Aluminum plastic film, electrochemical device comprising same and electronic device comprising same

Abstract

The invention discloses an aluminum-plastic film, an electrochemical device comprising the aluminum-plastic film and an electronic device comprising the aluminum-plastic film, and belongs to the technical field of energy storage. The aluminum plastic film comprises a nylon layer, an aluminum layer and a PP composite layer which are sequentially arranged, the PP composite layer comprises a bonding supporting PP layer, a self-repairing PP layer and a wear-resisting PP layer which are sequentially arranged, the thicknesses of the bonding supporting PP layer, the self-repairing PP layer and the wear-resisting PP layer are t1, t2 and t3 respectively, and t1, t2 and t3 meet the condition that t1: t2: t3 = (1-2): (1-2): (2-3). The anti-wear strength of the aluminum-plastic film can be effectively improved, the aluminum-plastic film is endowed with excellent scratch self-healing capacity, the problem that the inner layer of the aluminum-plastic film is damaged due to pole piece step difference in an electrochemical device is fundamentally solved, and therefore the safety and stability of the electrochemical device are improved.

Description

Technical Field

[0001] This application relates to the field of electrochemical energy storage technology, and more specifically, to an aluminum-plastic film and an electrochemical device and an electronic device comprising the same. Background Technology

[0002] Electrochemical devices (especially lithium-ion batteries) have become core power sources in many fields, including new energy vehicles, 3C products, and energy storage systems, due to their significant advantages such as high energy density, long cycle life, and no memory effect. Lithium-ion batteries are typically packaged in aluminum-plastic film. In the event of a safety hazard, the film usually bulges or cracks at the seal to release energy, reducing the risk of explosion and effectively improving the safety of the electrochemical device. As a key packaging material for soft-pack lithium-ion batteries, the aluminum-plastic film typically consists of three layers: an outer nylon layer, a middle aluminum layer, and an inner PP layer. Its main purpose is to provide insulation, protection, and encapsulation.

[0003] In the production and use of lithium-ion batteries, the presence of the OH region (overhang region, referring to the area where the negative electrode extends beyond the positive electrode in both length and width) creates a height gradient at the winding and stacking of cell electrodes. During lithium-ion battery formation or cycling, the edges of the single-sided positive electrode foil or single-sided empty foil area frequently rub against the inner layer of the aluminum-plastic film, causing damage to the inner layer. The single-sided aluminum foil may fold, and in severe cases, the Al layer may be exposed. The electrolyte comes into contact with the Al layer and undergoes a chemical reaction, resulting in leakage. Leakage affects the performance, capacity, and lifespan of lithium-ion batteries, pollutes the environment, and can also cause bulging, or even short circuits and fires.

[0004] Currently, most aluminum-plastic films have a single-layer or simple composite inner layer, focusing only on resistance to electrolyte corrosion. Their wear resistance design is not optimized for electrode gradient differences, making them prone to scratches and damage under frequent friction. Once scratched or damaged, the inner layer of the aluminum-plastic film cannot repair itself, and the damage accumulates until the Al layer is exposed. Even with some modified aluminum-plastic films that improve mechanical strength, it is still difficult to completely avoid the progressive damage caused by long-term friction at the electrode edges. Furthermore, the inner layer of the aluminum-plastic film suffers from layered crystallization due to the coating process, further weakening its mechanical strength and wear resistance.

[0005] Therefore, solving the problem of damage to the inner layer of aluminum-plastic film caused by electrode step differences in electrochemical devices is of great significance for improving the safety performance and stability of electrochemical devices. Summary of the Invention

[0006] The purpose of this application is to overcome the shortcomings of the existing technology and provide an aluminum-plastic film, an electrochemical device including the same, and an electronic device including the same. This application can effectively improve the wear resistance of the aluminum-plastic film and endow it with excellent scratch self-healing ability, fundamentally solving the problem of damage to the inner layer of the aluminum-plastic film caused by electrode step differences in electrochemical devices, thereby improving the safety and stability of the electrochemical device.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: The first aspect of this application provides an aluminum-plastic film, comprising a nylon layer, an aluminum layer and a PP composite layer disposed sequentially, wherein the PP composite layer comprises an adhesive support PP layer, a self-healing PP layer and a wear-resistant PP layer disposed sequentially, wherein the thicknesses of the adhesive support PP layer, the self-healing PP layer and the wear-resistant PP layer are t1, t2 and t3 respectively, and t1, t2 and t3 satisfy: t1:t2:t3=(1~2):(1~2):(2~3); The adhesive support PP layer is composed of polypropylene; the self-healing PP layer is composed of polypropylene and self-healing microcapsules; the wear-resistant PP layer is composed of polypropylene and carbon nitride / graphene foam composite powder.

[0008] In some embodiments, the total thickness of the PP composite layer is T, wherein T satisfies: 40μm≤T≤80μm.

[0009] In some implementations, t1, t2, and t3 satisfy the following conditions: 5μm≤t1≤25μm, 5μm≤t2≤25μm, and 10μm≤t3≤50μm.

[0010] In some embodiments, the adhesive support PP layer comprises the following components by weight percentage: 65-80% random copolymer polypropylene, 10-15% maleic anhydride modified polypropylene, and 10-15% polyolefin elastomer.

[0011] In some embodiments, the random copolymer polypropylene has a melt flow rate of 2.0~3.5 g / 10min under test conditions of 230°C and 2.16 kg.

[0012] In some embodiments, the grafting rate of the maleic anhydride-modified polypropylene is 0.8 to 1.2%.

[0013] In some embodiments, the maleic anhydride-modified polypropylene has a melt flow rate of 3.0~5.0 g / 10min under test conditions of 230°C and 2.16 kg.

[0014] In some embodiments, the Shore hardness D of the polyolefin elastomer is 55 to 65.

[0015] In some embodiments, the polyolefin elastomer has a melt flow rate of 1.5~3.0 g / 10min under test conditions of 230°C and 2.16 kg.

[0016] In some embodiments, the self-healing PP layer comprises the following components by weight percentage: 60-70% block copolymer polypropylene, 15-20% polyolefin elastomer, 10-15% self-healing microcapsules, and 1-3% dispersant.

[0017] In some embodiments, the core material of the self-healing microcapsule is an isocyanate prepolymer, and the wall material is a urea-formaldehyde resin-gelatin composite wall material.

[0018] In some embodiments, the average particle size of the self-healing microcapsules is 5-10 μm.

[0019] In some embodiments, the wall thickness of the self-healing microcapsule is 1~2 μm.

[0020] In some embodiments, the dispersant includes at least one of stearamide dispersants, palmitamide dispersants, and erucamide dispersants.

[0021] In some embodiments, the wear-resistant PP layer comprises the following components by weight percentage: 70-75% random copolymer polypropylene, 5-8% carbon nitride / graphene foam composite powder, 5-10% organic modified nano-silica, and 2-5% slip agent.

[0022] In some embodiments, the graphene content in the carbon nitride / graphene foam composite powder is 5-10% by mass, and the carbon nitride content is 90-95% by mass.

[0023] In some embodiments, the average particle size of the organically modified nano-silica is 70-90 nm.

[0024] In some embodiments, the slip agent includes at least one of high-temperature resistant silicone slip agents, polydimethylsiloxane (PDMS) slip agents, and fatty acid amide slip agents.

[0025] A second aspect of this application provides an electrochemical device comprising the aforementioned aluminum-plastic film.

[0026] In some embodiments, the electrochemical device further includes a battery cell comprising a positive electrode, a negative electrode, and a separator located between the positive and negative electrode. The negative electrode includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. The positive electrode includes a positive current collector and a positive active layer disposed on at least one surface of the positive current collector. The distance between the positive current collector and the negative active layer is H, which is the height difference of the OH region of a single-sided positive electrode. H satisfies: 39μm≤H≤65μm.

[0027] In some implementations, T and H satisfy the condition: T > H.

[0028] In some implementations, T, H, and t3 satisfy: [0.4 + (H - 39) / 130] × T ≤ t3 ≤ 0.6T.

[0029] A third aspect of this application provides an electronic device including the electrochemical device described above.

[0030] The beneficial effects of this application are as follows: By using a PP composite layer and controlling the thickness ratio of its bonding support PP layer, self-healing PP layer, and wear-resistant PP layer, this application can effectively improve the wear resistance of the aluminum-plastic film and endow it with excellent scratch self-healing ability, fundamentally solving the problem of damage to the inner layer of the aluminum-plastic film caused by the electrode step difference in electrochemical devices, thereby improving the safety and stability of electrochemical devices. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the battery cell described in this application. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0034] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0035] In this application, there are no particular restrictions on the specific dispersion and mixing methods.

[0036] Unless otherwise specified, all components, raw materials, or instruments used in the embodiments and comparative examples of this application are commercially available.

[0037] General definition The term "binder" refers to a substance used to bond inorganic fillers to or to each other in a porous substrate material. Any organic binder that can bond inorganic fillers to or to each other in a porous substrate material may be used herein. Some non-limiting examples of organic binders include polyesters, polyamides, polyacrylic acid, polyethers, polyimides, polyolefins, rubbers, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, cellulose, cellulose derivatives, latexes, and combinations thereof.

[0038] Positive / Negative Electrode Active Materials: As used herein and in the claims, the term "positive / negative electrode active material" (also known as cathode active material / anode active material) is defined as a material that is electrochemically active in the positive / negative electrode or cathode / anode. Active materials should be understood as materials capable of capturing and releasing Li and / or Na ions when subjected to voltage changes over a predetermined time period.

[0039] I. Aluminum-plastic film This application provides an aluminum-plastic film, comprising a nylon layer, an aluminum layer and a PP composite layer arranged in sequence. The PP composite layer comprises an adhesive support PP layer, a self-healing PP layer and a wear-resistant PP layer arranged in sequence. The thicknesses of the adhesive support PP layer, the self-healing PP layer and the wear-resistant PP layer are t1, t2 and t3, respectively, and t1, t2 and t3 satisfy: t1:t2:t3=(1~2):(1~2):(2~3).

[0040] The inventors of this application have discovered that the safety and stability of the electrochemical device, as well as the damage to the inner layer of the aluminum-plastic film caused by electrode step differences, are significantly correlated with the thickness ratio of the bonding support PP layer, the self-healing PP layer, and the wear-resistant PP layer in the aluminum-plastic film. This application controls the thickness ratio of the bonding support PP layer, the self-healing PP layer, and the wear-resistant PP layer to (1~2):(1~2):(2~3). The synergistic effect of each layer in the aluminum-plastic film forms a complete protective system of "support-self-healing-wear resistance": the bonding support PP layer provides the aluminum-plastic film with a strong bond to the current collector and stable structural support; the self-healing PP layer can quickly function to repair the damage when the wear-resistant PP layer is scratched; the wear-resistant PP layer directly resists the wear of the electrode foil edge, effectively protecting the wear-resistant PP layer, effectively improving the wear resistance of the aluminum-plastic film, and giving it excellent scratch self-healing ability. This fundamentally solves the problem of damage to the inner layer of the aluminum-plastic film caused by electrode step differences in the electrochemical device, thereby improving the safety and stability of the electrochemical device.

[0041] The structure of the aluminum-plastic film described in this application is highly compatible with existing aluminum-plastic film composite processes. In actual production, there is no need for large-scale modifications to existing production lines, which greatly reduces production costs and technical barriers, and facilitates rapid promotion and application.

[0042] In some embodiments, the total thickness of the PP composite layer is T, and T, t1, t2, and t3 satisfy: T = t1 + t2 + t3, 40 μm ≤ T ≤ 80 μm, for example, it can be 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm or any two of these values.

[0043] In some implementations, t1 satisfies: 5μm≤t1≤25μm, for example, it can be 5μm, 6μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 25μm or any two of these values. If the thickness of the adhesive support PP layer is too small, the effective contact area of ​​the maleic anhydride modified polypropylene in the adhesive support PP layer is reduced, the peel strength between it and the current collector layer is reduced, and it is easy to delaminate after immersion in electrolyte; at the same time, insufficient polyolefin elastomer content leads to a decrease in impact resistance, wrinkling defects are prone to occur during three-layer co-extrusion, and cracking is prone to occur with deformation of the current collector after heat sealing; excessive etching is prone to occur during plasma treatment, and the increased surface roughness actually reduces the adhesion. If the thickness of the adhesive support PP layer is too large, the material cost increases, and the bonding strength becomes ineffectively redundant; at the same time, it will also squeeze the space of the self-healing PP layer.

[0044] In some implementations, t2 satisfies: 5μm ≤ t2 ≤ 25μm, for example, it can be a range of 5μm, 6μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 25μm, or any two of these values. If the thickness of the self-healing PP layer is too small, the self-healing microcapsules will not have sufficient load-bearing capacity, resulting in a decreased healing rate; the interfacial bonding area, which acts as a bridge between layers, will decrease, leading to an increased interfacial peeling rate after thermal cycling; furthermore, the high concentration of self-healing microcapsules makes them prone to agglomeration, forming particle protrusions after extrusion, increasing friction and wear. If the thickness of the self-healing PP layer is too large, the extruded wear-resistant PP layer will become thinner, increasing the wear depth after friction and causing a loss of wear resistance.

[0045] In some implementations, t3 satisfies: 10μm≤t3≤50μm, for example, it can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm or any two of these values. If the wear-resistant PP layer thickness is too small, the carbon nitride / graphene three-dimensional network structure is incomplete, and the wear depth increases after repeated friction, directly penetrating to the self-healing PP layer; this reduces the surface pencil hardness, making the electrode prone to rigid scratches, exceeding the self-healing range; at the same time, the thickness of the lubricating agent film is insufficient, and the friction coefficient increases after cycling, increasing wear. If the wear-resistant PP layer thickness is too large, the inorganic filler ratio is too high, leading to an increase in Shore hardness D, and the extrusion bonding support PP layer is too small, causing the aluminum-plastic film to delaminate after vibration testing; during three-layer co-extrusion, the melt flow is mismatched, resulting in interlayer flow marks, and the surface flatness decreases, increasing the risk of local wear.

[0046] In some embodiments, the adhesive support PP layer comprises the following components by weight percentage: 65-80% random copolymer polypropylene, 10-15% maleic anhydride modified polypropylene, and 10-15% polyolefin elastomer.

[0047] In some embodiments, the melt flow rate of the random copolymer polypropylene is 2.0~3.5 g / 10min under test conditions of 230°C and 2.16 kg, for example, it can be 2.0 g / 10min, 2.2 g / 10min, 2.4 g / 10min, 2.6 g / 10min, 2.8 g / 10min, 3.0 g / 10min, 3.2 g / 10min, 3.4 g / 10min, 3.5 g / 10min, or any two of these values. The test standard for melt flow rate is GB / T 3682.1-2018.

[0048] In some embodiments, the grafting rate of the maleic anhydride-modified polypropylene is 0.8% to 1.2%, for example, it can be a range of 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, or any two of these values. The grafting rate is determined using conventional chemical titration.

[0049] In some embodiments, the maleic anhydride-modified polypropylene has a melt flow rate of 3.0~5.0 g / 10min under test conditions of 230°C and 2.16 kg, for example, it can be 3.0 g / 10min, 3.2 g / 10min, 3.4 g / 10min, 3.6 g / 10min, 3.8 g / 10min, 4.0 g / 10min, 4.2 g / 10min, 4.4 g / 10min, 4.6 g / 10min, 4.8 g / 10min, 5.0 g / 10min or any two of these values.

[0050] In some embodiments, the Shore hardness D of the polyolefin elastomer is 55 to 65, for example, it can be a range of 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 or any two of these values. The hardness testing standard is GB / T2411-2008.

[0051] In some embodiments, the polyolefin elastomer has a melt flow rate of 1.5 to 3.0 g / 10 min under test conditions of 230°C and 2.16 kg, for example, it can be 1.5 g / 10 min, 1.8 g / 10 min, 2.0 g / 10 min, 2.2 g / 10 min, 2.4 g / 10 min, 2.6 g / 10 min, 2.8 g / 10 min, 3.0 g / 10 min, or any two of these values.

[0052] In some embodiments, the self-healing PP layer comprises the following components by weight percentage: 60-70% block copolymer polypropylene, 15-20% polyolefin elastomer, 10-15% self-healing microcapsules, and 1-3% dispersant.

[0053] In some embodiments, the core material of the self-healing microcapsule is an isocyanate prepolymer, and the wall material is a urea-formaldehyde resin-gelatin composite wall material.

[0054] In some embodiments, the method for preparing the self-healing microcapsules includes the following steps: (1) Preparation of aqueous phase: Dissolve gelatin (wall material component 1) in deionized water, heat to 50-55℃, add emulsifier, stir until dissolved, adjust pH to 4-5 to obtain aqueous phase; (2) Preparation of oil phase: The isocyanate prepolymer (core material) is mixed with toluene and ultrasonically dispersed to obtain the oil phase; (3) Emulsification: The oil phase is slowly dripped into the aqueous phase and stirred at 800-1000 r / min at 50-60℃ for 20-30 min to form a W / O type emulsion with an emulsion particle size of 5-10 μm; (4) Wall material polymerization: Add urea-formaldehyde resin prepolymer (wall material component 2) dropwise to the emulsion, heat to 55-60℃, keep warm and stir for 1-2 h, and the urea-formaldehyde resin and gelatin crosslink to form a composite wall material; (5) Post-processing: Cool to room temperature, centrifuge at 2000-3000 r / min for 8-10 min, wash with deionized water 2-3 times, and vacuum dry at 60-65℃ for 3-4 h to obtain self-healing microcapsules.

[0055] In some embodiments, the average particle size of the self-healing microcapsules is 5 to 10 μm, for example, it can be a range of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any two of these values.

[0056] In some embodiments, the wall thickness of the self-healing microcapsule is 1~2 μm.

[0057] In some embodiments, the dispersant includes at least one of stearamide dispersants, palmitamide dispersants, and erucamide dispersants.

[0058] In some embodiments, the wear-resistant PP layer comprises the following components by weight percentage: 70-75% random copolymer polypropylene, 5-8% carbon nitride / graphene foam composite powder, 5-10% organic modified nano-silica, and 2-5% slip agent.

[0059] In some embodiments, the graphene content in the carbon nitride / graphene foam composite powder is 5-10% by mass, and the carbon nitride content is 90-95% by mass.

[0060] In some embodiments, the method for preparing the carbon nitride / graphene foam composite powder includes the following steps: Urea and graphene powder were mixed at a mass ratio of (90-95):(5-10), and deionized water was added for ultrasonic dispersion to form a uniform suspension. The suspension was then transferred to a hydrothermal reactor and reacted at 180-200℃ for 8-10 h. After the reaction was completed, the mixture was cooled to room temperature, and the product was separated by centrifugation. The product was then washed 3-4 times with deionized water and ethanol, and vacuum dried at 115-120℃ for 5-6 h. Subsequently, the product was calcined at 500-550℃ for 1-2 h under a nitrogen atmosphere, ground, and sieved to obtain carbon nitride / graphene foam composite powder with a particle size of 1-3 μm.

[0061] In some embodiments, the average particle size of the organically modified nano-silica is 70-90 nm.

[0062] In some embodiments, the organically modified nano-silica is prepared using a silane coupling agent modification method, the steps of which are as follows: γ-aminopropyltriethoxysilane (KH-550) is added to the original nano-silica with an average particle size of 60-80 nm for modification, resulting in organically modified nano-silica with an average particle size of 70-90 nm and a modification rate ≥95%. After modification, hydrophobic groups are introduced onto its surface, allowing it to tightly bind with the polypropylene molecular chains and significantly improving the surface hardness of the layer.

[0063] In some embodiments, the slip agent includes at least one of high-temperature resistant silicone slip agents, polydimethylsiloxane (PDMS) slip agents, and fatty acid amide slip agents.

[0064] This application does not impose any particular restrictions on the nylon layer and aluminum layer in the aluminum-plastic film, as long as the purpose of this application can be achieved.

[0065] Preparation method of aluminum-plastic film: A nylon layer, an aluminum layer, and a PP composite layer are laminated using a dry lamination process at a lamination temperature of 70-80℃ and a lamination pressure of 0.3-0.4MPa to obtain an aluminum-plastic film.

[0066] II. Electrochemical Device This application provides an electrochemical device comprising the aforementioned aluminum-plastic film.

[0067] In some embodiments, the electrochemical device further includes a positive electrode, a negative electrode, a diaphragm, and an electrolyte, wherein the diaphragm is located between the positive and negative electrodes.

[0068] The electrochemical device of this application includes any device in which an electrochemical reaction occurs, and specific examples include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0069] positive electrode The electrochemical device of this application includes a positive electrode, wherein the positive electrode includes a positive electrode current collector and a positive electrode active layer disposed on both sides of the positive electrode current collector.

[0070] In some implementations, the type of positive current collector is not particularly limited, and it may be any material known to be suitable for use as a positive current collector.

[0071] In some embodiments, the positive current collector includes metallic materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper.

[0072] There are no particular restrictions on the form of the positive electrode current collector. When the positive electrode current collector is a metallic material, it can be in the form of metal foil, metal cylinder, metal strip, metal plate, metal foil, metal mesh, stamped metal, foamed metal, etc. When the positive electrode current collector is a carbon material, it can be in the form of carbon plate, carbon film, carbon cylinder, etc.

[0073] In some embodiments, the positive electrode active layer includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent.

[0074] In some embodiments, the positive electrode active material is selected from LiCoO2, LiNiO2, and LiNi x Mn y O2, Li 1+ z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al z The group consisting of O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4, LiMnPO4 and combinations thereof, wherein each x is independently 0.2 to 0.9; each y is independently 0.1 to 0.45; and each z is independently 0 to 0.2.

[0075] In some embodiments, the positive electrode active material is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2; where -0.2≤x≤0.2, 0≤a<1, 0≤b<1, 0≤c<1 and a+b+c≤1.

[0076] In some embodiments, the positive electrode active material has the general formula Li 1+x Ni a Mn b Co c Al (1-a-b-c)O2, where 0.33≤a≤0.92, 0.33≤a≤0.9, 0.33≤a≤0.8, 0.5≤a≤0.92, 0.5≤a≤0.9, 0.5≤a≤0.8, 0.6≤a≤0.92 or 0.6≤a≤0.9; 0≤b≤0.5, 0≤b≤0.3, 0.1≤b≤0.5, 0.1≤b≤0.4, 0.1≤b≤0.3, 0.1≤b≤0.2 or 0.2≤b≤0.5; 0≤c≤0.5, 0≤c≤0.3, 0.1≤c≤0.5, 0.1≤c≤0.4, 0.1≤c≤0.3, 0.1≤c≤0.2 or 0.2≤c≤0.5.

[0077] In some embodiments, the positive electrode active material is doped with a dopant selected from the group consisting of Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof.

[0078] In some embodiments, the positive electrode active material includes LiNi. 0.33 Mn 0.33 Co 0.33 O2(NMC333), LiNi 0.4 Mn 0.4 Co 0.2 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2(NMC532), LiNi 0.6 Mn 0.2 Co 0.2 O2(NMC622), LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.8 Mn 0.1 Co 0.1 O2(NMC811), LiNi 0.92 Mn 0.04 Co 0.04 O2, LiNi 0.8 Co 0.15 Al 0.05 At least one of O2 (NCA) and LiNiO2 (LNO).

[0079] In some embodiments, the positive electrode binder includes a binder material, which includes at least one of the following: polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer. This application is not limited to the above materials and also includes other materials that can be used as a battery positive electrode binder.

[0080] In some embodiments, the positive electrode conductive agent includes at least one of carbon, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon tubes, carbon nanotubes, activated carbon, and mesoporous carbon. This application is not limited to the above materials, but also includes other materials that can be used as positive electrode conductive agents in batteries.

[0081] negative electrode The negative electrode includes a negative electrode current collector and a negative electrode active layer disposed on both sides of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material, a negative electrode binder and a negative electrode conductive agent.

[0082] In this application, there are no particular restrictions on the negative electrode current collector, as long as it can achieve the purpose of this application. For example, it can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper, or composite current collector, etc.

[0083] In some embodiments, the negative electrode active material includes natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesophase carbon microspheres (MCMB), Sn, SnO2, SnO, and Li4Ti5O. 12 The material is selected from at least one of LTO, Si, silicon-carbon composites, silicon-nitrogen composites, and silicon-oxygen composites. This application is not limited to the above-mentioned materials, but also includes other materials that can be used as negative electrode active materials in batteries.

[0084] In some embodiments, the negative electrode binder includes at least one of the following: polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, polyacrylamide, styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylic acid-acrylonitrile-acrylamide copolymer, acrylic acid-acrylonitrile-acrylate copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acryloyl rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyvinyl alcohol, polyvinyl acetate, polyepoxychloropropane, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, carboxymethyl chitosan, polyester, polyamide, polyether, polyimide, polycarboxylic acid ester, polycarboxylic acid, polyurethane, alginate, fluorinated polymer, chlorinated polymer, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropylene. This application is not limited to the above materials and also includes other materials that can be used as battery negative electrode binders.

[0085] In some embodiments, the negative electrode conductive agent includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon tubes, carbon nanotubes, activated carbon, and mesoporous carbon. This application is not limited to the above materials, but also includes other materials that can be used as negative electrode conductive agents in batteries.

[0086] In some embodiments, the distance between the positive current collector and the negative active layer is H, wherein H satisfies: 39μm≤H≤65μm, for example, it can be 39μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm or any two of these values.

[0087] In some implementations, T and H satisfy the condition: T > H.

[0088] In some implementations, T, H, and t3 satisfy: [0.4 + (H - 39) / 130] × T ≤ t3 ≤ 0.6T.

[0089] diaphragm The separator separates the negative and positive electrodes and provides a pathway for lithium-ion migration. The use of the separator is not particularly limited, as long as it is a separator commonly used in lithium-ion secondary batteries. In particular, separators with low resistance to electrolyte ion movement and excellent electrolyte permeability are preferred. Specifically, porous polymer membranes can be used, such as porous polymer membranes formed from polyolefin-based polymers (e.g., ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, ethylene / methacrylate copolymers, etc.) or laminated structures with two or more layers. Alternatively, nonwoven fabrics formed from conventional porous nonwoven fabrics (e.g., glass fibers with high melting points, polyethylene terephthalate fibers, etc.) can be used. Furthermore, coated separators containing ceramic components or polymer materials to ensure heat resistance or mechanical strength can be used, and can optionally be used as single-layer or multi-layer structures.

[0090] Generally, a diaphragm includes a substrate and a coating applied to the surface of the substrate.

[0091] electrolyte The electrochemical device of this application also includes an electrolyte.

[0092] In some embodiments, the electrolyte includes a liquid electrolyte.

[0093] In some embodiments, the liquid electrolyte includes a non-aqueous solvent and a lithium salt.

[0094] In some embodiments, the lithium salt includes at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB, and lithium difluoroborate.

[0095] In some embodiments, the non-aqueous solvent may be at least one of carbonate compounds, carboxylic acid ester compounds, and ether compounds.

[0096] In some embodiments, the carbonate compound includes at least one of chain carbonate compounds, cyclic carbonate compounds, and fluorocarbonate compounds.

[0097] In some embodiments, the chain carbonate compound includes diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), and combinations thereof. Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), vinyl ethylene carbonate (VEC), and combinations thereof. Examples of fluorinated carbonate compounds are at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, and trifluoromethylethylene carbonate.

[0098] In some embodiments, examples of carboxylic acid ester compounds are at least one of methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid lactone, valerate lactone, mevalonate lactone, caprolactone, and methyl formate.

[0099] In some embodiments, examples of ether compounds are dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.

[0100] In some embodiments, the non-aqueous solvent also includes at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters.

[0101] III. Electronic Devices This application provides an electronic device, including the electrochemical device described in this application.

[0102] The application of the electrochemical device in this application is not particularly limited, and it can be used in any electronic device known in the prior art. In some embodiments, the electrochemical device includes, but is not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, android robots, etc.

[0103] The following uses a lithium-ion battery as an example and combines specific embodiments to illustrate the preparation of a lithium-ion battery. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation method is within the scope of this application.

[0104] Example 1 The method for preparing a lithium-ion battery includes the following steps: 1. Preparation of the negative electrode sheet: The negative electrode active material silicon-carbon (60% by mass of silicon), conductive agent Super P, and binder PAA are thoroughly mixed in a deionized water solvent system at a weight ratio of 97.6:1.1:1.3 to obtain a negative electrode active material slurry (30% solid content). This slurry is then coated on both sides of the negative electrode current collector copper foil (8μm thick) and cold-pressed to obtain the negative electrode sheet.

[0105] 2. Preparation of the positive electrode sheet: The positive electrode active material LiCoO2, conductive agent acetylene black, conductive carbon nanotubes, and binder polyvinylidene fluoride (PVDF) were fully dispersed in an N-methylpyrrolidone solvent system at a weight ratio of 97.6:0.5:0.6:1.3 to prepare a positive electrode active material slurry (solid content 78%). The slurry was uniformly coated on both sides of an aluminum current collector (thickness 8μm), and then cold-pressed and slit to obtain the positive electrode sheet.

[0106] 3. Preparation of the diaphragm: The diaphragm is a porous PE membrane (4.5 μm thick, 50% porosity).

[0107] 4. Preparation of electrolyte: At room temperature, in an argon-filled glove box (H2O < 1 ppm, O2 < 1 ppm), ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) were mixed in a volume ratio of 30:10:40:20 to prepare a mixed organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent at a ratio of 1 mol / L to prepare an electrolyte.

[0108] 5. Preparation of lithium-ion secondary batteries Cell fabrication: The above-mentioned cathode electrode, separator, and anode electrode are wound or stacked to produce a bare cell.

[0109] Packaging: Bare cells are packaged using aluminum-plastic film with different PP composite layers, depending on the application scenario.

[0110] The aluminum-plastic film comprises a nylon layer (25 μm thick), an aluminum layer (40 μm thick), and a PP composite layer arranged sequentially. The PP composite layer comprises an adhesive support PP layer, a self-healing PP layer, and a wear-resistant PP layer arranged sequentially. The thicknesses of the adhesive support PP layer, the self-healing PP layer, and the wear-resistant PP layer are t1, t2, and t3, respectively, satisfying t1:t2:t3=1:1:2. The total thickness of the PP composite layer is T=40 μm, and t1=10 μm, t2=10 μm, and t3=20 μm are calculated. When the height difference of the OH region of the single-sided aluminum foil electrode sheet, i.e., the distance H between the positive electrode current collector and the negative electrode active layer, is 39 μm, T>H.

[0111] The adhesive support PP layer comprises the following components by weight percentage: The composition comprises 70% random copolymer polypropylene, 15% maleic anhydride-modified polypropylene, and 15% polyolefin elastomer. The melt flow rate of the random copolymer polypropylene is 3.0 g / 10 min; the grafting rate of the maleic anhydride-modified polypropylene is 1%; and the Shore hardness of the polyolefin elastomer is 60.

[0112] The self-healing PP layer comprises the following components by weight percentage: The composition includes 65% block copolymer polypropylene, 20% polyolefin elastomer, 12% self-healing microcapsules, and 3% dispersant. The dispersant is a stearamide-based dispersant.

[0113] The method for preparing the self-healing microcapsules includes the following steps: (1) Preparation of aqueous phase: Dissolve 5g of gelatin in 100mL of deionized water, heat to 50℃, add 0.3g of sodium dodecylbenzenesulfonate (emulsifier), stir until dissolved, adjust pH to 4.5, and obtain aqueous phase.

[0114] (2) Preparation of oil phase: 20g of isocyanate prepolymer (core material) was mixed with 5mL of toluene and ultrasonically dispersed for 5min to obtain the oil phase.

[0115] (3) Emulsification: The oil phase is slowly dripped into the aqueous phase and stirred at 1000 r / min for 30 min at 50℃ to form a W / O type emulsion (the emulsion particle size is 5-10 μm).

[0116] (4) Wall material polymerization: Add 8g of urea-formaldehyde resin prepolymer to the emulsion, heat to 60℃, keep warm and stir for 2h, and the urea-formaldehyde resin and gelatin crosslink to form a composite wall material.

[0117] (5) Post-processing: Cool to room temperature, centrifuge (3000r / min, 10min), wash 3 times with deionized water, and vacuum dry at 60℃ for 4h to obtain self-healing microcapsules.

[0118] The wear-resistant PP layer comprises the following components by weight percentage: The composition includes 83% random copolymer polypropylene, 6% carbon nitride / graphene foam composite powder, 8% organically modified nano-silica, and 3% slip agent. The slip agent is a high-temperature resistant silicone slip agent with a molecular weight of 5000-8000 and a thermal decomposition temperature ≥300℃.

[0119] The preparation method of the carbon nitride / graphene foam composite powder includes the following steps: Urea and graphene powder were mixed at a mass ratio of 95:5, and deionized water was added and ultrasonically dispersed for 30 min to form a uniform suspension. The suspension was transferred to a hydrothermal reactor and reacted at 200℃ for 8 h. After the reaction was completed, the mixture was cooled to room temperature, and the product was separated by centrifugation. The product was washed three times with deionized water and ethanol, dried under vacuum at 120℃ for 6 h, and then calcined at 550℃ for 2 h under a nitrogen atmosphere. After grinding, the product was sieved to obtain carbon nitride / graphene foam composite powder with an average particle size of 1-3 μm.

[0120] The method for preparing the organically modified nano-silica includes the following steps: Nano-silica with an average particle size of 60-80 nm was modified by adding γ-aminopropyltriethoxysilane (KH-550) at a mass ratio of 100:3 to obtain organically modified nano-silica with an average particle size of 70-90 nm and a modification rate of ≥95%.

[0121] The method for preparing the aluminum-plastic film includes: (I) Preparation of PP composite layer: 1. Refining of PP Composite Layer Raw Materials: Prepare the raw materials for the bonding and supporting PP layer, self-healing PP layer, and wear-resistant PP layer according to the formula ratio. In addition to ensuring the purity of basic raw materials such as random copolymer polypropylene and maleic anhydride modified polypropylene, the self-healing microcapsules in the self-healing PP layer need to be pretreated by high-speed shearing (15000r / min) and ultrasonic-assisted dispersion (400W) to break up the agglomerated particles in advance. The carbon nitride / graphene foam composite powder in the wear-resistant PP layer needs to be premixed with the dispersant to ensure uniform distribution in the PP matrix.

[0122] 2. Co-extrusion molding Pre-treated raw materials for bonding and support PP layer, self-healing PP layer and wear-resistant PP layer are respectively added to three dedicated single screw extruders, with screw length-to-diameter ratio set to 25:1 and compression ratio to 3:1 to ensure uniform melt plasticization; Control the extrusion temperature of each layer: the barrel temperature of the bonding and support PP layer and the wear-resistant PP layer is 180-190℃, and the die head temperature is 185℃; the barrel temperature of the self-healing PP layer is 175-185℃ to prevent high temperature from damaging the microcapsules of the urea-formaldehyde resin-gelatin composite wall material. After the three-layer melt is combined through a co-extrusion die, it is quickly shaped by a 30°C cooling roller to obtain a PP composite layer. Finally, the bonding support PP layer side of the PP composite layer is subjected to plasma treatment to further activate the surface polar groups.

[0123] (ii) The nylon layer, aluminum layer and PP composite layer are laminated by a dry lamination process at a lamination temperature of 80℃ and a lamination pressure of 0.4MPa to obtain the finished aluminum-plastic film.

[0124] Examples 2-5, Comparative Examples 6-8 Examples 2-5 and Comparative Examples 6-8 differ from Example 1 in that the values ​​of H, T, t1, t2, and t3 are changed.

[0125] Examples 6-9 The difference between Examples 6-9 and Example 1 is that the weight percentages of random copolymer polypropylene, maleic anhydride modified polypropylene, and polyolefin elastomer in the adhesive support PP layer are changed.

[0126] Examples 10-13 The difference between Examples 10-13 and Example 1 is that the weight percentages of block copolymer polypropylene, polyolefin elastomer, self-healing microcapsules, and dispersant in the self-healing PP layer are changed.

[0127] Examples 14-17 Examples 14-17 differ from Example 1 in that the weight percentages of random copolymer polypropylene, carbon nitride / graphene foam composite powder, organic modified nano silica, and slip agent in the wear-resistant PP layer are changed.

[0128] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the aluminum-plastic film uses a single-layer structure (bonding support PP layer) with a thickness of 40μm, and does not have a wear-resistant PP layer and a self-healing PP layer.

[0129] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the aluminum-plastic film uses a double-layer structure with a thickness of 40μm (20μm wear-resistant PP layer + 20μm adhesive support PP layer), and no self-healing PP layer is provided.

[0130] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the aluminum-plastic film uses a double-layer structure with a thickness of 40μm (5μm self-healing PP layer + 35μm wear-resistant PP layer), and no adhesive support PP layer is provided.

[0131] Comparative Examples 4-5: The difference between Comparative Examples 4-5 and Example 1 is that the values ​​of t1, t2, and t3 are changed.

[0132] The parameters involved in the embodiments and comparative examples are shown in Table 1.

[0133] Table 1 The ingredients and formulations involved in the examples and comparative examples are shown in Table 2.

[0134] Table 2 Test methods 1. Energy density: Charge the finished battery cell to 4.53V with constant current and constant voltage at 0.5C, and cut off at 0.02C; then discharge it to 3.0V with constant current at 0.2C, and record the capacity C0 and energy W0; the plateau voltage V0 = W0 / C0.

[0135] The thickness of the battery in its half-charge state was tested using a 600PPG tester, and the length and width of the battery were measured using a thickness gauge.

[0136] Energy density ED = C0 * V0 / (length * width * thickness) * 1000, unit: Wh / L.

[0137] 2. Fast charging cycle test: Cyclic tests were conducted under normal temperature conditions. Charging modes: 3C CC to 4.25V, 2.5CCC to 4.35V, 2C CC to 4.4V, 1.5C CC to 4.5V, CV to 1.2C, 1.2C CC to 4.55V, CV to 0.26C; Discharging mode: 0.7C DC to 3.0V.

[0138] 1000-week Fading = Discharge capacity in week 1000 / Discharge capacity in week 1 * 100%; 3. Abrasion resistance: The wear depth of the PP composite layer surface after 500 rubs was measured using a Martindale abrasion tester, with the unit being μm.

[0139] 4. The calculation method for self-healing efficiency is as follows: 1) Sample preparation and scratch creation: (1) Cut a 10mm×10mm sample from the finished PP composite layer, ensuring that the wear-resistant PP layer is facing upwards and that there are no initial defects on the surface.

[0140] (2) Using a blade scratch tester, standard scratches were prepared on the sample surface: the applied force was 0.5N, the scratch length was 5mm, and the depth was controlled to be 3-5μm (simulating the actual wear depth of the edge of the empty foil of the electrode). The initial shape of the scratches was recorded.

[0141] (3) Self-healing condition setting The sample with standard scratches was placed in a constant temperature chamber simulating the internal environment of a battery: temperature 40-80℃ (normal operating temperature range of the battery), pressure 0.1-0.3MPa (internal pressure during cell cycling), and samples were taken for testing at two time points, 2h and 4h.

[0142] (4) Image acquisition and parameter measurement High-resolution images of the scratched area were captured using a microscope (magnification ≥200x), and images of the initial scratch and the scratch after self-healing were collected respectively.

[0143] (5) Measure and record key parameters using image analysis software (ImageJ).

[0144] 2) Formula for calculating self-healing rate The volume self-healing rate is used as the core criterion, and the formula is as follows: y=[1-Wt*Dt / (W0*D0)]*100%; y is the self-healing rate of the scratch volume (%). W0 is the initial average width of the scratch (μm); D0 is the initial average scratch depth (μm). Wt represents the average width (μm) of the residual scratch after self-healing time t. Dt represents the average depth (μm) of the residual scratch after self-healing time t.

[0145] (5) The wear degree of the aluminum-plastic film PP composite layer in the cycled battery cell is determined by disassembling the 1000cls cycled battery cell and testing the thickness of the aluminum-plastic film PP composite layer using a 3D microscope, a 3D profilometer, and a CP tester. The difference in thickness of the aluminum-plastic film PP composite layer before and after cycling is used to determine the risk of battery cell leakage and the strength of aluminum-plastic film encapsulation.

[0146] The test results are shown in Table 3.

[0147] Table 3: Test Data As shown in Table 3, this application enables lithium-ion batteries to have excellent cycle stability and safety by controlling the thickness ratio of the bonding support PP layer, the self-healing PP layer, and the wear-resistant PP layer in the aluminum-plastic film.

[0148] Comparing Comparative Examples 1-3 with Example 1, it can be seen that Comparative Example 1, lacking both a wear-resistant and self-healing PP layers, suffered aluminum leakage due to repeated friction, resulting in serious cracking and safety risks. In contrast, the aluminum-plastic film used in Example 1, while maintaining the same energy density, effectively suppressed the risk of wear and cracking of the inner layer caused by the step height difference in the OH region. Comparative Example 2, lacking a self-healing PP layer, resulted in repeated expansion of the wear-resistant layer over long cycles without timely repair, leading to aluminum leakage and even liquid leakage risks, and a decrease in cycle retention rate. Comparative Example 3, lacking an adhesive support PP layer, suffered from weak interlayer bonding due to non-integrated nature, resulting in low peel strength between the coating layer and the inner layer of the aluminum-plastic film, making it prone to detachment and losing its self-healing function, leading to an extremely high risk of leakage. Therefore, by sequentially setting an adhesive support PP layer, a self-healing PP layer, and a wear-resistant PP layer, this application can effectively improve the wear resistance and scratch self-healing ability of the aluminum-plastic film, which is beneficial to solving the problem of damage to the inner layer of the aluminum-plastic film caused by the electrode step difference in electrochemical devices, thereby improving the safety of electrochemical devices.

[0149] Comparing Comparative Examples 4 and 5 with Example 1, it can be seen that the thickness ratios of the adhesive support PP layer, self-healing PP layer, and wear-resistant PP layer in Comparative Examples 4 and 5 are not within the range defined in this application, and the wear resistance and scratch self-healing ability of the aluminum-plastic film are affected to a certain extent. Therefore, by controlling the thickness ratio of the adhesive support PP layer, self-healing PP layer, and wear-resistant PP layer, this application can improve the wear resistance and scratch self-healing ability of the aluminum-plastic film, thereby improving the safety and stability of the electrochemical device.

[0150] Comparing Example 4 with Comparative Example 6, it can be seen that the thickness of the PP composite layer in Comparative Example 6 does not meet the requirement of T>H. After encapsulation, the wear-resistant PP layer cannot completely cover the electrode step difference area. The edge of the empty electrode foil directly squeezes the aluminum-plastic film. In the later stage of the cycle, the aluminum-plastic film is highly ruptured, and the risk of leakage of the electrochemical device is high.

[0151] A comparison of Example 2 and Comparative Example 7 shows that in Comparative Example 7, when the thickness of the wear-resistant PP layer does not meet the condition [0.4 + (H - 39) / 130] × T ≤ t3 ≤ 0.6T, the thickness of the wear-resistant PP layer is insufficient and cannot resist the wear of the electrode edge. In the later stages of cycling, penetrating scratches appear on the wear-resistant PP layer, leading to a high risk of leakage in the electrochemical device and severe capacity decay. Therefore, this application improves the safety and stability of the electrochemical device by controlling T, H, and t3 to satisfy [0.4 + (H - 39) / 130] × T ≤ t3 ≤ 0.6T.

[0152] As can be seen from the comparison between Example 3 and Comparative Example 8, although increasing the thickness of H and T seems to significantly improve safety, the energy density is severely lost due to the increased thickness, and it is difficult to fit the electrode step difference area during packaging, resulting in local wrinkles. In the later stages of cycling, there is still a risk of rupture and leakage at the wrinkled areas.

[0153] In summary, this application significantly improves the protective performance, structural stability, and production compatibility of aluminum-plastic film through the synergistic effect of height difference matching design, three-layer integrated full-function structure, and compliant thickness control. It solves key problems of existing aluminum-plastic film such as "wear penetration, interface separation, performance degradation, and process incompatibility", and has practical application value and promotion advantages.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. An aluminum laminate film characterized by comprising: The PP composite layer comprises a bonding support PP layer, a self-repairing PP layer and a wear-resistant PP layer arranged in sequence, and thicknesses of the bonding support PP layer, the self-repairing PP layer and the wear-resistant PP layer are t1, t2 and t3 respectively, and the t1, t2 and t3 satisfy t1:t2:t3=(1~2):(1~2):(2~3). The bonding support PP layer comprises polypropylene, the self-repairing PP layer comprises polypropylene and self-repairing microcapsules, and the wear-resistant PP layer comprises polypropylene and carbon nitride / graphene foam composite powder.

2. The aluminum laminate film according to claim 1, characterized by The total thickness of the PP composite layer is T, and the T satisfies 40 μm≤T≤80 μm. And / or, the t1, t2 and t3 satisfy 5 μm≤t1≤25 μm, 5 μm≤t2≤25 μm and 10 μm≤t3≤50 μm.

3. The AIF according to claim 1, wherein, At least one of (1)-(3) is included: (1) The bonding support PP layer comprises the following components in percentage by weight: random copolymerized polypropylene 65-80%, maleic anhydride modified polypropylene 10-25% and polyolefin elastomer 10-15%; (2) The self-repairing PP layer comprises the following components in percentage by weight: block copolymerized polypropylene 60-70%, polyolefin elastomer 15-20%, self-repairing microcapsules 10-15% and dispersant 1-3%; (3) The wear-resistant PP layer comprises the following components in percentage by weight: random copolymerized polypropylene 70-85%, carbon nitride / graphene foam composite powder 5-8%, organically modified nano-silicon dioxide 5-10% and slip agent 2-5%.

4. The aluminum laminate film according to claim 3, characterized by At least one of (4)-(7) is included in the bonding support PP layer: (4) The random copolymerized polypropylene has a melt flow rate of 2.0-3.5 g / 10 min under the test condition of 230 ℃ and 2.16 kg; (5) The maleic anhydride modified polypropylene has a grafting rate of 0.8-1.2%; (6) The maleic anhydride modified polypropylene has a melt flow rate of 3.0-5.0 g / 10 min under the test condition of 230 ℃ and 2.16 kg; (7) The polyolefin elastomer has a melt flow rate of 1.5-3.0 g / 10 min under the test condition of 230 ℃ and 2.16 kg.

5. The aluminum laminate film according to claim 3, characterized by At least one of (8)-(10) is included in the self-repairing PP layer: (8) The self-repairing microcapsules have an average particle size of 5-10 μm; (9) The core material of the self-repairing microcapsules is isocyanate prepolymer, and the wall material is urea-formaldehyde resin-gelatin composite wall material; (10) The dispersant comprises at least one of stearic acid amide dispersant, palmitic acid amide dispersant and erucic acid amide dispersant.

6. The aluminum laminate film according to claim 3, wherein At least one of (11)-(13) is included in the wear-resistant PP layer: (11) The graphene mass percentage content of the carbon nitride / graphene foam composite powder is 5-10%, and the carbon nitride mass percentage content is 90-95%; (12) The average particle size of the organically modified nano-silicon dioxide is 70-90 nm; and (13) The average particle size of the organically modified nano-silicon dioxide is 70-90 nm. (13) The slip agent includes at least one of a high-temperature resistant silicone slip agent, a polydimethylsiloxane slip agent, and a fatty acid amide slip agent.

7. An electrochemical device, characterized by, The aluminum-plastic film includes any one of claims 1-6.

8. The electrochemical device of claim 7, wherein, Further comprising an electric core, the electric core includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector, and a distance between the positive electrode current collector and the negative electrode active layer is H, and the H satisfies: 39 μm≤H≤65 μm.

9. The electrochemical device of claim 8, wherein, The T, H satisfy: T>H; and the T, H, t3 satisfy: [0.4+(H-39) / 130]×T≤t3≤0.6T.

10. An electronic device, comprising: The electrochemical device includes any one of claims 8-9.

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