Electrode assembly, battery, and electric device

Abstract

The present application relates to an electrode assembly, a battery, and an electric device. The electrode assembly comprises a negative electrode sheet, a separator, and a positive electrode sheet. The separator is arranged on one side of the negative electrode sheet; the separator comprises a base material and a bonding layer; the bonding layer is arranged on the surface of the base material; the bonding layer comprises first polymers; and the first polymers are copolymers of vinylidene fluoride and hexafluoropropylene. The positive electrode sheet is arranged on the side of the separator facing away from the negative electrode sheet; the positive electrode sheet comprises a current collector layer and an active material layer which are stacked; the active material layer is arranged on the surface of the current collector layer and faces the bonding layer; the active material layer comprises active particles and second polymers; the second polymers are granular; the second polymers are dispersed in the active particles; and the second polymers are bonded to the first polymers.

Description

[Corrected 28.11.2024 in accordance with Rule 26] Electrode assemblies, batteries and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 28, 2024, with application number 2024103707018 and application name “Electrode Plate, Battery and Electrical Equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery, and an electrical device. Background Art

[0003] In the actual application of batteries, in order to improve the interface performance of the electrode assembly and enhance the bonding performance between the diaphragm and the electrode plate, the diaphragm is often made of a rubber-coated diaphragm. During the preparation process, the diaphragm needs to be preheated in a tunnel furnace and then hot-pressed so that the diaphragm can bond with the electrode plate. However, tunnel furnace equipment is expensive, and hot pressing requires high energy consumption, which increases the preparation cost of the electrode assembly. If the diaphragm and the electrode plate are directly bonded at room temperature, the bonding force between the diaphragm and the electrode plate is too weak, which will cause the diaphragm to wrinkle on the surface of the electrode plate, thereby affecting the cycle performance of the battery. Summary of the Invention

[0004] In view of this, the present application provides an electrode assembly, a battery and an electrical device, wherein the electrode assembly can press the negative electrode plate, the diaphragm and the positive electrode plate without hot pressing, and the diaphragm has a good bonding effect with the negative electrode plate and the positive electrode plate, and the preparation cost of the electrode assembly is low.

[0005] The present application provides an electrode assembly, which includes: a negative electrode plate, a separator and a positive electrode plate, the separator is arranged on one side of the negative electrode plate, the separator includes a substrate and an adhesive layer, the adhesive layer is arranged on the surface of the substrate, the adhesive layer includes a first polymer, and the first polymer is a copolymer of vinylidene fluoride and hexafluoropropylene; the positive electrode plate is arranged on the side of the separator away from the negative electrode plate, the positive electrode plate includes a stacked current collector layer and an active material layer, the active material layer is arranged on the surface of the current collector layer and facing the adhesive layer, the active material layer includes active particles and a second polymer, the second polymer is granular, the second polymer is dispersed in the active particles, and the second polymer is bonded to the first polymer.

[0006] The present application also provides a battery, which includes a shell, an electrolyte and an electrode assembly provided by the present application. The shell has a receiving cavity and is used to receive the electrolyte and the electrode assembly. The electrolyte is used to infiltrate at least a portion of the electrode assembly.

[0007] The present application also provides an electrical device, which includes a device body and a battery provided in the present application, and the battery is used to power the device body.

[0008] In the present application, the negative electrode sheet, the separator, and the positive electrode sheet are stacked in sequence, the separator includes a substrate and an adhesive layer, and the adhesive layer includes a first polymer, the first polymer is a copolymer of vinylidene fluoride and hexafluoropropylene, then compared to the solution where the first polymer is polyvinylidene fluoride, the regularity of the copolymer of vinylidene fluoride and hexafluoropropylene is lower than that of polyvinylidene fluoride, so that the melting point of the copolymer of vinylidene fluoride and hexafluoropropylene is lower than that of polyvinylidene fluoride, then when the negative electrode sheet, the separator, and the positive electrode sheet are pressed together, there is no need to put the separator into a tunnel furnace for preheating, the separator can be deformed during the pressing process and bonded to the positive electrode sheet, so that the negative electrode sheet, the separator, and the positive electrode sheet are well bonded together. In the assembly process of the electrode assembly provided in the present application, the separator does not need to be preheated in a tunnel furnace or hot pressed, and the separator can be bonded to the positive electrode sheet with a good bonding effect, which is conducive to reducing the energy consumption requirements for preparing the electrode assembly, thereby reducing the preparation cost of the electrode assembly. Furthermore, the active material layer includes active particles and a second polymer, and the second polymer is dispersed in the active particles. In other words, the second polymer is partially exposed on the surface of the active material layer facing the adhesive layer. When the adhesive layer and the active material layer are arranged facing each other, the first polymer and the second polymer are bonded, achieving bonding between the positive electrode plate and the separator. During the pressing process, the first polymer and the second polymer are both deformed and tightly adhered together, resulting in extremely strong bonding between the positive electrode plate and the separator. Compared to the solution where the first polymer of the separator is directly bonded to the active particles, the second polymer is made of a softer material, the active particles are made of a harder material, and the first polymer is also made of a softer material. The bonding between the first polymer and the second polymer is stronger, further strengthening the bonding between the separator and the positive electrode plate. Furthermore, the negative electrode sheet, the separator and the positive electrode sheet are stacked and then wound and pressed together, and the negative electrode sheet, the separator and the positive electrode sheet are bound to each other, and the positive electrode sheet is tightly bonded to the separator, which can prevent the separator from separating from the positive electrode sheet, thereby also achieving a tight fit between the separator and the negative electrode sheet. The separator of the present application has good adhesion to the positive electrode sheet, so that the separator and the negative electrode sheet can also be well bonded together, so that the separator can suppress the thermal expansion of the negative electrode sheet during the charge and discharge process, and the separator can still be well bonded to the negative electrode sheet after the negative electrode sheet shrinks, avoiding wrinkles on the surface of the negative electrode sheet, avoiding wrinkles on the separator and causing an increase in the internal resistance of the battery, and preventing active ions in the battery from depositing lithium at the wrinkles on the surface of the negative electrode sheet, thereby increasing the service life of the electrode assembly, and also helping to improve the energy density and cycle performance of the battery when the electrode assembly is used in the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0010] FIG1 is a schematic structural diagram of an electrode assembly according to an embodiment of the present application;

[0011] FIG2 is a schematic diagram of the cross-sectional structure of a diaphragm according to an embodiment of the present application;

[0012] FIG3 is a schematic cross-sectional view of a positive electrode sheet according to an embodiment of the present application;

[0013] FIG4 is a schematic cross-sectional view of an electrode assembly according to an embodiment of the present application;

[0014] FIG5 is a schematic diagram of a top view of the structure of a diaphragm according to an embodiment of the present application;

[0015] FIG6 is a scanning electron microscope image of a bonding portion according to an embodiment of the present application;

[0016] FIG7 is a schematic structural diagram of a battery according to an embodiment of the present application;

[0017] FIG8 is a schematic diagram of an exploded structure of a battery according to an embodiment of the present application;

[0018] FIG9 is a circuit block diagram of an electric device according to an embodiment of the present application;

[0019] FIG10 is a schematic structural diagram of an electrical device according to an embodiment of the present application.

[0020] Description of reference numerals:

[0021] 100-electrode assembly, 110-negative electrode sheet, 120-diaphragm, 121-substrate, 122-adhesive layer, 123-first polymer, 124-adhesive portion, 130-positive electrode sheet, 131-current collector layer, 132-active material layer, 133-active particles, 134-second polymer, 200-battery, 210-shell, 211-receiving cavity, 212-side shell, 213-top cover, 300-electrical equipment, 310-equipment body. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0024] References herein to "embodiments" or "implementations" mean that a particular feature, structure, or characteristic described in connection with the embodiments or implementations may be included in at least one embodiment of the present application. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor do they constitute independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In practical battery applications, to improve the interfacial properties of the electrode assembly and enhance the bonding between the diaphragm and the electrode plates, a rubber-coated diaphragm is often used. During the manufacturing process, the diaphragm requires preheating in a tunnel furnace and then hot pressing to ensure adhesion between the diaphragm and the electrode plates. However, tunnel furnace equipment is expensive, and hot pressing requires high energy consumption, which reduces the production efficiency of the electrode assembly and increases the production cost of the electrode assembly.

[0026] If the diaphragm and the electrode plate are directly bonded at room temperature, the bonding force between the diaphragm and the electrode plate is too small, so that when the electrode assembly is injected and the battery is formed, a gap will appear between the diaphragm and the electrode plate. The diaphragm cannot follow the volume change of the electrode plate, which will cause the diaphragm to wrinkle on the surface of the electrode plate. Furthermore, the appearance of wrinkles will further affect the transmission path of active ions in the battery. Under normal circumstances, after the active ions are deintercalated from the positive electrode plate, they will be evenly embedded in the negative electrode plate through the electrolyte. If the diaphragm has wrinkles on the surface of the electrode plate, it may cause some active ions to be unable to be smoothly embedded in the negative electrode plate, causing the active ions to precipitate on the surface of the negative electrode plate, thereby affecting the battery's cycle performance and fast charging performance.

[0027] Referring to Figures 1 to 4, the present application provides an electrode assembly 100, which includes: a negative electrode sheet 110, a separator 120, and a positive electrode sheet 130. The separator 120 is arranged on one side of the negative electrode sheet 110, and the separator 120 includes a substrate 121 and an adhesive layer 122. The adhesive layer 122 is arranged on the surface of the substrate 121, and the adhesive layer 122 includes a first polymer 123, which is a copolymer of vinylidene fluoride and hexafluoropropylene; the positive electrode sheet 130 is arranged on the substrate 121. The separator 120 is on a side away from the negative electrode plate 110, and the positive electrode plate 130 includes a stacked current collector layer 131 and an active material layer 132. The active material layer 132 is arranged on the surface of the current collector layer 131 and faces the adhesive layer 122. The active material layer 132 includes active particles 133 and a second polymer 134. The second polymer 134 is granular and dispersed in the active particles 133. The second polymer 134 is bonded to the first polymer 123.

[0028] It can be understood that the negative electrode sheet 110 , the separator 120 and the positive electrode sheet 130 are stacked in sequence.

[0029] It can be understood that the adhesive layer 122 is arranged on the surface of the substrate 121. The adhesive layer 122 can be arranged on one surface of the substrate 121, or the adhesive layer 122 is two layers, and the two layers of the adhesive layer 122 are respectively arranged on the two surfaces opposite to the substrate 121.

[0030] It can be understood that the active material layer 132 is arranged facing the bonding layer 122, and the active material layer 132 and the bonding layer 122 are arranged facing each other to achieve adhesion between the active material layer 132 and the bonding layer 122, and then achieve adhesion between the positive electrode sheet 130 and the separator 120.

[0031] It can be understood that the first polymer 123 is partially embedded in the active material layer 132 , and the second polymer 134 is partially embedded in the adhesive layer 122 .

[0032] In this embodiment, the negative electrode sheet 110, the separator 120 and the positive electrode sheet 130 are stacked in sequence, the separator 120 includes a substrate 121 and an adhesive layer 122, and the adhesive layer 122 includes a first polymer 123, and the first polymer 123 is a copolymer of vinylidene fluoride and hexafluoropropylene. Compared with the solution in which the first polymer 123 is polyvinylidene fluoride, the regularity of the copolymer of vinylidene fluoride and hexafluoropropylene is lower than that of polyvinylidene fluoride, so that the melting point of the copolymer of vinylidene fluoride and hexafluoropropylene is lower than that of polyvinylidene fluoride. When the negative electrode sheet 110, the separator 120 and the positive electrode sheet 130 are pressed together, there is no need to put the separator 120 into a tunnel furnace for preheating. The separator 120 can be deformed during the pressing process and bonded to the positive electrode sheet 130, so that the negative electrode sheet 110, the separator 120 and the positive electrode sheet 130 are better fitted together. During the assembly process of the electrode assembly 100 provided in the present application, the diaphragm 120 does not need to be preheated in a tunnel furnace or hot pressed, and the diaphragm 120 can be bonded to the positive electrode plate 130 with a good bonding effect, which is beneficial to reducing the energy consumption requirements for preparing the electrode assembly 100, thereby reducing the preparation cost of the electrode assembly 100. Furthermore, the active material layer 132 includes active particles 133 and a second polymer 134, and the second polymer 134 is dispersed in the active particles 133. In other words, the second polymer 134 is partially exposed on the surface of the active material layer 132 facing the adhesive layer 122. When the adhesive layer 122 and the active material layer 132 are arranged facing each other, the first polymer 123 and the second polymer 134 are bonded, thereby achieving bonding between the positive electrode plate 130 and the diaphragm 120. During the pressing process, the first polymer 123 and the second polymer 134 are deformed and tightly adhered together, so that the positive electrode plate 130 and the diaphragm 120 have extremely strong bonding properties. Compared to a solution in which the first polymer 123 of the separator 120 is directly bonded to the active particles 133, the second polymer 134 is made of a softer material, the active particles 133 are made of a harder material, and the first polymer 123 is also made of a softer material. This results in a stronger bond between the first polymer 123 and the second polymer 134, further enhancing the bond between the separator 120 and the positive electrode sheet 130. Furthermore, after the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are stacked, wound, and pressed together, the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are mutually bound, and the positive electrode sheet 130 is tightly bonded to the separator 120, preventing the separator 120 from separating from the positive electrode sheet 130, thereby achieving a tight fit between the separator 120 and the negative electrode sheet 110.The diaphragm 120 and the positive electrode sheet 130 of the embodiment of the present application have good adhesion properties, so that the diaphragm 120 and the negative electrode sheet 110 can also be well bonded together, so that the diaphragm 120 can inhibit the thermal expansion of the negative electrode sheet 110 during the charging and discharging process, and the diaphragm 120 can still be well bonded to the negative electrode sheet 110 after the negative electrode sheet 110 shrinks, avoiding the formation of wrinkles on the surface of the negative electrode sheet 110, and avoiding the formation of wrinkles on the diaphragm 120 that lead to an increase in the internal resistance of the battery 200. It can also avoid the active ions in the battery 200 from depositing lithium at the wrinkles on the surface of the negative electrode sheet 110, thereby increasing the service life of the electrode assembly 100, and is also beneficial to improving the energy density and cycle performance of the battery 200 when the electrode assembly 100 is applied to the battery 200.

[0033] It can be understood that the negative electrode sheet 110, the separator 120 and the positive electrode sheet 130 are stacked and then wound, and the negative electrode sheet 110, the separator 120 and the positive electrode sheet 130 can be pressed together by cold pressing to form the electrode assembly 100, so that the negative electrode sheet 110, the separator 120 and the positive electrode sheet 130 have strong bonding properties.

[0034] Optionally, the material of the substrate 121 is selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0035] Optionally, in some embodiments, when the material of the substrate 121 is selected from polyethylene, the separator 120 further includes a heat-resistant layer, which is disposed between the substrate 121 and the adhesive layer 122 to improve the heat resistance of the separator 120, thereby enabling the separator 120 to withstand the heat released by the positive electrode plate 130 and the negative electrode plate 110 during the charge and discharge process, thereby increasing the service life of the separator 120. Optionally, the heat-resistant layer is a ceramic layer.

[0036] Optionally, the active particles 133 are selected from at least one of lithium transition metal oxides and modified materials thereof. In some embodiments, the active particles 133 are lithium iron phosphate. The modified material may be a doped and / or coated lithium transition metal oxide. Preferably, the lithium transition metal oxide may be, but is not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide.

[0037] Optionally, the material of the current collector layer 131 is selected from aluminum. In some embodiments, the current collector layer 131 is aluminum foil. The current collector layer 131 is used to collect and transmit the current of the active material layer 132.

[0038] Optionally, the substrate 121 includes a plurality of micropores arranged in an array. When the electrode assembly 100 is applied to the battery 200 , the micropores allow active ions in the electrolyte to pass through.

[0039] In some embodiments, the melting point of the first polymer 123 ranges from 100°C to 140°C.

[0040] Specifically, the melting point of the first polymer 123 is 100°C, 102°C, 105°C, 108°C, 110°C, 112°C, 115°C, 118°C, 120°C, 122°C, 125°C, 128°C, 130°C, 132°C, 135°C, 136°C, 138°C and 140°C, etc.

[0041] In this embodiment, the first polymer 123 is a copolymer of vinylidene fluoride and hexafluoropropylene. Compared to a solution in which the first polymer 123 is polyvinylidene fluoride, the first polymer 123 in this embodiment has a lower melting point. When the melting point of the first polymer 123 is within the range of 100°C to 140°C, the melting point of the first polymer 123 is within a reasonable range. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the separator 120 does not need to be preheated in a tunnel furnace. The separator 120 can deform during the pressing process and adhere to the positive electrode sheet 130, thereby achieving better adhesion between the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130. This helps reduce the energy consumption required for manufacturing the electrode assembly 100, thereby reducing the manufacturing cost of the electrode assembly 100. Furthermore, when the electrode assembly 100 is used in the battery 200, the expansion of the separator 120 is within a reasonable range, allowing the separator 120 to effectively bond with the negative electrode sheet 110, thereby effectively inhibiting the expansion and deformation of the negative electrode sheet 110. As a result, the separator 120 can maintain a stable shape and have a long service life, resulting in the electrode assembly 100 having high safety performance when used in the battery 200. If the melting point of the first polymer 123 is too high, the separator 120 must be preheated in a tunnel furnace before the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together. This allows the separator 120 to deform and bond with the positive electrode sheet 130 during the pressing process. This increases the energy consumption of the electrode assembly 100 manufacturing process, makes the manufacturing process more complex, and increases the manufacturing cost of the electrode assembly 100. When the melting point of the first polymer 123 is too low, the thermal stability of the adhesive layer 122 is poor, causing the separator 120 to swell excessively. When the electrode assembly 100 is assembled into the battery 200 and the battery 200 is charged and discharged, the negative electrode tab 110 expands significantly due to heat. The excessive expansion of the separator 120 weakens the bonding force between the separator 120 and the negative electrode tab 110, thereby weakening the separator 120's ability to suppress deformation of the negative electrode tab 110 and reducing the safety performance of the electrode assembly 100 when used in the battery 200.

[0042] Preferably, the melting point of the first polymer 123 is in the range of 125°C to 140°C. Specifically, the melting point of the first polymer 123 may be, but is not limited to, 125°C, 128°C, 130°C, 132°C, 135°C, 136°C, 138°C, or 140°C. When the first polymer 123 is applied to the electrode assembly 100, the separator 120 and the positive electrode plate 130 have better adhesion.

[0043] More preferably, the melting point of the first polymer 123 is 135° C. When the first polymer 123 is applied to the electrode assembly 100 , the separator 120 and the positive electrode plate 130 have optimal adhesion performance.

[0044] In some embodiments, the glass transition temperature Tg of the second polymer 134 is in the range of 35°C ≤ Tg ≤ 60°C.

[0045] Specifically, the glass transition temperature Tg of the second polymer 134 may be, but is not limited to, 35°C, 40°C, 42°C, 45°C, 48°C, 50°C, 52°C, 55°C, 58°C, and 60°C.

[0046] It can be understood that the glass transition temperature is the temperature at which a polymer material changes from a solid to a plastic flow.

[0047] In this embodiment, the glass transition temperature (Tg) of the second polymer 134 satisfies the range of 35°C ≤ Tg ≤ 60°C. The glass transition temperature of the second polymer 134 is within a reasonable range, and the fluidity of the second polymer 134 is within a reasonable range when the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together. On the one hand, the second polymer 134 is fully bonded to the first polymer 123, thereby achieving good adhesion between the positive electrode sheet 130 and the separator 120. On the other hand, the second polymer 134 is prevented from blocking the pores of the substrate 121 of the separator 120, which would increase the internal resistance of the battery 200 when the electrode assembly 100 is used in the battery 200. As a result, the battery 200 has a higher energy density and better cycle performance when the electrode assembly 100 is used in the battery 200. When the glass transition temperature of the second polymer 134 is too high, the fluidity of the second polymer 134 is too poor when the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, increasing the difficulty of the second polymer 134 and the first polymer 123 bonding to each other, thereby reducing the bonding performance between the first polymer 123 and the second polymer 134, and ultimately reducing the bonding performance between the positive electrode sheet 130 and the separator 120, thereby reducing the bonding performance between the separator 120 and the negative electrode sheet 110. When the electrode assembly 100 is used in the battery 200, the separator 120 cannot limit the expansion of the negative electrode sheet 110 during charging and discharging, and the separator 120 may wrinkle on the surface of the positive electrode sheet 130 or the surface of the negative electrode sheet 110, which in turn increases the internal resistance of the battery 200 or causes lithium deposition on the surface of the negative electrode sheet 110, thereby reducing the energy density and cycle performance of the electrode assembly 100 when used in the battery 200. When the glass transition temperature of the second polymer 134 is too low, the fluidity of the second polymer 134 is too good when the negative electrode plate 110, the diaphragm 120 and the positive electrode plate 130 are pressed together. Although the first polymer 123 and the second polymer 134 can be well blended together and have good adhesion properties, the second polymer 134 may block the pores of the substrate 121 of the diaphragm 120. When the electrode assembly 100 is applied to the battery 200, the impedance of the active ions in the electrolyte passing through the diaphragm 120 is increased, resulting in an increase in the internal resistance of the battery 200, thereby reducing the safety performance of the battery 200 and shortening the service life of the battery 200.

[0048] In some embodiments, in the raw material of the first polymer 123 , the molar ratio α of vinylidene fluoride to hexafluoropropylene is in the range of 1≤α≤9.

[0049] Specifically, the molar ratio α of vinylidene fluoride to hexafluoropropylene may be, but is not limited to, 1, 1.2, 1.5, 2, 2.5, 3, 3.6, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, and 9.

[0050] It is understandable that the molar ratio of vinylidene fluoride to hexafluoropropylene can be regulated to adjust the regularity of the first polymer 123, thereby achieving the regulation of the melting point of the first polymer 123.

[0051] In the raw materials of the first polymer 123 provided in this embodiment, vinylidene fluoride and hexafluoropropylene are copolymerized to form the first polymer 123. The molar ratio of vinylidene fluoride to hexafluoropropylene can be adjusted to determine the proportion of vinylidene fluoride to hexafluoropropylene in the first polymer 123. When the molar ratio α of vinylidene fluoride to hexafluoropropylene satisfies the range of 1≤α≤9, the molar ratio of vinylidene fluoride to hexafluoropropylene is within a reasonable range. On the one hand, the low regularity of the first polymer 123 results in a low melting point of the first polymer 123. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the separator 120 does not need to be preheated; the separator 120 can deform during the pressing process and bond to the positive electrode sheet 130. This reduces energy consumption and simplifies the preparation process of the electrode assembly 100, thereby reducing the preparation cost of the electrode assembly 100. On the other hand, it can avoid that the proportion of vinylidene fluoride in the first polymer 123 is too large, which causes the diaphragm 120 to swell too much at high temperature, so that when the electrode assembly 100 is applied to the battery 200 and the battery 200 is charged and discharged, the diaphragm 120 can tightly adhere to the positive electrode plate 130 and fit the negative electrode plate 110, effectively avoiding the diaphragm 120 from wrinkling on the surface of the positive electrode plate 130 or the surface of the negative electrode plate 110, avoiding the increase of the internal resistance of the battery 200, and making the battery 200 have higher safety performance and energy density. When the molar ratio α of vinylidene fluoride to hexafluoropropylene is too large, the monomers comprising the first polymer 123 contain too much vinylidene fluoride or too little hexafluoropropylene. Consequently, the copolymer formed by the vinylidene fluoride and hexafluoropropylene has a high degree of regularity. In other words, the copolymer formed by the vinylidene fluoride and hexafluoropropylene is similar to polyvinylidene fluoride. Consequently, the melting point of the first polymer 123 is similar to that of polyvinylidene fluoride, resulting in a relatively high melting point. When the first polymer 123 is applied to the separator 120 and the negative electrode sheet 110, separator 120, and positive electrode sheet 130 are pressed together, the separator 120 must be preheated in a tunnel furnace before it can deform and bond with the positive electrode sheet 130 during the pressing process. This increases energy consumption and complexity during the preparation of the electrode assembly 100, increasing the production cost of the electrode assembly 100. When the molar ratio α of vinylidene fluoride to hexafluoropropylene is too low, there is too little vinylidene fluoride or too much hexafluoropropylene in the monomers constituting the first polymer 123. This results in a low regularity of the copolymer formed by vinylidene fluoride and hexafluoropropylene, causing the melting point of the first polymer 123 to be too low. However, a high proportion of vinylidene fluoride can also lead to excessive swelling of the first polymer 123 at high temperatures.When the electrode assembly 100 is applied to the battery 200 and the battery 200 is charged and discharged, the degree of swelling of the diaphragm 120 is too large, thereby reducing the degree of fit between the diaphragm 120 and the positive electrode sheet 130 or the negative electrode sheet 110, and ultimately causing wrinkles to appear on the surface of the diaphragm 120 on the surface of the positive electrode sheet 130 or the surface of the negative electrode sheet 110, ultimately increasing the internal resistance of the battery 200 and reducing the safety performance and energy density of the battery 200.

[0052] Referring to FIG. 5 , in some embodiments, the adhesive layer 122 includes a plurality of adhesive portions 124 arranged at intervals, and a width D1 of the adhesive portion 124 is in the range of 200 μm ≤ D1 ≤ 1000 μm.

[0053] Specifically, the value of the width D1 of the bonding portion 124 can be, but is not limited to, 200μm, 220μm, 250μm, 300μm, 340μm, 380μm, 400μm, 450μm, 480μm, 500μm, 520μm, 580μm, 600μm, 650μm, 700μm, 740μm, 780μm, 800μm, 850μm, 900μm, 950μm and 1000μm, etc.

[0054] It can be understood that the width of the adhesive portion 124 is the maximum radial dimension of the orthographic projection of the adhesive portion 124 on the surface of the substrate 121 facing the adhesive layer 122 .

[0055] In this embodiment, the adhesive portion 124 increases the contact area between the separator 120 and the positive electrode sheet 130 , thereby improving the adhesive performance between the separator 120 and the positive electrode sheet 130 . When the width D1 of the adhesive portion 124 satisfies the range of 200μm≤D1≤1000μm, the width of the adhesive portion 124 is within a reasonable range. When the diaphragm 120 and the positive electrode sheet 130 are arranged facing each other, the contact area between the adhesive portion 124 and the positive electrode sheet 130 is within a reasonable range. On the one hand, the adhesive portion 124 and the positive electrode sheet 130 can effectively contact and bond, so that the bonding performance between the positive electrode sheet 130 and the diaphragm 120 is good, thereby avoiding the diaphragm 120 from wrinkling on the surface of the positive electrode sheet 130 or the surface of the negative electrode sheet 110; on the other hand, it can avoid the adhesive portion 124 from blocking the pores of the substrate 121 of the diaphragm 120 and increasing the impedance of active ions passing through the diaphragm 120, so that when the electrode assembly 100 is applied to the battery 200, the battery 200 has higher safety performance, longer cycle life and higher energy density. When the width of the bonding portion 124 is too large, the maximum radial dimension of the positive projection of the bonding portion 124 on the surface of the substrate 121 facing the bonding layer 122 is too large. Although the bonding layer 122 can increase the contact area between the diaphragm 120 and the positive electrode plate 130, the bonding layer 122 may block the pores of the substrate 121 of the diaphragm 120. When the electrode assembly 100 is applied to the battery 200, the impedance of the active ions in the electrolyte passing through the diaphragm 120 is increased, resulting in an increase in the internal resistance of the battery 200, thereby reducing the safety performance of the battery 200 and shortening the service life of the battery 200. When the width of the adhesive portion 124 is too small, when the diaphragm 120 and the positive electrode sheet 130 are arranged facing each other, the contact area between the adhesive portion 124 and the positive electrode sheet 130 is too small, making it difficult for the adhesive portion 124 to be tightly bonded to the positive electrode sheet 130, thereby reducing the bonding performance between the positive electrode sheet 130 and the diaphragm 120, and thus causing the diaphragm 120 to be wrinkled on the surface of the positive electrode sheet 130.

[0056] It can be understood that the adhesive layer 122 includes a plurality of adhesive portions 124 arranged at intervals. In other words, the plurality of adhesive portions 124 are arranged at intervals on the surface of the substrate 121 .

[0057] Optionally, the adhesive portion 124 is provided on the surface of the substrate 121 in the shape of a bump.

[0058] In this embodiment, the adhesive portion 124 is arranged in the shape of a convex point on the surface of the substrate 121. When the adhesive layer 122 and the active material layer 132 are arranged facing each other, compared with the solution in which the adhesive portion 124 is recessed in the surface of the substrate 121, the adhesive portion 124 is more likely to contact with the second polymer 134 and achieve adhesion with the second polymer 134, thereby making the diaphragm 120 and the positive electrode plate 130 have better bonding properties.

[0059] Optionally, in some embodiments, the adhesive portion 124 is provided on the surface of the substrate 121 by spin spraying.

[0060] Compared with the embodiment in which the first polymer 123 is fully covered on the surface of the substrate 121, the adhesive portion 124 in this solution is arranged on the surface of the substrate 121 by rotary spraying. On the one hand, the width of the adhesive portion 124 can be made large enough. When the negative electrode plate 110, the diaphragm 120 and the positive electrode plate 130 are pressed together, the contact area between the diaphragm 120 and the positive electrode plate 130 can be increased, thereby realizing the connection between the adhesive portion 124 and the positive electrode plate 130, so that the diaphragm 120 and the positive electrode plate 130 have a better bonding effect. On the other hand, by rotating the adhesive portion 124 to be spaced apart on the surface of the substrate 121 by spraying, the first polymer 123 can be prevented from blocking the pores of the substrate 121 of the diaphragm 120, so that when the electrode assembly 100 is applied to the battery 200, the impedance of the active ions in the battery 200 passing through the diaphragm 120 can be avoided from increasing, thereby improving the dynamic performance of the electrode assembly 100 when applied to the battery 200.

[0061] In some embodiments, the distance D2 between two adjacent adhesive portions 124 is in the range of 50 μm ≤ D2 ≤ 500 μm.

[0062] Specifically, the value of the distance D2 between two adjacent bonding parts 124 can be, but is not limited to, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, 220μm, 250μm, 280μm, 300μm, 320μm, 350μm, 380μm, 400μm, 420μm, 450μm and 500μm, etc.

[0063] In this embodiment, multiple adhesive portions 124 are spaced apart on the surface of the substrate 121, with a certain spacing between the adhesive portions 124. When the distance D2 between two adjacent adhesive portions 124 satisfies the range of 50 μm ≤ D2 ≤ 500 μm, the distance between the two adjacent adhesive portions 124 is within a suitable range, and the distribution density of the adhesive portions 124 on the surface of the substrate 121 is within a reasonable range. On the one hand, when the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the contact area between the adhesive portions 124 and the active material layer 132 of the positive electrode sheet 130 is within a reasonable range, thereby improving the adhesion between the positive electrode sheet 130 and the separator 120. On the other hand, the adhesive portions 124 can be prevented from occupying excessive space on the surface of the substrate 121 and blocking pores in the separator 120, thereby preventing the resistance of active ions passing through the separator 120 from increasing, thereby improving the performance of the electrode assembly 100. When the distance D2 between two adjacent bonding portions 124 is too large, the bonding portions 124 are too sparsely distributed on the surface of the substrate 121. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the contact area between the bonding portion 124 and the active material layer 132 of the positive electrode sheet 130 is too small, resulting in poor adhesion between the positive electrode sheet 130 and the separator 120. This, in turn, causes wrinkles in the separator 120 on the surface of the positive electrode sheet 130 or the surface of the negative electrode sheet 110, reducing the performance of the electrode assembly 100. When the distance D2 between two adjacent bonding portions 124 is too small, the bonding portions 124 are too densely distributed on the surface of the substrate 121. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the adhesive portion 124 maintains a reasonable contact area with the active material layer 132 of the positive electrode sheet 130, resulting in good adhesion between the positive electrode sheet 130 and the separator 120. However, the adhesive portion 124 occupies excessive surface space on the substrate 121, potentially blocking pores on the surface of the substrate 121. When the electrode assembly 100 is used in a battery 200, the impedance of active ions passing through the separator 120 is increased, thereby increasing the internal resistance of the battery 200 and reducing the dynamic performance of the battery 200.

[0064] Please refer to Figure 6. Optionally, in the bonding portion 124, the first polymer 123 exists in the form of agglomerates. In other words, the bonding portion 124 includes a plurality of stacked agglomerates of the first polymer 123, and the radial size of the agglomerates of the first polymer 123 ranges from 3μm to 8μm.

[0065] Specifically, the radial dimension of the agglomerates of the first polymer 123 may be, but is not limited to, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.6 μm, 5.8 μm, 6 μm, 6.2 μm, 6.4 μm, 6.5 μm, 7 μm, 7.2 μm, 7.5 μm and 8 μm, etc.

[0066] In this embodiment, the first polymer 123 is formed by emulsion polymerization of vinylidene fluoride and hexafluoropropylene to form a nanoscale emulsion, followed by spray granulation to form aggregates of the first polymer 123. Furthermore, the aggregates of the first polymer 123 are sprayed onto the surface of the substrate 121 by methods such as rotary spraying, with multiple aggregates of the first polymer 123 forming the bonding portion 124. When the radial dimensions of the aggregates of the first polymer 123 fall within the range of 3 μm to 8 μm, the radial dimensions of the aggregates of the first polymer 123 are within a reasonable range. Furthermore, given a constant width of the bonding portion 124, the number of aggregates of the first polymer 123 is within a reasonable range. When the negative electrode plate 110, the separator 120, and the positive electrode plate 130 are pressed together, the number of bonding sites between the aggregates of the first polymer 123 and the second polymer 134 is within a reasonable range, resulting in good bonding between the positive electrode plate 130 and the separator 120. On the other hand, this prevents the first polymer 123 aggregates from being too small and blocking the pores of the substrate 121, thereby ensuring that the battery 200 has a higher energy density and better cycle performance when the electrode assembly 100 is used in the battery 200. When the radial dimensions of the first polymer 123 aggregates are too large, the number of first polymer 123 aggregates is relatively small, given a constant width of the adhesive portion 124. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the first polymer 123 aggregates disperse and contact and bond with the second polymer 134 of the active material layer 132. The fewer the number of first polymer 123 aggregates, the fewer bonding sites there are between the first polymer 123 and the second polymer 134, resulting in poorer bonding between the adhesive layer 122 and the active material layer 132. When the radial size of the agglomerates of the first polymer 123 is too small, the agglomerates of the first polymer 123 may block the pores of the substrate 121, thereby increasing the internal resistance of the battery 200 when the electrode assembly 100 is applied to the battery 200, thereby causing the energy density of the battery 200 to be low and the cycle performance to be poor when the electrode assembly 100 is applied to the battery 200.

[0067] In some embodiments, the spraying amount C of the adhesive layer 122 is in the range of: 0.5 g / m 2 ≤C≤1.0g / m 2 .

[0068] Specifically, the spraying amount C of the adhesive layer 122 may be, but is not limited to, 0.5 g / m 2 , 0.8g / m 2 , 1g / m 2 , 1.5g / m 2 , 2g / m 2 , 2.5g / m 2 , 3g / m 2 3.5g / m 2 , 4g / m 2 4.5g / m 2 , 5g / m 2 , 5.5g / m 2 , 6g / m 2 , 6.5g / m 2 , 7g / m 2 , 7.5g / m 2 , 8g / m 2 , 8.5g / m 2 , 9g / m 2 , 9.5g / m 2 and 10g / m 2 wait.

[0069] It can be understood that the spraying amount of the adhesive layer 122 can be the spraying amount of the first polymer 123 on a single surface of the substrate 121 .

[0070] In this embodiment, when the spraying amount C of the adhesive layer 122 meets the range of 0.5 g / m 2 ≤C≤1.0g / m 2When the amount C of the adhesive layer 122 sprayed is within a reasonable range. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the contact area between the adhesive layer 122 and the active material layer 132 is within a reasonable range. This not only achieves good bonding between the separator 120 and the positive electrode sheet 130, but also prevents the adhesive layer 122 from blocking the pores of the substrate 121 of the separator 120. As a result, when the electrode assembly 100 is used in the battery 200, the electrode assembly 100 has good performance, and the battery 200 has good cycle performance and safety performance. When the amount C of the adhesive layer 122 sprayed is too large, the total amount of the first polymer 123 sprayed on the surface of the substrate 121 is excessive. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the contact area between the adhesive layer 122 and the active material layer 132 is too large. Although the adhesive layer 122 and the active material layer 132 can be tightly bonded, resulting in good adhesion between the separator 120 and the positive electrode sheet 130, the first polymer 123, when sprayed onto the surface of the substrate 121, may block the pores of the substrate 121, thereby affecting the impedance of active ions in the electrolyte passing through the separator 120 and reducing the cycle performance of the electrode assembly 100 when used in the battery 200. When the spray amount C of the adhesive layer 122 is too small, the total spray amount of the first polymer 123 on the surface of the substrate 121 is too small. When the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the contact area between the adhesive layer 122 and the active material layer 132 is too small, making it difficult for the separator 120 to adhere tightly to the positive electrode sheet 130, and thus making it difficult for the separator 120 to fit tightly to the negative electrode sheet 110. When the electrode assembly 100 is used in a battery 200, the separator 120 may develop wrinkles on the surface of the positive electrode sheet 130 or the surface of the negative electrode sheet 110, resulting in an increase in the internal resistance of the battery 200. Active ions in the battery 200 may also be deposited as lithium in the wrinkles on the surface of the negative electrode sheet 110, thereby reducing the energy density, safety performance, and cycle performance of the battery 200.

[0071] In some embodiments, in the active material layer 132 , the mass fraction A of the second polymer 134 is in the range of 2%≤A≤5%.

[0072] It can be understood that in the active material layer 132 , the mass fraction of the second polymer 134 is the ratio of the mass of the second polymer 134 to the mass of the active material layer 132 .

[0073] Specifically, the mass fraction A of the second polymer 134 can be, but is not limited to, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.3%, 4.5%, 4.6%, 4.7%, 4.9% and 5%, etc.

[0074] In this embodiment, the second polymer 134 is dispersed in the active particles 133 in a granular form. The second polymer 134 is softer than the active particles 133. Compared with the solution in which the adhesive layer 122 of the diaphragm 120 is directly bonded to the active particles 133, the bonding performance between the adhesive layer 122 and the second polymer 134 is better, thereby making the diaphragm 120 and the positive electrode plate 130 tightly bonded, and the diaphragm 120 and the negative electrode plate 110 tightly fitted. When the mass fraction A of the second polymer 134 satisfies the range of 2% ≤ A ≤ 5%, the mass fraction of the second polymer 134 is within a reasonable range, and the second polymer 134 is exposed on the surface of the active material layer 132 facing the adhesive layer 122. Furthermore, when the adhesive layer 122 and the active material layer 132 are disposed facing each other, the adhesive layer 122 and the second polymer 134 have a larger contact area, thereby achieving better adhesion between the adhesive layer 122 and the active material layer 132, ultimately achieving better adhesion between the separator 120 and the positive electrode sheet 130. When the mass fraction A of the second polymer 134 is too high, the proportion of the second polymer 134 in the active material layer 132 is too high, and accordingly, the mass proportion of the active particles 133 is too low, resulting in too little active material in the positive electrode sheet 130 that can participate in the reaction, thereby reducing the energy density of the battery 200 when the electrode assembly 100 is used in the battery 200. Furthermore, if the mass fraction of the second polymer 134 is too high, a greater portion of the second polymer 134 will be exposed on the surface of the active material layer 132. The second polymer 134 may block the pores of the substrate 121, thereby increasing the internal resistance of the battery 200 when the electrode assembly 100 is used in the battery 200. If the mass fraction A of the second polymer 134 is too low, the second polymer 134 accounts for too little of the active material layer 132, resulting in a smaller area occupied by the second polymer 134 exposed on the surface of the active material layer 132 facing the bonding layer 122. When the bonding layer 122 and the active material layer 132 are positioned facing each other, the majority of the bonding layer 122 adheres to the active particles 133, while only a small portion adheres to the second polymer 134. This, in turn, results in poor adhesion between the separator 120 and the positive electrode sheet 130.

[0075] Preferably, in the active material layer 132, the mass fraction A of the second polymer 134 is in the range of 3% ≤ A ≤ 4%. Specifically, the mass fraction A of the second polymer 134 can be, but is not limited to, 3%, 3.2%, 3.4%, 3.6%, 3.8%, and 4%. When the second polymer 134 is applied to the electrode assembly 100, the separator 120 and the positive electrode plate 130 have excellent adhesion.

[0076] More preferably, in the active material layer 132 , the mass fraction A of the second polymer 134 is 3%. When the second polymer 134 is applied to the electrode assembly 100 , the separator 120 and the positive electrode sheet 130 have optimal bonding performance.

[0077] In some embodiments, before the negative electrode plate 110 , the separator 120 , and the positive electrode plate 130 are pressed together, the second polymer 134 is spherical or quasi-spherical, and the median particle size D3 of the second polymer 134 is in the range of 5 μm≤D3≤10 μm.

[0078] It can be understood that spherical refers to a sphere with a sphericity greater than 0.7.

[0079] Specifically, the median particle size D3 of the second polymer 134 can be, but is not limited to, 5 μm, 5.2 μm, 5.5 μm, 6 μm, 6.3 μm, 6.5 μm, 6.8 μm, 7 μm, 7.2 μm, 7.5 μm, 7.8 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm and 10 μm, etc.

[0080] It can be understood that before the negative electrode plate 110, the separator 120 and the positive electrode plate 130 are pressed together, the second polymer 134 is spherical or quasi-spherical; after the negative electrode plate 110, the separator 120 and the positive electrode plate 130 are pressed together, the second polymer 134 is granular.

[0081] In this embodiment, before the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, the second polymer 134 is spherical or quasi-spherical, and the median particle size D3 of the second polymer 134 satisfies the range of 5 μm ≤ D3 ≤ 10 μm. This allows the second polymer 134 to partially appear on the surface of the active material layer 132 facing the adhesive layer 122 when the second polymer 134 is fully mixed with the active particles 133. The material of the second polymer 134 is softer than that of the active particles 133, and the material of the first polymer 123 is also softer, resulting in a stronger bond between the first polymer 123 and the second polymer 134 than between the first polymer 123 and the active particles 133. The second polymer 134 can appear on the surface of the active material layer 132 and effectively bond with the first polymer 123, thereby achieving better adhesion between the positive electrode sheet 130 and the separator 120. When the median particle size of the second polymer 134 is too large, then under the condition of a certain mass fraction of the second polymer 134 , the number of spheres of the second polymer 134 is too small, so that the second polymer 134 can be uniformly dispersed in the active particles 133 . In other words, after the second polymer 134 and the active particles 133 are mixed, the number of the second polymer 134 spheres is too large, which increases the distance between two adjacent second polymer 134 spheres. Even if the negative electrode plate 110, the diaphragm 120 and the positive electrode plate 130 are pressed together, the contact area between the first polymer 123 and the second polymer 134 is still very small, which results in poor bonding between the diaphragm 120 and the positive electrode plate 130. In addition, the bonding area between the first polymer 123 and the second polymer 134 is uneven, which results in poor bonding between a part of the diaphragm 120 and the positive electrode plate 130, which results in the diaphragm 120 falling off from the surface of the positive electrode plate 130 and poor performance of the electrode assembly 100. When the median particle size of the second polymer 134 is too small, after the second polymer 134 and the active particles 133 are mixed, the second polymer 134 is difficult to be exposed on the surface of the active material layer 132 facing the adhesive layer 122. When the active material layer 132 and the adhesive layer 122 are arranged facing each other, the adhesive portion 124 of the adhesive layer 122 can only bond with the active particles 133 in the active material layer 132, but cannot contact and bond with the second polymer 134 in the active material layer 132, thereby reducing the bonding performance between the separator 120 and the positive electrode sheet 130, thereby poorly performing the electrode assembly 100.

[0082] Preferably, before the negative electrode plate 110, the separator 120, and the positive electrode plate 130 are pressed together, the second polymer 134 is spherical or quasi-spherical, and the median particle size D3 of the second polymer 134 is in the range of 7 μm ≤ D3 ≤ 9 μm. Specifically, the median particle size D3 of the second polymer 134 can be, but is not limited to, 7 μm, 7.2 μm, 7.5 μm, 7.8 μm, 8 μm, 8.5 μm, and 9 μm. When the second polymer 134 is applied to the electrode assembly 100, the separator 120 and the positive electrode plate 130 have excellent adhesion.

[0083] More preferably, before the negative electrode plate 110, the separator 120, and the positive electrode plate 130 are pressed together, the second polymer 134 is spherical or quasi-spherical, and the median particle size D3 of the second polymer 134 is 8 μm. When the second polymer 134 is applied to the electrode assembly 100, the separator 120 and the positive electrode plate 130 have optimal adhesion.

[0084] In some embodiments, the second polymer 134 is selected from at least one of polymethyl methacrylate, polyvinylidene fluoride, and polyethylene.

[0085] In this embodiment, the second polymer 134 is selected from at least one of polymethyl methacrylate, polyvinylidene fluoride and polyethylene, so that when the active material layer 132 and the adhesive layer 122 are arranged facing each other, the second polymer 134 has a certain fluidity and can be staggered and bonded with the adhesive portion 124 of the adhesive layer 122, thereby making the active material layer 132 and the adhesive layer 122 have good bonding properties, thereby making the separator 120 and the positive electrode plate 130 have good bonding properties.

[0086] Optionally, in some embodiments, the active material layer 132 further includes a first additive, and the first additive is used to bind the active particles 133 and the second polymer 134 .

[0087] In this embodiment, the first additive is used to bond the active particles 133 and the second polymer 134 , so that the active material layer 132 is bonded into a unified whole, thereby improving the overall performance of the positive electrode sheet 130 .

[0088] Optionally, the first additive is a water-based binder, and the first additive is selected from at least one of polyacrylic acid, polyvinylidene fluoride, and polytetrafluoroethylene.

[0089] Optionally, in some embodiments, the active material layer 132 further includes a first conductive agent, and the first conductive agent is used to improve the conductive performance of the active material layer 132 .

[0090] Optionally, the first conductive agent is selected from at least one of conductive carbon, graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0091] Optionally, the negative electrode plate 110 includes a negative electrode current collector layer (not shown) and a negative electrode active layer (not shown), the negative electrode active layer is arranged on the surface of the negative electrode current collector layer 131, and the negative electrode active layer includes a negative electrode active material, and the negative electrode active material is selected from at least one of metallic lithium, artificial graphite, natural graphite, graphene and other composite materials.

[0092] Optionally, the negative electrode current collector layer 131 is selected from copper. The negative electrode current collector layer 131 is copper foil.

[0093] Optionally, the negative electrode active layer further includes a second additive, a second conductive agent and a negative electrode thickener, wherein the second additive is used to bind the components in the negative electrode active layer to improve the overall performance of the negative electrode active layer; the second conductive agent is used to improve the conductivity of the negative electrode active layer; and the thickener is used to improve the adhesion of the negative electrode active layer.

[0094] Optionally, the second conductive agent is selected from at least one of acetylene black, conductive carbon black, carbon nanotubes, carbon fibers, graphene, and the like.

[0095] Optionally, the second additive includes at least one of asphalt binder, styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyacrylate, carboxymethyl cellulose (CMC), sodium alginate, etc.

[0096] Optionally, the negative electrode thickener is selected from at least one of sodium carboxymethyl cellulose (CMC), polyacrylamide (PAM) and polymethacrylate (PMA).

[0097] Please refer to Figures 7 and 8. The present application also provides a battery 200, which includes a shell 210, an electrolyte and the electrode assembly 100 provided in the present application. The shell 210 has a receiving cavity 211 and is used to receive the electrolyte and the electrode assembly 100. The electrolyte is used to infiltrate at least a portion of the electrode assembly 100.

[0098] In this embodiment, the battery 200 includes the electrode assembly 100 provided herein. The separator 120 and the positive electrode sheet 130 in the electrode assembly 100 have good bonding properties, and the separator 120 and the negative electrode sheet 110 have good adhesion properties. When the electrolyte and the electrode assembly 100 are assembled in the battery 200, the active ions in the electrolyte can move freely within the battery 200 and be embedded in or released from the positive electrode sheet 130 or the negative electrode sheet 110, thereby realizing the charge and discharge process of the battery 200. Among them, the diaphragm 120 and the positive electrode sheet 130 have good bonding properties, and the diaphragm 120 and the negative electrode sheet 110 also have good bonding properties, which can prevent the diaphragm 120 from wrinkling on the surface of the positive electrode sheet 130 or the surface of the negative electrode sheet 110, and then avoid affecting the embedding or detachment of active ions on the surface of the positive electrode sheet 130 or the negative electrode sheet 110, avoid increasing the internal resistance of the battery 200, and also avoid the precipitation of active ions on the surface of the negative electrode sheet 110 and affecting the safety performance of the battery 200, ultimately making the battery 200 have higher safety performance, cycle performance and energy density.

[0099] Optionally, the battery 200 may be a cylindrical battery, a square battery, a soft-pack battery, etc. When the battery 200 is a cylindrical battery 200 , the negative electrode sheet 110 , the separator 120 , and the positive electrode sheet 130 do not need to be pressed together.

[0100] Optionally, the battery 200 may be a lithium-ion battery, a sodium-ion battery, or the like.

[0101] Optionally, the housing 210 includes a side shell 212 and a top cover 213 , and the side shell 212 and the top cover 213 enclose the receiving cavity 211 .

[0102] Optionally, the electrolyte includes a solvent and an electrolyte, the solvent is used to dissolve the electrolyte, and the electrolyte includes active ions.

[0103] Optionally, the solvent includes at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, ethyl acetate, ethyl propionate, propyl propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and ethylene glycol dimethyl ether.

[0104] Optionally, the electrolyte includes at least one of lithium hexafluorophosphate, lithium difluorosulfonyl imide, lithium difluorophosphate, lithium trifluoromethylsulfonyl imide, lithium trifluoromethanesulfonate, and lithium perchlorate.

[0105] The technical solution of this application is further described below with reference to a number of embodiments.

[0106] Example 1 to Example 8, Comparative Example 1:

[0107] 1. Preparation of diaphragm 120:

[0108] 20g of a copolymer of vinylidene fluoride and hexafluoropropylene, 3g of styrene-butadiene rubber, and 1g of sodium carboxymethyl cellulose were added to 100g of deionized water, stirred evenly, and then coated onto the surface of substrate 121 by rotary spraying to form an adhesive layer 122 on the surface of substrate 121. After drying, the separators 120 of Examples 1 to 8 and Comparative Example 1 were obtained. The styrene-butadiene rubber was used to enhance the adhesion between the copolymer of vinylidene fluoride and hexafluoropropylene and substrate 121, and the sodium carboxymethyl cellulose was used to suspend and thicken the 20g of the copolymer of vinylidene fluoride and hexafluoropropylene in the deionized water.

[0109] The formation process of the first polymer 123 is as follows: adding an appropriate amount of vinylidene fluoride and an appropriate amount of hexafluoropropylene, forming a nano-scale emulsion of vinylidene fluoride and hexafluoropropylene through emulsion polymerization, and then forming agglomerates of the first polymer 123 through spray granulation.

[0110] The melting point values ​​of the first polymer 123 and the spraying amount of the adhesive layer 122 of Examples 1 to 8 and Comparative Example 1 are shown in Table 1. Furthermore, the adhesive layer 122 of Examples 1 to 8 includes a plurality of adhesive portions 124, which are spaced apart and disposed in the form of protrusions on the surface of the substrate 121. The adhesive layer 122 of Comparative Example 1 includes a plurality of adhesive portions 124, which are recessed in the surface of the substrate 121. The morphology of the adhesive portion 124 can be obtained by scanning electron microscopy (SEM). The morphology of the adhesive portion 124 on the surface of the substrate 121 is mainly obtained by controlling the wettability of the slurry of the adhesive layer 122. If the wettability of the slurry is good, after spreading and drying, the adhesive portion 124 of comparative example 1 is recessed in the surface of the substrate 121; if the wettability of the slurry is poor, after spreading and drying, the adhesive portions 124 of Examples 1 to 8 are arranged in the shape of convex points on the surface of the substrate 121.

[0111] 2. Preparation of positive electrode sheet 130:

[0112] 8 grams of polyacrylic acid powder (first additive) was dispersed in 200 grams of deionized water. 5 to 15 grams (including but not limited to 5 grams, 8 grams, 10 grams, 12 grams, and 15 grams) of polymethyl methacrylate (second polymer 134), 7 grams of conductive carbon (first conductive agent), and 85 grams of lithium iron phosphate (active particles 133) were then added to the deionized water and uniformly mixed to form a positive electrode slurry. The positive electrode slurry was then coated on both surfaces of an aluminum foil (current collector layer 131). After drying, cold pressing, slitting, and cutting, the positive electrode sheets 130 of Examples 1 to 8 and Comparative Example 1 were obtained. The mass fraction A of the second polymer 134 and the median particle size D3 of the second polymer 134 in the negative electrode sheets 110 of Examples 1 to 8 and Comparative Example 1 are shown in Table 1.

[0113] 3. Preparation of negative electrode sheet 110:

[0114] 10 grams of carboxymethyl cellulose (second additive) was dispersed in 88.7 grams of deionized water, and then 88 grams of graphite (second conductive agent) and 2 grams of carboxymethyl cellulose (negative electrode thickener) were added to the deionized water and mixed evenly to form a negative electrode slurry. The negative electrode slurry was coated on both surfaces of the copper foil (negative electrode current collector layer 131). After drying, cold pressing, slitting, and cutting, the negative electrode sheets 110 of Examples 1 to 8 and Comparative Example 1 were obtained.

[0115] 4. Preparation of electrolyte:

[0116] In an argon atmosphere glove box with a moisture content of ≤1ppm, ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were mixed in a mass ratio of 1:1:1, and then the dry electrolyte lithium hexafluorophosphate was dissolved in the solvent, stirred until completely dissolved and evenly mixed to obtain an electrolyte.

[0117] 5. Assembly of Battery 200

[0118] The separator 120, positive electrode sheet 130 and negative electrode sheet 110 of Examples 1 to 8 and Comparative Example 1 prepared above are stacked in sequence so that the separator 120 is located between the positive electrode sheet 130 and the negative electrode sheet 110, and then wound to obtain the electrode assembly 100. The electrode assembly 100 is placed in the shell 210, and after drying, the above-mentioned electrolyte is injected. After standing, forming, packaging and other processes, the implementation battery 1 to the implementation battery 8 and the comparative battery 1 are obtained, wherein the separator 120, positive electrode sheet 130 and negative electrode sheet 110 of Example 1 are arranged in the implementation battery 1, the separator 120, positive electrode sheet 130 and negative electrode sheet 110 of Example 2 are arranged in the implementation battery 2, the separator 120, positive electrode sheet 130 and negative electrode sheet 110 of the comparative battery 1 are arranged in the comparative battery 1, and so on.

[0119] Table 1 below shows the structural parameters of the electrode assembly 100 of Examples 1 to 8 and Comparative Example 1.

[0120] Table 1: Structural parameters of the electrode assembly 100 of Examples 1 to 8 and Comparative Example 1.

[0121] Performance test of battery 200:

[0122] (1) Performance test of electrode assembly 100:

[0123] 1. Swelling performance test of the first polymer 123:

[0124] The first polymer 123 of Examples 1 to 8 and Comparative Example 1 was tested. Specifically, 139.5 grams of N-methylpyrrolidone (NMP) was added to a beaker at a rotation speed of 500 rpm. A weighed amount of 10.5 grams of the first polymer 123 was then added to the beaker to prepare a 7% by weight adhesive solution containing the first polymer 123. The adhesive film was then baked. The N-methylpyrrolidone was used to dissolve the first polymer 123.

[0125] Furthermore, the film is weighed to record its first weight W1, then immersed in dimethyl carbonate (DMC) for 4 to 48 hours (e.g., 4 hours, 8 hours, 12 hours, 24 hours, or 48 hours). The film is then removed and the liquid on the surface is wiped off. The film is then weighed to record its second weight W2. The swelling degree SD of the first polymer 123 is then calculated as: SD = (W2 - W1) / W1 × 100%. The swelling degree SD values ​​of the first polymer 123 in Examples 1 to 8 and Comparative Example 1 after immersion in the DMC system for 24 hours are shown in Table 2.

[0126] 2. Test of the bonding performance of the diaphragm 120 and the positive electrode sheet 130:

[0127] The separators 120 and positive electrode sheets 130 of Examples 1 to 8 and Comparative Example 1 were cut into 100 mm × 100 mm squares, and then cold-pressed under the following conditions: a temperature of 25°C, a pressure of 4.5 MPa, and a time of 40 seconds. After the pressing, the separators 120 and positive electrode sheets 130 were removed and subjected to a peel strength test in accordance with the national standard GB / T 2791-1995. The cold-press adhesion values ​​of the separators 120 and positive electrode sheets 130 of Examples 1 to 8 and Comparative Example 1 under the conditions of a temperature of 25°C, a pressure of 4.5 MPa, and a time of 40 seconds are shown in Table 2.

[0128] (2) Capacity test of battery 200:

[0129] The following treatments were performed on Example Batteries 1 to 8 and Comparative Battery 1:

[0130] Step 1, let it stand for 2 hours; step 2, discharge at a constant current of 0.5C rate to 2.5V; step 3, let it stand for 30 minutes; step 4, charge at a constant current of 0.5C rate to 3.65V, and discharge at a constant voltage of 3.65V to 0.05C; step 5, let it stand for 30 minutes; step 6, discharge at a constant current of 0.5C rate to 2.5V, repeat steps 4 to 6 3 times, and record the last discharge capacity, recorded as C0. The capacity value C0 of battery 200 of implementation battery 1 to implementation battery 8 and comparison battery 1 is shown in Table 2.

[0131] (3) Internal resistance test of battery 200:

[0132] The test temperature was 25°C. After formation, implementation batteries 1 to implementation batteries 8 and comparison battery 1 were charged at a constant current of 0.5C to 3.65V. Then, they were charged at a constant voltage of 3.65V to a current of 0.05C and allowed to stand for 10 minutes. Then, they were discharged at a constant current of 0.5C to 2.5V and allowed to stand for 10 minutes. The capacity at this step was used as the benchmark.

[0133] Furthermore, at 25°C, the battery was charged at a constant current of 0.5C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, and allowed to rest for 10 minutes. The battery was then discharged at a constant current of 0.5C for 0.5 minutes, with the voltage of battery 200 at this point recorded as V1. The battery was then discharged at a constant current of 0.5C for 0.5 minutes, with the voltage of battery 200 at this point recorded as V2. The DC resistance (DCR) values ​​corresponding to 50% SOC (State of Charge) for Example Batteries 1 to 8 and Comparative Battery 1 were calculated using the formula DCR = (V1 - V2) / 0.5C, in units of mΩ. The DC resistance (DCR) values ​​for Example Batteries 1 to 8 and Comparative Battery 1 are shown in Table 2.

[0134] (IV) Interface wrinkle test of negative electrode sheet 110:

[0135] The following treatments were performed on Example Batteries 1 to 8 and Comparative Battery 1:

[0136] Step 1, stand for 2 hours; Step 2, charge to 2.5V at a constant power rate of 1P; Step 3, stand for 30 minutes; Step 4, discharge to 3.65V at a constant power rate of 1P; Step 5, stand for 30 minutes; Step 6, repeat steps 3 to 5 11 times, and after full charge, disassemble the implementation battery 1 to the implementation battery 8 and the comparison battery 1 to observe the interface wrinkles of the negative electrode sheet, min; ④CP 1P to 3.65V; ⑤Rest 30min; ⑥ Repeat 3-6 steps 11 times; After full charge, disassemble the interface to observe the wrinkle state. The interface wrinkles of the negative electrode sheet 110 of the implementation battery 1 to the implementation battery 8 and the comparison battery 1 are shown in Table 2.

[0137] Table 2 below shows the performance parameters of implementation batteries 1 to 8 and comparison battery 1.

[0138] As shown in Tables 1 and 2, in Examples 1 to 3, the melting point of the first polymer 123 is within a reasonable range. Furthermore, as the melting point of the first polymer 123 decreases, under the same conditions, the swelling of the first polymer 123 increases, the cold press adhesion between the separator 120 and the positive electrode sheet 130 increases, the interface wrinkling of the negative electrode sheet 110 improves, and the DC impedance of the battery 200 increases. This is because: as the melting point of the first polymer 123 gradually decreases, during the process of pressing the negative electrode plate 110, the separator 120 and the positive electrode plate 130, there is no need to put the separator 120 into a tunnel furnace for preheating. The first polymer 123 of the separator 120 can be deformed during the pressing process and bonded to the positive electrode plate 130. Moreover, as the melting point of the first polymer 123 decreases, the first polymer 123 is more likely to deform under cold pressing conditions, so that the cold pressing bonding force between the separator 120 and the positive electrode plate 130 is larger, thereby enhancing the bonding performance between the separator 120 and the positive electrode plate 130. Furthermore, the negative electrode sheet 110, the diaphragm 120 and the positive electrode sheet 130 are arranged in sequence, and the diaphragm 120 and the positive electrode sheet 130 have good bonding properties, so that the diaphragm 120 and the negative electrode sheet 110 have a good degree of fit, so that the diaphragm 120 can inhibit the negative electrode sheet 110 from expanding due to heat during the charging and discharging process, and the diaphragm 120 can still fit the negative electrode sheet 110 well after the negative electrode sheet 110 shrinks, avoiding wrinkles on the surface of the negative electrode sheet 110, thereby continuously improving the interface wrinkles of the negative electrode sheet 110. However, correspondingly, the melting point of the first polymer 123 decreases, and the thermal stability of the first polymer 123 decreases. During the charging and discharging process of the battery 200, the positive electrode plate 130 and / or the negative electrode plate 110 releases heat, and the diaphragm 120 may soften or melt in a high temperature environment, making it impossible for the diaphragm 120 to maintain a stable shape, thereby increasing the impedance of the active ions in the electrolyte passing through the diaphragm 120, and then increasing the internal resistance of the battery 200.

[0139] It is understood that the swelling degree SD of the first polymer 123 after being immersed in a dimethyl carbonate system for 24 hours satisfies the range of 50%≤SD≤150%. Specifically, the swelling degree SD may be, but is not limited to, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150%, and the like.

[0140] In this embodiment, the first polymer 123 is a copolymer of vinylidene fluoride and hexafluoropropylene. As the molar ratio of vinylidene fluoride to hexafluoropropylene decreases, the melting point of the first polymer 123 decreases, and accordingly, the degree of swelling of the first polymer 123 increases. When the swelling degree of the first polymer 123 satisfies the range of 50% ≤ SD ≤ 150%, the swelling degree of the first polymer 123 is within a reasonable range. This moderate swelling of the first polymer 123 increases the contact area between the first polymer 123 and the second polymer 134, thereby improving the adhesion between the separator 120 and the positive electrode 130. Furthermore, this prevents excessive swelling of the first polymer 123 from altering its molecular structure, thereby preventing a decrease in the cohesive force of the first polymer 123 and allowing the first polymer 123 to maintain a stable bond with the second polymer 134. When the swelling degree of the first polymer 123 is too large, the molecular structure of the first polymer 123 may be destroyed during the swelling process, thereby reducing the cohesive force of the first polymer 123, making it impossible for the first polymer 123 to stably bond with the second polymer 134. When the swelling degree of the first polymer 123 is too small, when the adhesive layer 122 and the active material layer 132 are arranged facing each other, the contact area between the first polymer 123 and the second polymer 134 is still too small, thereby deteriorating the bonding performance between the separator 120 and the positive electrode sheet 130.

[0141] In Examples 2, 4, and 5, the amount of adhesive layer 122 sprayed was within a reasonable range. Furthermore, as the amount of adhesive layer 122 sprayed increased, the cold-pressed bonding strength between the separator 120 and the positive electrode sheet 130 also increased, and the interface wrinkles of the negative electrode sheet 110 were also improved. However, the DC impedance of the battery 200 also increased accordingly. This is because: as the amount of adhesive layer 122 sprayed increases, the contact area between the adhesive layer 122 and the active material layer 132 of the positive electrode sheet 130 gradually increases when the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are pressed together, thereby enhancing the adhesion between the separator 120 and the positive electrode sheet 130. This in turn allows the separator 120 to better fit the negative electrode sheet 110, allowing the separator 120 to suppress the thermal expansion of the negative electrode sheet 110 during the charge and discharge process. Moreover, the separator 120 can still better fit the negative electrode sheet 110 after the negative electrode sheet 110 shrinks, thereby preventing wrinkles on the surface of the negative electrode sheet 110. This continuously improves the interface wrinkles of the negative electrode sheet 110. However, correspondingly, as the spraying amount of the adhesive layer 122 gradually increases, the area occupied by the adhesive layer 122 on the surface of the substrate 121 gradually increases, and the adhesive layer 122 may block the pores of the substrate 121, thereby increasing the impedance of the active ions in the electrolyte passing through the diaphragm 120, thereby increasing the internal resistance of the battery 200 and reducing the cycle performance of the battery 200 to a certain extent.

[0142] In Examples 2, 6, and 8, the mass fraction of the second polymer 134 was within a reasonable range. Furthermore, as the mass fraction of the second polymer 134 gradually increased, the cold press bonding strength between the separator 120 and the positive electrode sheet 130 gradually increased, and the interface wrinkling of the negative electrode sheet 110 was also improved. However, correspondingly, the capacity of the battery 200 decreased and the DC impedance of the battery 200 gradually increased. This is because: as the mass fraction of the second polymer 134 gradually increases, more of the second polymer 134 can be exposed on the surface of the active material layer 132 facing the adhesive layer 122. When the active material layer 132 and the adhesive layer 122 are arranged facing each other, the adhesive layer 122 and the second polymer 134 have a larger contact area, which gradually improves the adhesion between the separator 120 and the positive electrode sheet 130. At the same time, the degree of adhesion between the separator 120 and the negative electrode sheet 110 is also increased, so that the separator 120 can suppress the thermal expansion of the negative electrode sheet 110 during the charge and discharge process. After the negative electrode sheet 110 shrinks, the separator 120 can still well adhere to the negative electrode sheet 110, avoiding wrinkles on the surface of the negative electrode sheet 110. This continuously improves the interface wrinkles of the negative electrode sheet 110. However, as the mass fraction of the second polymer 134 gradually increases, the mass proportion of the active particles 133 in the active material layer 132 decreases, resulting in too little active material in the positive electrode sheet 130 that can participate in the reaction, thereby reducing the capacity of the battery 200. In addition, as the mass fraction of the second polymer 134 increases, more of the second polymer 134 is exposed on the surface of the active material layer 132, and the second polymer 134 may block the pores of the substrate 121, thereby increasing the internal resistance of the battery 200.

[0143] In Comparative Example 1, the melting point of the first polymer 123 is 150° C., which is greater than the melting point of the first polymer 123 in Examples 1 to 8. The adhesive portion 124 of Comparative Example 1 is recessed in the surface of the substrate 121 , and the active material layer 132 in Comparative Example 1 does not include the second polymer 134 . This makes the swelling degree SD of the first polymer 123 in Comparative Example 1 much smaller than the swelling degree SD of the first polymer 123 in Examples 1 to 8. The cold pressing bonding force of the diaphragm 120 and the positive electrode sheet 130 in Comparative Battery 1 is much smaller than the cold pressing bonding force of the diaphragm 120 and the positive electrode sheet 130 in Implementation Battery 1 to Implementation Battery 8. The interface of the negative electrode sheet 110 of Comparative Battery 1 is severely wrinkled. This is because: on the one hand, the adhesive portion 124 of Comparative Example 1 is recessed in the surface of the substrate 121, so when the active material layer 132 and the adhesive layer 122 are arranged facing each other, the adhesive portion 124 of Comparative Example 1 is difficult to adhere to the active material layer 132, and the contact area between the adhesive portion 124 and the active material layer 132 is small, which weakens the adhesion performance between the separator 120 and the positive electrode sheet 130; further, the active material layer 132 of Comparative Example 1 does not include the second polymer 134, so the first polymer 1 23 directly adheres to the active particles 133, the bonding effect between the first polymer 123 and the active particles 133 is poor, which in turn makes the bonding performance between the diaphragm 120 and the positive electrode plate 130 poor, and the bonding effect between the diaphragm 120 and the negative electrode plate 110 is poor. The diaphragm 120 cannot inhibit the thermal expansion of the negative electrode plate 110 during the charge and discharge process, and the diaphragm 120 cannot fit the negative electrode plate 110 after the negative electrode plate 110 shrinks, resulting in severe wrinkles on the surface of the negative electrode plate 110.

[0144] Please refer to Figures 9 and 10. The present application also provides an electric device 300. The electric device 300 includes a device body 310 and a battery 200 provided in the present application. The battery 200 is used to power the device body 310.

[0145] It can be understood that the battery 200 is electrically connected to the device body 310 .

[0146] In this embodiment, the battery 200 has high safety performance, cycle performance and energy density, so that the battery 200 can provide stable power to the device body 310, which is beneficial to improving the user experience.

[0147] Optionally, the power-consuming device 300 in the embodiment of the present application may be, but is not limited to, a portable electronic device such as a mobile phone, tablet computer, laptop computer, desktop computer, smart bracelet, smart watch, e-reader, game console, or other portable electronic device. Alternatively, it may be a vehicle such as a car, truck, sedan, van, freight train, high-speed train, electric vehicle, or other similar vehicle. Furthermore, it may be various household appliances. The power-consuming device 300 in the embodiment of FIG. 10 of the present application is an energy storage battery cabinet.

[0148] It can be understood that the electrical device 300 described in this embodiment is merely a form of the electrical device 300 used by the battery 200, and should not be understood as a limitation on the electrical device 300 provided in this application, nor should it be understood as a limitation on the electrical device 300 provided in each embodiment of this application.

[0149] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, unless there is a contradiction between them.

[0150] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrode assembly, wherein: The electrode assembly comprises: negative electrode; A diaphragm, the diaphragm being disposed on one side of the negative electrode plate, the diaphragm comprising a substrate and an adhesive layer, the adhesive layer being disposed on a surface of the substrate, the adhesive layer comprising a first polymer, the first polymer being a copolymer of vinylidene fluoride and hexafluoropropylene; A positive electrode sheet, wherein the positive electrode sheet is arranged on the side of the diaphragm away from the negative electrode sheet, the positive electrode sheet includes a stacked current collector layer and an active material layer, the active material layer is arranged on the surface of the current collector layer and faces the adhesive layer, the active material layer includes active particles and a second polymer, the second polymer is granular, the second polymer is dispersed in the active particles, and the second polymer is bonded to the first polymer.

2. The electrode assembly according to claim 1, wherein The melting point of the first polymer ranges from 100°C to 140°C.

3. The electrode assembly according to claim 1, wherein The glass transition temperature Tg of the second polymer is in the range of 35°C≤Tg≤60°C.

4. The electrode assembly according to claim 1, wherein In the raw material of the first polymer, the molar ratio α of vinylidene fluoride to hexafluoropropylene is in the range of 1≤α≤9.

5. The electrode assembly according to claim 1, wherein The adhesive layer includes a plurality of adhesive portions arranged at intervals, and a width D1 of the adhesive portion is in the range of 200 μm ≤ D1 ≤ 1000 μm.

6. The electrode assembly according to claim 5, wherein: The range of the distance D2 between two adjacent bonding portions is: 50 μm ≤ D2 ≤ 500 μm.

7. The electrode assembly according to claim 6, wherein: The range of the spraying amount C of the adhesive layer is: 0.5g / m 2 ≤C≤1.0g / m 2 .

8. The electrode assembly according to any one of claims 1 to 7, wherein: In the active material layer, the mass fraction A of the second polymer is in the range of 2%≤A≤5%.

9. The electrode assembly according to claim 8, wherein Before the negative electrode sheet, the separator, and the positive electrode sheet are pressed together, the second polymer is spherical or quasi-spherical, and the median particle size D3 of the second polymer is in the range of 5 μm≤D3≤10 μm.

10. The electrode assembly according to claim 1, wherein The second polymer is selected from at least one of polymethyl methacrylate, polyvinylidene fluoride and polyethylene.

11. A battery, wherein: The battery comprises a shell, an electrolyte, and the electrode assembly according to any one of claims 1 to 10, wherein the shell has a receiving cavity for receiving the electrolyte and the electrode assembly, and the electrolyte is used to soak at least a portion of the electrode assembly.

12. An electrical device, wherein: The electrical device includes a device body and the battery according to claim 11, and the battery is used to power the device body.

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