A solid-state battery protective film, a solid-state battery including the same, and an electric device

Abstract

This application discloses a solid-state battery protective film, a solid-state battery containing the same, and an electrical device thereof, belonging to the field of battery technology. The solid-state battery protective film provided by this application includes a first polymer containing specific functional groups and a second polymer with specific chemical bonds, as well as a specific type of catalyst and N,N-dimethylformamide. When subsequently applied in a solid-state battery, it can effectively absorb sulfur vapor and oxygen generated during solid-state battery cycling, thereby improving the thermal stability, cycle performance, and safety performance of the solid-state battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a solid-state battery protective film, a solid-state battery containing the same, and an electrical device thereof. Background Technology

[0002] Lithium-ion batteries are currently widely used in 3C digital products, electric vehicles, and energy storage power stations. However, their safety performance still needs improvement, primarily due to the presence of flammable electrolytes. Therefore, scientists have proposed replacing the flammable electrolyte in traditional lithium-ion batteries with a non-flammable solid electrolyte, resulting in what is known as an all-solid-state battery.

[0003] Currently, all-solid-state batteries are packaged in pouch cells. Pouch cells have several drawbacks. First, they are less safe under mechanical abuse and prone to thermal runaway. Second, all-solid-state batteries using high-energy-density positive and negative electrode active materials experience significant volume expansion, making the aluminum-plastic film of pouch cells susceptible to localized breakage during cycling. Furthermore, all-solid-state pouch cells require additional clamps for pressurization, posing a significant challenge to battery system design. Summary of the Invention

[0004] The purpose of this application is to solve the technical problem that all-solid-state batteries, especially high-energy-density solid-state batteries, are prone to thermal runaway in the prior art, and to propose a solid-state battery protective film that, when applied to solid-state batteries, enables the corresponding solid-state batteries to have good thermal stability and cycle performance.

[0005] To achieve the above objectives, a first aspect of this application provides a solid-state battery protective film, the solid-state battery protective film comprising a first polymer, a second polymer, a catalyst, and N,N-dimethylformamide; The molecular structure of the first polymer contains at least one functional group selected from carbonyl, amino, and hydroxyl groups; The molecular structure of the second polymer contains carbon-carbon double bonds and / or ether bonds; The catalyst includes at least one of metal chlorides and sulfates.

[0006] In some embodiments, the mass ratio of the first polymer to the second polymer is 1:(0.5~0.8).

[0007] In some embodiments, the mass content of the catalyst is 0.5% to 2% based on the total mass of the solid-state battery protective film.

[0008] In some embodiments, the N,N-dimethylformamide content is 0.1% to 1% by mass, based on the total mass of the solid-state battery protective film.

[0009] In some embodiments, the first polymer includes at least one of polyacetylimide, polyvinylpyrrolidone, and chitosan.

[0010] In some embodiments, the second polymer includes at least one of natural rubber, polybutadiene, and polyethylene glycol.

[0011] In some embodiments, the catalyst includes at least one of ferrous chloride and manganese sulfate.

[0012] In some embodiments, the weight-average molecular weight of the first polymer and the weight-average molecular weight of the second polymer are each independently 500,000 to 1,000,000.

[0013] In some embodiments, the catalyst has an average particle size of 0.5 μm to 2 μm.

[0014] A second aspect of this application provides a solid-state battery comprising a cell, a solid-state battery protective film of the present application disposed on at least a portion of the surface of the cell, and a casing.

[0015] In some embodiments, the thickness of the solid-state battery protective film is 0.1 to 10 mm.

[0016] In some embodiments, the yield strength of the outer shell under tensile conditions is 100 MPa to 600 MPa.

[0017] In some embodiments, the housing comprises nickel-plated steel.

[0018] In some embodiments, an elastic buffer layer is also provided between the solid-state battery protective film and the outer casing.

[0019] In some embodiments, the thickness of the elastic buffer layer is 1 to 50 mm.

[0020] In some embodiments, the elastic cushioning layer includes at least one of rubber, silicone, and foam.

[0021] In some embodiments, the battery cell includes integrated positive and negative electrode sheets and a solid electrolyte membrane; the integrated positive and negative electrode sheets include a copper-aluminum composite current collector, and a negative electrode sheet disposed near the copper side and a positive electrode sheet disposed near the aluminum side; the positive electrode sheet includes a positive active material layer on the side away from the copper-aluminum composite current collector, the positive active material layer including a positive active material, the positive active material including Li a Ni x Co y M zO2, where M is at least one of Mn, Ti, Al, Zr, Ta, and W, 0.95 ≤ a ≤ 1.05, 0.33 ≤ x ≤ 0.98, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

[0022] In some embodiments, the solid electrolyte membrane includes a solid electrolyte, and the solid electrolyte includes at least one of a sulfide solid electrolyte and a halide solid electrolyte.

[0023] In a third aspect of the present application, an electrical device is provided, including the solid-state battery described in the present application.

[0024] Compared with the prior art, the beneficial effects of the present application are as follows: The solid-state battery protective film provided by the present application includes a first polymer containing specific functional groups and a second polymer with specific chemical bonds. It also includes a specific type of catalyst and N,N-dimethylformamide. When applied to a solid-state battery later, it can effectively absorb sulfur vapor and oxygen generated during the cycling of the solid-state battery, thereby improving the thermal stability of the solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic structural diagram of the solid-state battery prepared in Example 1: 1 - all-solid-state battery cell, 2 - elastic buffer layer, 3 - outer shell, 4 - solid-state battery protective film, 5 - integrated positive and negative electrode sheet, 6 - positive electrode sheet, 7 - copper-aluminum composite current collector, 8 - aluminum side of the composite current collector, 9 - copper side of the composite current collector, 10 - negative electrode sheet, 11 - solid electrolyte membrane. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0027] In the present application, for the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, as well as an open technical solution including the listed features.

[0028] 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.

[0029] In one embodiment of this application, a solid-state battery protective film is provided, the solid-state battery protective film comprising a first polymer, a second polymer, a catalyst and N,N-dimethylformamide (DMF). The molecular structure of the first polymer contains at least one functional group selected from carbonyl, amino, and hydroxyl groups; The molecular structure of the second polymer contains carbon-carbon double bonds and / or ether bonds; The catalyst includes at least one of metal chlorides and sulfates.

[0030] The solid-state battery protective film provided in this application includes a first polymer containing specific functional groups and a second polymer containing specific chemical bonds, as well as a specific type of catalyst and N,N-dimethylformamide. When subsequently applied in solid-state batteries, it can effectively absorb sulfur vapor and oxygen generated during solid-state battery cycling, thereby achieving high energy density solid-state batteries with excellent thermal stability and cycling performance.

[0031] Specifically, solid-state batteries release active sulfur (sulfur vapor) during cycling or at high temperatures. The released sulfur vapor reacts violently with oxygen released from the positive electrode active material, leading to thermal runaway and reducing battery safety. The first polymer provided in this application contains at least one functional group among carbonyl, amino, and hydroxyl groups in its molecular structure. These functional groups can generate strong coordination or chemical reactions with sulfur molecules, thereby effectively absorbing sulfur vapor generated during solid-state battery cycling. The second polymer provided in this application contains carbon-carbon double bonds and / or ether bonds in its molecular structure, which can react with oxygen, thereby effectively absorbing oxygen generated during solid-state battery cycling. The presence of the catalyst and N,N-dimethylformamide can further promote the absorption of sulfur vapor by the first polymer and the absorption of oxygen by the second polymer. Therefore, the four substances work together to effectively reduce the side reactions of sulfur vapor and oxygen, protect the electrode and electrolyte interface, and thus improve the thermal stability of the solid-state battery. Since the above four components can effectively improve the thermal stability of the solid-state battery, materials with higher energy density can be introduced into the solid-state battery or the solid-state battery can be assembled in an internal series manner, thereby achieving a high-energy-density solid-state battery with good thermal stability.

[0032] It should be noted that the testing method for at least one functional group among carbonyl, amino, and hydroxyl groups in the molecular structure of the first polymer and carbon-carbon double bonds and / or ether bonds in the molecular structure of the second polymer is as follows: Take the solid-state battery protective film, dissolve it in N,N-dimethylformamide (DMF), and perform gel permeation chromatography (including a multi-angle laser light scattering detector) on the solution. The two polymers are distinguished based on the refractive index results, thus separating the two polymers. Further, take solutions of the two polymers separately, drop one of them onto a KBr salt plate, and after the solvent evaporates, a uniform transparent film is formed. Subsequently, Fourier transform infrared spectroscopy is used for testing. Specifically, if at 1850 cm⁻¹... -1 ~1650 cm -1 A peak at 3500 cm⁻¹ indicates the presence of a carbonyl group; a peak at 3500 cm⁻¹ indicates the presence of a carbonyl group. -1 ~3300 cm -1 The presence of two peaks at 3600-3200 cm⁻¹ indicates the presence of amino groups; if the peaks are at 3600-3200 cm⁻¹... -1 The presence of a peak at a certain location indicates the presence of hydroxyl groups; another method involves nuclear magnetic resonance spectroscopy testing, and if a peak is observed at a certain location... 1 A signal in the 4.5 ppm to 6.5 ppm range in ¹H NMR indicates the presence of a carbon-carbon double bond; if... 1 The presence of a signal in the 3.3 ppm to 4.0 ppm range in ¹H NMR indicates the presence of an ether bond.

[0033] It should be noted that the test method for the catalyst type is inductively coupled plasma atomic emission spectrometry (ICP-AES). A solid-state battery protective film is dissolved in aqua regia, and ICP-AES is performed. The inorganic composition is inferred based on the measured inorganic element content.

[0034] In some embodiments, the mass ratio of the first polymer to the second polymer is 1:(0.5~0.8).

[0035] For example, the mass ratio of the first polymer and the second polymer can be any point value between 1:(0.5~0.8) or a range value between any two points, such as 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, etc.

[0036] It should be noted that the method for testing the mass ratio of the first polymer and the second polymer is nuclear magnetic resonance spectroscopy. Specifically, a solid-state battery protective film is taken, dissolved in DMF, and the solution is subjected to nuclear magnetic resonance spectroscopy. Then, based on the area ratio of the characteristic proton peaks in the two polymers, the mass ratio of the two polymers is calculated.

[0037] This application research found that the mass ratio of the first polymer and the second polymer affects the absorption effect of sulfur vapor and oxygen, and also affects the mechanical properties of the solid-state battery protective film; when the mass ratio of the first polymer and the second polymer is selected within the above range, the thermal stability of the solid-state battery can be better improved, and the safety performance of the solid-state battery can be improved.

[0038] In some embodiments, the mass content of the catalyst is 0.5% to 2% based on the total mass of the solid-state battery protective film.

[0039] For example, based on the total mass of the solid-state battery protective film, the mass content of the catalyst can be any point value or a range between any two points between 0.5% and 2%, such as 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, etc.

[0040] It should be noted that the method for testing the mass content of the catalyst is inductively coupled plasma atomic emission spectrometry (ICP-AES). Specifically, a solid-state battery protective film is taken, dissolved in aqua regia, and subjected to ICP-AES. The actual mass of the catalyst is calculated based on the measured concentration of inorganic elements, and then the actual mass of the catalyst is divided by the initial mass of the film to obtain the mass content of the catalyst.

[0041] This study found that the amount of catalyst added affects the absorption capacity of the first polymer for sulfur vapor and the absorption capacity of the second polymer for oxygen. When the mass content of the catalyst is selected within the above range, sulfur vapor and oxygen can be removed more efficiently, reducing corrosion of the solid electrolyte and electrode interface, reducing side reactions caused by sulfur and oxygen, reducing the occurrence of chain exothermic reactions, and effectively improving the thermal stability and safety performance of solid-state batteries.

[0042] It should be noted that the mass content of the catalyst can be adjusted by controlling the amount of catalyst added during the preparation process.

[0043] In some embodiments, the mass content of N,N-dimethylformamide is 0.1% to 1% based on the total mass of the solid-state battery protective film.

[0044] For example, based on the total mass of the solid-state battery protective film, the mass content of N,N-dimethylformamide can be any point value or a range between any two points between 0.1% and 1%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%.

[0045] It should be noted that the test method for the mass content of N,N-dimethylformamide is thermogravimetric analysis. Specifically, the solid-state battery protective film is subjected to thermogravimetric analysis, and the mass loss before 150°C corresponds to the mass content of DMF.

[0046] This study found that the amount of N,N-dimethylformamide added affects the absorption of sulfur vapor by the first polymer, and also affects the structural stability of the solid-state battery protective film. When the mass content of N,N-dimethylformamide is further selected within the above range, the overall performance of the solid-state battery prepared subsequently is better.

[0047] It should be noted that the mass content of N,N-dimethylformamide can be controlled by adjusting the amount of N,N-dimethylformamide added during the preparation process.

[0048] In some embodiments, the first polymer includes at least one of polyacetylimide (PI), polyvinylpyrrolidone (PVP), and chitosan (CS).

[0049] This application research found that polyacetylimide contains carbonyl groups, polyvinylpyrrolidone contains carbonyl groups, and chitosan contains hydroxyl and amino groups. Selecting these types of substances as the first polymer not only provides excellent sulfur vapor absorption capacity, but also demonstrates that polyvinylpyrrolidone exhibits good thermal stability and excellent mechanical properties; polyvinylpyrrolidone is an excellent sulfur carrier with strong anchoring ability for sulfides; and chitosan has a large sulfur vapor adsorption capacity. Therefore, further selecting these types of substances as the first polymer can better improve the thermal stability and safety performance of solid-state batteries.

[0050] In some embodiments, the second polymer includes at least one of natural rubber (NR), polybutadiene (PB), and polyethylene glycol (PEG).

[0051] This study found that natural rubber contains carbon-carbon double bonds, polybutadiene contains carbon-carbon double bonds, and polyethylene glycol contains ether bonds. Selecting these types of substances as the second polymer reveals that natural rubber possesses excellent elasticity and film-forming properties, and can effectively adapt to volume changes during cycling while absorbing oxygen; polybutadiene has a relatively controllable structure and good elasticity and mechanical properties; and polyethylene glycol not only participates in oxygen absorption but also has a certain ability to improve interfacial contact. Therefore, further selecting these types of substances as the second polymer can more effectively improve the thermal stability and cycle performance of solid-state batteries.

[0052] In some embodiments, the catalyst includes at least one of ferrous chloride and manganese sulfate.

[0053] This study found that the type of catalyst affects catalytic efficiency and also the structural stability of the solid-state battery protective film. When the catalyst is further selected to be of the above-mentioned type, the overall performance of the solid-state battery prepared subsequently is better.

[0054] In some embodiments, the weight-average molecular weight of the first polymer and the weight-average molecular weight of the second polymer are each independently between 500,000 and 1,000,000.

[0055] For example, the weight-average molecular weight of the first polymer and the weight-average molecular weight of the second polymer can each be any point value between 500,000 and 1,000,000 or a range between any two points, such as 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 950,000, 1,000,000, etc.

[0056] It should be noted that the weight-average molecular weight of the first and second polymers was determined using gel permeation chromatography (with a multi-angle laser light scattering detector). Specifically, a solid-state battery protective film was taken, dissolved in DMF, and the solution was subjected to gel permeation chromatography (with a multi-angle laser light scattering detector). The two polymers were distinguished based on the refractive index results, and the weight-average molecular weight of each polymer was further determined.

[0057] This study found that the weight-average molecular weight of the first polymer and the second polymer not only affects their respective absorption capacity for sulfur vapor and oxygen, but also affects the mechanical properties of the solid-state battery protective film. When the weight-average molecular weights of the first polymer and the second polymer are further selected to be independently within the above range, the overall performance of the obtained solid-state battery is better.

[0058] In some embodiments, the average particle size of the catalyst is 0.5 μm to 2 μm.

[0059] For example, the average particle size of the catalyst can be any point value or a range between any two points between 0.5 μm and 2 μm, such as 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, etc.

[0060] It should be noted that the average particle size of the catalyst was measured using scanning electron microscopy (SEM). Specifically, a solid-state battery protective film was subjected to SEM testing; the spherical morphology within the film represented the catalyst, and the particle size of the catalyst was determined using SEM.

[0061] This study found that the average particle size of the catalyst affects its catalytic effect on the absorption of sulfur vapor by the first polymer and the absorption of oxygen by the second polymer, and also affects its dispersion uniformity in the system. When the average particle size of the catalyst is selected within the above range, excellent catalytic activity and high stability can be obtained, thereby making the overall performance of the solid-state battery prepared subsequently better.

[0062] It should be noted that the average particle size of the catalyst can be controlled by the crushing and sieving process of the catalyst.

[0063] A second aspect of this application provides a solid-state battery, the solid-state battery comprising a cell, a solid-state battery protective film as described in this application disposed on at least a portion of the surface of the cell, and a casing.

[0064] This application research found that by placing the solid-state battery protective film described in this application on at least a portion of the surface of the battery cell, it can effectively absorb sulfur vapor and oxygen generated during cycling without affecting the positive and negative electrode structures in the battery cell. Therefore, it can ensure the energy density of the solid-state battery. In fact, the presence of the solid-state battery protective film improves the thermal stability of the solid-state battery. The positive and negative electrodes of the battery cell can be made of materials with higher energy density. The presence of the solid-state battery protective film can absorb sulfur vapor and oxygen generated by high-energy-density materials during cycling, thereby improving the thermal stability and safety performance of the solid-state battery.

[0065] In some embodiments, the housing is disposed on the surface of the solid-state battery protective film.

[0066] In some embodiments, the thickness of the solid-state battery protective film is 0.1 mm to 10 mm.

[0067] For example, the thickness of the solid-state battery protective film can be any point value or a range between any two points between 0.1 mm and 10 mm, such as 0.1 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.

[0068] In some embodiments, the thickness of the solid-state battery protective film is 2 mm to 5 mm. For example, it can be 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc.

[0069] It should be noted that the test method for the thickness of the solid-state battery protective film is as follows: take a solid-state battery and measure the thickness of the solid-state battery protective film with a vernier caliper.

[0070] This study found that the thickness of the solid-state battery protective film affects the content of the first and second polymers within the solid-state battery system, thereby influencing the absorption capacity and adsorption capacity for sulfur vapor and oxygen. Simultaneously, the thickness also affects the protective film's ability to adapt to volume expansion and contraction during solid-state battery cycling. Furthermore, a suitable thickness range for the protective film can prevent it from occupying excessive space within the solid-state battery, thus indirectly reducing the content of active materials. Therefore, when the thickness of the solid-state battery protective film is further selected within the aforementioned range, the resulting solid-state battery exhibits superior overall performance.

[0071] It should be noted that the thickness of the solid-state battery protective film can be controlled by changing the mass of the mixture that can form the solid-state battery protective film introduced during the preparation process.

[0072] In some embodiments, the yield strength of the outer shell under tensile conditions is 100 MPa to 600 MPa.

[0073] For example, the yield strength of the shell under tensile conditions can be any point value or a range between any two points between 100 MPa and 600 MPa, such as 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa, 600 MPa, etc.

[0074] It should be noted that the test method for the yield strength of the outer shell under tensile conditions is as follows: take the solid-state battery, disassemble it to obtain the outer shell, and then conduct the test according to the tensile method in GB / T228.1-2021.

[0075] This study found that the yield strength of the casing under tensile conditions affects its ability to resist internal pressure changes and external abuse in solid-state batteries, as well as its ability to adapt to internal volume changes and improve safe pressure relief. When the yield strength of the casing under tensile conditions is further selected within the above range, the safety performance of solid-state batteries can be effectively improved.

[0076] It should be noted that the yield strength of the outer shell under tensile conditions can be controlled by changing the chemical composition of the outer shell material and the preparation process.

[0077] In some embodiments, the housing comprises nickel-plated steel.

[0078] This study found that nickel-plated steel has good corrosion resistance and electrical conductivity, as well as excellent mechanical strength and weldability; therefore, choosing a casing that includes nickel-plated steel can better help achieve the excellent overall performance of solid-state batteries.

[0079] In some embodiments, an elastic buffer layer is also provided between the solid-state battery protective film and the outer casing.

[0080] This study found that introducing an elastic buffer layer between the solid-state battery protective film and the casing can better improve the solid-state battery's ability to adapt to volume changes during cycling and its ability to buffer against external shocks, thereby effectively improving the thermal stability and cycle performance of the solid-state battery.

[0081] In some embodiments, the thickness of the elastic buffer layer is 1 mm to 50 mm.

[0082] For example, the thickness of the elastic buffer layer can be any point value or a range between any two points between 1mm and 50mm, such as 1mm, 2mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, etc.

[0083] It is found in the research of this application that the thickness of the elastic buffer layer affects the buffering capacity, and also affects the heat dissipation capacity and the overall energy density (if it is too thick, it will occupy the space of the solid-state battery, resulting in a decrease in the content of the active material and indirectly affecting the energy density). When the thickness of the elastic buffer layer is further selected within the above range, the comprehensive performance of the obtained solid-state battery is better.

[0084] In some embodiments, the elastic buffer layer includes at least one of rubber, silica gel, and foam.

[0085] It is found in the research of this application that selecting the above types of substances to prepare the elastic buffer layer is simple and easy to obtain, and has excellent buffering capacity.

[0086] In some embodiments, the battery cell includes a positive and negative integrated electrode sheet and a solid electrolyte membrane; the positive and negative integrated electrode sheet includes a copper-aluminum composite current collector, a negative electrode sheet disposed close to the copper side, and a positive electrode sheet disposed close to the aluminum side; the positive electrode sheet away from the copper-aluminum composite current collector side includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes Li a Ni x Co y M z O2, where M is at least one of Mn, Ti, Al, Zr, Ta, and W, 0.95 ≤ a ≤ 1.05, 0.33 ≤ x ≤ 0.98, 0 < y < 1, 0 < z < 1, and x + y + z = 1.

[0087] It is found in the research of this application that selecting the above types of positive electrode active materials and adopting the internal series structure design of the positive and negative integration can provide a relatively high energy density.

[0088] In some embodiments, the solid electrolyte membrane includes a solid electrolyte, and the solid electrolyte includes at least one of a sulfide solid electrolyte and a halide solid electrolyte.

[0089] This application has no special requirements for the selection of sulfide solid electrolytes and halide solid electrolytes, and they can be sulfide solid electrolytes and halide solid electrolytes commonly used in the art. Exemplarily, the sulfide solid electrolyte can be Li 10 GeP2S 12 (LGPS), Li7P3S 11 , Li6PS5Cl (LPSC), Li 5.5 PS 4.5 Cl 1.5 , Li3PS4, etc.; the halide solid electrolyte can be Li3InCl6, Li 2.5 ZrCl 5.5O 0.5 wait.

[0090] In some embodiments, the solid electrolyte membrane further includes a binder.

[0091] This application does not have any special requirements for the selection of adhesives, and any adhesive conventionally used in the art can be used. For example, the adhesive can be any one of hydrogenated styrene-butadiene-styrene block copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), polyacrylonitrile-butadiene (NBR), and styrene-butadiene rubber (SBS).

[0092] In some embodiments, the positive electrode active material layer further includes a positive electrode conductive agent, a positive electrode binder, and a solid electrolyte.

[0093] This application does not have any special requirements for the selection of the positive electrode conductive agent, and any positive electrode conductive agent conventionally used in the art can be used. For example, the positive electrode conductive agent can be any one of carbon black (Super P), carbon fiber (VGCF), carbon nanotubes (CNT), and acetylene black.

[0094] This application does not have any special requirements for the selection of the positive electrode binder, and any positive electrode binder conventionally used in the art can be used. For example, the positive electrode binder can be any one of hydrogenated styrene-butadiene-styrene block copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), polyisobutylene (PIB), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR).

[0095] This application does not have any special requirements for the selection of the solid electrolyte; any solid electrolyte conventionally used in the art can be used. For example, the solid electrolyte can be any one of a sulfide solid electrolyte or a halide solid electrolyte.

[0096] This application does not have any particular requirements regarding the selection of sulfide solid electrolytes and halide solid electrolytes; any sulfide solid electrolyte or halide solid electrolyte conventionally used in the art can be used. For example, the sulfide solid electrolyte can be Li... 10 GeP2S 12 (LGPS), Li7P3S 11 Li6PS5Cl (LPSC), Li 5.5 PS 4.5 Cl 1.5 Li3PS4, etc.; the halide solid electrolyte can be Li3InCl6, Li 2.5 ZrCl 5.5 O 0.5 wait.

[0097] In some embodiments, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector.

[0098] In some embodiments, the negative electrode active material layer includes a negative electrode active material, a negative electrode binder, a negative electrode conductive agent, and a solid electrolyte.

[0099] This application does not have any special requirements for the selection of the negative electrode active material; any negative electrode active material conventionally available in the art can be used. For example, the negative electrode active material can be any one of graphite, silicon-oxygen materials, silicon-carbon materials, pure silicon materials, or silicon alloy materials.

[0100] This application does not have any special requirements for the selection of the negative electrode binder; any negative electrode binder conventionally available in the art can be used. For example, the negative electrode binder may be any one of polytetrafluoroethylene (PTFE), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), polyacrylonitrile-butadiene (NBR), and styrene-butadiene rubber (SBS).

[0101] This application does not have any special requirements for the selection of the negative electrode conductive agent; any negative electrode conductive agent conventionally available in the art can be used. For example, the negative electrode conductive agent can be any one of carbon black (Super P), carbon fiber (VGCF), carbon nanotubes (CNT), or acetylene black.

[0102] This application does not have any special requirements for the selection of the solid electrolyte; any solid electrolyte conventionally used in the art can be used. For example, the solid electrolyte can be Li6PS5Cl, Li 5.5 PS 4.5 Cl 1.5 Any one of them.

[0103] In one embodiment of this application, an electrical device is provided, including the solid-state battery described in this application.

[0104] For example, non-limiting examples of the above-mentioned electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0105] Example 1 This application provides a solid-state battery, the preparation method of which includes the following steps: (1) Preparation of positive electrode sheet: The positive electrode active material (Ni92, i.e. LiNi) is prepared by... 0.92 Co 0.04 Mn0.04 O2), solid electrolyte (lithium phosphorus sulfur chloride, LPSCl), positive electrode conductive agent (VGCF), and positive electrode binder (PTFE) are mixed in a mass ratio of 80:17:2:1, and then rolled by a roller press to obtain a sheet-shaped positive electrode. The sheet-shaped positive electrode is then combined with the aluminum side of a copper-aluminum composite current collector by a roller press to obtain a positive electrode sheet. (2) Preparation of integrated positive and negative electrode: The negative active material (pure silicon), solid electrolyte (lithium phosphorus sulfur chloride, LPSCl), negative conductive agent (VGCF), and negative binder (SEPS) are weighed in a mass ratio of 90:5:5, and then xylene is added and stirred to obtain a negative slurry; then the slurry is coated on the reverse side of the positive electrode prepared in step (1) (i.e. the copper side of the copper-aluminum composite current collector), and baked at 80°C for 6 hours to obtain an integrated positive and negative electrode; (3) Preparation of solid electrolyte membrane: Weigh solid electrolyte (LPSCl) and binder (NBR) at a mass ratio of 96:4, then add xylene, stir, the solid content is 50%, and coat to obtain solid electrolyte membrane; (4) Use a punching machine to cut the positive and negative integrated electrode sheet and the solid electrolyte membrane into round sheets, and then stack the cut positive and negative integrated electrode sheet and the solid electrolyte membrane in sequence, wherein the positive electrode side of the positive and negative integrated electrode sheet faces the negative electrode side of the positive and negative integrated electrode sheet. (5) By placing the stacked cells into an isostatic pressing device for densification molding, a fully solid bare cell is obtained; (6) The first polymer (polyacetylimide with a weight average molecular weight of 750,000), the second polymer (natural rubber with a weight average molecular weight of 750,000), and the catalyst (FeCl2 with an average particle size of 1 μm) were dissolved in N,N-dimethylformamide. After stirring for 10 h, the mixture was coated onto a PET substrate and dried at 60 °C for 6 h to obtain a solid battery protective film with a thickness of 5 mm. Then, the solid battery protective film was separated from the substrate and wrapped around the surface of the prepared all-solid battery cell. The catalyst content was 1% by mass, the N,N-dimethylformamide content was 0.5% by mass, and the mass ratio of the first polymer to the second polymer was 1:0.6. (7) Weld the positive and negative electrodes of the all-solid cell to the positive and negative current collectors. Place the elastic buffer layer (made of foam with a thickness of 25 mm) and the all-solid cell in a cylindrical shell (made of nickel-plated steel containing the alloy element Mn, with a yield strength of 300 MPa under tensile conditions). Then perform shell-cover encapsulation (the negative electrode is connected to the shell, the positive electrode is connected to the cover plate, and there is an insulating component between the positive and negative electrodes); thus obtaining a solid-state battery.

[0106] The structural schematic diagram of the obtained solid-state battery is as follows: Figure 1 As shown.

[0107] Examples 2-3 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the type of the first polymer is adjusted to achieve the parameters in Tables 1-2.

[0108] Examples 4-5 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the weight-average molecular weight of the first polymer is adjusted to achieve the parameters in Tables 1-2.

[0109] Examples 6-7 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the type of the second polymer is adjusted to achieve the parameters in Tables 1-2.

[0110] Examples 8-9 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the weight-average molecular weight of the second polymer is adjusted to achieve the parameters in Tables 1-2.

[0111] Examples 10-11 This application provides a solid-state battery. The difference between the preparation method of the solid-state battery and that of Example 1 is that the amount of the first polymer and the second polymer added is adjusted to achieve the parameters in Tables 1-2.

[0112] Example 12 This application provides a solid-state battery. The difference between the preparation method of the solid-state battery and that of Example 1 is that the type of catalyst is adjusted to achieve the parameters in Tables 1-2.

[0113] Examples 13-14 This application provides a solid-state battery. The difference between the preparation method of the solid-state battery and that of Example 1 is that the average particle size of the catalyst is adjusted to achieve the parameters in Tables 1-2.

[0114] Examples 15-16 This application provides a solid-state battery. The difference between the preparation method of the solid-state battery and that of Example 1 is that the amount of catalyst added is adjusted to achieve the parameters in Tables 1-2.

[0115] Examples 17-18 This application provides a solid-state battery. The difference between the preparation method of the solid-state battery and that of Example 1 is that the amount of N,N-dimethylformamide added is adjusted to achieve the parameters in Tables 1-2.

[0116] Examples 19-20 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the chemical composition and preparation process of the outer shell are adjusted to change the yield strength of the outer shell under tensile conditions, thereby achieving the parameters in Tables 1-2. In Example 19, the alloying elements in the material of the cylindrical shell were adjusted to Ti and Al; In Example 20, the alloying elements in the material of the cylindrical shell were adjusted to Nb, V, Ti, Cr, and Mo.

[0117] Examples 21-23 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the mass of the mixture coated on the PET substrate is adjusted to change the thickness of the solid-state battery protective film, thereby achieving the parameters in Tables 1-2.

[0118] Examples 24-25 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the amount of foam added is adjusted to change the thickness of the elastic buffer layer, thereby achieving the parameters in Tables 1-2.

[0119] Example 26 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that no elastic buffer layer is introduced to achieve the parameters in Tables 1-2.

[0120] Example 27 This application provides a solid-state battery. The difference between the preparation method of the solid-state battery and that of Example 1 lies in adjusting the type of positive electrode active material to achieve the parameters in Tables 1-2; specifically, Ni80 and LiNi. 0.8 Co 0.1 Mn 0.1 O2).

[0121] Example 28 This application provides a solid-state battery. The difference between the solid-state battery preparation method and that of Example 1 is that the type of solid electrolyte in the solid electrolyte membrane is adjusted to achieve the parameters in Tables 1-2.

[0122] Comparative Example 1 This application provides a solid-state battery as a comparative example, the preparation method of which includes the following steps: (1) Preparation of positive electrode sheet: The positive electrode active material (Ni92, i.e. LiNi) is prepared by... 0.92 Co 0.04 Mn 0.04O2), solid electrolyte (lithium phosphorus sulfur chloride, LPSCl), positive electrode conductive agent (VGCF), and positive electrode binder (PTFE) are mixed in a mass ratio of 80:17:2:1, and then rolled by a roller press to obtain a sheet-shaped positive electrode. The sheet-shaped positive electrode is then combined with the aluminum side of a copper-aluminum composite current collector by a roller press to obtain a positive electrode sheet. (2) Preparation of integrated positive and negative electrode: The negative active material (pure silicon), negative conductive agent (CNT), and negative binder (PAA) are weighed in a mass ratio of 90:5:5, and then stirred with xylene to obtain a negative slurry; then the slurry is coated on the reverse side of the positive electrode prepared in step (1) (i.e., the copper side of the copper-aluminum composite current collector), and baked at 80°C for 6 hours to obtain an integrated positive and negative electrode; (3) Preparation of solid electrolyte membrane: Weigh solid electrolyte (LPSCl) and binder (NBR) at a mass ratio of 96:4, then add 30 mL of xylene, stir, the solid content is 50%, and coat to obtain solid electrolyte membrane; (4) Use a punching machine to cut the positive and negative integrated electrode sheet and the solid electrolyte membrane into round sheets, and then stack the cut positive and negative integrated electrode sheet and the solid electrolyte membrane in sequence, wherein the positive electrode side of the positive and negative integrated electrode sheet faces the negative electrode side of the positive and negative integrated electrode sheet. (5) By placing the stacked cells into an isostatic pressing device for densification molding, a fully solid bare cell is obtained; (6) Weld tabs to the positive and negative terminals of the solid-state cell respectively, and encapsulate them with aluminum-plastic film to obtain a solid-state battery.

[0123] Comparative Example 2 This application provides a solid-state battery in a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that no first polymer is added.

[0124] Comparative Example 3 This application provides a solid-state battery in a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that no second polymer is added.

[0125] Comparative Example 4 This application provides a solid-state battery as a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that no catalyst is added.

[0126] Comparative Example 5 This application provides a solid-state battery as a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that N,N-dimethylformamide is replaced with acetone.

[0127] Comparative Example 6 This application provides a solid-state battery in a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that polyethylene (weight-average molecular weight of 750,000) is used instead of the first polymer.

[0128] Comparative Example 7 This application provides a solid-state battery in a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that polyethylene (weight-average molecular weight of 750,000) is used instead of the second polymer.

[0129] Comparative Example 8 This application provides a solid-state battery in a comparative example. The difference between the preparation method of the solid-state battery and that of Example 1 is that aluminum oxide is used instead of ferrous chloride.

[0130] The types and weight-average molecular weights (Mw1) of the first polymer, the types and weight-average molecular weights (Mw2) of the second polymer, the mass ratio (M) of the first polymer and the second polymer, the type, mass content (W1) and average particle size (D) of the catalyst, the mass content (W2) of N,N-dimethylformamide, the thickness (h1) of the solid-state battery protective film, the type of the outer shell and the yield strength (σ) under tensile conditions, the thickness (h2) and type of the elastic buffer layer, the type of the positive electrode active material, and the type of solid electrolyte in the solid electrolyte membrane are shown in Tables 1-2. Table 1 Table 2 The solid-state batteries prepared in the examples and comparative examples were subjected to performance tests, including the following aspects: 1. Thermal stability test: The test is conducted using a battery thermal abuse test chamber. First, the temperature is raised from room temperature to 130℃ and held for 30 minutes. Then, the temperature is raised at 5℃ intervals and held for 30 minutes at each temperature. The highest temperature that the solid-state battery can tolerate without thermal runaway is the temperature of the thermal chamber. 2. Cyclic performance test: Connect the positive and negative terminals of the battery to the Xinwei charge-discharge tester respectively, and perform 500 cycle tests on the battery at a voltage range of 4.25~2.5V and a charge-discharge rate of 0.5C. The test results are shown in Table 3. Table 3 As can be seen from Table 3, when the technical solution provided in this application is adopted, the obtained solid-state battery has excellent thermal stability and cycle performance; specifically, the obtained solid-state battery has a hot box temperature of over 200℃ and a capacity retention rate of over 80%. As can be seen from Examples 1-28 and Comparative Example 1, the solid-state battery has poor safety and cycle performance when no solid-state battery protective film is introduced. As can be seen from Examples 1-28 and Comparative Examples 2-5, excellent overall performance can be achieved when the solid-state battery protective film simultaneously includes the first polymer, the second polymer, the catalyst, and N,N-dimethylformamide described in this application. As can be seen from Examples 1-28 and Comparative Examples 6-8, excellent overall effects can be achieved when the types of the first polymer, the second polymer, and the catalyst selected are within the range given in this application.

[0131] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of this application and not 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. A solid-state battery protective film, characterized in that, The solid-state battery protective film comprises a first polymer, a second polymer, a catalyst, and N,N-dimethylformamide; The molecular structure of the first polymer contains at least one functional group selected from carbonyl, amino, and hydroxyl groups; The molecular structure of the second polymer contains carbon-carbon double bonds and / or ether bonds; The catalyst includes at least one of metal chlorides and sulfates.

2. The solid-state battery protective film according to claim 1, characterized in that, The mass ratio of the first polymer to the second polymer is 1:(0.5~0.8). And / or, based on the total mass of the solid-state battery protective film, the mass content of the catalyst is 0.5% to 2%; And / or, based on the total mass of the solid-state battery protective film, the mass content of N,N-dimethylformamide is 0.1% to 1%.

3. The solid-state battery protective film according to claim 1, characterized in that, The first polymer includes at least one of polyacetylimide, polyvinylpyrrolidone, and chitosan; And / or, the second polymer includes at least one of natural rubber, polybutadiene, and polyethylene glycol; And / or, the catalyst includes at least one of ferrous chloride and manganese sulfate.

4. The solid-state battery protective film according to claim 1, characterized in that, The weight-average molecular weight of the first polymer and the weight-average molecular weight of the second polymer are each independently between 500,000 and 1,000,000. And / or, the average particle size of the catalyst is 0.5 μm to 2 μm.

5. A solid-state battery, characterized in that, The solid-state battery includes a cell, a solid-state battery protective film as described in any one of claims 1 to 4 disposed on at least a portion of the surface of the cell, and a casing.

6. The solid-state battery according to claim 5, characterized in that, The thickness of the solid-state battery protective film is 0.1 mm to 10 mm; And / or, the yield strength of the outer shell under tensile conditions is 100MPa~600MPa; And / or, the housing comprises nickel-plated steel.

7. The solid-state battery according to claim 6, characterized in that, An elastic buffer layer is also provided between the solid-state battery protective film and the outer casing.

8. The solid-state battery according to claim 7, characterized in that, The thickness of the elastic buffer layer is 1 mm to 50 mm; And / or, the elastic buffer layer includes at least one of rubber, silicone, and foam.

9. The solid-state battery according to claim 5, characterized in that, The battery cell includes an integrated positive and negative electrode sheet and a solid electrolyte membrane; the integrated positive and negative electrode sheet includes a copper-aluminum composite current collector, a negative electrode sheet disposed near the copper side, and a positive electrode sheet disposed near the aluminum side; the side of the positive electrode sheet away from the copper-aluminum composite current collector includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes Li a Ni x Co y M z O2, where M is at least one of Mn, Ti, Al, Zr, Ta, and W, 0.95 ≤ a ≤ 1.05, 0.33 ≤ x ≤ 0.98, 0 < y < 1, 0 < z < 1, and x + y + z = 1; And / or, the solid electrolyte membrane comprises a solid electrolyte, which comprises at least one of a sulfide solid electrolyte and a halide solid electrolyte.

10. An electrical appliance, characterized in that, Including the solid-state battery as described in any one of claims 5 to 9.

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