Solid electrolyte, preparation method thereof and solid-state battery

Abstract

The invention belongs to the technical field of batteries, and discloses a solid electrolyte, a preparation method thereof and a solid-state battery. Relates to the technical field of batteries. The solid electrolyte comprises the following raw material components: a lithium salt, a polymeric monomer, a plasticizer and an initiator, wherein the polymeric monomer comprises a first monomer and a second monomer; the first monomer comprises an acrylic monomer containing an ether oxygen chain segment; the second monomer comprises one or more of a fluorine-containing acrylic acid monomer and an acrylic acid monomer containing a weak polar functional group, and the acrylic acid monomer containing the weak polar functional group comprises one or more of amino acrylate, 2, 3-dibromopropyl propylene, 2-(trimethylsiloxy) ethyl methacrylate and isobornyl methacrylate. According to the solid electrolyte provided by the invention, the cycle performance of the solid-state battery containing the solid electrolyte can be improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a solid electrolyte and its preparation method, and a solid battery. Background Technology

[0002] Compared to existing liquid lithium-ion batteries, solid-state batteries have advantages such as safety, non-flammability, high mechanical and thermal stability, ease of processing, and the ability to achieve higher energy density and cycle life.

[0003] Solid-state electrolytes are a crucial component of solid-state batteries. Polyether-based solid-state electrolytes, such as polyethylene oxide (PEG), are currently the most widely used polymer electrolyte materials. However, the application of these polymers at high voltages is limited by insufficient oxidation stability due to the lone pair electrons on their ether oxygen atoms. Furthermore, the strong coordination between lithium ions and ether oxygen atoms in polyether-based solid-state electrolytes not only hinders the dissociation during lithium-ion transport but also forms a solvated structure lacking anion coordination, affecting lithium-ion transport kinetics. Moreover, the poor oxidation stability of polyether electrolytes themselves leads to the formation of a polymer-derived organic-based cathode interphase (CEI), which reduces the oxygen stability of the cathode active material surface and affects the cycle stability of the solid-state battery. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a solid electrolyte and its preparation method, as well as a solid-state battery. The solid electrolyte provided by this invention can improve the cycle performance of solid-state batteries containing it.

[0005] In a first aspect, the present invention provides a solid electrolyte, the raw material components of which include lithium salt, polymeric monomer, plasticizer and initiator, wherein the polymeric monomer includes a first monomer and a second monomer; the first monomer includes an acrylic monomer containing an ether oxygen segment; the second monomer includes one or more of a fluorinated acrylic monomer and an acrylic monomer containing a weakly polar functional group, wherein the acrylic monomer containing a weakly polar functional group includes one or more of aminoacrylate, 2,3-dibromopropylpropylene, 2-(trimethylsiloxy)ethyl methacrylate, and isobornyl methacrylate.

[0006] According to the solid electrolyte of the present invention, a polymer electrolyte with anion-rich solvation structure is constructed by in-situ polymerization of two miscible monomers—a strongly solvated first monomer and a weakly solvated second monomer. When a chain segment with weak solvation capability is introduced, the solid electrolyte promotes the dissociation of lithium ions from the polymer chain and encourages more anions to participate in the formation of solvation structure contact ion pairs (CIPs) and ion aggregates (AGGs). Ultimately, an interface layer rich in inorganic components such as LiF is formed on the positive and negative electrode surfaces. The uniformly deposited positive electrode interface CEI exhibits a bilayer structure: the dense outer LiF provides an efficient ion transport pathway, enhancing the activity of the oxygen reduction reaction; the inner structure on the positive electrode surface can significantly suppress oxygen peroxidation. In summary, the solid electrolyte proposed in this invention significantly improves the redox kinetics of the positive electrode active material under high voltage, effectively accelerates the interfacial ion transport kinetics in solid-state batteries, and effectively suppresses interfacial side reactions such as oxygen release involved in the operation of solid-state batteries. This improves the interfacial stability between the positive electrode active material and the electrolyte, resulting in excellent cycle stability of the solid-state battery.

[0007] In addition, the solid electrolyte according to the above embodiments of the present invention may also have the following additional technical features: In some embodiments of the present invention, the molar ratio of the first monomer to the second monomer is 1:(1-9). This improves the cycle performance of solid-state batteries containing the monomer.

[0008] In some embodiments of the present invention, the acrylic monomer containing the ether oxygen segment includes one or more of ethoxyethoxyethyl acrylate, poly(ethylene glycol) methyl ether acrylate, 2-methoxyethyl acrylate, and glycidyl methacrylate. This can improve the cycle performance of solid-state batteries containing it.

[0009] In some embodiments of the present invention, the fluorinated acrylic monomer includes one or more of perfluoropropyl methacrylate, heptafluorobutyl acrylate, nonafluorohexyl acrylate, dodecafluoroheptyl acrylate, and pentafluorophenyl acrylate. This improves the cycle performance of solid-state batteries containing it.

[0010] In some embodiments of the present invention, the plasticizer includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, trimethyl phosphate, triethyl phosphate, fluoroethylene carbonate, dimethyl carbonate, fluoroether, 1,3-dioxolane, and trioxymethylene. This can improve the cycle performance of solid-state batteries containing the plasticizer.

[0011] In some embodiments of the present invention, the lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(pentafluoroethanesulfonyl)imide, lithium difluorooxalateborate, lithium tetrafluoroborate, lithium perchlorate, and lithium nitrate. This improves the cycle performance of solid-state batteries containing the lithium salt.

[0012] In some embodiments of the present invention, the initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide, and potassium persulfate. This can improve the cycle performance of solid-state batteries containing these initiators.

[0013] In some embodiments of the present invention, the lithium salt accounts for 5%-50% of the total mass of the solid electrolyte. This improves the cycle performance of solid-state batteries containing the lithium salt.

[0014] In some embodiments of the present invention, the plasticizer accounts for 10%-50% of the total mass of the solid electrolyte. This can improve the cycle performance of solid-state batteries containing the plasticizer.

[0015] In some embodiments of the present invention, the initiator accounts for 0.1%-5% of the total mass of the solid electrolyte. This improves the cycle performance of solid-state batteries containing the initiator.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned solid electrolyte. According to an embodiment of the present invention, the method includes: mixing a first monomer and a second monomer under an inert gas atmosphere to obtain a monomer mixture; Under inert gas protection, lithium salt, plasticizer, and initiator are added to the monomer mixture, and polymerization is carried out by heating to obtain a solid electrolyte. Therefore, the solid electrolyte prepared according to the embodiments of the present invention can improve the cycle performance of batteries containing it.

[0017] In some embodiments of the present invention, the inert gas contains <0.1 ppm water and <0.1 ppm oxygen. Therefore, the prepared solid electrolyte can improve the cycle performance of batteries containing it.

[0018] In some embodiments of the present invention, the heating polymerization temperature is 60℃-100℃ and the time is 2h-12h.

[0019] In a third aspect, the present invention provides a solid-state battery. The solid-state battery includes the solid electrolyte described in the first aspect of the invention, or a solid electrolyte prepared using the method described in the second aspect. Thus, the solid-state battery containing this solid electrolyte exhibits excellent cycle performance.

[0020] In some embodiments of the present invention, the solid-state battery includes a positive electrode sheet comprising a lithium-rich manganese-based layered oxide. This improves the cycle performance of the solid-state battery.

[0021] In some embodiments of the present invention, the solid-state battery includes a negative electrode sheet, the negative electrode sheet includes a negative current collector, and metallic lithium is deposited in situ on the negative current collector during charging. Therefore, the solid-state battery exhibits excellent cycle performance and energy density.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 The Raman spectra of the solid electrolyte and lithium salt of Examples 1-3 and Comparative Example 1 of the present invention are shown.

[0024] Figure 2 The time-of-flight secondary ion mass spectrum of the lithium-rich manganese-based basal oxide surface of Example 1 of the present invention is shown.

[0025] Figure 3 The cycle performance graphs of the solid-state batteries of Embodiment 3 and Comparative Example 1 of the present invention are shown. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] In a first aspect, the present invention provides a solid electrolyte comprising the following raw material components: a lithium salt, a polymeric monomer, a plasticizer, and an initiator; wherein the polymeric monomer comprises a first monomer and a second monomer; the first monomer comprises an acrylic monomer containing an ether oxygen segment; and the second monomer comprises one or more of a fluorinated acrylic monomer and an acrylic monomer containing a weakly polar functional group, wherein the acrylic monomer containing a weakly polar functional group comprises one or more of aminoacrylate (AA), 2,3-dibromopropylpropylene (BA), 2-(trimethylsiloxy)ethyl methacrylate (SA), and isobornyl methacrylate (IBA).

[0028] According to the solid electrolyte of the present invention, a polymer electrolyte with anion-rich solvation structure is constructed by in-situ polymerization of two miscible monomers—a strongly solvated first monomer and a weakly solvated second monomer. When a chain segment with weak solvation capability is introduced, the solid electrolyte can promote the dissociation of lithium ions from the polymer chain and encourage more anions to participate in the formation of solvation structure contact ion pairs (CIPs) and ion aggregates (AGGs), thereby promoting the formation of a negative anion solvation structure in the solid electrolyte. Finally, an interface layer rich in inorganic components such as LiF is formed on the positive and negative electrode surfaces, and the uniformly deposited positive electrode interface CEI exhibits a bilayer structure: the dense outer LiF provides an efficient ion transport pathway and enhances the activity of the oxygen reduction reaction; the inner structure can significantly inhibit oxygen peroxidation on the positive electrode surface. In summary, the solid electrolyte proposed in this invention significantly improves the redox kinetics of the cathode active material under high voltage, effectively accelerates the interfacial ion transport kinetics in the solid battery, and effectively suppresses interfacial side reactions such as oxygen release involved in the operation of the solid battery, thereby improving the interfacial stability between the cathode active material and the electrolyte and enabling the solid battery to have excellent cycle stability.

[0029] It is understandable that the stability of the interfacial layer in a solid electrolyte depends critically on the chemical structure of the solid electrolyte, and constructing an inorganic-rich positive electrode electrolyte interfacial layer (CEI) can enhance the cycle stability of the battery. Forming a dense LiF passivation layer on the positive electrode surface deactivates its catalytic activity, thereby eliminating parasitic reactions and ensuring compatibility with both the positive and negative electrodes under high voltage.

[0030] According to an embodiment of the present invention, the molar ratio of the first monomer to the second monomer is 1:(1-9). For example, the molar ratio of the first monomer to the second monomer can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc. By controlling the molar ratio of the first monomer to the second monomer within the above range, the content of the weakly solvated second monomer is sufficient, which further promotes more anions to participate in the formation of solvated structure contact ion pairs (CIPs) and ion aggregates (AGGs) structures, promotes the formation of a solvated structure of negative anions in the solid electrolyte, and finally forms an interface layer rich in inorganic components such as LiF on the positive and negative electrode surfaces. The uniformly deposited positive electrode interface CEI exhibits a bilayer structure, thereby improving the cycle performance of the solid-state battery containing it.

[0031] According to embodiments of the present invention, the acrylic monomer containing the ether oxygen segment includes one or more of ethoxyethoxyethyl acrylate (EOEOEA), poly(ethylene glycol) methyl ether acrylate (PE), 2-methoxyethyl acrylate (2-MTA), and glycidyl methacrylate (GMA). Therefore, the solid electrolyte formed by copolymerizing the first and second monomers exhibits stronger interfacial stability with the positive electrode. The solvation structure forming negative anions in the solid electrolyte effectively accelerates the interfacial ion transport kinetics in the solid-state battery, thereby improving the reversibility, cycle performance, and rate performance of the electrochemical reaction in the solid-state battery containing it, and enhancing the overall battery performance.

[0032] According to some embodiments of the present invention, the fluorinated acrylic monomer includes one or more of fluoropropyl methacrylate (FF), heptafluorobutyl acrylate (SF), nonafluorohexyl acrylate (NF), dodecafluoroheptyl acrylate (TF), and pentafluorophenyl acrylate (PFA). Therefore, the solid electrolyte formed by copolymerizing the second and first monomers exhibits stronger interfacial stability with the positive electrode. The solvation structure forming negative anions in the solid electrolyte effectively accelerates interfacial ion transport kinetics in the solid-state battery, thereby improving the reversibility, cycle performance, and rate performance of the electrochemical reaction in the solid-state battery containing it, and enhancing the overall battery performance.

[0033] According to some embodiments of the present invention, the plasticizer includes one or more of ethylene glycol dimethyl ether (DME), ethylene glycol diethyl ether (DEE), tetraethylene glycol dimethyl ether (TEGDME), trimethyl phosphate (TMP), triethyl phosphate (TEP), fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), fluoroether (HFE), 1,3-dioxolane (DOL), and trioxymethylene (TXA). The above plasticizers can improve the stability and ionic conductivity of solid electrolytes, further improve the chemical stability of solid electrolytes, and thus improve the cycle performance of batteries containing them.

[0034] According to some embodiments of the present invention, the lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTfO), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium difluorooxalateborate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), and lithium nitrate (LiNO3). The above lithium salts have strong stability, higher thermal stability and stronger hydrolysis resistance compared to lithium hexafluorophosphate, and better compatibility with the polymer system used, further improving the chemical stability of the solid electrolyte and thus improving the cycle performance of the battery containing it.

[0035] According to some embodiments of the present invention, the initiator includes one or more of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), and potassium persulfate (KSO).

[0036] According to some embodiments of the present invention, based on the total mass of the solid electrolyte, the mass percentage of the lithium salt is 5%-50%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. By controlling the mass percentage of lithium salt in the solid electrolyte within the above range, the lithium salt content is high enough to help construct anion-rich solvation structure, but not so high as to affect the mechanical properties of the solid electrolyte, so that the solid battery has excellent cycle performance.

[0037] According to some embodiments of the present invention, based on the total mass of the solid electrolyte, the mass percentage of the plasticizer is 10%-50%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. Controlling the mass percentage of the plasticizer in the solid electrolyte within the above range ensures that the plasticizer content is high enough to help improve the ionic conductivity of the solid electrolyte, but not so high as to have a negative effect on the stability of the negative electrode, thereby improving the cycle performance of the battery containing it.

[0038] According to some embodiments of the present invention, the initiator accounts for 0.1%-5% of the total mass of the solid electrolyte. For example, it can be 0.1%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, etc. Controlling the mass percentage of the initiator in the solid electrolyte within the above range ensures that the solid electrolyte contains sufficient polymer monomers, which can improve the mechanical properties of the polymer electrolyte, inhibit dendrite growth, and ensure that the solid electrolyte has excellent ionic conductivity.

[0039] In a second aspect, the present invention provides a method for preparing the solid electrolyte described in the first aspect, comprising: S1. Under the protection of an inert gas, the first monomer and the second monomer are mixed to obtain a monomer mixture.

[0040] S2. Under inert gas protection, lithium salt, plasticizer and initiator are added to the monomer mixture, and the mixture is heated to polymerize, thereby obtaining a solid electrolyte.

[0041] According to some embodiments of the present invention, the inert gas in steps S1 and S2 has a water content of <0.1 ppm and an oxygen content of <0.1 ppm. For example, the water content can be 0.01 ppm, 0.03 ppm, 0.05 ppm, 0.07 ppm, 0.09 ppm, etc., and the oxygen content can be 0.01 ppm, 0.03 ppm, 0.05 ppm, 0.07 ppm, 0.09 ppm, etc. This can reduce side reactions, improve the stability of the solid electrolyte, and thus improve the cycle performance of the solid battery.

[0042] According to some embodiments of the present invention, the heating polymerization temperature is 60℃-100℃, and the time is 2h-12h. For example, the heating polymerization temperature can be 60℃, 70℃, 80℃, 90℃, 100℃, etc., and the heating polymerization time can be 2h, 4h, 5h, 7h, 9h, 10h, 12h, etc. Thus, by controlling the heating polymerization conditions within the above range, the monomers can fully react to form copolymers, thereby improving the cycle performance of solid-state batteries.

[0043] According to some embodiments of the present invention, the inert gas is at least one of helium and argon.

[0044] The following is a specific embodiment of the preparation of the solid electrolyte of the present invention: Under inert gas protection, lithium salt is added to a mixed solvent of monomers and plasticizers, followed by an initiator. The mixture is stirred thoroughly to obtain an electrolyte precursor solution. The solution is then heated to a certain temperature (60℃-100℃) and subjected to a polymerization reaction for a certain time (2h-12h) to obtain the desired polymer solid electrolyte.

[0045] In a third aspect, the present invention provides a solid-state battery. The solid-state battery includes the solid electrolyte described in the first aspect of the invention, or a solid electrolyte prepared using the method described in the second aspect. Thus, the solid-state battery containing this solid electrolyte exhibits excellent cycle performance.

[0046] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0047] Typically, a positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector, wherein the positive active material layer includes a positive active material.

[0048] In some embodiments of the present invention, the positive electrode current collector may include a metal foil or a composite positive electrode current collector. For example, the metal foil may be aluminum foil. The composite positive electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. For example, the composite positive electrode current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0049] As an example, the positive electrode active material includes, but is not limited to, at least one of metal oxide positive electrode active materials and polyanionic positive electrode active materials.

[0050] As an example, the metal oxide cathode active materials include, but are not limited to, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium-rich manganese-based materials, lithium manganese oxide (LiMn2O4), and lithium nickel-manganese oxide (LiNi). 0.5 Mn 1.5 At least one of O4, iron(III) oxide (Fe3O4), and lithium vanadate.

[0051] As an example, the polyanionic cathode active material includes, but is not limited to, at least one of lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), lithium manganese iron phosphate, lithium vanadium phosphate (Li3V2(PO4)3), lithium vanadium oxyphosphate (LiVOPO4), lithium cobalt phosphate (LiCoPO4), lithium nickel phosphate (LiNiPO4), lithium iron silicate (Li2FeSiO4), lithium iron fluorosulfate (LiFeSO4F), lithium iron borate (LiFeBO3), and lithium iron titanate (Li2FeTiO4).

[0052] According to some embodiments of the present invention, the solid-state battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes lithium-rich manganese-based morphological oxide (LRMO). LRMO has high specific capacity and high operating voltage, but when the charging voltage exceeds 4.5V, it faces challenges such as irreversible redox reactions and complex interface evolution at high voltages, which hinder the transport kinetics of lithium ions.

[0053] In the present invention, when the lithium-rich manganese-based layered oxide is used as the positive electrode active material in a solid-state battery, a double-layer CEI is formed at the positive electrode interface by the solid electrolyte. The outer dense LiF provides an efficient ion transport path, enhancing the activity of the oxygen reduction reaction; the inner layer structure replaces some of the surface unsaturated manganese coordination sites on the positive electrode surface with stable Mn-F, which can significantly inhibit the over-oxidation phenomenon of oxygen. That is to say, the lithium-rich manganese-based layered oxide in combination with the solid electrolyte of the present invention significantly improves the redox kinetic performance of the lithium-rich manganese-based layered oxide and effectively inhibits the interfacial side reactions such as oxygen release involved in the operation of the solid-state battery, resulting in excellent cycle performance, rate performance, and energy density of the solid-state battery.

[0054] It can be understood that the chemical general formula of the lithium-rich manganese-based layered oxide can be xLi2MnO3·(1-x)LiTMO2, where 0 < x < 1, and TM includes one or more of Ni, Co, and Mn.

[0055] According to some embodiments of the present invention, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0056] According to some embodiments of the present invention, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0057] According to some embodiments of the present invention, the positive electrode sheet can be prepared by the following method: dispersing the components for preparing the positive electrode sheet, such as the positive electrode active material, conductive agent, and binder, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0058] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0059] According to some embodiments of the present invention, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0060] According to some embodiments of the present invention, the negative electrode active material includes, but is not limited to, at least one of graphite, graphene, soft carbon, hard carbon, elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen composite materials, silicon-based alloys, elemental tin, tin oxides, tin-based alloys, lithium metal, lithium alloys, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

[0061] According to some embodiments of the present invention, the negative electrode active material layer may optionally include a binder. The binder may include at least one selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0062] According to some embodiments of the present invention, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0063] According to some embodiments of the present invention, the negative electrode active material layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0064] According to some embodiments of the present invention, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0065] According to some embodiments of the present invention, the solid-state battery includes a negative electrode sheet, the negative electrode sheet includes a negative current collector, and metallic lithium is deposited in situ on the negative current collector during charging. Thus, the solid-state battery is a negative-electrode lithium-ion solid-state battery. During the preparation of the solid-state battery, there is no lithium metal in the negative electrode, i.e., only the negative current collector is included. Therefore, the amount of negative electrode used is relatively small, and the solid-state battery exhibits excellent cycle performance and energy density. Experiments have shown that a negative-electrode-free pouch battery (9.0 Ah) using the solid electrolyte of the present invention achieves 604 Wh / kg. -1 and 1027WhL -1 Its ultra-high energy density.

[0066] This invention does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0067] According to some embodiments of the present invention, the material of the separator may include at least one of glass fiber, non-woven fabric, polyolefin membrane, aromatic polyamide membrane, polytetrafluoroethylene membrane, and polyethersulfone membrane.

[0068] According to some embodiments of the present invention, the thickness of the isolation membrane can be 10μm-25μm, for example, 10μm, 11μm, 12μm, 25μm, etc.

[0069] The present disclosure will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0070] Example 1 Preparation of electrolyte precursor fluid The first monomer, ethoxyethoxyethyl acrylate (EOEOEA), and the second monomer, butyl heptafluoroacrylate (SF), were mixed in a molar ratio of 1:1 to obtain a monomer mixture. LiTFSI and LiTfO were added to the monomer mixture, with the mass fraction of LiTFSI and LiTfO in the electrolyte precursor solution being 10%. Add 10% by weight of plasticizer DME to the electrolyte precursor fluid and 0.1% by weight of initiator AIBN to obtain the electrolyte precursor fluid.

[0071] Since the electrolyte precursor fluid eventually forms a solid electrolyte, the above-mentioned mass percentage is the mass percentage of the electrolyte precursor fluid, which is also the mass percentage of the solid electrolyte.

[0072] Solid-state battery fabrication Positive electrode preparation: The positive electrode active material (chemical formula Li) is prepared... 1.2 Mn 0.54 Co 0.13 Ni 0.13 O2 (LRMO), binder PVDF, and conductive agent carbon black are dispersed in N-methylpyrrolidone in a mass ratio of 8:1:1 to form a positive electrode slurry. The positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0073] Negative electrode preparation: The negative electrode consists only of a negative current collector, which is a copper foil with a thickness of 6 μm.

[0074] The positive electrode, electrolyte precursor liquid, separator (made of polyethylene with a thickness of 25μm), and negative electrode are assembled into the battery in sequence. The in-situ polymerization of the electrolyte is completed by reacting at 60℃ for 4 hours. After standing for 6 hours, the solid-state battery is prepared.

[0075] Example 2 Preparation of electrolyte precursor fluid The first monomer, 2-methoxyethyl 2-acrylate (2-MTA), and the second monomer, fluoropropyl methacrylate (FF), were mixed in a molar ratio of 1:1 to obtain a monomer mixture. LiTFSI and LiFSI were added to the monomer mixture, with the mass fraction of LiTFSI and LiFSI in the electrolyte precursor solution being 20%. Add 20% (w / w) of plasticizer DEE to the electrolyte precursor fluid and 0.2% (w / w) of initiator AIBN to the electrolyte precursor fluid to obtain the electrolyte precursor fluid.

[0076] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0077] Example 3 Preparation of electrolyte precursor fluid The first monomer, poly(ethylene glycol) methyl ether acrylate (PE), and the second monomer, butyl heptafluoroacrylate (SF), were mixed in a molar ratio of 1:1 to obtain a monomer mixture. LiTFSI was added to the monomer mixture, with a mass fraction of 24% in the electrolyte precursor solution. Add 30% by mass of plasticizer TMP to the electrolyte precursor fluid and 0.2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0078] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0079] Example 4 Preparation of electrolyte precursor fluid The first monomer, glycidyl methacrylate (GMA), and the second monomer, nonafluorohexyl acrylate (NF), were mixed at a molar ratio of 1:1 to obtain a monomer mixture. LiFSI and LiNO3 were added to the monomer mixture, with the mass fraction of LiFSI and LiNO3 in the electrolyte precursor solution being 36%. Add 40% by mass of plasticizer FEC to the electrolyte precursor fluid and 2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0080] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0081] Example 5 Preparation of electrolyte precursor fluid The first monomer, glycidyl methacrylate (GMA), and the second monomer, nonafluorohexyl acrylate (NF), were mixed at a molar ratio of 1:1 to obtain a monomer mixture. LiFSI and LiClO4 were added to the monomer mixture, with the mass fraction of LiFSI and LiClO4 in the electrolyte precursor solution being 30%. Add 35% HFE plasticizer and 2% BPO initiator to the electrolyte precursor solution to obtain the electrolyte precursor solution.

[0082] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0083] Example 6 Preparation of electrolyte precursor fluid The first monomer, poly(ethylene glycol) methyl ether acrylate (PE), and the second monomer, butyl heptafluoroacrylate (SF), were mixed in a molar ratio of 1:1 to obtain a monomer mixture. LiTFSI was added to the monomer mixture, with a mass fraction of 24% in the electrolyte precursor solution. Add 30% by mass of plasticizer TMP to the electrolyte precursor fluid and 0.5% by mass of initiator KSO to obtain the electrolyte precursor fluid.

[0084] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0085] Example 7 Preparation of electrolyte precursor fluid The first monomer, poly(ethylene glycol) methyl ether acrylate (PE), and the second monomer, nonafluorohexyl acrylate (NF), were mixed in a molar ratio of 1:1 to obtain a monomer mixture. LiFSI was added to the monomer mixture, with the mass fraction of LiFSI in the electrolyte precursor solution being 30%. Add 30% by mass of plasticizer TEP to the electrolyte precursor fluid and 0.2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0086] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0087] Example 8 Preparation of electrolyte precursor fluid The first monomer, poly(ethylene glycol) methyl ether acrylate (PE), and the second monomer, butyl heptafluoroacrylate (SF), were mixed in a molar ratio of 1:4 to obtain a monomer mixture. LiTFSI was added to the monomer mixture, with a mass fraction of 24% in the electrolyte precursor solution. Add 30% by mass of plasticizer TMP to the electrolyte precursor fluid and 0.2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0088] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0089] Example 9 Preparation of electrolyte precursor fluid The first monomer, poly(ethylene glycol) methyl ether acrylate (PE), and the second monomer, butyl heptafluoroacrylate (SF), were mixed in a molar ratio of 1:9 to obtain a monomer mixture. LiTFSI was added to the monomer mixture, with a mass fraction of 24% in the electrolyte precursor solution. Add 30% by mass of plasticizer TMP to the electrolyte precursor fluid and 0.2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0090] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0091] Example 10 Preparation of electrolyte precursor fluid The first monomer, poly(ethylene glycol) methyl ether acrylate (PE), and the second monomer, nonafluorohexyl acrylate (NF), were mixed in a molar ratio of 1:9 to obtain a monomer mixture. LiTFSI was added to the monomer mixture, with a mass fraction of 24% in the electrolyte precursor solution. Add 30% by mass of plasticizer TMP to the electrolyte precursor fluid and 0.2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0092] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0093] Comparative Example 1 Preparation of electrolyte precursor fluid Poly(ethylene glycol) methyl ether acrylate (PE) was selected as the monomer solution, and LiTFSI was added to the monomer solution. The mass fraction of LiTFSI in the electrolyte precursor fluid was 20%. Add 30% by mass of plasticizer TEP to the electrolyte precursor fluid and 0.2% by mass of initiator AIBN to obtain the electrolyte precursor fluid.

[0094] Solid-state batteries are assembled using the electrolyte precursor fluid; the processes and parameters not specified in this embodiment are the same as in Example 1.

[0095] Testing and Analysis 1. Raman spectroscopy was performed on the solid electrolytes of Examples 1-3 and Comparative Example 1, as well as the lithium salt (LiTFSI), to analyze the solvation structure of the solid electrolytes. The results were obtained. Figure 1 As can be seen, in the solid electrolyte of Comparative Example 1, lithium salt anions are mainly in the form of free anions (FA), and anions hardly participate in the solvation structure of lithium ions. In the solid electrolytes of Examples 1-3, the proportion of contact ion pairs (CIP) and aggregates (AGG) increases, indicating that more anions participate in the solvation structure of lithium ions, forming an anion-rich solvation structure.

[0096] 2. The CEI of the lithium-rich manganese-based substrate oxide surface in Example 1 was analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMs), and the results were obtained. Figure 2 ,Depend on Figure 2 It can be seen that with increasing splashing time, LiF2 is observed preferentially.- The signal intensity increased, indicating that the outer layer of CEI is mainly composed of LiF; with further increase in sputtering time, MnF3 - The increased signal intensity indicates that the inner layer of the CEI is primarily composed of Mn-F. The above characterization analysis demonstrates that, using the solid electrolyte of this embodiment, a bilayer CEI structure is formed on the surface of the lithium-rich manganese-based basal oxide.

[0097] 3. Solid-state battery 1.0 C first-cycle, 100-cycle specific capacity, and 100-cycle capacity retention rate test: Test voltage range: 2.0-4.7 V. Activation was performed at 0.05 C in the first cycle, followed by long-cycle testing at 1.0 C. (1.0 C = 250 mAh g) -1 ).

[0098] The test results are shown in Table 1.

[0099] The cycle performance graphs for Example 3 and Comparative Example 1 are shown below. Figure 3 As shown, it can be seen that, compared with Example 1, the solid-state battery containing the solid electrolyte of Example 3 of the present invention has excellent cycle performance.

[0100] Table 1

[0101] According to Table 1, the solid electrolyte of this invention is used to assemble a solid battery. The performance results in Table 1 are compared with those of Comparative Example 1: the specific capacity can be increased by 3-26 mAh / g, the rate response under high current density is improved, and the capacity retention rate after 100 cycles is increased from 42.3% to a maximum of 90.0%.

[0102] In summary, the solid-state electrolyte of this invention employs a copolymer structure of strongly and weakly coordinated monomers, which promotes the formation of anion-rich solvation structures and constructs a stable bilayer CEI structure consisting of a LiF-rich outer layer and a Mn-F-rich inner layer. This suppresses oxygen release from the cathode surface and improves cathode stability. The solid-state electrolyte proposed in this invention improves the reversibility of electrochemical reactions, cycle performance, and rate performance, thereby enhancing the overall battery performance. It achieves ultra-high energy density in pouch cells.

[0103] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," "some implementations," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. 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, without contradiction, 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.

[0104] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A solid state electrolyte, characterized by, Raw material components of the solid-state electrolyte include: a lithium salt, a polymer monomer, a plasticizer and an initiator, the polymer monomer includes a first monomer and a second monomer; The first monomer includes an ether oxygen chain segment-containing acrylic monomer; The second monomer includes one or more of a fluorine-containing acrylic monomer and a weak polar functional group-containing acrylic monomer, wherein the weak polar functional group-containing acrylic monomer includes one or more of an amino acrylate, 2,3-dibromopropyl acrylate, 2-(trimethylsiloxy)ethyl methacrylate, and isobornyl methacrylate.

2. The solid-state electrolyte of claim 1, wherein, The mass ratio of the first monomer to the second monomer is 1: (1-9).

3. The solid-state electrolyte of claim 1 or 2, wherein, The ether oxygen chain segment-containing acrylic monomer includes one or more of ethoxyethoxyethyl acrylate, poly(ethylene glycol) methyl ether acrylate, 2-methoxyethyl acrylate, and glycidyl methacrylate.

4. The solid-state electrolyte of claim 1 or 2, wherein, The fluorine-containing acrylic monomer includes one or more of perfluoropropyl methacrylate, heptafluorobutyl acrylate, nonafluorohexyl acrylate, dodecafluoroheptyl acrylate, and pentafluorophenyl acrylate.

5. The solid-state electrolyte of claim 1 or 2, wherein, The plasticizer includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, trimethyl phosphate, triethyl phosphate, fluoroethylene carbonate, dimethyl carbonate, fluoroether, 1,3-dioxolane, and trimeric formaldehyde; and / or, The lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(pentafluoroethanesulfonyl)imide, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium perchlorate, and lithium nitrate; and / or, The initiator includes one or more of azobisisobutyronitrile, dibenzoyl peroxide, and potassium persulfate.

6. The solid-state electrolyte of claim 1 or 2, wherein, The mass percentage of the lithium salt is 5%-50% based on the total mass of the solid-state electrolyte; and / or, The mass percentage of the plasticizer is 10%-50% based on the total mass of the solid-state electrolyte; and / or, The mass percentage of the initiator is 0.1%-5% based on the total mass of the solid-state electrolyte.

7. A method of preparing the solid-state electrolyte of any one of claims 1-6, characterized in that, The method includes: Mixing the first monomer and the second monomer under inert gas protection to obtain a monomer mixture; Adding the lithium salt, the plasticizer and the initiator to the monomer mixture under inert gas protection, and heating to polymerize to obtain the solid-state electrolyte.

8. The method of claim 7, wherein, The inert gas has a water content of <0.1 ppm and an oxygen content of <0.1 ppm; and / or, The temperature of the heating polymerization is 60-100°C, and the time is 2-12 h.

9. A solid state battery, characterized by The battery includes the solid-state electrolyte of any one of claims 1-6 or the solid-state electrolyte prepared by the method of claim 7 or 8.

10. The solid-state battery of claim 9, wherein, The solid-state battery includes a positive electrode sheet, and the positive electrode sheet includes a lithium-rich manganese-based layered oxide; and / or, The solid-state battery includes a negative electrode sheet, and the negative electrode sheet includes a negative electrode current collector, and the solid-state battery forms metal lithium in situ on the negative electrode current collector when charging.

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