Electrode assembly, battery and electric device

Abstract

The invention relates to the technical field of batteries, in particular to an electrode assembly, a battery and an electric device. The electrode assembly comprises a positive electrode, a negative electrode and a solid electrolyte layer, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one side surface of the positive electrode current collector; the positive electrode active material layer comprises a positive electrode active material, a first binder and a first solid electrolyte; the solid electrolyte layer comprises a base layer, a positive solid electrolyte membrane arranged on one side surface, close to the positive electrode, of the base layer and a negative solid electrolyte membrane arranged on one side surface, close to the negative electrode, of the base layer; the positive electrode solid electrolyte membrane comprises a second solid electrolyte; the negative electrode solid electrolyte membrane comprises a third solid electrolyte and a second binder; the first binder penetrates through a second solid electrolyte gap of the positive electrode solid electrolyte membrane and is in fusion connection with the base layer; and the second binder is in fusion connection with the base layer. By forming the integrated electrode assembly, stable interface contact is maintained, so that the battery performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and more particularly to an electrode assembly, a battery and a power utilization device. BACKGROUND

[0002] Among different types of all-solid-state batteries, sulfide all-solid-state lithium metal batteries have become a research hotspot due to the highest room temperature ionic conductivity and better mechanical processing performance of sulfide electrolyte; however, there are still many problems in sulfide all-solid-state lithium metal batteries, which hinder their commercial application. Among them, the insufficient ductility of the solid-state electrolyte leads to poor physical contact between the lithium negative electrode and the electrolyte, thereby affecting the interface charge transport and electrochemical reaction. In addition, dendrite growth and negative electrode volume change during charging and discharging will cause stress accumulation at the interface, thereby leading to physical contact failure of the lithium negative electrode / electrolyte interface and impedance growth. The lithium negative electrode / electrolyte interface impedance growth will cause the voltage polarization of the all-solid-state battery to increase, the rate performance to decrease and the capacity to attenuate. SUMMARY

[0003] Therefore, the purpose of the present application is to at least solve one of the problems in the related art. To this end, the present application provides an electrode assembly, a battery and a power utilization device, which maintain stable interface contact by forming an integrated electrode assembly, thereby improving the performance of the battery.

[0004] To solve the above technical problems, the present application is implemented as follows:

[0005] According to one aspect of the present application, the present application provides an electrode assembly, comprising a positive electrode, a negative electrode and a solid-state electrolyte layer;

[0006] The positive electrode comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one side surface of the positive electrode current collector; the positive electrode active material layer comprises a positive electrode active material, a first binder and a first solid-state electrolyte;

[0007] The solid-state electrolyte layer comprises a base layer, a positive electrode solid-state electrolyte film arranged on the side surface of the base layer close to the positive electrode, and a negative electrode solid-state electrolyte film arranged on the side surface of the base layer close to the negative electrode; the positive electrode solid-state electrolyte film comprises a second solid-state electrolyte; the negative electrode solid-state electrolyte film comprises a third solid-state electrolyte and a second binder;

[0008] The first binder is melt-connected with the base layer through the second solid-state electrolyte gap of the positive electrode solid-state electrolyte film; and the second binder is melt-connected with the base layer.

[0009] In some embodiments, the positive active material comprises one or more of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese iron phosphate, lithium nickel oxide, lithium cobalt oxide, elemental sulfur;

[0010] In some embodiments, the first binder comprises one or more of polyvinyl acetate, polyvinylidene fluoride, polyacrylonitrile, polyimide, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyamide, polytetrafluoroethylene.

[0011] In some embodiments, the first solid-state electrolyte comprises one or more of lithium lanthanum zirconate, lithium lanthanum titanate, lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium zirconium aluminum phosphate, Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, Li6PS5I.

[0012] In some embodiments, the mass ratio of the positive active material, the first binder, and the first solid-state electrolyte in the positive active material layer is (85-99):(0.5-5):(0.5-10).

[0013] In some embodiments, the base layer is a porous membrane.

[0014] In some embodiments, the material of the base layer comprises one or more of polyvinyl acetate, polyvinylidene fluoride, polyacrylonitrile, polyimide, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyamide, polytetrafluoroethylene.

[0015] In some embodiments, the second solid-state electrolyte comprises one or more of lithium lanthanum zirconate, lithium lanthanum titanate, lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium zirconium aluminum phosphate, Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, Li6PS5I.

[0016] In some embodiments, the third solid-state electrolyte comprises one or more of lithium lanthanum zirconate, lithium lanthanum titanate, lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium zirconium aluminum phosphate, Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, Li6PS5I.

[0017] And / or, the second binder comprises one or more of polyvinyl acetate, polyvinylidene fluoride, polyacrylonitrile, polyimide, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyamide, polytetrafluoroethylene;

[0018] And / or, the thickness of the solid electrolyte layer is 5 μm to 50 μm.

[0019] And / or, the thickness of the negative electrode solid electrolyte film is 1 μm to 3 μm.

[0020] In some embodiments, the first binder is the same material as the base layer; and / or, the second binder is the same material as the base layer.

[0021] In some embodiments, the melting connection is by hot pressing.

[0022] And / or, the temperature of the hot pressing is 50℃ to 150℃.

[0023] And / or, the pressure of the hot pressing is 10 MPa to 100 MPa.

[0024] And / or, the time of the hot pressing is 5 s to 100 s.

[0025] In some embodiments, the negative electrode solid electrolyte film further comprises lithium powder.

[0026] And / or, the D50 particle size of the lithium powder is 50 nm to 1000 nm.

[0027] And / or, the mass ratio of the lithium powder, the third solid electrolyte, and the second binder is (85-99):(0.5-10):(0.5-5).

[0028] In some embodiments, the negative electrode comprises lithium metal.

[0029] The lithium metal is meltingly connected with the lithium powder.

[0030] According to another aspect of the present application, the present application provides a battery comprising the electrode assembly described in the above technical solution.

[0031] According to yet another aspect of the present application, the present application provides an electrical device comprising the battery described in the above technical solution.

[0032] The technical solution of the present application has at least the following beneficial effects:

[0033] 1. In the embodiment of the present application, the electrode assembly is connected with the two side adhesives through the base layer of the solid electrolyte layer, so that the negative electrode and the electrolyte, and the electrolyte and the positive electrode are in close contact, forming an integrated level group, which can maintain stable and good contact of the interface while bearing the repeated volume changes of the positive and negative electrodes during the charging and discharging process, thereby improving the battery performance.

[0034] 2. In the preferred embodiment of the embodiment of the present application, the polyvinyl acetate porous membrane is used as the base layer, which can significantly enhance the ductility and flexibility of the solid electrolyte layer and increase the practical processability. On the other hand, the ductility, filling property and viscoelasticity of the polyvinyl acetate porous membrane material can better fill the gaps of the crystalline solid electrolyte, inhibit the growth of lithium dendrites and reduce the probability of thermal runaway during the battery cycle process.

[0035] 3. In the preferred embodiment of the embodiment of the present application, the same material is used for the adhesive in the positive active material layer and the base layer in the solid electrolyte layer, which forms better fusion during heat treatment, thereby forming an integrated electrode on the positive side and ensuring the stable contact of the positive electrode and the solid electrolyte.

[0036] 4. In the preferred embodiment of the embodiment of the present application, the same material is used for the adhesive in the modification layer on the negative side of the solid electrolyte layer and the base layer in the solid electrolyte layer, which forms better fusion during heat treatment, thereby forming an integrated electrode on the negative side and ensuring the stable contact of the modification layer and the solid electrolyte layer. In addition, by adding lithium powder in the modification layer on the negative side of the solid electrolyte layer, fusion can be formed with the lithium metal of the negative electrode during heat treatment, thereby ensuring the stable contact of the modification layer and the lithium metal layer.

[0037] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. DETAILED DESCRIPTION

[0038] The application will be further described with reference to the following examples. It should be understood that these examples are intended to illustrate the application and are not intended to limit the scope of the application.

[0039] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be approximations which can be rounded off. The endpoints of the ranges and / or values are not to be construed as limited. It is specifically intended that the endpoints be comprised fully within the range values unless the context clearly indicates otherwise. The disclosure of ranges includes endpoints.

[0040] In the description of this application, "same chemical composition" should be interpreted broadly, that is, the main components of the two have the same chemical composition, or the two have substantially the same chemical composition, but may have errors or impurities within the acceptable range that can be understood by those skilled in the art.

[0041] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0042] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0045] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] At present, all-solid-state lithium metal batteries still have the following technical problems: (1) Change in the volume of solid electrolyte layer: During the charging and discharging process, the interlayer stress caused by the transport of lithium ions in traditional sulfide solid electrolytes and oxide solid electrolytes increases continuously, which increases the volume and thickness of the solid electrolyte layer and reduces the transport efficiency; (2) Insufficient ductility of solid electrolyte: Once the solid electrolyte forms cracks or has poor contact with lithium metal, it cannot form an SEI film and has self-healing properties like liquid electrolytes. It is more likely to cause the lithium ion transport channel to break and form lithium dendrites. The continuous growth of dendrites may penetrate the electrolyte, causing the battery to short-circuit, generate a lot of heat, and increase the temperature, which may lead to thermal runaway. The poor ductility of solid electrolyte can lead to short circuit problems in the contact between positive and negative electrodes under external impact; (3) Difficulty in battery densification: There are pore defects inside the battery. Low density will reduce the performance of solid battery, and the pressure on the edge of the electrode may lead to problems such as overlapping short circuits; thus hindering its commercial application.

[0047] Based on this, the present invention addresses the aforementioned technical problems and improves battery performance to a certain extent by forming an integrated electrode assembly, maintaining stable interface contact and good contact properties. Specifically, the present invention adopts the following technical solution:

[0048] According to one aspect of the present invention, an electrode assembly is provided, comprising a positive electrode, a negative electrode, and a solid electrolyte layer;

[0049] The positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector; the positive electrode active material layer includes a positive electrode active material, a first binder, and a first solid electrolyte;

[0050] The solid electrolyte layer includes a base layer, a positive electrode solid electrolyte membrane disposed on the surface of the base layer near the positive electrode, and a negative electrode solid electrolyte membrane disposed on the surface of the base layer near the negative electrode; the positive electrode solid electrolyte membrane includes a second solid electrolyte; the negative electrode solid electrolyte membrane includes a third solid electrolyte and a second binder;

[0051] The first adhesive is fused to the base layer through the second solid electrolyte gap in the positive electrode solid electrolyte membrane; the second adhesive is fused to the base layer.

[0052] In a specific embodiment of the present invention, the electrode assembly includes a positive electrode, a negative electrode, and a solid electrolyte layer, preferably composed of a positive electrode, a negative electrode, and a solid electrolyte layer; wherein the solid electrolyte layer is disposed between the positive electrode and the negative electrode. Specifically, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector; wherein the positive electrode active material layer includes a positive electrode active material, a first binder, and a first solid electrolyte; the solid electrolyte layer includes a base layer, a positive electrode solid electrolyte membrane disposed on the surface of the base layer near the positive electrode, and a negative electrode solid electrolyte membrane disposed on the surface of the base layer near the negative electrode; the positive electrode solid electrolyte membrane includes a second solid electrolyte; the negative electrode solid electrolyte membrane includes a third solid electrolyte and a second binder. Therefore, the positive electrode active material layer of the positive electrode is in contact with the positive electrode solid electrolyte membrane of the solid electrolyte layer; the negative electrode solid electrolyte membrane of the solid electrolyte layer is in contact with the negative electrode.

[0053] In a specific embodiment of the present invention, the first adhesive is fused to the base layer through the gaps in the second solid electrolyte in the positive electrode solid electrolyte membrane; the second adhesive is fused to the base layer. It should be noted that fusion bonding is a bonding method that achieves adhesion by heating to locally melt the material. Specifically, it utilizes thermal energy to bring the material at the interface to a molten state, and under pressure, the molecular chains diffuse and re-entangle, ultimately cooling and solidifying to form a strong overall connection. Compared with the traditional adhesive bonding method, fusion bonding achieves interface fusion through the molecular movement of the material in a molten state, resulting in superior connection strength and stability. Furthermore, the base layer of the solid electrolyte layer in the electrode assembly is fused to the adhesives on both sides, ensuring close contact between the negative electrode and the electrolyte, and between the electrolyte and the positive electrode, forming an integrated electrode assembly. This assembly can simultaneously withstand repeated volume changes of the positive and negative electrodes during charging and discharging while maintaining stable interface contact and good contact performance, thereby improving battery performance.

[0054] In a specific embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer, wherein the positive electrode active material layer is disposed on at least one surface of the positive electrode current collector; wherein, the positive electrode current collector may be a metal foil or a composite current collector, for example, as a metal foil, an aluminum current collector foil may be used; the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer; the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0055] In a specific embodiment of the present invention, the positive electrode active material layer includes a positive electrode active material, a first binder, and a first solid electrolyte; wherein, the positive electrode active material preferably includes lithium nickel cobalt manganese oxide (LiNiO2). x Co y Mn 1-x-y O2 (NCM), lithium iron phosphate (LiFePO4), lithium nickel cobalt aluminum oxide (LiNi) x Co y Al 1-x-y O2), lithium manganese iron phosphate (LiFe) x Mn 1-x The cathode active material is selected from one or more of PO4, lithium nickel oxide (LiNiO2), lithium cobalt oxide (LiCoO2), and elemental sulfur (S), with lithium nickel cobalt manganese oxide being more preferred. The present invention does not impose any special restrictions on the source of the cathode active material; commercially available products well known to those skilled in the art can be used.

[0056] In a specific embodiment of the present invention, the first adhesive preferably comprises one or more of the following: polyvinyl acetate (PEVA), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide (PI), polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), and polytetrafluoroethylene (PTFE), more preferably polyvinyl acetate (PEVA), which has better viscoelasticity than other materials and can achieve more stable contact with solid electrolytes and active materials. The present invention does not impose any special restrictions on the source of the first adhesive; commercially available products well known to those skilled in the art can be used.

[0057] In a specific embodiment of the present invention, the first solid electrolyte preferably includes lithium lanthanum zirconate (Li7La3Zr2O). 12 (LLZO for short) and lithium lanthanum titanate (Li 3x La 2 / (3-x) TiO3 (LLTO) and lithium titanium aluminum phosphate (Li) 1+x Al x Ti 2-x (PO4)3, abbreviated as LATP, lithium aluminum germanium phosphate (Li) 1+x Al x Ge 2-x (PO4)3), lithium aluminum zirconium phosphate (Li 1+x Al x Zr 2-xOne or more of (PO4)3), Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I, more preferably one or more of sulfide solid electrolytes LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I, and even more preferably LiPSCl. The present invention does not impose any special restrictions on the source of the first solid electrolyte; commercially available products well known to those skilled in the art can be used.

[0058] In a specific embodiment of the present invention, the mass ratio of the positive electrode active material, the first binder and the first solid electrolyte in the positive electrode active material layer is preferably (85-99):(0.5-5):(0.5-10), more preferably (86-93):(1-4):(6-10).

[0059] The present invention does not impose any special restrictions on the preparation method of the positive electrode. A mixture including the above-mentioned positive electrode active material, the first binder and the first solid electrolyte is coated onto the positive electrode current collector using a method known to those skilled in the art. After conventional molding process, a composite positive electrode can be obtained; which can then be further used to prepare electrode components.

[0060] In a specific embodiment of the present invention, the solid electrolyte layer includes a base layer and a positive electrode solid electrolyte membrane and a negative electrode solid electrolyte membrane disposed on both sides of the base layer, wherein the positive electrode solid electrolyte membrane is in contact with the positive electrode active material layer in the positive electrode, and the negative electrode solid electrolyte membrane is in contact with the negative electrode.

[0061] In a specific embodiment of the present invention, the base layer is preferably a porous membrane that can provide support; the material of the base layer preferably includes one or more of the following: polyvinyl acetate (PEVA), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide (PI), polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), and polytetrafluoroethylene (PTFE), more preferably polyvinyl acetate (PEVA). In a preferred embodiment of the present invention, the base layer is made of polyvinyl acetate (PEVA), which has better viscoelasticity than other materials and can achieve more stable contact with the solid electrolyte and active materials. The present invention uses a porous polyvinyl acetate membrane as a support membrane, which can significantly enhance the ductility and flexibility of the solid electrolyte layer and increase its practical processability. On the other hand, by utilizing the ductility, filling properties and viscoelasticity of the porous polyvinyl acetate material, it can better fill the gaps in the crystalline solid electrolyte, inhibit lithium dendrite growth, and reduce the probability of thermal runaway during battery cycling.

[0062] In a specific embodiment of the present invention, the positive electrode solid electrolyte membrane includes a second solid electrolyte; the second solid electrolyte preferably includes lithium lanthanum zirconate (Li7La3Zr2O). 12 (LLZO for short) and lithium lanthanum titanate (Li 3x La 2 / (3-x) TiO3 (LLTO) and lithium titanium aluminum phosphate (Li) 1+x Al x Ti 2-x (PO4)3, abbreviated as LATP, lithium aluminum germanium phosphate (Li) 1+x Al x Ge 2-x (PO4)3), lithium aluminum zirconium phosphate (Li 1+x Al x Zr 2-x One or more of (PO4)3), Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I, more preferably one or more of sulfide solid electrolytes LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I, and even more preferably LiPSCl. The present invention does not impose any special restrictions on the source of the second solid electrolyte; commercially available products well known to those skilled in the art can be used.

[0063] The present invention does not impose any special restrictions on the preparation method of the positive electrode solid electrolyte membrane. The material including the above-mentioned second solid electrolyte is coated on one side of the base layer and then hot-pressed to obtain a base layer with a positive electrode solid electrolyte membrane on one side, which is well known to those skilled in the art. This base layer can then be further used to prepare a solid electrolyte layer and an electrode assembly.

[0064] In a specific embodiment of the present invention, the negative electrode solid electrolyte membrane comprises a third solid electrolyte and a second binder; wherein, the third solid electrolyte preferably comprises lithium lanthanum zirconate (Li7La3Zr2O). 12 (LLZO for short) and lithium lanthanum titanate (Li 3x La 2 / (3-x) TiO3 (LLTO) and lithium titanium aluminum phosphate (Li) 1+x Al x Ti 2-x (PO4)3, abbreviated as LATP, lithium aluminum germanium phosphate (Li) 1+x Al x Ge 2-x (PO4)3), lithium aluminum zirconium phosphate (Li 1+x Al x Zr 2-x (PO4)3), Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, Li6PS5I, more preferably one or more of the sulfide solid electrolytes LiPSCl, Li6PS5Cl, Li6PS5Br, Li6PS5I, and even more preferably LiPSCl. The present invention does not impose any special restrictions on the source of the third solid electrolyte; commercially available products well known to those skilled in the art can be used.

[0065] In a specific embodiment of the present invention, the second binder preferably comprises one or more of the following: polyvinyl acetate (PEVA), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide (PI), polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), and polytetrafluoroethylene (PTFE), more preferably polyvinyl acetate (PEVA), which has better viscoelasticity than other materials and can achieve more stable contact with solid electrolytes and active materials. The present invention does not impose any special restrictions on the source of the second binder; commercially available products well known to those skilled in the art can be used.

[0066] The present invention does not impose any special restrictions on the preparation method of the negative electrode solid electrolyte membrane. A mixture including the third solid electrolyte and the second binder, which is well known to those skilled in the art, is coated on the other side of the substrate on which the positive electrode solid electrolyte membrane is laminated on one side. After conventional molding processes in the art, a solid electrolyte layer can be obtained; and then it can be further used to prepare an electrode assembly.

[0067] In a specific embodiment of the present invention, the thickness of the negative electrode solid electrolyte membrane is preferably 1 μm to 3 μm; the thickness of the solid electrolyte layer is preferably 5 μm to 50 μm.

[0068] In a specific embodiment of the present invention, the first adhesive is made of the same material as the base layer; based on this, the present invention uses the same material for the first adhesive in the positive electrode active material layer and the base layer in the solid electrolyte layer, so that better fusion is achieved during heat treatment, thereby forming an integrated electrode on the positive electrode side and ensuring stable contact between the positive electrode and the solid electrolyte.

[0069] In a specific embodiment of the present invention, the second adhesive is made of the same material as the base layer; based on this, the present invention uses the same material for the second adhesive in the negative electrode solid electrolyte membrane on the negative electrode side of the solid electrolyte layer and the base layer in the solid electrolyte layer, so that better fusion is formed during heat treatment, thereby forming an integrated electrode on the negative electrode side, ensuring stable contact between the negative electrode solid electrolyte membrane and the solid electrolyte layer.

[0070] In a specific embodiment of the present invention, the negative electrode solid electrolyte membrane preferably includes lithium powder in addition to the aforementioned third solid electrolyte and second binder; furthermore, the negative electrode solid electrolyte membrane can also be considered as a lithium modification layer. The present invention does not impose any special restrictions on the source of the lithium powder, and commercially available products well known to those skilled in the art can be used; the D50 particle size of the lithium powder is preferably 50 nm to 1000 nm, more preferably 100 nm to 500 nm.

[0071] In a specific embodiment of the present invention, the mass ratio of the lithium powder to the third solid electrolyte and the second binder is preferably (85-99):(0.5-10):(0.5-5), and more preferably (90-94):(5-7):(1-3).

[0072] In a specific embodiment of the present invention, the negative electrode preferably comprises lithium metal; as described above, the negative electrode solid electrolyte membrane is in contact with the negative electrode; when the negative electrode solid electrolyte membrane comprises lithium powder, the lithium metal and the lithium powder are fused together. The present invention, by adding lithium powder to the negative electrode solid electrolyte membrane on the negative electrode side of the solid electrolyte layer, enables it to fuse with the lithium metal of the negative electrode during heat treatment, thereby ensuring a stable contact between the modification layer and the lithium metal layer.

[0073] In a preferred embodiment of the present invention, the negative electrode is a copper-lithium composite foil. Combining the preparation methods described in the above technical solutions, the electrode assembly can be further prepared using assembly methods well-known to those skilled in the art. As an example, it may include the following steps:

[0074] The positive electrode solid electrolyte membrane side of the solid electrolyte layer prepared in the above technical solution is covered on the above composite positive electrode, and then the above negative electrode is attached to the negative electrode solid electrolyte membrane side of the solid electrolyte layer and fused together to form the integrated electrode assembly provided by the present invention.

[0075] In a specific embodiment of the present invention, the preferred method of fusion bonding is hot pressing; the preferred temperature of the hot pressing is 50℃ to 150℃; specifically, it can be 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃; the preferred pressure of the hot pressing is 10MPa to 100MPa; specifically, it can be 10MPa, 20MPa, 30MPa, 40MPa, 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, or 100MPa; the preferred time of the hot pressing is 5s to 100s; specifically, it can be 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s, 70s, 75s, 80s, 85s, 90s, 95s, or 100s. By adjusting the temperature, pressure, and time parameters of the hot pressing, a good fusion bonding effect can be achieved based on the specific material selection, so that the electrode assembly forms an integrated structure. This structure can withstand repeated positive and negative electrode volume changes during charging and discharging while maintaining stable interface contact and good contact, thereby improving battery performance.

[0076] According to another aspect of the present invention, a battery is provided, comprising the electrode assembly described in the above-described technical solution. Thus, the battery possesses all the features and advantages of the electrode assembly described in the above-described technical solution, which will not be repeated here. In the present invention, the battery may specifically be an all-solid-state battery. Specifically, the battery may include an outer packaging, which can be used to encapsulate the aforementioned electrode assembly and other necessary or non-essential functional components; when the battery includes the aforementioned electrode assembly, regardless of whether other necessary or non-essential functional components are also used in the battery, it can be considered an embodiment of the present invention.

[0077] According to another aspect of the present invention, an electrical device is provided, comprising the battery described in the above-described technical solution. Thus, the electrical device possesses all the features and advantages of the battery described in the above-described technical solution, which will not be repeated here. Specifically, the battery can serve as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, and energy storage systems.

[0078] The following detailed description of this application is based on specific embodiments, but the implementation and protection of this invention are not limited thereto. The following embodiments are only some embodiments of this application and are not intended to limit this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products, and the sulfide solid electrolyte used is LiPSCl.

[0079] Example 1

[0080] (1) Preparation of solid electrolyte thin films:

[0081] Take polyvinyl acetate porous membrane PEVA (Shandong Haoyao New Material Co., Ltd., CAS: 9003-20-7, item number: HY5656) and sulfide solid electrolytes (SEs), and mix the sulfide solid electrolytes (SEs) according to an areal density of 3 mg / cm³. 2 The coating was applied to a porous polyvinyl acetate (PEVA) film and pressurized at 50°C and 40 MPa for 30 min to obtain an SEs@PEVA solid electrolyte membrane.

[0082] (2) Preparation of composite cathode:

[0083] Ternary material NCM (811), sulfide solid electrolytes (SEs), and polyvinyl acetate (PEVA) powder were mixed evenly at a mass ratio of 90:8:2, with an areal density of 3 mg / cm³. 2 It is applied to an aluminum current collector with a thickness of 12μm.

[0084] (3) Preparation of composite negative electrode:

[0085] Lithium powder, sulfide solid electrolytes (SEs), and polyvinyl acetate (PEVA) powder were mixed evenly at a mass ratio of 92:6:2, with an areal density of 3 mg / cm³. 2 SEs@PEVA@Li is formed by coating the negative electrode side of the SEs@PEVA solid electrolyte membrane.

[0086] (4) Preparation of composite units:

[0087] The lithium-free side of the aforementioned solid electrolyte film SEs@PEVA@Li was covered on the composite positive electrode, and the lithium-containing side of the copper-lithium composite foil was attached to the SEs@PEVA@Li. The hot-pressing temperature was 90℃, the hot-pressing pressure was 50MPa, and the hot-pressing time was 60s to obtain the composite unit, i.e., the electrode assembly. The final thickness of SEs@PEVA@Li was 10μm, and the thickness of the @Li part (the negative electrode solid electrolyte film) was 2μm.

[0088] Example 2

[0089] (1) Preparation of solid electrolyte thin films:

[0090] Take a porous polyvinyl acetate (PEVA) film and a sulfide solid electrolyte (SEs), and mix the SEs according to an areal density of 2 mg / cm³. 2 The coating was applied to a porous polyvinyl acetate (PEVA) film and pressurized at 50°C and 40 MPa for 30 min to obtain an SEs@PEVA solid electrolyte membrane.

[0091] (2) Preparation of composite cathode:

[0092] Ternary material NCM (811), sulfide solid electrolytes (SEs), and polyvinyl acetate (PEVA) powder were mixed evenly at a mass ratio of 90:8:2, with an areal density of 2 mg / cm³. 2 It is applied to an aluminum current collector with a thickness of 12μm.

[0093] (3) Preparation of composite negative electrode:

[0094] Lithium powder, sulfide solid electrolytes (SEs), and polyvinyl acetate (PEVA) powder were mixed evenly at a mass ratio of 92:6:2, with an areal density of 2 mg / cm³. 2 SEs@PEVA@Li is formed by coating the negative electrode side of the SEs@PEVA solid electrolyte membrane.

[0095] (4) Preparation of composite units:

[0096] The lithium-free side of the aforementioned solid electrolyte film SEs@PEVA@Li was covered on the composite positive electrode, and the lithium-containing side of the copper-lithium composite foil was attached to the SEs@PEVA@Li. The hot-pressing temperature was 90℃, the hot-pressing pressure was 50MPa, and the hot-pressing time was 60s to obtain the composite unit, i.e., the electrode assembly. The final thickness of SEs@PEVA@Li was 20μm, of which the thickness of the @Li portion (the negative electrode solid electrolyte film) was 2μm.

[0097] Example 3

[0098] (1) Preparation of solid electrolyte thin films:

[0099] Take a porous polyvinyl acetate (PEVA) film and a sulfide solid electrolyte (SEs), and mix the SEs according to an areal density of 3 mg / cm³. 2 The coating was applied to a porous polyvinyl acetate (PEVA) film, and then pressurized at 30°C and 80 MPa for 30 min to obtain an SEs@PEVA solid electrolyte membrane.

[0100] (2) Preparation of composite cathode:

[0101] Ternary material NCM (811), sulfide solid electrolytes (SEs), and polyvinyl acetate (PEVA) powder were mixed evenly at a mass ratio of 90:8:2, with an areal density of 3 mg / cm³. 2 It is applied to an aluminum current collector with a thickness of 12μm.

[0102] (3) Preparation of composite negative electrode:

[0103] Lithium powder, sulfide solid electrolytes (SEs), and polyvinyl acetate (PEVA) powder were mixed evenly at a mass ratio of 92:6:2, with an areal density of 3 mg / cm³. 2 SEs@PEVA@Li is formed by coating the negative electrode side of the SEs@PEVA solid electrolyte membrane.

[0104] (4) Preparation of composite units:

[0105] The lithium-free side of the aforementioned solid electrolyte film SEs@PEVA@Li was covered on the composite positive electrode, and the lithium-containing side of the copper-lithium composite foil was attached to the SEs@PEVA@Li. The hot-pressing temperature was 90℃, the hot-pressing pressure was 50MPa, and the hot-pressing time was 60s to obtain the composite unit, i.e., the electrode assembly. The final thickness of SEs@PEVA@Li was 15μm, of which the thickness of the @Li portion (the negative electrode solid electrolyte film) was 2μm.

[0106] Example 4

[0107] The electrode assembly was obtained using the preparation method provided in Example 1, with the only difference being:

[0108] Replace all of the polyvinyl acetate (PEVA; including porous film material and adhesive) with polymethyl methacrylate (PMMA).

[0109] Example 5

[0110] The electrode assembly was obtained using the preparation method provided in Example 1, with the only difference being:

[0111] The material of the porous membrane in the solid electrolyte membrane was replaced with PMMA instead of polyvinyl acetate.

[0112] Example 6

[0113] The electrode assembly was obtained using the preparation method provided in Example 1, with the only difference being:

[0114] Replace the sulfide solid electrolyte with LATP.

[0115] Comparative Example 1

[0116] The electrode assembly was obtained using the preparation method provided in Example 1, with the only difference being:

[0117] The solid electrolyte membrane does not contain a porous polyvinyl acetate (PEVA) membrane.

[0118] Comparative Example 2

[0119] The electrode assembly was obtained using the preparation method provided in Example 1, with the only difference being:

[0120] Lithium powder is not added in step (3).

[0121] Battery fabrication, testing methods and conditions:

[0122] Electrode fabrication: A lithium-copper composite sheet was used as the negative electrode, with dimensions of 100mm × 55mm. The prepared positive composite electrode was used as the positive electrode, with dimensions of 96mm × 51mm. A composite solid electrolyte membrane was used as the separator. For the full battery, the capacity ratio of the positive to negative electrodes was 1.1. The assembly process adopted a soft-pack stacking method. Stacking: The positive electrode sheet, electrolyte membrane, and negative electrode sheet were stacked or wound in sequence to obtain a cell with a designed capacity of 5Ah. Assembly: The stacked cell was hot-pressed and placed in an aluminum-plastic film for top and side sealing. The charge / discharge cutoff voltage was set to 2.8–4.2V, the charge / discharge current was 1A / g, and the test was completed after 2000 cycles.

[0123] Table 1 Performance test data

[0124]

[0125] Experimental results show that, after 2000 cycles of electrochemical testing, the batteries provided in Examples 1-6 of this invention exhibit a significant advantage in capacity retention compared to the battery in Comparative Example 1 without a supporting solid electrolyte membrane. Furthermore, the batteries in Examples 1-6 with lithium powder modification on the negative electrode side show a significant advantage in cycle performance compared to the battery in Comparative Example 2 without lithium powder modification on the negative electrode side. Simultaneously, the ACR data of the batteries demonstrates that Examples 1-3 of this invention, by using suitable homogeneous materials for fusion bonding to form an integrated electrode assembly with better bonding effect, can maintain stable interfacial contact, thereby improving battery performance.

[0126] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0127] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0128] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode assembly, characterized in that, Includes a positive electrode, a negative electrode, and a solid electrolyte layer; The positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector; the positive electrode active material layer includes a positive electrode active material, a first binder, and a first solid electrolyte; The solid electrolyte layer includes a base layer, a positive electrode solid electrolyte membrane disposed on the surface of the base layer near the positive electrode, and a negative electrode solid electrolyte membrane disposed on the surface of the base layer near the negative electrode; the positive electrode solid electrolyte membrane includes a second solid electrolyte; the negative electrode solid electrolyte membrane includes a third solid electrolyte and a second binder; The first adhesive is fused to the base layer through the second solid electrolyte gap in the positive electrode solid electrolyte membrane; the second adhesive is fused to the base layer.

2. The electrode assembly according to claim 1, characterized in that, The positive electrode active material includes one or more of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese iron phosphate, lithium nickel oxide, lithium cobalt oxide, and elemental sulfur. And / or, the first adhesive comprises one or more of the following: ethylene vinyl acetate, polyvinylidene fluoride, polyacrylonitrile, polyimide, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyamide, and polytetrafluoroethylene. And / or, the first solid electrolyte comprises one or more of lithium lanthanum zirconate, lithium lanthanum titanate, lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium zirconium aluminum phosphate, Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I. And / or, the mass ratio of the positive electrode active material, the first binder and the first solid electrolyte in the positive electrode active material layer is (85-99):(0.5-5):(0.5-10).

3. The electrode assembly according to claim 1, characterized in that, The base layer is a porous membrane; And / or, the material of the base layer includes one or more of the following: polyvinyl acetate, polyvinylidene fluoride, polyacrylonitrile, polyimide, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyamide, and polytetrafluoroethylene.

4. The electrode assembly according to claim 1, characterized in that, The second solid electrolyte includes one or more of the following: lithium lanthanum zirconate, lithium lanthanum titanate, lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium zirconium aluminum phosphate, Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I. And / or, the third solid electrolyte includes one or more of lithium lanthanum zirconate, lithium lanthanum titanate, lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium zirconium aluminum phosphate, Li3MgOCl, Li3CaOCl, Li3SrOCl, Li3BaOCl, LiPSCl, Li6PS5Cl, Li6PS5Br, and Li6PS5I. And / or, the second adhesive comprises one or more of the following: ethylene vinyl acetate, polyvinylidene fluoride, polyacrylonitrile, polyimide, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, polyamide, and polytetrafluoroethylene. And / or, the thickness of the solid electrolyte layer is 5 μm to 50 μm; And / or, the thickness of the negative electrode solid electrolyte membrane is 1 μm to 3 μm.

5. The electrode assembly according to claim 1, characterized in that, The first adhesive is made of the same material as the base layer; and / or, the second adhesive is made of the same material as the base layer.

6. The electrode assembly according to claim 1, characterized in that, The fusion bonding method is hot pressing; And / or, the temperature of the hot pressing is 50°C to 150°C; And / or, the pressure of the hot pressing is 10 MPa to 100 MPa; And / or, the hot pressing time is 5s to 100s.

7. The electrode assembly according to any one of claims 1 to 6, characterized in that, The negative electrode solid electrolyte membrane also includes lithium powder; And / or, the D50 particle size of the lithium powder is 50nm to 1000nm; And / or, the mass ratio of the lithium powder to the third solid electrolyte and the second binder is (85-99):(0.5-10):(0.5-5).

8. The electrode assembly according to any one of claims 7, characterized in that, The negative electrode comprises lithium metal; The lithium metal and the lithium powder are fused together.

9. A battery, characterized in that, Includes the electrode assembly as described in any one of claims 1 to 8.

10. An electrical device, characterized in that, Includes the battery as described in claim 9.

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