA) resin with a 10wt% vinyl acetate (VA) content, boehmite, crosslinker TMCH (1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane), and coupling agent KH-560 (glycidoxypropyltrimethoxysilane) were added to an open mill in a mass ratio of 90:10:3.5:5.5. The mixture was milled for 10 minutes at a temperature of 93±3°C. After the milling, the sample was placed in a mold frame and then placed in an oven at 93°C for 10 minutes. After the heat treatment, the sample was placed in a flat vulcanizer and pressed at a pressure of 10 MPa for 10 minutes.

[0147] Comparative Example 3

[0148] A polyethylene ceramic diaphragm with a thickness of 20 microns was used as the base membrane, PVDF-HFP was prepared into a 10% aqueous solution, and then coated on the surface of the ceramic material layer by roller coating. After drying, a polymer adhesive layer with a thickness of 3 μm was formed on the base membrane to obtain a diaphragm.

[0149] Other operations are the same as those in Example 1, except that the above-mentioned diaphragm with a polymer adhesive layer is used, and no adhesive layer is provided.

[0150] Performance testing:

[0151] 1. Bonding Layer Porosity Test: Using the mercury intrusion method defined in GB / T 21650.1-2008, "Determination of Pore Size Distribution and Porosity of Solid Materials by Mercury Intrusion and Gas Adsorption - Part 1: Mercury Intrusion," the pore volume is indirectly measured by measuring the volume of mercury that enters the bonding layer. During the mercury intrusion process, mercury is forced into the pores of the bonding layer, and the porosity and pore size distribution can be calculated based on the change in mercury volume.

[0152] Specific test conditions:

[0153] Temperature: Room temperature, 25±3℃; use mercury intrusion instrument, set the pressure range to 0-3000psi

[0154] Test method:

[0155] Sample preparation: The adhesive layer was soaked in N-methylpyrrolidone (NMP) or polycarbonate (PC) for 2 h, dried naturally, and made into a 4 mm diameter disc as the adhesive layer sample for porosity testing.

[0156] Install the sample: Place the disc sample into the sample chamber of the mercury intrusion instrument and ensure it is well sealed.

[0157] Start the test: Set the pressure range on the mercury intrusion porosimeter and begin the test. As the pressure increases, mercury will gradually enter the pores of the sample. Record the changes in pressure and mercury volume during the experiment.

[0158] Data collection and recording: After the test is completed, obtain experimental data from the mercury intrusion instrument, including the volume of mercury entering the sample and the corresponding pressure value. Record this data.

[0159] Data processing and analysis: Porosity values ​​were read from the mercury intrusion porosimeter device.

[0160] 2. Bending moment test: Referring to GB / T 9341-2008 "Test for Bending Properties of Plastics", the bending moment of the adhesive layer joint in the battery cell of the battery product can be directly tested.

[0161] Test conditions: Temperature: room temperature, 25±3℃; use bending moment tester.

[0162] Test method:

[0163] 1) Fix the hot-pressed adhesive layer and current collector sample on the bracket of the bending moment testing machine to ensure that the sample remains horizontal during the test.

[0164] 2) Adjust the loading device so that it is directly below the sample to apply the bending load.

[0165] 3) Apply a bending load along the stacking direction of the adhesive layer and current collector, and record the displacement and deformation of the sample. Observe and record any damage to the sample during the loading process. When the sample shows damage (i.e., cracks or breaks visible to the naked eye), record the load value at that time.

[0166] 4) Calculate the bending moment based on the test results. The bending moment calculation formula is: M = PL / 2 (where P is the load value and L is the length of the sample, that is, the length between the two test supports).

[0167] 3. Peel strength test: Refer to GB / 2792-2014 "Test method for peel strength of adhesive tape". The peel strength between the adhesive layer and the corresponding separator or current collector can be directly tested through the battery cell.

[0168] Test conditions: Temperature: 25℃±3℃;

[0169] Testing equipment: universal testing machine, roller glue machine;

[0170] Test method:

[0171] 1) Take part of the battery cell including the adhesive layer, retain the adhesive layer and the current collector, remove the part without the adhesive layer to obtain a long and thin strip sample, cut it into a sample to be tested with a length of 100 mm, and apply tape to the surface of the current collector of the sample to be tested to ensure that there are no bubbles between the tape and the current collector and that it is flat;

[0172] 2) Apply tape to the surface of the adhesive layer of the sample to be tested, away from the current collector, so that the tape position coincides with the tape position on the current collector surface;

[0173] 3) Roll the tape onto the sample to be tested and perform a peeling test (see the attached diagram for the peeling test). Figure 10 ).

[0174] 4) Data processing: The measured sample is subjected to a uniform tensile force, which results in complete separation between the adhesive layer and the current collector. The force required to peel off the adhesive layer interface is the peel force, and the peel force per unit width (perpendicular to the peeling direction) is the peel strength.

[0175] 4. Cycle performance test:

[0176] Test conditions: Temperature 25℃±3℃

[0177] Testing process:

[0178] Discharge: 1 / 3C discharge to 2.0V; stand for 30 minutes

[0179] Charging: 1 / 3C charge to 3.8V, leave for 30 minutes

[0180] Perform N discharge-charge cycles under the above discharge-charge conditions, record the third discharge capacity as C1, the Nth discharge capacity as Cn-2, and the Nth capacity retention rate as Cn-2 / C1. When the capacity retention rate reaches 80%, record N data and the number of cycles as N-2.

[0181] 5. Yield test:

[0182] (1) Observe the appearance: If no damage, electrode misalignment, foil exposure or material falling is observed with the naked eye, it is qualified; otherwise, it is unqualified.

[0183] (2) Short circuit rate: The product is qualified if no short circuit occurs during the 200V high voltage impact test.

[0184] If both the appearance and short-circuit rate meet the requirements, it is a good product; otherwise, it is a defective product.

[0185] Table 1

[0186]

[0187]

[0188] Note: The ratios in the above table represent the mass ratios of EVA resin, boehmite, crosslinking agent TMCH and coupling agent KH-560.

[0189] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0190] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0191] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0192] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0193] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0194] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A battery, characterized in that: The invention comprises an electrode, a separator and an adhesive layer. The adhesive layer is located between the electrode and the separator, and the porosity of the adhesive layer is 38% to 76%.

2. The battery according to claim 1, characterized in that The porosity of the adhesive layer is 50% to 65%.

3. The battery according to claim 1 or 2, characterized in that The adhesive layer is located at an edge of a surface of the electrode facing the separator.

4. The battery according to any one of claims 1 to 3, characterized in that The electrode includes a current collector and an active material layer located on the surface of the current collector, wherein the current collector has a hollow foil area where the active material layer is not provided; and the adhesive layer is in contact with the hollow foil area of ​​the current collector.

5. The battery according to claim 4, characterized in that The current collector includes a coating area and an adhesive area, the orthographic projection of the active material layer on the current collector is located in the coating area, and the orthographic projection of the adhesive layer on the current collector is located in the adhesive area; The adhesive region is closer to the edge of the current collector than the coating region.

6. The battery according to any one of claims 1 to 5, characterized in that The peel strength between the electrode and the adhesive layer is 10 N / m to 20 N / m, preferably 12 N / m to 18 N / m.

7. The battery according to any one of claims 1 to 6, characterized in that The peel strength between the separator and the adhesive layer is 10 N / m to 20 N / m, preferably 12 N / m to 18 N / m.

8. The battery according to claim 4, characterized in that The adhesive layer and the current collector together form an adhesive structure, and the bending moment of the adhesive structure in the stacking direction of the adhesive layer and the current collector is 10000N·m to 20000N·m, preferably 12000N·m to 14000N·m.

9. The battery according to any one of claims 1 to 8, characterized in that The electrode includes a tab, which is connected to the current collector. The adhesive layer is provided on an edge of the current collector on a side connected to the tab.

10. The battery according to any one of claims 1 to 9, characterized in that The battery is a wound battery, and the adhesive layer is provided on both sides of the opposite edges of the electrode in a direction perpendicular to the winding direction.

11. The battery according to any one of claims 1 to 10, characterized in that: The battery is a laminated battery, and the adhesive layer is provided on each edge of the surface of the electrode facing the separator.

12. The battery according to any one of claims 1 to 11, characterized in that The adhesive layer includes one or more of polymethyl methacrylate, polyethyl methacrylate, polystyrene, polyvinyl chloride, polyethylene-vinyl acetate copolymer, polyethylene oxide, polyethylene succinate, polyethylene wax, polyvinylidene fluoride and its copolymer, polyurethane, polyimide, polyacrylonitrile, polyacrylic acid, styrene-butadiene rubber, carboxylic acid cellulose, polyethylene glycol, acrylamide, cyanate ester and silicone rubber.

13. The battery according to any one of claims 1 to 12, characterized in that The electrode satisfies at least one of the following conditions: The electrode is in sheet shape; The electrodes include a positive electrode and a negative electrode, and the separator is stacked between the positive electrode and the negative electrode.

14. A battery assembly, characterized in that: The invention comprises one or more batteries according to any one of claims 1 to 13.

15. An electrical device, characterized in that: The invention comprises the battery according to any one of claims 1 to 13 or the battery assembly according to claim 14.

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