High-dispersity and low-crystallinity composite solid electrolyte and all-solid-state lithium metal battery

Abstract

The invention relates to the technical field of batteries, in particular to a high-dispersity and low-crystallinity composite solid electrolyte and an all-solid-state lithium metal battery. The composite solid electrolyte comprises a polymer matrix, a lithium salt, an inorganic filler and a quaternary ammonium salt surfactant, the mass ratio of the polymer matrix to the lithium salt to the inorganic filler to the quaternary ammonium salt surfactant is 100: (60-80): (10-20): (1-15). Through the quaternary ammonium salt additive, the inorganic filler is uniformly dispersed in a polymer matrix, and the crystallinity of polyethylene oxide (PEO) is effectively reduced, so that the ion transmission performance of the electrolyte and the cycling stability of a battery are remarkably improved, and the problem that organic-inorganic interfaces between PEO and LLZTO in the composite solid electrolyte are incompatible is systematically solved; and a key technical path is provided for developing a new generation of energy storage devices with high safety, long cycle life and excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state lithium metal battery technology, specifically to a highly dispersed, low-crystallinity composite solid electrolyte and an all-solid-state lithium metal battery. Background Technology

[0002] With the increasing global demand for sustainable energy and the rapid development of the new energy industry, lithium-ion batteries, as one of the most widely used energy storage devices, occupy an important position in consumer electronics, electric vehicles, and large-scale energy storage. However, traditional liquid electrolytes pose safety hazards such as flammability, leakage, and short circuits caused by lithium dendrite growth, and their energy density is gradually approaching its theoretical limit, making it difficult to meet the future demands for high-energy-density and high-safety energy storage. Against this backdrop, lithium metal solid-state batteries have emerged as a promising alternative due to their high theoretical specific capacity (3860 mAh·g). -1 With its low redox potential (-3.04V vs. SHE), it is considered a core solution for the next generation of power batteries, and solid electrolyte (SSE), as its core component, directly determines the upper limit of battery performance.

[0003] Currently, widely studied solid-state electrolytes mainly fall into three categories: inorganic solid-state electrolytes, polymer solid-state electrolytes, and organic / inorganic composite solid-state electrolytes. Polymer solid-state electrolytes include polyethylene oxide (PEO), polyacrylonitrile (PAC), and polyvinylidene fluoride (PVDF). PEO-based polymer solid-state electrolytes are the most widely studied polymer electrolytes. While they are easy to prepare, have controllable shapes, low cost, and good flexibility, their high crystallinity at room temperature leads to insufficient ionic conductivity and a narrow electrochemical window, making them difficult to meet commercialization requirements. Polymer solid-state electrolytes primarily conduct lithium ions through chain segment movement in amorphous regions. To reduce crystallinity and improve ionic conductivity, common methods or strategies include cross-linking, forming block copolymers, adding plasticizers, and introducing inorganic fillers. Among all these attempts, dispersing inorganic fillers within a polymer matrix to synthesize organic / inorganic composite solid-state electrolytes is considered a highly promising technology for solid-state lithium metal batteries. This is because this composite approach can not only effectively improve ionic conductivity but also, to some extent, enhance the electrolyte's mechanical properties and thermal stability.

[0004] Among them, LLZTO (Li 6.4 La3Zr 1.4 Ta 0.6 O 12As a typical perovskite-type inorganic solid electrolyte, LLZTO possesses high ionic conductivity and good chemical stability, and is widely used in the modification of PEO-based composite solid electrolytes. However, the surface of LLZTO contains a large number of hydroxyl groups, which easily undergo side reactions with the PEO matrix. Furthermore, LLZTO particles tend to agglomerate, resulting in poor dispersion within the PEO matrix. Consequently, the composite solid electrolyte exhibits high interfacial contact impedance, and the ion transport efficiency still falls short of the requirements for high-performance solid-state batteries.

[0005] In summary, existing organic / inorganic composite solid-state electrolytes still suffer from the following key problems: 1. Filler agglomeration and uneven dispersion: Inorganic fillers are prone to agglomeration in polymer matrices, leading to reduced crystallinity, discontinuous ion transport channels, and exacerbating uneven lithium dendrite deposition. 2. Poor interfacial compatibility: Insufficient interfacial compatibility between polymers and inorganic fillers reduces the interfacial contact area, lowers ion transport efficiency, and increases interfacial impedance. 3. Balancing mechanical properties and conductivity: While high inorganic filler content improves conductivity, it may worsen interfacial compatibility and induce lithium dendrite growth. Therefore, developing a composite solid-state electrolyte that can simultaneously address the problems of poor inorganic filler dispersion and high polymer matrix crystallinity is of great significance for promoting the industrialization of solid-state lithium metal batteries. Summary of the Invention

[0006] In view of this, the purpose of this invention is to solve the compatibility problem between polymers and inorganic fillers, achieve uniform dispersion of nanofillers in polymers, thereby improving the performance of composite solid-state electrolytes and promoting the practical application of all-solid-state lithium metal batteries. To this end, this invention provides a highly dispersible, low-crystallinity composite solid-state electrolyte and an all-solid-state lithium metal battery. Quaternary ammonium salt additives are used in the solid electrolyte to achieve uniform dispersion of inorganic fillers in the polymer matrix and effectively reduce the crystallinity of polyethylene oxide (PEO), thereby significantly improving the ion transport performance of the electrolyte and the cycle stability of the battery. This method systematically solves the problem of organic-inorganic interface incompatibility between PEO and LLZTO in composite solid-state electrolytes by optimizing the distribution of fillers, providing a key technical path for developing next-generation energy storage devices with high safety, long cycle life, and excellent electrochemical performance.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: According to one aspect of the present invention, a highly dispersible, low-crystallinity composite solid electrolyte is provided, comprising a polymer matrix, a lithium salt, an inorganic filler, and a quaternary ammonium salt surfactant. The mass ratio of the polymer matrix, lithium salt, inorganic filler, and quaternary ammonium salt surfactant is 100:60~80:10~20:1~15.

[0008] In some embodiments, the weight ratio of the inorganic filler to the quaternary ammonium salt surfactant is 1:5~20.

[0009] In some embodiments, the inorganic filler includes at least one of lithium lanthanum zirconium tantalum oxide (LLZTO), lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), lithium zirconium chloride (Li2ZrCl6), lithium tantalum chloride (LiTaCl6), lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LGTP), and lithium phosphorus sulfur chloride (LPSCl).

[0010] In some embodiments, the polymer is at least one of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene chloride (PVDC), and polypropylene oxide (PPO).

[0011] In some of these embodiments, the polymer is polyethylene oxide (PEO).

[0012] In some of these embodiments, the lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiBF4 (lithium tetrafluoroborate), LiPF6 (lithium hexafluorophosphate), LiClO4 (lithium perchlorate), lithium bis(oxalateborate) (LiBOB), lithium trifluoromethanesulfonate (LiCF3SO3), lithium arsenate (LiAsF4), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0013] In some of these embodiments, the lithium salt is lithium bis(trifluoromethanesulfonylimide) (LiTFSI).

[0014] In some of these embodiments, the quaternary ammonium salt surfactant is selected from at least one of tetrabutylammonium fluoride (TBAF), hexadecyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride (OTAC), and hexadecyltrimethylammonium bromide (CTAB).

[0015] In some of these embodiments, the quaternary ammonium salt surfactant is tetrabutylammonium fluoride (TBAF).

[0016] The tetrabutylammonium fluoride (TBAF) is a key modifier, not merely used as a conventional dispersant, but rather used to fluorinate the LLZTO surface through in-situ reaction, while simultaneously adjusting the crystallinity of the PEO segments, specifically achieving the following functions: 1. The F⁻ ions in TBAF undergo an in-situ substitution reaction with the hydroxyl groups (-OH) on the surface of LLZTO, eliminating the active hydroxyl groups on the surface of LLZTO, inhibiting the side reactions between LLZTO and the PEO matrix, and forming a Li-F inorganic interface layer rich in F on the surface of LLZTO. This interface layer has excellent ionic conductivity and can serve as a fast transport channel for Li⁺ in the composite electrolyte, reducing the interfacial transport barrier. 2. The quaternary ammonium salt cations in TBAF can be embedded in the intercrystalline interstices of PEO, disrupting the regular arrangement of PEO molecular chains, reducing the crystallinity of PEO, and improving the room temperature mobility of PEO chain segments, thereby improving the overall ionic conductivity of the composite electrolyte. 3. The formed fluorine-based interfacial phase can induce the formation of stable SEI (solid electrolyte interfacial phase) and CEI (cathode electrolyte interfacial phase) at the interface between the solid electrolyte and the electrode, inhibiting the growth and penetration of lithium dendrites, while reducing interfacial side reactions between the electrolyte and the electrode, and improving the cycle stability of the composite electrolyte.

[0017] In some embodiments, the composite solid electrolyte further includes an organic solvent; The organic solvent is at least one of methanol, ethanol, isopropanol, and acetonitrile.

[0018] According to another aspect of the present invention, the present invention also provides an all-solid-state lithium metal battery, comprising an electrolyte, a negative electrode and a positive electrode; wherein the electrolyte comprises the above-described composite solid-state electrolyte.

[0019] In some of these embodiments, the negative electrode is a lithium metal negative electrode.

[0020] In some of these embodiments, the lithium metal anode is at least one of lithium metal foil, lithium sheet, lithium alloy, hard carbon, or titanium-based anode.

[0021] In some of these embodiments, the positive electrode includes a current collector, a positive electrode active material, a binder, and a conductive agent.

[0022] In some embodiments, the current collector is an aluminum foil, a carbon-coated aluminum foil, or a stainless steel foil.

[0023] In some embodiments, the positive electrode active material is selected from at least one of lithium iron phosphate, lithium vanadium phosphate, lithium manganese oxide, lithium titanium chloride, and lithium cobalt oxide.

[0024] In some embodiments, the adhesive is selected from at least one of polyvinylidene fluoride, polyamide, polyvinyl alcohol, and carboxymethyl cellulose.

[0025] In some of these embodiments, the conductive agent is selected from at least one of acetylene black, Ketjen black, and Super P.

[0026] According to another aspect of the present invention, the present invention also provides a method for preparing the above-mentioned all-solid-state lithium metal battery, comprising the following steps: (1) Preparation of composite solid electrolyte; (2) Preparation of positive electrode sheet: The raw materials including positive electrode active material, binder and conductive agent are coated on the current collector; (3) Assembly.

[0027] In some of these embodiments, step (1) includes: first mixing the inorganic filler and the quaternary ammonium salt surfactant; then adding the polymer matrix and the lithium salt.

[0028] In some embodiments, step (1) of the preparation method of the composite solid electrolyte includes the following steps: S1 LLZTO surface in-situ fluorine modification treatment: LLZTO inorganic filler was dispersed in an organic solvent and stirred to form a uniform suspension. Quaternary ammonium salt surfactants were added to the suspension and stirred at 30-80℃ for 6-24 hours. After the reaction was completed, the solid product was collected by centrifugation and washed 3-5 times with the same organic solvent to remove unreacted quaternary ammonium salt surfactants. Finally, the washed solid product was placed in a vacuum drying oven and dried at 60-80℃ for 12-24 hours to obtain the surface-modified inorganic filler. The organic solvent is at least one selected from methanol, ethanol, isopropanol, and acetonitrile, preferably ethanol; Preparation of S2 composite electrolyte slurry: Weigh the polymer matrix and lithium salt according to the mass ratio. Add the polymer matrix to the organic solvent and stir at 50-70℃ until the polymer matrix is ​​completely dissolved to form a polymer matrix solution. Add the lithium salt to the polymer matrix solution and continue stirring for 2-6 hours until the lithium salt is completely dissolved to obtain a mixed solution. Add the surface-modified inorganic filler prepared in step S1 and stir at room temperature for 8-16 hours until a uniform, particle-free mixed slurry is formed. S3 Composite Solid Electrolyte Membrane Molding: The mixed slurry obtained in step S2 is uniformly coated onto a clean polytetrafluoroethylene plate by casting, with the casting thickness controlled at 50-200 μm. The substrate coated with the slurry is placed in a vacuum drying oven and dried at 40-80℃ for 12-24 h to remove organic solvents, thus obtaining a pre-formed composite electrolyte membrane. The pre-formed composite electrolyte membrane is peeled off from the substrate, placed in a mold, and hot-pressed at 60-120℃ and 5-15 MPa for 5-30 min. After cooling to room temperature, a uniform, dense, highly stable, low-resistance PEO-based composite solid electrolyte membrane is obtained.

[0029] In step S2, the organic solvent is at least one of methanol, ethanol, isopropanol and acetonitrile, preferably acetonitrile. Acetonitrile has excellent solubility for quaternary ammonium salt additives and lithium salts, and has a moderate boiling point, making it easy to dry and remove. It is also compatible with ethanol, which simplifies the solvent recovery process.

[0030] Implementing the technical solution of the present invention has at least the following beneficial effects: 1. This invention constructs an "organic additive (TBAF, chemical formula C)". 16 H 36 FN), inorganic filler (chemical formula Li) 6.4 La3Zr 1.4 Ta 0.6 O 12 A quaternary synergistic system of LLZTO, polymer matrix (PEO), and lithium salt (LiTFSI) was developed. In-situ surface modification of LLZTO was achieved by introducing tetrabutylammonium fluoride. Utilizing the interaction between F⁻ ions and the LLZTO lattice, hydroxyl groups on the LLZTO surface were eliminated, constructing a F-rich interfacial transition layer with high ion transport capacity on the filler surface. This interfacial layer not only effectively improved the dispersion of LLZTO in the PEO matrix, but more importantly, broke through the traditional PEO / LLZTO interface transport barrier, lowered the Li⁺ transport barrier, and significantly improved the room-temperature ionic conductivity and mechanical strength of the composite solid electrolyte. Simultaneously, the addition of tetrabutylammonium fluoride constructed a stable fluorine-based interfacial phase, suppressing interfacial side reactions and lithium dendrite growth. The resulting lithium metal battery exhibited excellent cycle stability at 0.5C, overcoming the limitations of traditional single-modification strategies and meeting the practical application requirements of solid-state lithium metal batteries.

[0031] 2. This invention is the first to apply tetrabutylammonium fluoride (TBAF) to the modification of PEO / LLZTO-based composite solid electrolytes, breaking through the technical limitation that conventional surfactants can only improve dispersibility. Through in-situ fluorine modification reaction, a Li-F inorganic interface layer is formed on the LLZTO surface, which not only eliminates the side reactions caused by the active hydroxyl groups on the LLZTO surface, but also constructs a Li⁺ fast transport channel, significantly reducing the interfacial contact resistance of the composite electrolyte and improving the ionic conductivity.

[0032] 3. This invention effectively reduces the crystallinity of PEO by embedding the quaternary ammonium salt cation of TBAF into the PEO crystal region, thereby improving the room-temperature mobility of PEO chain segments and further optimizing the overall ion transport efficiency of the composite electrolyte. The resulting composite solid electrolyte achieves a room-temperature ionic conductivity of 1.2 × 10⁻⁻⁻⁶. 4 -1.5×10⁻ 4 The S / cm ratio is much higher than that of pure PEO electrolyte and conventional PEO / LLZTO composite electrolyte without TBAF modification.

[0033] 4. The composite solid electrolyte prepared by this invention has significantly improved mechanical strength, with tensile strength reaching 25-35 MPa. At the same time, the stable SEI / CEI interface phase induced by the fluorine-based interface phase effectively inhibits the growth and penetration of lithium dendrites. Lithium symmetric batteries using this electrolyte can cycle stably for more than 1000 hours without short circuits, which is far superior to the cycle stability of conventional composite electrolytes.

[0034] 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

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0036] Figure 1 The XRD patterns are of the composite solid electrolytes prepared in Example 1 and Comparative Example 3.

[0037] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0038] The present application will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0039] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[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] In the field of all-solid-state lithium metal batteries, a commonly used technical approach to achieve a solid electrolyte with both high ionic conductivity and good mechanical properties is to incorporate inorganic fillers into a polymer matrix to prepare an organic / inorganic composite solid electrolyte. Specifically, this approach involves mixing a polymer matrix, lithium salt, and inorganic solid electrolyte powder in a solvent, followed by casting into a film. Its basic working principle is to combine the flexibility of the polymer phase with the ionic conductivity of the inorganic filler to construct a continuous ion transport network. It has been widely studied primarily because it theoretically offers a good balance between ionic conductivity and interfacial contact performance.

[0047] However, when this approach is applied to practical battery systems that aim for higher energy density and cycle stability, its performance is less than ideal. A fundamental contradiction lies in the fact that while this approach introduces more inorganic fillers to improve ionic conductivity, its inherent design inevitably compromises the uniformity of filler dispersion in the matrix, and may even disrupt ion transport channels. Specifically, in a typical composite system of polyethylene oxide and garnet oxide fillers, as the filler content increases, particle agglomeration intensifies, disrupting continuous ion transport paths and causing a bottleneck in improving ionic conductivity.

[0048] Through in-depth analysis, the inventors discovered that the root causes of the aforementioned contradictions are multifaceted: From the perspective of filler dispersion, inorganic filler nanoparticles have high surface energy and lack effective physical or chemical interactions with the polymer matrix, making them prone to aggregation during solution blending and film formation. From the perspective of polymer crystallinity, polymer matrices, represented by polyethylene oxide, have chains that easily arrange themselves in an orderly manner to form highly crystalline regions, while lithium ion migration mainly occurs in amorphous regions, and higher crystallinity significantly hinders ion transport. These factors combined make it difficult for traditional simple blending strategies to simultaneously optimize filler dispersion and matrix crystallinity, limiting breakthroughs in the overall performance of composite electrolytes.

[0049] To overcome the aforementioned contradictions, this invention proposes a different technical approach. Its core concept lies in introducing a specific organic additive into a composite system comprising a polymer matrix, lithium salt, and inorganic filler, thereby synergistically improving two key aspects: the filler-matrix interface and the polymer chain arrangement. This additive can act simultaneously on the surface of the inorganic filler and the polymer molecular chains, effectively promoting uniform dispersion of the filler and inhibiting polymer crystallization without significantly sacrificing the mechanical integrity of the electrolyte. In other words, a composite component design strategy is provided to address the problem of uneven filler dispersion and high polymer crystallinity jointly restricting ion transport in composite solid electrolytes, offering a pathway to construct more efficient and stable ion conduction channels. Specifically, the specific implementation scheme of this invention is as follows: According to one aspect of the present invention, a highly dispersible, low-crystallinity composite solid electrolyte is provided, comprising a polymer matrix, a lithium salt, an inorganic filler, and a quaternary ammonium salt surfactant. The mass ratio of the polymer matrix, lithium salt, inorganic filler, and quaternary ammonium salt surfactant is 100:60~80:10~20:1~15.

[0050] In some embodiments, the weight ratio of the inorganic filler to the quaternary ammonium salt surfactant is 1:5~20.

[0051] In some embodiments, the inorganic filler includes at least one of lithium lanthanum zirconium tantalum oxide (LLZTO), lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), lithium zirconium chloride (Li2ZrCl6), lithium tantalum chloride (LiTaCl6), lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LGTP), and lithium phosphorus sulfur chloride (LPSCl).

[0052] In some embodiments, the polymer is at least one of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene chloride (PVDC), and polypropylene oxide (PPO).

[0053] In some of these embodiments, the polymer is polyethylene oxide (PEO).

[0054] In some of these embodiments, the lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiBF4 (lithium tetrafluoroborate), LiPF6 (lithium hexafluorophosphate), LiClO4 (lithium perchlorate), lithium bis(oxalateborate) (LiBOB), lithium trifluoromethanesulfonate (LiCF3SO3), lithium arsenate (LiAsF4), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0055] In some of these embodiments, the lithium salt is lithium bis(trifluoromethanesulfonylimide) (LiTFSI).

[0056] In some of these embodiments, the quaternary ammonium salt surfactant is selected from at least one of tetrabutylammonium fluoride (TBAF), hexadecyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride (OTAC), and hexadecyltrimethylammonium bromide (CTAB).

[0057] In some of these embodiments, the quaternary ammonium salt surfactant is tetrabutylammonium fluoride (TBAF).

[0058] The tetrabutylammonium fluoride (TBAF) is a key modifier, not merely used as a conventional dispersant, but rather used to fluorinate the LLZTO surface through in-situ reaction, while simultaneously adjusting the crystallinity of the PEO segments, specifically achieving the following functions: 1. The F⁻ ions in TBAF undergo an in-situ substitution reaction with the hydroxyl groups (-OH) on the surface of LLZTO, eliminating the active hydroxyl groups on the surface of LLZTO, inhibiting the side reactions between LLZTO and the PEO matrix, and forming a Li-F inorganic interface layer rich in F on the surface of LLZTO. This interface layer has excellent ionic conductivity and can serve as a fast transport channel for Li⁺ in the composite electrolyte, reducing the interfacial transport barrier. 2. The quaternary ammonium salt cations in TBAF can be embedded in the intercrystalline interstices of PEO, disrupting the regular arrangement of PEO molecular chains, reducing the crystallinity of PEO, and improving the room temperature mobility of PEO chain segments, thereby improving the overall ionic conductivity of the composite electrolyte. 3. The formed fluorine-based interfacial phase can induce the formation of stable SEI (solid electrolyte interfacial phase) and CEI (cathode electrolyte interfacial phase) at the interface between the solid electrolyte and the electrode, inhibiting the growth and penetration of lithium dendrites, while reducing interfacial side reactions between the electrolyte and the electrode, and improving the cycle stability of the composite electrolyte.

[0059] In some embodiments, the composite solid electrolyte further includes an organic solvent; The organic solvent is at least one of methanol, ethanol, isopropanol, and acetonitrile.

[0060] According to another aspect of the present invention, the present invention also provides an all-solid-state lithium metal battery, comprising an electrolyte, a negative electrode and a positive electrode; wherein the electrolyte comprises the above-described composite solid-state electrolyte.

[0061] In some of these embodiments, the negative electrode is a lithium metal negative electrode.

[0062] In some of these embodiments, the lithium metal anode is at least one of lithium metal foil, lithium sheet, lithium alloy, hard carbon, or titanium-based anode.

[0063] In some of these embodiments, the positive electrode includes a current collector, a positive electrode active material, a binder, and a conductive agent.

[0064] In some embodiments, the current collector is an aluminum foil, a carbon-coated aluminum foil, or a stainless steel foil; In some of these embodiments, the positive electrode active material is selected from at least one of lithium iron phosphate, lithium vanadium phosphate, lithium manganese oxide, lithium titanium chloride, and lithium cobalt oxide. In some embodiments, the adhesive is selected from at least one of polyvinylidene fluoride, polyamide, polyvinyl alcohol, and carboxymethyl cellulose; In some of these embodiments, the conductive agent is selected from at least one of acetylene black, Ketjen black, and Super P.

[0065] According to another aspect of the present invention, the present invention also provides a method for preparing the above-mentioned all-solid-state lithium metal battery, comprising the following steps: (1) Preparation of composite solid electrolyte; (2) Preparation of positive electrode sheet: The raw materials including positive electrode active material, binder and conductive agent are coated on the current collector; (3) Assembly.

[0066] In some of these embodiments, step (1) includes: first mixing the inorganic filler and the quaternary ammonium salt surfactant; then adding the polymer matrix and the lithium salt.

[0067] In some embodiments, step (1) of the preparation method of the composite solid electrolyte includes the following steps: S1 LLZTO surface in-situ fluorine modification treatment: LLZTO inorganic filler was dispersed in an organic solvent and stirred to form a uniform suspension. Quaternary ammonium salt surfactants were added to the suspension and stirred at 30-80℃ for 6-24 hours. After the reaction was completed, the solid product was collected by centrifugation and washed 3-5 times with the same organic solvent to remove unreacted quaternary ammonium salt surfactants. Finally, the washed solid product was placed in a vacuum drying oven and dried at 60-80℃ for 12-24 hours to obtain the surface-modified inorganic filler. The organic solvent is at least one selected from methanol, ethanol, isopropanol, and acetonitrile, preferably ethanol; Preparation of S2 composite electrolyte slurry: Weigh the polymer matrix and lithium salt according to the mass ratio. Add the polymer matrix to the organic solvent and stir at 50-70℃ until the polymer matrix is ​​completely dissolved to form a polymer matrix solution. Add the lithium salt to the polymer matrix solution and continue stirring for 2-6 hours until the lithium salt is completely dissolved to obtain a mixed solution. Add the surface-modified inorganic filler prepared in step S1 and stir at room temperature for 8-16 hours until a uniform, particle-free mixed slurry is formed. S3 Composite Solid Electrolyte Membrane Molding: The mixed slurry obtained in step S2 is uniformly coated onto a clean polytetrafluoroethylene plate by casting, with the casting thickness controlled at 50-200 μm. The substrate coated with the slurry is placed in a vacuum drying oven and dried at 40-80℃ for 12-24 h to remove organic solvents, thus obtaining a pre-formed composite electrolyte membrane. The pre-formed composite electrolyte membrane is peeled off from the substrate, placed in a mold, and hot-pressed at 60-120℃ and 5-15 MPa for 5-30 min. After cooling to room temperature, a uniform, dense, highly stable, low-resistance PEO-based composite solid electrolyte membrane is obtained.

[0068] In step (2), the organic solvent is at least one of methanol, ethanol, isopropanol and acetonitrile, preferably acetonitrile. Acetonitrile has excellent solubility for quaternary ammonium salt additives and lithium salts, and has a moderate boiling point, making it easy to dry and remove. It is also compatible with ethanol, which can simplify the solvent recovery process.

[0069] In this application, "composite solid electrolyte" refers to any solid-state ion conductor formed by combining inorganic fillers with a polymer matrix, lithium salt, and specific additives, aiming to construct a continuous ion transport channel. For example, it may include, but is not limited to, systems comprising polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium lanthanum zirconium tantalum oxide (LLZTO), and tetrabutylammonium fluoride (TBAF), or combinations comprising other optional polymers listed in the claims, lithium salts, inorganic fillers, and quaternary ammonium salt surfactants. The mass ratio of the polymer matrix, lithium salt, inorganic filler, and quaternary ammonium salt surfactant is configured to achieve a synergistic effect of uniform filler dispersion and reduced polymer crystallinity; specifically, this mass ratio may be 100:60~80:10~20:1~15.

[0070] In this application, "polymer matrix" refers to any polymeric material capable of dissolving lithium salts and providing a matrix for lithium ion migration. For example, it may include, but is not limited to, at least one of: polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene chloride (PVDC), and polypropylene oxide (PPO).

[0071] In this application, "lithium salt" refers to any lithium-containing compound capable of dissociating lithium ions and providing a migratory current carrier. For example, it may include, but is not limited to, at least one of: lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium bis(oxalateborate)borate (LiBOB), lithium trifluoromethanesulfonate (LiCF3SO3), lithium arsenic fluoride (LiAsF4), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0072] In this application, "inorganic filler" refers to any inorganic solid electrolyte particle that can introduce additional lithium-ion transport pathways and affect polymer crystallization behavior. For example, it may include, but is not limited to, at least one of: lithium lanthanum zirconium tantalum oxide (LLZTO), lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), lithium zirconium chloride (Li2ZrCl6), lithium tantalum chloride (LiTaCl6), lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), and lithium phosphorus sulfur chloride (LPSCl).

[0073] In this application, "quaternary ammonium salt surfactant" refers to any organic additive with a quaternary ammonium cationic structure that can act simultaneously on the surface of inorganic fillers and polymer segments to achieve the dual functions of inhibiting filler agglomeration and reducing polymer crystallinity. For example, it may include, but is not limited to, at least one of: tetrabutylammonium fluoride (TBAF), hexadecyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium chloride (DTAC), octadecyltrimethylammonium chloride (OTAC), and hexadecyltrimethylammonium bromide (CTAB).

[0074] In this application, "mass ratio" specifically refers to the mass ratio of the polymer matrix, the lithium salt, the inorganic filler, and the quaternary ammonium salt surfactant in the composite solid electrolyte. This ratio is configured to produce a synergistic effect to jointly optimize ionic conductivity. Specifically, the mass ratio of the polymer matrix, lithium salt, inorganic filler, and quaternary ammonium salt surfactant can be 100:60~80:10~20:1~15.

[0075] In this application, "weight ratio" specifically refers to the mass ratio between inorganic fillers and quaternary ammonium salt surfactants. This ratio is configured to enable the quaternary ammonium salt surfactant to effectively disperse a corresponding amount of inorganic filler. Specifically, the weight ratio of the inorganic filler to the quaternary ammonium salt surfactant can be 1:5 to 20.

[0076] In this application, "all-solid-state lithium metal battery" refers to any electrochemical energy storage device that uses lithium metal or lithium-containing metal materials as the negative electrode and completely replaces the liquid electrolyte with a solid electrolyte. For example, it may include, but is not limited to, coin cells or pouch cells assembled with the composite solid electrolyte as the electrolyte layer, a lithium metal negative electrode, and a positive electrode containing active materials such as lithium iron phosphate.

[0077] In this application, the term "negative electrode" in the context of all-solid-state lithium metal batteries specifically refers to the electrode in the battery where an oxidation reaction occurs, and whose active material includes metallic lithium. For example, it may include, but is not limited to, at least one of: metallic lithium foil, lithium sheet, lithium alloy, hard carbon, or titanium-based negative electrode materials.

[0078] In this application, the term "positive electrode" in the context of all-solid-state lithium metal batteries specifically refers to the electrode in the battery where a reduction reaction occurs, which is typically a composite material coated on a current collector. For example, it may include, but is not limited to, a composite structure comprising a current collector, a positive electrode active material coated thereon, a binder, and a conductive agent; wherein the positive electrode active material may be selected from at least one of lithium iron phosphate, lithium vanadium phosphate, lithium manganese oxide, lithium titanium chloride, and lithium cobalt oxide.

[0079] The present application will be described in detail below with reference to the accompanying drawings and embodiments. However, the implementation and protection of the present invention are not limited thereto. The following embodiments are only some embodiments of the present application and are not intended to limit the present 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 in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0080] Example 1 A method for preparing an all-solid-state lithium metal battery includes the following steps: (1) In-situ surface modification treatment of LLZTO: 25g of LLZTO inorganic filler was dispersed in 200mL of ethanol and stirred to form a uniform suspension. 2.5g of TBAF was added to the suspension and the mixture was stirred at 50℃ for 12h. After the reaction was completed, the solid product was collected by centrifugation and washed three times with ethanol to remove unreacted TBAF. The washed solid product was placed in a vacuum drying oven and dried at 70℃ for 18h to obtain the in-situ modified inorganic filler.

[0081] (2) Preparation of composite electrolyte slurry: Weigh 100g PEO (Mv=600000) and add it to 300mL acetonitrile. Stir at 60℃ until PEO is completely dissolved to form a PEO solution. Add 13g LiTFSI to the PEO solution and continue stirring for 4h until the lithium salt is completely dissolved to obtain a PEO-LiTFSI mixed solution. Add 25g of the in-situ modified inorganic filler prepared in step (1) to the mixed solution and stir at room temperature for 12h to form a uniform mixed slurry.

[0082] (3) Forming of composite solid electrolyte membrane: The mixed slurry was uniformly coated onto a polytetrafluoroethylene plate by casting, with the casting thickness controlled at 100 μm. The plate coated with the slurry was placed in a vacuum drying oven and dried at 60°C for 18 h to remove acetonitrile, thus obtaining a pre-formed composite electrolyte membrane. The pre-formed membrane was peeled off, placed in a mold, and hot-pressed at 90°C and 10 MPa for 15 min. After cooling to room temperature, a composite solid electrolyte membrane was obtained.

[0083] (4) Assembly of stainless steel symmetrical batteries 304 stainless steel (SS) sheets were used as the reference electrode. A symmetrical stainless steel cell based on a polymer solid electrolyte was assembled in an argon-filled glove box (where oxygen and moisture content were both below 0.01 PPM). The polymer solid electrolyte was sandwiched between two stainless steel blocking electrodes. The assembly sequence was: negative electrode shell, spring sheet, gasket, PEO-based solid electrolyte, gasket, and positive electrode shell. After assembly, the cell was placed in a coin cell packaging machine and sealed under a pressure of 50 MPa. The assembled cell was then placed in a 30°C oven and allowed to stand for 1 hour.

[0084] (5) Assembly of lithium symmetric batteries The PEO-based solid electrolyte obtained above was used to assemble Li||CSEs||Li coin cells. Lithium metal sheets were selected, and half-cells based on polymer solid electrolytes were assembled in an argon-filled glove box (where oxygen and moisture content were both below 0.01 PPM). The polymer solid electrolyte obtained above was sandwiched between lithium metal sheets, and the assembly sequence was: negative electrode shell, spring sheet, spacer, lithium metal sheet, PEO-based solid electrolyte, lithium metal sheet, and positive electrode shell. After the assembly was completed, the battery was placed in a coin cell packaging machine and sealed under a pressure of 50 MPa. The assembled battery was then placed in a 30°C oven for 2 hours.

[0085] Example 2 The raw material composition and preparation method are the same as in Example 1, except that the amount of TBAF added is adjusted to 1.5g and the amount of LLZTO added is adjusted to 20g. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0086] Example 3 The raw material composition and preparation method are the same as in Example 1, except that the amount of TBAF added is adjusted to 2g and the amount of LLZTO added is adjusted to 30g. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0087] Example 4 The raw material composition and preparation method are the same as in Example 1, except that: the reaction temperature in step (1) is 30°C and the reaction time is 24h; the hot pressing temperature in step (3) is 60°C, the hot pressing pressure is 5MPa, and the hot pressing time is 30min. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0088] Example 5 The raw material composition and preparation method are the same as in Example 1, except that the amount of TBAF added is adjusted to 3g and the amount of LLZTO added is adjusted to 15g. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0089] Comparative Example 1 This comparative example uses a conventional PEO-LiTFSI-LLZTO composite solid electrolyte. The raw material composition, addition amount, and preparation method are basically the same as in Example 1, except that TBAF is not added in step (1), and unmodified LLZTO inorganic filler is used directly. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0090] Comparative Example 2 This comparative example is a PEO-LiTFSI-LLZTO composite solid electrolyte with added conventional surfactants. The raw material composition and preparation method are basically the same as in Example 1, except that 2.5g of PEG-2000 is used to replace TBAF in step (1) to disperse LLZTO. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0091] Comparative Example 3 This comparative example uses pure PEO solid electrolyte. The raw material composition and preparation method are basically the same as in Example 1, except that LLZTO inorganic filler and TBAF are not added; it consists only of 100g of PEO and 13g of LiTFSI. The assembly of the stainless steel symmetric battery and the lithium symmetric battery is the same as in Example 1.

[0092] XRD tests were performed on the composite polymer-based solid electrolytes prepared in Example 1 and Comparative Example 3. XRD comparison spectra are shown below. Figure 1 As shown in the figure, PEO-LiTFSI exhibits sharp diffraction peaks near 19° and 23°, corresponding to the (120) and (112) crystal planes of its orthorhombic crystal system, indicating that pure PEO has a high degree of crystallinity and its PEO chain segments are highly ordered. After adding in-situ fluorine-modified LLZTO with TBAF, the intensity of the diffraction peaks near 19° and 23° is significantly reduced, indicating that the crystallization behavior of PEO is effectively suppressed, and the amorphous regions and disorder of the molecular chains in CSE are increased.

[0093] Example of effect 1: The stainless steel symmetric cells prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to electrochemical impedance spectroscopy (EIS) testing. Using a Princeton electrochemical workstation, EIS tests were performed at an amplitude of 10 mV within a frequency range of 0.01 Hz–1 MHz. The obtained impedance values ​​were used to calculate the ionic conductivity. The test temperature was 30 °C. Before recording the impedance response, the cells were kept at the corresponding temperature for at least 1 hour. The thickness of the electrolyte was measured to be 120 μm using vernier calipers. The bulk impedance of the electrolyte was fitted, and combined with the effective contact area between the electrolyte and the stainless steel sheet (the diameter of the stainless steel sheet was 15.8 mm), the ionic conductivity (σ, S·cm) of the electrolyte was calculated using Equation 1. -1 The results are shown in Table 1.

[0094] Formula 1 In the formula, σ represents the ionic conductivity (S·cm). -1 L represents the thickness of the polymer solid electrolyte membrane (cm), R represents the bulk impedance of the electrolyte membrane (Ω), and A represents the electrode area (cm²). 2 ).

[0095] Table 1 Electrolyte performance test results for each embodiment and comparative example Test Result Analysis 1. Comparison of Example 1 and Comparative Example 1 revealed that the room temperature ionic conductivity of Example 1 with added TBAF was 1.32 × 10⁻⁶. - 4 S / cm is the value of Comparative Example 1 (3.1 × 10⁻⁶) without TBAF. -5 The efficiency of the composite electrolyte is 4.26 times that of LLZTO (S / cm); the interfacial contact impedance is only 210Ω, far lower than the 920Ω of Comparative Example 1; the cycle time of the lithium symmetric battery is increased to 1200h, which is 6.67 times that of Comparative Example 1 (180h). This proves that the in-situ fluorine modification of TBAF significantly improves the interfacial compatibility between LLZTO and PEO, and greatly enhances the ion transport efficiency and cycle stability of the composite electrolyte.

[0096] 2. Comparison of Comparative Example 1 and Comparative Example 2 revealed that Comparative Example 2, which used the conventional surfactant PEG-2000, had significantly lower ionic conductivity, interfacial impedance, and cycle stability than Example 1. This indicates that TBAF did not improve performance through conventional dispersion, but rather achieved a significant performance improvement through a unique in-situ fluorine modification and PEO crystallinity adjustment mechanism.

[0097] 3. Comparison of Example 1 and Comparative Example 3 revealed that the ionic conductivity of pure PEO electrolyte was only 2.12 × 10⁻⁶.-5 With a capacitance of S / cm, an interfacial impedance as high as 1500Ω, and a cycle time of less than 100h, the composite electrolyte of this invention achieves a comprehensive improvement in conductivity, interfacial performance, and stability through the synergistic effect of TBAF and LLZTO, meeting the application requirements of high-performance solid-state batteries.

[0098] Application Example 1: A Solid-State Lithium Metal Battery (1) Preparation of positive electrode First, the active material lithium iron phosphate (LiFePO4, LFP), conductive agent (Super P), and binder (PVDF) were weighed in a mass ratio of 8:1:1, thoroughly mixed, and ground until homogeneous. Next, an appropriate amount of NMP solvent was added, and grinding continued until the slurry reached the desired viscosity. Then, the slurry was evenly coated onto the surface of carbon-coated aluminum foil using a doctor blade and pre-dried in a 60°C forced-air drying oven. Afterward, it was transferred to a vacuum drying oven and dried at 120°C for 12 hours. After the sample cooled naturally, the electrode sheet was cut into 11mm diameter round pieces using a cutting machine and stored in a glove box for later use.

[0099] (2) Assembly of all-solid-state lithium metal batteries The composite solid electrolytes (CSEs) and positive electrode obtained in Example 1 were used to assemble all-solid-state lithium metal batteries. The batteries were assembled in an argon-filled glove box (with oxygen and moisture content both below 0.01 PPM) according to the standard 2032 coin cell assembly process. The assembly sequence was: negative electrode shell, spring sheet, gasket, lithium sheet, PEO-based solid electrolyte, positive electrode, and positive electrode shell. After assembly, the entire battery was placed in a coin cell packaging machine and sealed under a pressure of 50 MPa. To increase the contact between the electrode and the electrolyte membrane and reduce the interface resistance, the battery was then left to stand in a 30°C oven for 6 hours.

[0100] Cyclic performance tests were conducted on the solid-state lithium battery at room temperature and a charge-discharge rate of 0.5C. The initial discharge specific capacity of the battery was 158 mAh / g. After 100 cycles, the capacity retention rate was 96.2%, with no significant capacity decay, demonstrating excellent cycle stability.

[0101] Application Example 2 A solid-state lithium battery is provided, wherein the positive electrode uses ternary material NCM811 as the active material, carbon nanotubes as the conductive agent, and styrene-butadiene rubber (SBR) as the binder, with a mass ratio of 8.5:0.8:0.7, and is coated on the surface of an aluminum foil current collector; the negative electrode uses graphite; and the solid electrolyte layer uses the composite solid electrolyte membrane prepared in Example 3.

[0102] The preparation method of the positive electrode and the assembly method of the solid-state lithium metal battery are the same as those in Application Example 1. Charge-discharge tests were conducted at room temperature at a rate of 0.2C. The initial discharge specific capacity was 210 mAh / g, and the capacity retention rate after 50 cycles was 95.8%. No lithium dendrite penetration was observed, significantly improving safety.

[0103] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0104] 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.

[0105] 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.

[0106] 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. A highly dispersible, low-crystallinity composite solid electrolyte, characterized in that, The composite solid electrolyte includes a polymer matrix, lithium salt, inorganic filler, and quaternary ammonium salt surfactant. The mass ratio of the polymer matrix, lithium salt, inorganic filler, and quaternary ammonium salt surfactant is 100:60~80:10~20:1~15.

2. The composite solid electrolyte according to claim 1, characterized in that, The weight ratio of the inorganic filler to the quaternary ammonium salt surfactant is 1:5~20.

3. The composite solid electrolyte according to claim 1, characterized in that, The inorganic filler includes at least one of lithium lanthanum zirconium tantalum oxide, lithium indium chloride, lithium yttrium chloride, lithium zirconium chloride, lithium tantalum chloride, lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, and lithium phosphorus sulfur chloride; And / or, the polymer matrix includes at least one of polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinylidene chloride, and polypropylene oxide; And / or, the lithium salt comprises at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium perchlorate, lithium bis(oxalateborate), lithium trifluoromethanesulfonate, lithium arsenate, and lithium bis(trifluoromethanesulfonyl)imide. And / or, the quaternary ammonium salt surfactant is selected from at least one of tetrabutylammonium fluoride, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride and hexadecyltrimethylammonium bromide.

4. The composite solid electrolyte according to any one of claims 1-3, characterized in that, The composite solid electrolyte also includes an organic solvent; The organic solvent is at least one of methanol, ethanol, isopropanol, and acetonitrile.

5. An all-solid-state lithium metal battery, characterized in that, The all-solid-state lithium metal battery includes an electrolyte, a negative electrode, and a positive electrode; the electrolyte includes any one of claims 1-4.

6. The all-solid-state lithium metal battery according to claim 5, characterized in that, The negative electrode is a lithium metal negative electrode; preferably, the lithium metal negative electrode is at least one of lithium foil, lithium sheet, lithium alloy, hard carbon, and titanium-based negative electrode.

7. The all-solid-state lithium metal battery according to claim 5 or 6, characterized in that, The positive electrode includes a current collector, a positive electrode active material, a binder, and a conductive agent.

8. The all-solid-state lithium metal battery according to claim 7, characterized in that, The current collector is aluminum foil, carbon-coated aluminum foil, or stainless steel foil; And / or, the positive electrode active material is selected from at least one of lithium iron phosphate, lithium vanadium phosphate, lithium manganese oxide, lithium titanium chloride, and lithium cobalt oxide; And / or, the adhesive is selected from at least one of polyvinylidene fluoride, polyamide, polyvinyl alcohol, and carboxymethyl cellulose; And / or, the conductive agent is selected from at least one of acetylene black, Ketjen black, and Super P.

9. A method for preparing an all-solid-state lithium metal battery according to any one of claims 5-8, characterized in that, Includes the following steps: (1) Preparation of composite solid electrolyte; (2) Preparation of positive electrode sheet: The raw materials including positive electrode active material, binder and conductive agent are coated on the current collector; (3) Assembly.

10. The preparation method according to claim 9, characterized in that, Step (1) includes: first mixing inorganic fillers and quaternary ammonium salt surfactants; then adding polymer matrix and lithium salt.

Images