A battery

Abstract

The present application relates to the technical field of batteries, and specifically relates to a battery. The battery comprises an electrolyte and a diaphragm, the diaphragm comprises a carrier layer and a polymer coating layer, the polymer coating layer comprises a first polymer coating layer corresponding to a positive electrode sheet and a second polymer coating layer corresponding to a negative electrode sheet, the first polymer coating layer comprises first particles distributed in a dispersed manner, the second polymer coating layer comprises second particles distributed in a dispersed manner, and the diaphragm satisfies the following relationship: 65<=A 3 <=470, A 3 =A 2 ‑A 1 ; the ratio of the weight of ethyl difluoroacetate to the weight of a cyclic carbonate in the electrolyte is 1.5-10. The battery of the present application not only can improve the problem of poor electrode structure stability caused by volume change of silicon-based materials, but also can make the diaphragm have higher adhesion strength and higher air permeability, improve the long cycle performance, low-temperature rate performance of the battery and reduce the high-temperature cycle voltage drop.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a battery. Background Technology

[0002] With the increasing demand for high energy density in lithium-ion batteries for new energy vehicles and portable electronic devices, silicon-based anode materials have become the most promising next-generation anode materials due to their extremely high theoretical specific capacity. However, silicon materials undergo severe volume expansion and contraction during charging and discharging, an inherent characteristic that severely restricts their commercial application.

[0003] During battery cycling, the repeated and intense expansion and contraction of the silicon-based negative electrode can damage the structural stability of the electrode assembly. On the one hand, the expansion stress causes relative displacement between the separator and the positive and negative electrode plates, resulting in poor interfacial contact, obstructed ion transport paths, increased interfacial impedance, and reduced battery dynamic performance. On the other hand, repeated expansion and contraction can cause the active material particles to break down. The broken active particles can easily puncture the separator, leading to micro-short circuits, which manifest as a significant increase in battery cycle voltage drop and reduced battery safety performance.

[0004] Existing technologies, such as nanostructuring of silicon-based materials, porous structures, carbon composites, and surface coatings, have alleviated volume expansion to some extent, but none have fundamentally solved the problem of poor overall structural stability of the electrode assembly during cycling, especially in simultaneously achieving good kinetic and safety performance. Therefore, it is crucial to invent a method that can effectively improve the poor structural stability of the electrode assembly caused by volume changes in silicon-based materials, while simultaneously enhancing the battery's kinetic and safety performance. Summary of the Invention

[0005] Research has shown that by controlling the differentiation of polymer coatings in the separator corresponding to the positive and negative electrodes, the problem of deteriorated electrode structure stability caused by volume changes in silicon-based materials (electrode structure stability includes relative displacement between the positive and negative electrodes and the separator and / or breakage of active material particles) can be improved or even overcome. However, excessive swelling of the differentiated coating in the electrolyte can lead to a large difference in permeability on both sides of the separator, resulting in different lithium ion transport impedances at the interfaces on both sides of the separator, which affects the kinetic performance of the battery.

[0006] To address the issues of poor electrode structural stability caused by volume changes in silicon-based materials and the differential coatings resulting from excessive swelling of the separator in the electrolyte in existing technologies, this invention provides a battery. The battery of this invention improves the poor electrode structural stability caused by volume changes in silicon-based materials. Through differentiated coatings on both sides of the separator, it reduces the risk of misalignment and damage to active material particles between the separator and the positive and negative electrodes due to the cyclic expansion of the negative electrode during battery cycling. This improves the battery's long-cycle stability and reduces high-temperature cycling voltage drop. Simultaneously, it allows the separator to swell moderately in the electrolyte, giving it both high adhesive strength and high permeability, thereby improving the battery's kinetic performance, particularly at low temperatures, and ultimately enhancing its low-temperature rate performance.

[0007] To achieve the above objectives, the present invention provides a battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive and negative electrodes. The separator includes a carrier layer and polymer coatings on both sides of the carrier layer. In the separator, the polymer coating corresponding to the positive electrode is a first polymer coating, and the polymer coating corresponding to the negative electrode is a second polymer coating. The first polymer coating includes first particles in a dispersed distribution, the first particles comprising acrylate polymers. The second polymer coating includes second particles in a dispersed distribution, the second particles comprising acrylate polymers. The separator satisfies the following relationship: 65 ≤ A 3 ≤470, where A 3 =A 2 -A 1 A 1 A represents the number of the first particles, expressed as individuals, within any 25μm × 19μm area on the surface of the first polymer coating. 2 The number of the second particles within any 25μm × 19μm area on the surface of the second polymer coating, expressed in units of individual particles;

[0008] The electrolyte comprises ethyl difluoroacetate and cyclic carbonate, wherein the weight ratio of ethyl difluoroacetate to cyclic carbonate is 1.5-10.

[0009] By employing the above technical solution, the present invention has at least the following advantages compared with the prior art:

[0010] In the battery of the present invention, the polymer coatings on both sides of the separator contain different numbers of acrylate polymer particles. By controlling the number of first particles in the first polymer coating and the number of second particles in the second polymer coating corresponding to the positive and negative electrodes respectively, the relationship 65≤A is satisfied. 3 ≤470, where A3 =A 2 -A 1 This method enables the adhesion strength between the negative electrode and the separator to be greater than that between the positive electrode and the separator. Improving the adhesion strength between the negative electrode and the separator allows for better adhesion between them under the volume change stress of the negative electrode, thus reducing the risk of negative electrode misalignment and electrode assembly deformation during long-cycle operation and improving the battery's long-cycle performance. Simultaneously, while ensuring that the positive electrode and the separator maintain an appropriate adhesion strength, controlling the adhesion strength between the positive electrode and the separator to be less than that between the negative electrode and the separator provides more buffer space for the positive electrode when subjected to internal expansion stress. It can also release the shear stress inside the battery. On the one hand, it can prevent the permanent separation of the interface between the electrode and the separator caused by the continuous accumulation of shear stress, further reducing the risk of deformation of the electrode assembly and reducing the battery's room temperature long cycle impedance. On the other hand, it can prevent the current collector of the electrode from breaking due to the continuous accumulation of shear stress, improving the battery's safety performance. Moreover, this stress buffering and release effect can reduce the fragmentation of electrode active particles during high temperature cycling, reduce the battery's high temperature cycling voltage drop, and enable the battery to have both high room temperature long cycle performance and low high temperature cycling voltage drop.

[0011] To address the issues of excessive swelling of the first and second particles affecting the overall permeability of the separator and increasing the difference in interfacial impedance, the battery of this invention also controls the weight ratio of the ethyl difluoroacetate to the cyclic carbonate, ensuring that the first and second particles swell appropriately in the electrolyte. This reduces the low-temperature polarization of the battery while ensuring that the electrolyte has a low viscosity, improving the overall lithium-ion transport rate. Consequently, the battery's low-temperature kinetic performance is enhanced, resulting in high room-temperature long-cycle performance, high low-temperature rate performance, and low high-temperature cycle voltage drop.

[0012] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0014] Figure 1 The diagram shown is one of the structural schematic diagrams of the separator in the battery of the present invention.

[0015] Figure 2The diagram shown is a second schematic diagram of the separator structure in the battery of the present invention.

[0016] Figure 3 The third schematic diagram shows the structure of the separator in the battery of the present invention.

[0017] Figure 4 The diagram shows a concave portion and a convex portion in the positive electrode sheet of the battery of the present invention.

[0018] Figure 5 The image shown is an SEM image of the first polymer coating in the separator of the battery according to the present invention.

[0019] Figure 6 The image shown is an SEM image of the second polymer coating in the separator of the battery according to the present invention. Detailed Implementation

[0020] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention. Unless otherwise specified herein, data ranges include endpoints.

[0021] It should be noted that the numerical designations such as "first" and "second" in this invention are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0022] This invention provides a battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive and negative electrodes. The separator includes a carrier layer and polymer coatings on both sides of the carrier layer. In the separator, the polymer coating corresponding to the positive electrode is a first polymer coating, and the polymer coating corresponding to the negative electrode is a second polymer coating. The first polymer coating includes first particles in a dispersed distribution, the first particles being composed of acrylate polymers. The second polymer coating includes second particles in a dispersed distribution, the second particles being composed of acrylate polymers. The separator satisfies the following relationship: 65 ≤ A 3 ≤470 (e.g., 65, 80, 100, 130, 150, 180, 200, 230, 250, 280, 300, 330, 350, 380, 400, 430, 450, or 470), where A 3 =A 2 -A 1 A 1 A represents the number of the first particles, expressed as individuals, within any 25μm × 19μm area on the surface of the first polymer coating. 2 The number of the second particles within any 25μm × 19μm area on the surface of the second polymer coating, expressed in units of individual particles;

[0023] The electrolyte comprises ethyl difluoroacetate and cyclic carbonate, wherein the weight ratio of the ethyl difluoroacetate to the cyclic carbonate is 1.5-10 (e.g., 1.5, 2, 3, 4, 5, 6, 7, 8, 9 or 10).

[0024] like Figure 1 , Figure 2 and Figure 3 As shown, the separator 1 includes a carrier layer 11 and polymer coatings located on both sides of the carrier layer 11. In the separator 1, the polymer coating corresponding to the positive electrode is a first polymer coating 121, and the polymer coating corresponding to the negative electrode is a second polymer coating 122.

[0025] In this invention, the first polymer coating comprises first particles in a dispersed distribution. It is understood that a dispersed distribution means that the first particles are dispersedly distributed within the first polymer coating, and that in the thickness direction X of the membrane, the first particles comprise only one layer or multiple layers in the first polymer coating, without the formation of large-particle agglomerates (see [reference]). Figure 5 (The first particle is circled in red). Similarly, the second polymer coating comprising dispersed second particles means that the second particles are dispersedly distributed within the second polymer coating, and that in the thickness direction X of the membrane, the second particles comprise only one layer or multiple layers in the second polymer coating, without large-size agglomerates (see [reference]). Figure 6 ).

[0026] In this invention, the "number of first particles within an area of ​​arbitrarily selected 25μm × 19μm on the surface of the first polymer coating" and the "number of second particles within an area of ​​arbitrarily selected 25μm × 19μm on the surface of the second polymer coating" can be measured by the following method. Specifically, taking the "number of first particles within an area of ​​arbitrarily selected 25μm × 19μm on the surface of the first polymer coating" as an example, 10 images of the first surface are acquired using SEM. In each image, an area of ​​25μm × 19μm is arbitrarily selected, resulting in 10 areas. The number of first particles in each of these 10 areas is counted, and the average value is taken as the measurement result. It is understood that both the first and second polymer coatings include coated and uncoated areas. The arbitrarily selected 25μm × 19μm area is located in the coated area; that is, the arbitrarily selected 25μm × 19μm area on the surface of the first polymer coating is located in the coated area of ​​the first polymer coating surface, and the arbitrarily selected 25μm × 19μm area on the surface of the second polymer coating is located in the coated area of ​​the second polymer coating surface.

[0027] Research has found that when the interfacial adhesion strength between the separator and the electrodes (including positive and negative electrodes) is too high, the electrolyte wettability at the separator-electrode interface and the battery's heat dissipation will be affected to some extent. Furthermore, during battery cycling, the positive electrode expands less while the negative electrode expands more, increasing the risk of misalignment of the negative electrode and deformation of the electrode assembly. Therefore, the increase in adhesion strength between the separator and the negative electrode needs to be greater than that between the separator and the positive electrode. If the increase in adhesion strength between the negative electrode and the positive electrode is the same, then when the positive electrode adhesion strength is appropriate, the negative electrode adhesion strength will be low, resulting in poor or negligible improvement in mitigating misalignment between the separator and the negative electrode. Conversely, when the negative electrode adhesion strength is appropriate, the positive electrode adhesion strength will be excessive, affecting the electrolyte wettability at the positive electrode interface and the battery's heat dissipation, thus impacting the battery's kinetic performance and high-temperature safety performance. Therefore, in order to improve the air permeability of the positive electrode side separator, the electrolyte wetting at the interface between the separator and the positive electrode, and the heat dissipation of the battery while ensuring adequate adhesion strength between the positive electrode and the separator, and simultaneously ensuring strong interfacial adhesion strength between the negative electrode and the separator to reduce the risk of negative electrode misalignment and electrode assembly deformation, the battery of this invention controls the number of first particles (containing polyacrylate polymers) in the first polymer coating corresponding to the positive and negative electrodes in the separator and the number of second particles (containing polyacrylate polymers) in the second polymer coating to satisfy the relationship 65≤A. 3 ≤470, and the first polymer coating comprising a smaller number of first particles corresponds to the positive electrode, and the second polymer coating comprising a larger number of second particles corresponds to the negative electrode.

[0028] The diaphragm is controlled to satisfy the relationship 65≤A 3≤470, on the one hand, the first polymer coating corresponding to the positive electrode contains fewer first particles of polyacrylate polymers, which can improve the air permeability of the positive electrode side separator, the electrolyte wetting at the interface between the separator and the positive electrode, and the heat dissipation of the battery while ensuring adequate adhesion between the positive electrode and the separator. On the other hand, the second polymer coating corresponding to the negative electrode contains more second particles of polyacrylate polymers, which can form a stronger bond between the separator and the negative electrode, ensuring that the bond strength between the negative electrode and the separator is strong enough to prevent separation between the separator and the negative electrode under the volume change stress of the negative electrode. This reduces the risk of misalignment of the negative electrode and deformation of the electrode assembly during long cycles, thereby reducing the long-cycle impedance of the battery and improving the long-cycle performance of the battery; When subjected to shear forces generated during battery cycling, the high bonding strength between the negative electrode and the separator maintains the stability of the interface between them. The relatively weaker bonding strength between the positive electrode and the separator allows for the release of internal shear stress through localized fine-tuning. This prevents permanent detachment of the interface between the electrode and the separator due to the continuous accumulation of shear stress, which could lead to deformation of the electrode assembly and reduce the battery's long-cycle impedance at room temperature. On the other hand, it can also prevent the current collector from breaking due to the continuous accumulation of shear stress, thus improving the battery's safety performance. Furthermore, this stress buffering and release effect can reduce the fragmentation of electrode active particles during high-temperature cycling, reducing the high-temperature cycling voltage drop of the battery. This allows the battery to have both high long-cycle performance at room temperature and low high-temperature cycling voltage drop.

[0029] However, the swelling of the first and second particles in the electrolyte reduces the permeability of the separator, especially the second polymer coating corresponding to the negative electrode. This increases the lithium-ion transport impedance on the negative electrode side, increasing battery polarization and hindering the improvement of the battery's low-temperature rate performance. Research has found that adding ethyl difluoroethylene and cyclic carbonate to the electrolyte, with the weight ratio of ethyl difluoroethylene to cyclic carbonate controlled at 1.5-10, prevents excessive swelling of the first and second particles (both composed of acrylate polymers) in the electrolyte, reducing their impact on the separator's permeability and thus lowering the battery's low-temperature impedance. Furthermore, it results in a lower electrolyte viscosity, reducing the overall low-temperature lithium-ion transport impedance and improving the battery's low-temperature rate performance. This allows the battery to achieve a combination of high long-cycle performance, high low-temperature rate performance, and low high-temperature cycle voltage drop.

[0030] When the weight ratio of ethyl difluoroacetate to cyclic carbonate is less than 1.5, the electrolyte viscosity is high. While adding cyclic carbonate reduces the swelling of the first and second particles in the electrolyte, thus lowering the battery impedance, this is insufficient to compensate for the high overall lithium-ion transport impedance caused by the excessive electrolyte viscosity, affecting the battery's low-temperature kinetic performance. When the weight ratio of ethyl difluoroacetate to cyclic carbonate is greater than 10, the effect on reducing the swelling of the first and second particles in the electrolyte is poor, affecting the membrane's permeability and consequently the low-temperature lithium-ion impedance, thus impacting the battery's low-temperature kinetic performance.

[0031] In this invention, by controlling the quantity relationship of acrylate polymer particles in the polymer coatings on both sides of the separator, and simultaneously controlling the weight ratio of ethyl difluoroethylene to cyclic carbonate in the electrolyte, compared with the prior art, it is possible to improve the poor electrode structure stability caused by the volume change of silicon-based materials, increase the adhesion strength between the separator and the positive and negative electrodes, and enable the battery to have both high long-cycle performance, high low-temperature rate performance, and low high-temperature cycle voltage drop. To further improve the effect, one or more of the technical features can be further optimized.

[0032] In some examples, the acrylate polymers include one or more of the following: polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, acrylate monomer-acrylonitrile copolymer, styrene-acrylate monomer copolymer, acrylate monomer-acrylonitrile-ethylene copolymer, styrene-acrylate monomer-acrylonitrile copolymer, acrylate monomer-ethylene copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-N,N-dimethylacrylamide copolymer, ethyl acrylate-2-(diethylamino)ethyl acrylate copolymer, ethyl acrylate-N,N-diethylacrylamide copolymer, and ethyl acrylate-2-(diethylamino)ethyl acrylate.

[0033] In this invention, the acrylate monomers include one or more of methyl methacrylate, butyl acrylate, n-propyl acrylate, octyl acrylate, ethyl methacrylate, isooctyl acrylate, octadecyl acrylate, ethyl acrylate, cyclohexyl acrylate, and 2-hydroxyethyl acrylate.

[0034] In some instances, the diaphragm satisfies the following relationship: 100 ≤ A 3 ≤400.

[0035] In some instances, A 1The range is 20-340 (e.g., 20, 50, 70, 100, 120, 150, 170, 200, 220, 250, 270, 300, 320 or 340).

[0036] In some instances, A 1 It is 35-215.

[0037] In some instances, A 2 For 87-810 (e.g., 87, 100, 130, 150, 180, 200, 230, 250, 280, 300, 330, 350, 380, 400, 430, 450, 480, 500, 530, 550, 580, 600, 630, 650, 680, 700, 730, 750, 780, 800, or 810).

[0038] In some instances, A 2 It is 110-615.

[0039] According to some specific implementation methods, A 1 For 20-340, A 2 The value is 87-810, and the diaphragm satisfies the following relationship: 65≤A 3 ≤470.

[0040] According to some specific implementation methods, A 1 For 35-215, A 2 The value is 110-615, and the diaphragm satisfies the following relationship: 100≤A 3 ≤400.

[0041] In some instances, the first polymer coating includes a coated area and an uncoated area, with the first particle located in the coated area.

[0042] In some instances, the second polymer coating includes a coated area and an uncoated area, with the second particle located in the coated area.

[0043] In some instances, the first particle and the second particle may be the same or different. In this invention, the difference between the first particle and the second particle refers to one or more differences in the particle composition, particle size, and particle mass swelling degree.

[0044] In some instances, the average particle size of the first particle is 0.5 μm to 1.2 μm (e.g., 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm or 1.2 μm).

[0045] In some instances, the average particle size of the first particle is 0.65 μm to 0.95 μm.

[0046] In some instances, the average particle size of the second particle is 0.5 μm to 1.2 μm (e.g., 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm or 1.2 μm).

[0047] In some instances, the average particle size of the second particle is 0.65 μm to 0.95 μm.

[0048] In this invention, the average particle size of the first particle and the average particle size of the second particle can be obtained by testing using the following methods. Specifically, taking the average particle size of the first particle as an example, in an SEM image of the surface of the first polymer coating taken at 5000x magnification, the particle size of any 100 first particles is measured using image analysis software (e.g., ImageJ, NanoMeasurer, Matlab, etc.). The average particle size of the 100 first particles is the average particle size of the first particle. It is understood that if no 100 first particles are observed in the image, multiple images are taken, and the average of the total particle sizes of the 100 first particles is taken as the average particle size.

[0049] In some instances, the Dv90 of the first particle is 0.65 μm to 4.5 μm (e.g., 0.65 μm, 0.8 μm, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, 3.3 μm, 3.5 μm, 3.8 μm, 4 μm, 4.3 μm, or 4.5 μm).

[0050] In this invention, the Dv90 of the first particle is the particle size corresponding to the cumulative particle size distribution reaching 90% in the volumetric particle size distribution of the first particle. In this invention, the volumetric particle size distribution of the first particle can be obtained by measuring the particle size of 800 first particles and statistically processing them in an SEM image taken at 5000x magnification on the surface of the first polymer coating, combined with image analysis software (e.g., ImageJ, NanoMeasurer, Matlab, etc.). It is understood that if no 800 first particles are observed in the image, multiple images are taken to obtain a total of 800 first particles. The Dv90 of the first particle can also be obtained by testing with a laser particle size analyzer. For example, before preparing the diaphragm, the Dv90 of the first particle can be measured using a laser particle size analyzer.

[0051] In some instances, the first particle was immersed in 2,2-difluoroethyl acetic acid for 4 hours at 90°C, and the mass swelling degree of the first particle was greater than 70%.

[0052] In some instances, the first particles are soaked in 2,2-difluoroethyl acetate for 4 hours at 90°C, and the mass swelling of the first particles is 71%-180% (e.g., 71%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150%, 155%, 160%, 165%, 170%, 175%, or 180%).

[0053] In some instances, the second particle was soaked in 2,2-difluoroethyl acetic acid for 4 hours at 90°C, and the mass swelling degree of the second particle was greater than 70%.

[0054] In some instances, the second particle is soaked in 2,2-difluoroethyl acetate for 4 hours at 90°C, and the mass swelling of the second particle is 71%-180% (e.g., 71%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150%, 155%, 160%, 165%, 170%, 175%, or 180%).

[0055] In some instances, the first polymer coating covers 10%-45% of the surface of the carrier layer (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45%).

[0056] In some instances, the first polymer coating has a coverage of 18%-35% on the surface of the carrier layer.

[0057] In some instances, the second polymer coating covers 10%-45% of the surface of the carrier layer (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45%).

[0058] In some instances, the second polymer coating covers 18%-35% of the surface of the carrier layer.

[0059] In this invention, the coverage rate of the first polymer coating on the carrier layer surface refers to the ratio of the area of ​​the orthographic projection of the first polymer coating on the carrier layer surface to the total area of ​​the carrier layer surface; the coverage rate of the second polymer coating on the carrier layer surface refers to the ratio of the area of ​​the orthographic projection of the second polymer coating on the carrier layer surface to the total area of ​​the carrier layer surface. In this invention, the coverage rates of the first and second polymer coatings on the carrier layer surface can be obtained by testing using the following method. Specifically, taking "the coverage rate of the first polymer coating on the carrier layer surface" as an example, an image of the surface of the first polymer coating is obtained using SEM, and a 10000µm area is randomly divided from the image. 2 The area (e.g., 100µm × 100µm) is divided into uniform 400 × 400 squares. If the area covered by the orthographic projection of the first polymer coating in a square exceeds half the area of ​​the square, then the square is considered to be occupied by the first polymer coating; otherwise, the square is not occupied by the first polymer coating. The total number of squares occupied by the first polymer coating is recorded as X. 1 Then coverage = (X 1 (400×400)×100%, repeat the above operation 5 times, and take the average value of the 5 times as the coverage of the first polymer coating on the surface of the carrier layer.

[0060] In some instances, the areal density of the first polymer coating is 0.3 g / m³. 2 -0.5g / m 2 (For example, 0.3g / m 2 0.33g / m 2 0.35g / m 2 0.38g / m 2 0.4g / m 2 0.43g / m 2 0.48g / m 2 or 0.5g / m 2 The areal density of the first polymer coating refers to the weight of the first polymer coating per unit area.

[0061] In some instances, the areal density of the second polymer coating is 0.3 g / m³. 2 -0.5g / m 2 (For example, 0.3g / m 2 0.33g / m 2 0.35g / m 2 0.38g / m 2 0.4g / m 2 0.43g / m2 0.48g / m 2 or 0.5g / m 2 The areal density of the second polymer coating refers to the weight of the second polymer coating per unit area.

[0062] In some instances, the first polymer coating further includes third particles, which are agglomerated particles. For example... Figure 5 As shown, the third particle is located in the square with the solid red line.

[0063] In some instances, the second polymer coating does not include a third particle.

[0064] According to some specific embodiments, the first polymer coating further includes a third particle, and the second polymer coating does not include the third particle.

[0065] According to some specific embodiments, the first polymer coating is composed of first particles and third particles, and the second polymer coating is composed of second particles. The first polymer coating and the second polymer coating may also contain or not contain additives, including one or more of dispersants and auxiliary binders.

[0066] In some instances, the composition of the third particle includes one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, polyhexafluoropropylene, fluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, acrylate monomer-acrylonitrile copolymer, styrene-acrylate monomer copolymer, acrylate monomer-acrylonitrile-ethylene copolymer, acrylate monomer-ethylene copolymer, styrene-acrylate monomer-acrylonitrile copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-N,N-dimethylacrylamide copolymer, ethyl acrylate-2-(diethylamino)ethyl acrylate copolymer, ethyl acrylate-N,N-diethylacrylamide copolymer, and ethyl acrylate-2-(diethylamino)ethyl acrylate.

[0067] In some instances, the third particle comprises secondary particles agglomerated from primary particles. The average particle size of the primary particles is 0.15 μm–0.25 μm (e.g., 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.2 μm, 0.21 μm, 0.22 μm, 0.23 μm, 0.24 μm, or 0.25 μm).

[0068] In some instances, the average particle size of the secondary particles of the third particle is 2μm-20μm (e.g., 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm or 20μm).

[0069] In some instances, the average particle size of the secondary particles of the third particle is 3.5 μm-18 μm.

[0070] In this invention, the secondary particles of the third particle are agglomerated from at least five primary particles. The average particle size of the secondary particles of the third particle can be determined by the following method: An image of the surface of the first polymer coating is obtained using SEM. On the scanned image, a square or rectangle with the smallest area completely surrounding one secondary particle of the third particle is drawn. That is, a square or rectangle with the smallest area where the edge of the secondary particle of the third particle meets at least one of the four sides of the square or rectangle is drawn. The length of one side of the square or the length of the long side of the rectangle is the particle size of the secondary particle of the third particle. In an SEM image of the surface of the first polymer coating taken at 5000x magnification, the average particle size of any 50 secondary particles of the third particle is taken. This operation is repeated 5 times, and the average value is taken as the average particle size of the secondary particles of the third particle. It should be noted that if 50 secondary particles of the third particle can be observed in the captured image, the average particle size of any 50 secondary particles of the third particle in the image is taken as the average particle size of the secondary particles of the third particle. If no 50 secondary particles of the third particle are observed in the image, multiple images are captured, and the average particle size of the total 50 secondary particles of the third particle is taken as the average particle size.

[0071] In some instances, the diaphragm satisfies the following relationship: 1.5 ≤ d 1 / d 2 ≤25 (e.g., 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25), where d 1 The average particle size of the secondary particles of the third particle is expressed in μm and d. 2Here, Dv90 is the value of the first particle, expressed in μm. Controlling the separator to satisfy the above relationship prevents excessive swelling of the first polymer coating at low and normal temperatures, improving the mechanical stability of the first polymer coating at low and normal temperatures, reducing the battery's low-temperature impedance and impedance during long-cycle operation at normal temperatures. Furthermore, it creates a certain gap at the interface between the positive electrode and the separator, improving the electrolyte wettability at this interface, mitigating the problem of high interface impedance caused by weak adhesion between the separator and the positive electrode, and further enhancing the battery's low-temperature rate performance.

[0072] In some instances, the diaphragm satisfies the following relationship: 4≤d 1 / d 2 ≤20.

[0073] In some specific implementations, d 1 For 2-20, d 2 The diaphragm has a value between 0.65 and 4.5, and satisfies the following relationship: 1.5 ≤ d 1 / d 2 ≤25.

[0074] In some specific implementations, d 1 It is 3.5-18, d 2 The diaphragm has a value between 0.65 and 4.5, and satisfies the following relationship: 4 ≤ d 1 / d 2 ≤20.

[0075] In some instances, the third particle is soaked in 2,2-difluoroethyl acetate at 90°C for 4 hours, and the mass swelling of the third particle is less than 40% (e.g., 39%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 1%, 0.5%, 0.1%, or 0%).

[0076] In this invention, the mass swelling degree can be obtained by testing it using the following method: Taking "the mass swelling degree of the third particle after soaking in 2,2-difluoroethyl acetic acid for 4 hours at 90°C" as an example, the third particle is poured into the mold and dried to form a plastic block; the plastic block of the second particle is weighed and recorded as M. 1 The solution was injected into 2,2-difluoroethyl acetate, ensuring the acetate completely submerged the gel block. The oven temperature was set to 90°C, and the system of the third gel block and 2,2-difluoroethyl acetate was heated for 4 hours to allow the third gel block to fully swell. After the set time, the residual electrolyte on the surface of the third gel block was wiped dry, and the weight was recorded as M. 2 The swelling degree S of the third granular adhesive block is calculated using the following formula: S=[(M 2 -M 1 ) / M1 ]×100%.

[0077] In this invention, the bonding strength between the third particle and the electrode sheet is less than the bonding strength between the first particle and the electrode sheet, and the bonding strength between the third particle and the electrode sheet is less than the bonding strength between the second particle and the electrode sheet. The bonding strength can be determined by the following method: The test coverage rate is F... 1 The adhesion strength Z of the coating containing only the third particle to the electrode sheet. 1 The test coverage rate is F 1 The adhesion strength Z of the coating containing only the first or second particle to the electrode. 2 If Z 2 >Z 1 If the adhesion strength of the third particle to the electrode is less than that of the first particle to the electrode, and the adhesion strength of the third particle to the electrode is less than that of the second particle to the electrode, then the adhesion strength is considered to be less than that of the first particle to the electrode. The adhesion strength can also be determined by the following method: The test coverage is F... 1 The adhesion strength Z of the coating containing only the third and first particles to the electrode sheet. 1 The test coverage rate is F 1 The adhesion strength Z of the coating containing only the first particle to the electrode sheet. 2 If Z 2 >Z 1 If the bonding strength between the third particle and the electrode is less than that between the first particle and the electrode, then it is considered that the bonding strength between the third particle and the electrode is less than that between the first particle and the electrode.

[0078] In some instances, the adhesion strength between the first polymer coating and the positive electrode is 6 N / m to 20 N / m.

[0079] In some instances, the adhesion strength between the second polymer coating and the negative electrode sheet is 8 N / m to 30 N / m.

[0080] In this invention, the adhesion strength between the first polymer coating and the positive electrode is less than the adhesion strength between the second polymer coating and the negative electrode.

[0081] In some instances, such as Figures 1-3 As shown, the carrier layer 11 includes a substrate layer 111 and an optional ("optionally" means that it may not be present) heat-resistant layer 112, the heat-resistant layer 112 being located on one or both sides of the surface of the substrate layer 111;

[0082] In some instances, the porosity of the substrate layer is 25%–70% (e.g., 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%).

[0083] In some instances, the thickness of the substrate layer is 3μm-10μm (e.g., 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm).

[0084] In some instances, the substrate layer comprises one or more of polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polytetrafluoroethylene, polyimide, polyethylene terephthalate, polybutylene terephthalate, poly(p-phenylene terephthalate), poly(m-phenylene isophthalate), or polymer derivatives thereof.

[0085] In some instances, the heat-resistant layer comprises heat-resistant particles and a first binder.

[0086] In some instances, the heat-resistant particles are composed of one or more of the following: boehmite, alumina, barium sulfate (BaSO4), magnesium oxide, magnesium hydroxide, silicon dioxide, tin dioxide, titanium dioxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, 1,3,5-triazine-2,4,6-triamine, melamine thiocyanate, melamine cyanurate, symmetrical triaminotriazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4,6-tris(2-pyridyl)triazine, 2-amino-4,6-methoxy-1,3,5-triazine, lithium aluminum titanium phosphate, uracil, cytosine, guanine, 4-amino-2,6-dihydroxypyrimidine, phenolic resin, and benzimidazole compounds.

[0087] In some instances, the benzimidazole compound is 2-mercaptobenzimidazole or a 2-mercaptobenzimidazole derivative, wherein the 2-mercaptobenzimidazole derivative includes 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-ethylbenzimidazole, 2-mercapto-5-propylbenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-5-ethoxybenzimidazole, 2-mercapto-5-hydroxybenzimidazole, 2-mercapto-5-aminobenzimidazole, 2-mercapto-5-chlorobenzimidazole, 2-mercapto-5-bromobenzimidazole, 2-mercapto- The benzimidazole compounds are selected from one or more of the following: 5-sulfonic acid benzimidazole, 2-mercapto-5-carboxybenzimidazole, 2-mercapto-5-nitrobenzimidazole, 2-mercapto-5-fluorobenzimidazole, 2-mercapto-5-fluorobenzimidazole, 2-mercapto-5,6-dichlorobenzimidazole, 2-mercapto-5-cyanobenzimidazole, lithium salt of 2-thiol-benzimidazole, sodium salt of 2-thiol-benzimidazole, potassium salt of 2-thiol-benzimidazole, calcium salt of 2-thiol-benzimidazole, magnesium salt of 2-thiol-benzimidazole, aluminum salt of 2-thiol-benzimidazole, and ammonium salt of 2-thiol-benzimidazole. These benzimidazole compounds contain polar groups such as mercapto (-SH), secondary amino (NH), and pyridine nitrogen atoms (N=). These polar groups give the separator good electrolyte wettability, which can further improve the rate performance of the battery at room temperature.

[0088] In some instances, the Dv50 of the heat-resistant particles is 0.15 μm to 2.5 μm (e.g., 0.15 μm, 0.5 μm, 0.7 μm, 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, 2.2 μm, or 2.5 μm). Controlling the Dv50 of the heat-resistant particles within the above range can improve the adhesion strength between the heat-resistant layer and the polymer coating, as well as the flexibility of the heat-resistant coating, improve the adhesion between the separator and the electrode, enhance the heat resistance of the separator, and also allow the heat-resistant coating to have suitable porosity, thereby improving the overall lithium-ion permeability of the separator and further improving the low-temperature rate performance of the battery.

[0089] In this invention, the Dv50 of the heat-resistant particles is the particle size corresponding to the cumulative particle size distribution reaching 50% in the volumetric particle size distribution of the heat-resistant particles. In this invention, the volumetric particle size distribution of the heat-resistant particles can be obtained by arbitrarily selecting a 100μm × 100μm area from an SEM image taken at 10000x magnification on the surface of the heat-resistant layer, and then measuring and statistically processing it using image analysis software (e.g., ImageJ, NanoMeasurer, Matlab, etc.). The Dv50 of the heat-resistant particles can also be obtained by testing with a laser particle size analyzer; for example, before preparing the diaphragm, the Dv50 of the heat-resistant particles can be measured using a laser particle size analyzer.

[0090] In some instances, the first adhesive comprises one or more of the following: polyvinyl alcohol, styrene-butadiene rubber, ethylene-vinyl acetate copolymer, sodium carboxymethyl cellulose, polyvinylpyrrolidone, acrylate adhesives, styrene-acrylic latex, polyacrylonitrile, polyvinyl acetate, polyacrylic acid, polyurethane, polyurethane-modified polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, or copolymer systems derived from the above polymers.

[0091] In some instances, the acrylate adhesive includes one or more of the following: polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, acrylate monomer-acrylonitrile copolymer, styrene-acrylate monomer copolymer, acrylate monomer-acrylonitrile-ethylene copolymer, styrene-acrylate monomer-acrylonitrile copolymer, acrylate monomer-ethylene copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-N,N-dimethylacrylamide copolymer, ethyl acrylate-2-(diethylamino)ethyl acrylate copolymer, ethyl acrylate-N,N-diethylacrylamide copolymer, and ethyl acrylate-2-(diethylamino)ethyl acrylate.

[0092] In some instances, the heat-resistant particles account for 90%-99% of the total weight of the heat-resistant layer (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%), and the first adhesive accounts for 1%-10% of the total weight of the heat-resistant layer (e.g., 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%).

[0093] In some instances, the thickness of the heat-resistant layer is 0.3 μm to 4.5 μm (e.g., 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, 3.3 μm, 3.5 μm, 3.8 μm, 4 μm, 4.3 μm, or 4.5 μm).

[0094] In some instances, the ethyl difluoroacetate comprises one or more of 2,2-difluoroethyl acetate and ethyl 2,2-difluoroacetate.

[0095] In some instances, the weight percentage of the ethyl difluoroacetate in the electrolyte is 10%-65% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or 65%).

[0096] In some instances, the ethyl difluoroacetate constitutes 25%-45% of the weight of the electrolyte.

[0097] In some instances, the cyclic carbonates include one or more of ethylene carbonate, propylene carbonate, and fluoroethylene carbonate.

[0098] In some instances, the cyclic carbonate in the electrolyte comprises 1% to 28% by weight (e.g., 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, or 28%).

[0099] In some instances, the cyclic carbonates constitute 10%-23% of the weight of the electrolyte.

[0100] In some instances, the electrolyte includes lithium salts, organic solvents, and additives.

[0101] In some instances, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium difluorooxalate borate, lithium dioxalate borate, and lithium tetrafluorooxalate phosphate.

[0102] In some instances, the organic solvent includes ethyl difluorocarbonate and cyclic carbonates selected from one or more of ethylene carbonate, propylene carbonate, and fluoroethylene carbonate.

[0103] In some instances, the organic solvent may also include one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl propionate (EP), propyl propionate (PP), ethyl butyrate, and propyl acetate.

[0104] In some instances, the additives include one or more of vinylene carbonate, dinitrile compounds, trinitrile compounds, fluorinated chain carbonates, and sulfur-containing oxygen double bond compounds.

[0105] In some instances, based on the total weight of the electrolyte, the lithium salt accounts for 8%-20% by weight (e.g., 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%), the organic solvent accounts for 50%-80% by weight (e.g., 50%, 55%, 60%, 65%, 70%, 75%, or 80%), and the additives account for 0%-30% by weight (e.g., 0%, 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, or 30%). When the weight percentage of the additives in the electrolyte is 0%, it indicates that the additives are not present in the electrolyte.

[0106] In some instances, such as Figure 4 As shown, the positive electrode 2 includes a first surface 21 and a second surface 22 that are opposite to each other in the thickness direction Y of the positive electrode 2. The first surface 21 includes a plurality of recesses 211, and the second surface 22 includes a plurality of protrusions 221, the protrusions corresponding to the recesses. In this invention, the protrusions and recesses can be obtained by conventional techniques in the art, for example, by using an embossing roller (with raised dots) through an embossing process.

[0107] In some instances, the battery satisfies the following relationship: 0.7 ≤ A 4 / A 3 ≤5 (e.g., 0.7, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5), where A 3 =A 2 -A 1 A 4 The number of protrusions within an area of ​​50mm × 50mm optionally on the second surface is expressed as a unit. Controlling the battery to satisfy the above relationship allows, on one hand, the protrusions to further increase the electrolyte wettability and electrolyte content at the interface between the positive electrode and the separator, as well as the electrolyte wettability of the positive electrode active layer. This improves the problem of high interfacial impedance caused by reduced adhesion strength, further reducing the battery's room-temperature impedance and room-temperature long-cycle impedance, thereby further improving the battery's room-temperature long-cycle performance and room-temperature rate performance. On the other hand, the protrusions can also improve the embedding effect between the positive electrode and the separator, providing buffer space for the expansion of the negative electrode and reducing or even preventing significant detachment or displacement of the separator from the positive electrode due to the expansion stress of the silicon-based material. This further reduces the battery's room-temperature long-cycle impedance. Furthermore, this stress buffering and release effect can prevent the current collector from breaking due to the continuous accumulation of shear stress, further improving the battery's safety performance. 4 / A 3When the capacitance is <0.7, the effect of improving electrolyte wetting through the protrusion to compensate for the reduced bonding strength between the positive electrode and the separator caused by the protrusion is not significant, which is not conducive to further improving the battery's long-cycle performance and rate performance at room temperature. 4 / A 3 When the value is greater than 5, the number of protrusions is too large, which is not conducive to the mechanical stability of the positive electrode sheet. This increases the risk of the positive electrode sheet breaking due to the pressure of expansion stress during long-term cycling, which is not conducive to improving the safety performance of the battery.

[0108] In some instances, the battery satisfies the following relationship: 0.8 ≤ A 4 / A 3 ≤3.2.

[0109] In some instances, the height of the protrusion is 3μm-50μm (e.g., 3μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm). In this invention, the height of the protrusion is the dimension by which the protrusion protrudes from the surface of the positive electrode sheet, specifically the distance between the highest point of the protrusion and the surface of the positive electrode sheet in the thickness direction of the positive electrode sheet.

[0110] In some instances, the width of the protrusion is 1mm-4mm (e.g., 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, or 4mm). In this invention, the width of the protrusion refers to the maximum distance between any two points on the edge line of the protrusion.

[0111] In some instances, the number of protrusions is 156 to 415 within an area of ​​optionally 50 mm × 50 mm on the second surface.

[0112] In some instances, the number of protrusions is 277 to 369 within an area of ​​optionally 50 mm × 50 mm on the second surface.

[0113] In some specific implementations, A 4 For 156-415, A 3 The range is 65-470, and the battery satisfies the following relationship: 0.7 ≤ A 4 / A 3 ≤5.

[0114] In some specific implementations, A 4 For 277-369, A 3 For a range of 100-400, the battery satisfies the following relationship: 0.8 ≤ A 4 / A 3 ≤3.2.

[0115] In some instances, the negative electrode sheet includes a negative current collector and a negative active layer located on one or both sides of the surface of the negative current collector.

[0116] In some instances, the negative electrode active layer comprises a silicon-based material.

[0117] In some instances, the silicon-based material includes one or more of elemental silicon particles, silicon-oxygen particles, silicon-carbon particles, silicon-nitrogen particles, and silicon alloy particles.

[0118] In some instances, the average particle size of the silicon-carbon particles is 6 μm-10 μm (e.g., 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm).

[0119] In some instances, the weight percentage of silicon in the negative electrode active layer is 4%-50% (e.g., 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%).

[0120] In some instances, the negative electrode active layer further includes a carbon-based material, a negative electrode conductive agent, and a negative electrode binder. The negative electrode conductive agent and the negative electrode binder can be conventional materials in the art.

[0121] In some instances, the carbon-based material includes one or more of artificial graphite and natural graphite.

[0122] In some instances, the positive electrode includes a positive current collector and a positive active layer located on one or both sides of the surface of the positive current collector.

[0123] In some instances, the positive electrode active layer comprises a positive electrode active material.

[0124] In some instances, the positive electrode active material includes a core and a coating layer, the coating layer being located on the surface of the core, the core comprising lithium cobalt oxide, and the coating layer comprising materials with the chemical formula Li7La. 3-a Zr 2-b M a+b O 12 The substance, wherein M is selected from one or more of Fe, Ti, Cu, and Mn, 0.01≤a≤0.5 (e.g., 0.01, 0.05, 0.1, 0.2, 0.3, 0.4 or 0.5), and 0.05≤b≤0.3 (e.g., 0.05, 0.1, 0.15, 0.2, 0.25 or 0.3).

[0125] In some instances, the thickness of the coating layer is 0.1 nm to 15 nm (e.g., 0.1 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm or 15 nm).

[0126] In other instances, the positive electrode active material includes one or more of lithium nickel oxide, lithium titanate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide.

[0127] In some instances, the positive electrode active layer further includes a positive electrode conductive agent and a positive electrode binder.

[0128] In some instances, the positive electrode conductive agent includes one or more of conductive carbon black, carbon nanotubes, conductive graphite, and graphene.

[0129] In some instances, the positive electrode binder includes one or more of polyvinylidene fluoride (PVDF), acrylic-modified PVDF, polyacrylate polymers, acrylic polymers, polytetrafluoroethylene, polyacrylonitrile, polyimide, styrene-butadiene rubber, and styrene-acrylic rubber.

[0130] In some instances, the battery is a lithium-ion rechargeable battery.

[0131] The application of the battery described in this invention is not particularly limited and can be used for a variety of known applications. Examples include: mobile computers, laptops, portable phones, e-book players, fax machines, copiers, printers, headphones, video recorders, LCD TVs, cleaners, calculators, tape recorders, radios, backup power supplies, automobiles, motorcycles, electric boats, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, cameras, large household batteries, energy storage power stations, etc.

[0132] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0133] The following examples illustrate the battery of the present invention.

[0134] Example 1

[0135] (1) Diaphragm

[0136] Heat-resistant granules (alumina) and polyacrylic acid are mixed in water and stirred thoroughly to obtain a mixed slurry with a solid content of 25%. The slurry is applied to one side of the substrate layer (PE) using a gravure roller at a 100% solid mass ratio of alumina:polyacrylic acid = 96:4. After drying in a multi-section oven at 60°C, a heat-resistant layer with a thickness of 1.5 μm is formed. First particles (composed of methyl methacrylate-acrylonitrile copolymer) and third particles (composed of vinylidene fluoride-hexafluoropropylene copolymer) are dispersed in a solvent water and stirred thoroughly to obtain a first slurry with a solid content of 10%. Second particles (composed of methyl methacrylate-acrylonitrile copolymer) are dispersed in a solvent water and stirred thoroughly to obtain a second slurry with a solid content of 10%. The first slurry is applied to the surface of the heat-resistant layer using a gravure roller, and the second slurry is applied to the other side of the substrate layer using the same gravure roller. After drying in a multi-section oven at 60°C, a polymer coating is formed.

[0137] The average particle size of the first particle is 0.7 μm, and the Dv90 (d) of the first particle is... 2 The particle size is 1 μm, and the mass swelling degree of the first particle is 90%. 1 The number is 106, and the average particle size (d) of the secondary particles of the third particle is... 1 The average particle size of the third particle is 11 μm, and its mass swelling degree is 35.1%; the average particle size of the second particle is 0.7 μm, and its mass swelling degree is 89.4%. 2 There are 242, A 3 =A 2 -A 1 =242-106=136, d 1 / d 2 =11 / 1=11; The coverage of the first polymer coating on the surface of the carrier layer is 25%, and the coverage of the second polymer coating on the surface of the carrier layer is 25%.

[0138] (2) Electrolyte

[0139] In an argon-filled glove box (moisture <1 ppm, oxygen <1 ppm), 2,2-difluoroethyl acetate (DFEA), propylene carbonate (PC), propyl propionate (PP), and ethyl propionate (EP) were mixed in a mass ratio of 39:5:16.5:10 to form a homogeneous solvent. LiPF6, 1,4-dicyano-2-butene, and fluoroethylene carbonate were then slowly added and stirred until homogeneous to obtain the electrolyte. The electrolyte contained 16% LiPF6 by weight, 1.5% 1,4-dicyano-2-butene, 5% propylene carbonate, 12% fluoroethylene carbonate, and 39% DFEA by weight. The weight ratio of ethyl difluoroethyl acetate (2,2-difluoroethyl acetate) to the cyclic carbonates was 2.29.

[0140] (3) Positive electrode plate

[0141] Lithium cobalt oxide, polyvinylidene fluoride (PVDF 500) binder, and conductive material (SuperP: carbon nanotubes = 2:1) were mixed in N-methylpyrrolidone (NMP) solvent at a weight ratio of 96:2:2 and continuously stirred under the action of a stirrer to form a homogeneous and fluid positive electrode slurry. Subsequently, the positive electrode slurry was coated on both sides of a 10 μm thick positive electrode current collector (aluminum foil) and dried in a vacuum oven at 120 °C for 6 hours. Then, it was rolled and slit to obtain the positive electrode sheet.

[0142] (4) Negative electrode sheet

[0143] Graphite, silicon carbide (Dv50=8μm), conductive material (carbon black: carbon nanotubes=1:4), sodium carboxymethyl cellulose, and binder (styrene-butadiene rubber: polyurethane=1:2) were mixed in an aqueous solvent at a weight ratio of 66:25:3:0.5:5.5 and continuously stirred under the action of a stirrer to form a homogeneous and fluid negative electrode slurry. Subsequently, the slurry was coated on both sides of an 8μm thick copper foil negative electrode current collector and dried in a vacuum oven at 120℃ for 6 hours. Then, after rolling and slitting, the negative electrode sheet was obtained.

[0144] (5) Lithium-ion battery preparation

[0145] The positive electrode sheet prepared in step (3), the separator prepared in step (1), and the negative electrode sheet prepared in step (4) are wound together to form a bare cell. Then the bare cell is placed in an aluminum-plastic film, and the electrolyte prepared in step (2) is injected into the dried bare cell. After vacuum sealing, room temperature standing, high temperature formation and other processes, a lithium-ion battery is obtained. In the prepared battery, the side of the separator with the heat-resistant coating is set opposite to the positive electrode sheet.

[0146] Example 2 group

[0147] This set of examples is used to illustrate when A 3 The effects of changes.

[0148] This embodiment is based on Embodiment 1, except that A is changed. 3 See Table 1 for details.

[0149] Table 1

[0150]

[0151] Example 3 Group

[0152] This set of examples illustrates the effects of changing the weight ratio of ethyl difluoroacetate to cyclic carbonate.

[0153] This example group is based on Example 1, except that the ratio of solvent and fluoroethylene carbonate is adjusted so that the weight of ethyl difluoroacetate and the weight of cyclic carbonate are as shown in Table 2.

[0154] Table 2

[0155]

[0156] Example 4 group

[0157] Example 4a

[0158] The experiment was conducted in accordance with Example 1, except that the cyclic carbonate was replaced with ethylene carbonate and fluoroethylene carbonate, wherein the weight percentage of ethylene carbonate in the electrolyte was adjusted to 3% and the weight percentage of fluoroethylene carbonate was 14%.

[0159] Example 4b

[0160] The experiment was carried out in accordance with Example 1, except that the cyclic carbonate was adjusted to propylene carbonate, ethylene carbonate and fluoroethylene carbonate, wherein the weight percentage of propylene carbonate in the electrolyte was 4%, the weight percentage of ethylene carbonate was adjusted to 2%, and the weight percentage of fluoroethylene carbonate was 11%.

[0161] Example 5 group

[0162] This set of examples is used to illustrate when d 1 / d 2 The effects of changes.

[0163] This embodiment group is carried out with reference to Embodiment 1, except that d is changed. 1 / d 2 See Table 3 for details.

[0164] Table 3

[0165]

[0166] Example 6 group

[0167] This set of examples is used to illustrate when A 4 / A 3 The effects of changes.

[0168] This embodiment is based on Embodiment 1, except that convex and concave portions are formed on the surface of the positive electrode sheet through an embossing process, thereby changing A. 4 / A 3 The height of the protrusion is 20 μm and the width of the protrusion is 1.5 mm, as detailed in Table 4.

[0169] Table 4

[0170]

[0171] Example 7 group

[0172] Example 7a

[0173] The experiment was conducted in accordance with Example 1, except that the composition of the heat-resistant particles was adjusted to uracil, the composition of the first particle was adjusted to methyl methacrylate-acrylonitrile-ethylene copolymer, the average particle size of the first particle was 0.85 μm, and the corresponding mass swelling degree of the first particle was 120.4%.

[0174] Example 7b

[0175] The experiment was conducted in accordance with Example 1, except that the composition of the first particle was adjusted to be propyl methacrylate-ethylene copolymer, the average particle size of the first particle was 0.95 μm, and the corresponding mass swelling degree of the first particle was 140.9%.

[0176] Example 8 group

[0177] Example 8a

[0178] The procedure was carried out in accordance with Example 1, except that the composition of the second particle was adjusted to be methyl methacrylate-styrene copolymer, the average particle size of the second particle was 1.2 μm, and the corresponding mass swelling degree of the second particle was 100.5%.

[0179] Example 8b

[0180] The procedure was carried out in accordance with Example 1, except that the composition of the second particle was adjusted to be polymethyl methacrylate, the average particle size of the second particle was 0.95 μm, and the corresponding mass swelling degree of the second particle was 150.1%.

[0181] Example 9 group

[0182] Example 9a

[0183] The procedure was carried out in accordance with Example 1, except that the third particle was composed of polyvinylidene fluoride and the mass swelling degree of the third particle was 30.3%.

[0184] Example 9b

[0185] The procedure was carried out in accordance with Example 1, except that the third particle was composed of methyl methacrylate-styrene copolymer and the mass swelling degree of the third particle was 38.7%.

[0186] Example 10

[0187] The procedure was carried out in accordance with Example 1, except that the heat-resistant particles were composed of 2-mercaptobenzimidazole.

[0188] Comparative Example 1

[0189] The procedure was carried out in accordance with Example 1, except that the first particle was adjusted to be composed of polyvinylidene fluoride (PVDF) particles with an average particle size of 0.2 μm, and the second particle was adjusted to be composed of polyvinylidene fluoride (PVDF) particles with an average particle size of 0.2 μm.

[0190] Comparative Example 2

[0191] The process was carried out in accordance with Example 1, except that the second polymer coating corresponds to the positive electrode and the first polymer coating corresponds to the negative electrode.

[0192] Comparative Example 3

[0193] The procedure is carried out in accordance with Example 1, except that A 3 Below 65, see Table 5 for details.

[0194] Comparative Example 4

[0195] The procedure is carried out in accordance with Example 1, except that A 3 For values ​​above 470, please refer to Table 5 for details.

[0196] Table 5

[0197]

[0198] Comparative Example 5

[0199] The experiment was conducted in accordance with Example 1, except that the weight percentage of 2,2-difluoroethyl acetate in the electrolyte was 18.3%, the weight percentage of cyclic carbonate was 13%, and the weight ratio of propylene carbonate and fluoroethylene carbonate remained unchanged. Therefore, the weight ratio of ethyl difluoroacetate to cyclic carbonate was 1.41.

[0200] Comparative Example 6

[0201] The process was carried out in accordance with Example 1, except that the weight percentage of 2,2-difluoroethyl acetate in the electrolyte was 11%, the weight percentage of cyclic carbonate was 1%, and the weight ratio of propylene carbonate and fluoroethylene carbonate remained unchanged. Therefore, the weight ratio of ethyl difluoroacetate to cyclic carbonate was 11.

[0202] Test case

[0203] The batteries prepared by the examples and comparative examples were tested as follows.

[0204] 1. Room temperature rate performance test

[0205] At an environment of 25℃±2℃, the battery is discharged at a constant current of 0.2C to 3V. The initial discharge capacity is recorded as Q. 0Let it stand for 10 minutes, then fully charge it at 0.7C (100% SOC), with a cutoff current of 0.025C, let it stand for 10 minutes, then discharge it to 3V at a 2C rate, and let it stand for 10 minutes. The discharge capacity at this point is recorded as Q. 1 Capacity retention rate at room temperature discharge rate: Q 1 / Q 0 ×100%.

[0206] 2. Low-temperature rate performance test

[0207] The lithium-ion battery was placed in a 25°C constant temperature chamber and left to stand for 30 minutes to allow it to reach a constant temperature. It was then charged at a constant current and constant voltage of 0.7C to 4.5V, with a cutoff current of 0.025C. After standing for 4 hours, it was discharged at a constant current of 0.2C to 3V, and the initial discharge capacity C was recorded. 0 Then, charge the battery to 4.5V using a constant current and constant voltage of 0.7C, with a cutoff current of 0.025C. Next, place the battery in a constant temperature chamber at -10℃ for 4 hours, and discharge it to 3V using a constant current of 0.5C. Record the final discharge capacity C. 1 At low temperature discharge capacity retention rate = (C 1 / C 0 ) × 100%.

[0208] 3. Room temperature cycling performance test and positive electrode current collector breakage test

[0209] The lithium-ion battery was placed at 25℃±3℃, then charged at a constant current of 1C to the upper limit voltage (4.5V), then charged at a constant voltage of 4.5V to 0.05C, and left to stand for 5 minutes; then discharged at a constant current of 0.5C to 3V, and the discharge capacity at this point was recorded as Q1. After standing for 5 minutes, this constituted one charge-discharge cycle. After 1000 charge / discharge cycles, the discharge capacity Q2 of the lithium-ion battery after 1000T cycles was recorded. The capacity retention rate (%) was then calculated as (Q2 / Q1)×100%.

[0210] After the cycle is completed, the battery is disassembled to check whether there are cracks and / or breaks in the positive electrode current collector. If there are cracks and / or breaks, it means that the positive electrode current collector has broken. If there are no cracks and / or breaks, it means that the positive electrode current collector has not broken. 50 battery samples are tested for each embodiment and comparative example. The number of batteries with broken positive electrode current collectors is N. The breakage rate of the positive electrode current collector is (N / 50)×100%.

[0211] 4. High-temperature cycling voltage drop test

[0212] At 45±2℃, the battery was charged at a constant current of 0.7C to the upper limit voltage of 4.5V, with a cutoff current of 0.05C. The initial thickness P0 of the battery was recorded. After standing for 5 minutes, it was discharged at a constant current of 0.2C to 3V. After standing for 5 minutes, the voltage was measured and recorded as the voltage before cycling, U. 0 .

[0213] Cyclic charging procedure: Charge the battery at a constant current of 0.7C to 4.5V, cut off the current at 0.05C, let it rest for 5 minutes, then discharge it at a constant current of 0.2C to 3V, and let it rest for 5 minutes. After 300 cycles, charge the battery at a constant current of 0.7C to the upper limit voltage of 4.5V, cut off the current at 0.05C, let it rest for 5 minutes, then discharge it at a constant current of 0.2C to 3V, let it rest for 5 minutes, and then remeasure the voltage, recording it as the post-cycle voltage U. 1 Voltage drop U = U 0 -U 1 .

[0214] The results are recorded in Table 6.

[0215] Table 6

[0216]

[0217]

[0218] As can be seen from Table 6, by comparing the comparative examples and the embodiments, it can be seen that the battery of the embodiments has significantly improved room temperature cycle capacity retention rate, significantly improved low temperature capacity retention rate, and reduced high temperature cycle voltage drop. This indicates that by controlling the quantity relationship of acrylate polymer particles in the polymer coatings on both sides of the separator, and simultaneously controlling the weight ratio of ethyl difluoroethylene to cyclic carbonate in the electrolyte, the battery can have both high long cycle performance, high low temperature rate performance, and low high temperature cycle voltage drop.

[0219] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A battery, characterized in that, The battery is a wound battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator located between the positive and negative electrodes. The separator includes a carrier layer and polymer coatings on both sides of the carrier layer. In the separator, the polymer coating corresponding to the positive electrode is a first polymer coating, and the polymer coating corresponding to the negative electrode is a second polymer coating. The first polymer coating comprises dispersed first particles, the first particles being composed of acrylate polymers. The second polymer coating comprises dispersed second particles, the second particles being composed of acrylate polymers. The coverage of the first polymer coating on the carrier layer surface and the coverage of the second polymer coating on the carrier layer surface are the same. The separator satisfies the following relationship: 65 ≤ A 3 ≤470, where A 3 =A 2 -A 1 A 1 A represents the number of the first particles, expressed as individuals, within any 25μm × 19μm area on the surface of the first polymer coating. 2 The number of the second particles, expressed as individuals, within any 25μm × 19μm area on the surface of the second polymer coating; A 1 For 20-340, and / or, A 2 It is 87-810; The electrolyte comprises ethyl difluorocarbonate and cyclic carbonate, wherein the weight ratio of ethyl difluorocarbonate to cyclic carbonate is 1.5-10, and the cyclic carbonate includes fluoroethylene carbonate; the weight percentage of ethyl difluorocarbonate in the electrolyte is 10%-65%, and / or the weight percentage of cyclic carbonate in the electrolyte is 1%-28%; The negative electrode sheet includes a negative current collector and a negative active layer located on one or both sides of the negative current collector, wherein the negative active layer comprises a silicon-based material.

2. The battery according to claim 1, wherein, The diaphragm satisfies the following relationship: 100≤A 3 ≤400; And / or, A 1 The range is 35-215; And / or, A 2 The value is 110-615; And / or, the acrylate polymers include one or more of the following: polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, acrylate monomer-acrylonitrile copolymer, styrene-acrylate monomer copolymer, acrylate monomer-acrylonitrile-ethylene copolymer, styrene-acrylate monomer-acrylonitrile copolymer, acrylate monomer-ethylene copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-N,N-dimethylacrylamide copolymer, ethyl acrylate-2-(diethylamino)ethyl acrylate copolymer, ethyl acrylate-N,N-diethylacrylamide copolymer, and ethyl acrylate-2-(diethylamino)ethyl acrylate. And / or, the ethyl difluoroacetate comprises one or more of 2,2-difluoroethyl acetate and ethyl 2,2-difluoroacetate; And / or, the cyclic carbonate further includes one or more of ethylene carbonate and propylene carbonate; And / or, the weight percentage of the ethyl difluoroacetate in the electrolyte is 25%-45%; And / or, the cyclic carbonate in the electrolyte accounts for 10%-23% by weight.

3. The battery according to claim 2, wherein, The acrylate monomers include one or more of the following: methyl methacrylate, butyl acrylate, n-propyl acrylate, octyl acrylate, ethyl methacrylate, isooctyl acrylate, octadecyl acrylate, ethyl acrylate, cyclohexyl acrylate, and 2-hydroxyethyl acrylate. And / or, the cyclic carbonate in the electrolyte accounts for 10%-23% by weight.

4. The battery according to claim 1, wherein, The first particle and the second particle may be the same or different; And / or, the average particle size of the first particle is 0.5 μm-1.2 μm; And / or, the average particle size of the second particle is 0.5 μm-1.2 μm; And / or, at 90°C, the first particles are soaked in 2,2-difluoroethyl acetate for 4 hours, and the mass swelling degree of the first particles is greater than 70%; And / or, at 90°C, the second particle is soaked in 2,2-difluoroethyl acetic acid for 4 hours, and the mass swelling degree of the second particle is greater than 70%.

5. The battery according to claim 1, wherein, The first polymer coating has a coverage of 10%-45% on the surface of the carrier layer; And / or, the second polymer coating has a coverage of 10%-45% on the surface of the carrier layer; And / or, the areal density of the first polymer coating is 0.3 g / m³. 2 -0.5g / m 2 ; And / or, the areal density of the second polymer coating is 0.3 g / m³. 2 -0.5g / m 2 .

6. The battery according to any one of claims 1-5, wherein, The first polymer coating also includes a third particle, which is an agglomerated particle; And / or, the second polymer coating does not include third particles; And / or, the first polymer coating has a coverage of 18%-35% on the surface of the carrier layer; And / or, the second polymer coating has a coverage of 18%-35% on the surface of the carrier layer; And / or, the average particle size of the first particle is 0.65 μm-0.95 μm; And / or, the average particle size of the second particle is 0.65 μm-0.95 μm; And / or, at 90°C, the first particles are soaked in 2,2-difluoroethyl acetate for 4 hours, and the mass swelling degree of the first particles is 71%-180%; And / or, at 90°C, the second particle is soaked in 2,2-difluoroethyl acetate for 4 hours, and the mass swelling degree of the second particle is 71%-180%; And / or, the weight percentage of the ethyl difluoroacetate in the electrolyte is 25%-45%; And / or, the positive electrode includes a first surface and a second surface opposite to each other in the thickness direction of the positive electrode, the first surface including a plurality of recesses, and the second surface including a plurality of protrusions, the protrusions corresponding to the recesses.

7. The battery according to claim 6, wherein, The diaphragm satisfies the following relationship: 1.5 ≤ d 1 / d 2 ≤25, where d 1 The average particle size of the secondary particles of the third particle is expressed in μm and d. 2 Dv90 of the first particle, in μm; And / or, the average particle size of the secondary particles of the third particle is 2μm-20μm; And / or, the Dv90 of the first particle is 0.65μm-4.5μm; And / or, wherein the third particle is soaked in 2,2-difluoroethyl acetate at 90°C for 4 hours, and the mass swelling degree of the third particle is less than 40%; And / or, the composition of the third particle includes one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, polyhexafluoropropylene, fluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, acrylate monomer-acrylonitrile copolymer, styrene-acrylate monomer copolymer, acrylate monomer-acrylonitrile-ethylene copolymer, acrylate monomer-ethylene copolymer, styrene-acrylate monomer-acrylonitrile copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-N,N-dimethylacrylamide copolymer, ethyl acrylate-2-(diethylamino)ethyl acrylate copolymer, ethyl acrylate-N,N-diethylacrylamide copolymer, and ethyl acrylate-2-(diethylamino)ethyl acrylate. And / or, the battery satisfies the following relationship: 0.7 ≤ A 4 / A 3 ≤5, where A 4 The number of protrusions within an area of ​​50mm × 50mm optionally on the second surface, in units of one; And / or, the height of the protrusion is 3μm-50μm; And / or, the width of the protrusion is 1mm-4mm; And / or, within an area of ​​optionally 50mm × 50mm on the second surface, the number of protrusions is 156 to 415.

8. The battery according to claim 1, wherein, The carrier layer includes a substrate layer and optionally a heat-resistant layer, the heat-resistant layer being located on one or both surfaces of the substrate layer; And / or, the carrier layer includes a substrate layer and optionally a heat-resistant layer, wherein the porosity of the substrate layer is 25%-70%; And / or, the carrier layer includes a substrate layer and optionally a heat-resistant layer, wherein the thickness of the substrate layer is 3μm-10μm; And / or, the carrier layer includes a substrate layer and optionally a heat-resistant layer, wherein the substrate layer comprises one or more of polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polytetrafluoroethylene, polyimide, polyethylene terephthalate, polybutylene terephthalate, poly(p-phenylene terephthalate), and poly(m-phenylene isophthalate).

9. The battery according to claim 8, wherein, The heat-resistant layer comprises heat-resistant particles and a first binder. Based on the total weight of the heat-resistant layer, the heat-resistant particles account for 90%-99% of the weight, and the first binder accounts for 1%-10% of the weight. And / or, the thickness of the heat-resistant layer is 0.3μm-4.5μm; And / or, the heat-resistant layer comprises heat-resistant particles and a first binder, wherein the heat-resistant particles are composed of one or more of the following: boehmite, alumina, barium sulfate (BaSO4), magnesium oxide, magnesium hydroxide, silicon dioxide, tin dioxide, titanium dioxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, 1,3,5-triazine-2,4,6-triamine, melamine thiocyanate, melamine cyanurate, symmetric triaminotriazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4,6-tris(2-pyridyl)triazine, 2-amino-4,6-methoxy-1,3,5-triazine, lithium aluminum titanium phosphate, uracil, cytosine, guanine, 4-amino-2,6-dihydroxypyrimidine, phenolic resin, and benzimidazole compounds. And / or, the heat-resistant layer comprises heat-resistant particles and a first binder, wherein the heat-resistant particles have a Dv50 of 0.15 μm to 2.5 μm; And / or, the heat-resistant layer comprises heat-resistant particles and a first adhesive, wherein the first adhesive comprises one or more of the following: polyvinyl alcohol, styrene-butadiene rubber, ethylene-vinyl acetate copolymer, sodium carboxymethyl cellulose, polyvinylpyrrolidone, acrylate adhesives, styrene-acrylic latex, polyacrylonitrile, polyvinyl acetate, polyacrylic acid, polyurethane, polyurethane-modified polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, or copolymer systems derived from the above polymers.

10. The battery according to claim 1, wherein, The silicon-based material includes one or more of elemental silicon particles, silicon-oxygen particles, silicon-carbon particles, silicon-nitrogen particles, and silicon alloy particles; And / or, the positive electrode sheet includes a positive current collector and a positive active layer located on one or both surfaces of the positive current collector. The positive active layer includes a positive active material, which includes a core and a coating layer. The coating layer is located on the surface of the core. The core includes lithium cobalt oxide, and the coating layer includes materials with the chemical formula Li7La. 3-a Zr 2-b M a+ b O 12 The substance is selected from one or more of Fe, Ti, Cu, and Mn, where 0.01≤a≤0.5 and 0.05≤b≤0.3.

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