All-solid-state composite solid electrolyte membrane, method for preparing same, and use thereof

Abstract

The application provides a preparation method of a full solid composite solid electrolyte film, and belongs to the technical field of solid electrolytes. In view of the problems of existing inorganic filler aggregation, low ion conductivity at room temperature and poor interface stability of an organic-inorganic composite solid electrolyte film, the application uses LLZTO inorganic electrolyte with high ion conductivity as a skeleton material, uses a polymer electrolyte PPC as a filler, effectively inhibits the agglomeration of the inorganic phase by using the three-dimensional form of the LLZTO, constructs a fast transmission channel for lithium ions, synchronously eliminates the Li2CO3 layer formed on the inorganic surface under air exposure by catalyzing the slow decomposition of the PPC into PC by the LLZTO, and improves the compatibility of the solid-solid contact interface. The composite solid electrolyte has high ion conductivity, improves the lithium ion migration number of the composite solid electrolyte, expands the electrochemical window, and greatly improves the cycle stability of the full battery.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte technology, specifically relating to an all-solid composite solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Solid-state lithium batteries significantly improve the safety and stability of lithium-ion batteries by using solid-state electrolytes (SSE) instead of traditional flammable liquid electrolytes. They have become the industry's recognized preferred solution for next-generation batteries and a core focus of future battery technology competition.

[0003] Solid-state electrolytes (SSEs) are the core material for solid-state lithium batteries, and the most critical step in their development lies in preparing solid-state electrolytes with superior performance. Currently, all-solid-state composite solid-state electrolytes (CPEs) on the market combine the high ionic conductivity and mechanical strength of inorganic electrolytes with the flexibility of polymeric electrolytes, making them the most promising SSEs for application. Despite the significant advantages of CPEs in many aspects, their practical application faces the following obstacles: (1) The dispersibility of ceramic fillers in polymer matrices often affects their performance, especially the spontaneous aggregation of nanoscale filler particles, which can hinder the development of Li + The transport of these materials leads to a decrease in ionic conductivity, which limits the amount of ceramic filler in the polymer matrix. (2) The random distribution of the filler leads to cross-junctions, discontinuous networks and agglomeration, which in turn has an adverse effect on its electrochemical performance; (3) Solid-solid contact between solid electrode and electrolyte can lead to interfacial incompatibility and poor cycle stability, which in turn has a negative impact on the electrochemical performance of solid lithium battery.

[0004] Therefore, conducting multi-level integrated design to achieve continuous lithium-ion channel construction, improved interface affinity, and enhanced structural stability is crucial for promoting the practical application of all-solid-state composite solid electrolytes. Summary of the Invention

[0005] This invention provides an all-solid composite solid electrolyte membrane, its preparation method, and its application. By compositing an LLZTO framework with polypropylene carbonate (PPC), the inorganic filler exists in a three-dimensional form, which not only avoids particle agglomeration but also constructs a continuous and interconnected ion transport channel. As a biodegradable polymer, PPC's carbonate groups in its molecular chain can coordinate with lithium salts and promote dissociation. It also has good compatibility with lithium metal and is environmentally friendly. This invention solves the technical problems of uneven dispersion of inorganic fillers, low conductivity, and poor interface stability in existing all-solid composite solid electrolytes.

[0006] To solve the above problems, the solution of the present invention is as follows: A method for preparing an all-solid composite solid electrolyte membrane includes the following steps: Step S1, Preparation of inorganic filler butyl benzyl phthalate, polyvinyl butyral and the first solvent were stirred evenly to obtain a mixture. Then LLZTO filler was added, ultrasonically dispersed and magnetically stirred to obtain an inorganic filler slurry. Step S2, prepare the LLZTO framework The inorganic filler slurry was coated into a 100µm precursor film using a scraping process. After drying and rolling, the film was sliced ​​and then subjected to high-temperature rapid firing in a muffle furnace to obtain a three-dimensional LLZTO skeleton. Step S3, prepare composite electrolyte solution PPC and lithium salt are dispersed in a second solvent and mixed uniformly to obtain a composite electrolyte solution; Step S4: Prepare an all-solid composite solid electrolyte membrane. The composite electrolyte solution was drop-coated onto the LLZTO framework. After it was completely wetted, the second solvent was evaporated by vacuum drying to obtain an all-solid composite solid electrolyte membrane.

[0007] As a preferred improvement, in step S1, the first solvent is anhydrous ethanol; in the inorganic filler slurry, the mass ratio of butyl benzyl phthalate, polyvinyl butyral, anhydrous ethanol and LLZTO filler is 6:4:50:40.

[0008] As a preferred improvement, step S2, "coating the inorganic filler slurry into a 100µm precursor film using a blade coating process," specifically includes the following steps: The inorganic filler slurry was coated onto a polyethylene terephthalate matrix using a doctor blade to form a 100 µm precursor film.

[0009] As a preferred improvement, in step S2, the temperature conditions for high-temperature rapid firing in the muffle furnace are 1200℃ and the sintering time is 5min.

[0010] As a preferred improvement, in step S3, the lithium salt is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium difluorooxalate borate, and lithium dioxalate borate.

[0011] As a preferred improvement, in step S3, the molecular weight of the PPC is 50000 Da; the second solvent is anhydrous acetonitrile; in the composite electrolyte solution, the mass ratio of polypropylene carbonate to lithium salt is 5:1, and the mass-volume ratio of polypropylene carbonate to anhydrous acetonitrile is (1-2) g:10 mL.

[0012] As a preferred improvement, in step S4, "vacuum drying" specifically means: vacuum drying at 50℃ and -0.09MPa for 6 hours.

[0013] An all-solid composite solid electrolyte membrane is prepared by the above-described method for preparing an all-solid composite solid electrolyte membrane, wherein the thickness of the all-solid composite solid electrolyte membrane is 30-100µm.

[0014] An application of the all-solid composite solid electrolyte membrane as described above, used as a solid electrolyte membrane for lithium-ion batteries.

[0015] The beneficial effects of this invention are as follows: (1) The filler is mixed with butyl benzyl phthalate, polyvinyl butyral and anhydrous ethanol to form an inorganic slurry. The slurry is scraped and dried. Then the precursor film is sintered by high temperature and fast firing to prepare a three-dimensional LLZTO porous framework, constructing a continuous and interconnected network structure to avoid the aggregation of inorganic particles. (2) The synergistic catalytic effect of PPC and LLZTO promotes the dissociation of lithium salt, increases the transport path of lithium ions between polymer and inorganic filler, and improves lithium ion conductivity and active filler utilization. (3) By LLZTO catalyzing the degradation of PPC into propylene carbonate (PC), the Li2CO3 layer formed on the inorganic surface under air exposure is simultaneously eliminated, significantly improving the compatibility of the solid-solid contact interface, replacing the separator and electrolyte in traditional batteries at room temperature, and realizing the cycling of all-solid batteries at a wide temperature range.

[0016] In summary, this invention utilizes the synergistic effect of a three-dimensional LLZTO porous framework and PPC to achieve a synergistic effect from structure to performance, thereby reducing Li + The resistance generated during transportation due to packing agglomeration, and the resulting Li + The transport path becomes more directional, significantly improving ionic conductivity and solving the problems of incompatibility between the polymer matrix and active filler interface, uneven dispersion of active filler, difficulty in fully utilizing the intrinsic high ionic conductivity of active filler, low ionic conductivity of composite solid electrolytes, low specific capacity of the assembled SSLMB battery, short cycle life, and tortuous lithium-ion transport path in traditional composite solid electrolytes. The LFP-Li full cell prepared with the all-solid-state composite solid electrolyte membrane of this invention retains 81.96% of its capacity after 200 cycles at 0.5C. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a macroscopic photograph of the all-solid composite solid electrolyte membrane sample prepared in Example 1; Figure 2 This is a scanning electron microscope image of the surface of the all-solid composite solid electrolyte membrane sample prepared in Example 1; Figure 3 This is a cross-sectional scanning electron microscope image of the all-solid composite solid electrolyte membrane sample prepared in Example 1; Figure 4 The graph shows the relationship between the conductivity and temperature of the all-solid composite solid electrolyte membrane sample prepared in Example 1. Figure 5 The graph shows the relationship between the conductivity and temperature of the all-solid composite solid electrolyte membrane sample prepared in Example 2. Figure 6 The graph shows the relationship between the conductivity and temperature of the all-solid composite solid electrolyte membrane sample prepared in Example 3. Figure 7 The graph shows the electrochemical window test results of all-solid composite solid electrolyte membrane samples with different PPC contents prepared in Examples 1-3. Figure 8 The graph shows the charge-discharge cycle performance of the lithium symmetric battery of the all-solid composite solid electrolyte membrane sample prepared in Example 1. Figure 9 The graph shows the cycle performance of the all-solid-state composite solid electrolyte membrane sample prepared in Example 1, assembled with a lithium iron phosphate cathode and a lithium metal anode, at 30°C. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0019] This embodiment provides a method for preparing an all-solid-state composite solid electrolyte membrane, comprising the following steps: Step S1, Preparation of inorganic filler Butyl phthalate, polyvinyl butyral, and the first solvent were stirred until a homogeneous mixture was obtained. Then, LLZTO (Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The filler was ultrasonically dispersed and then magnetically stirred to obtain an inorganic filler slurry. Step S2, prepare the LLZTO framework The inorganic filler slurry was coated into a 100µm precursor film using a scraping process. After drying and rolling, the film was sliced ​​and then subjected to high-temperature rapid firing in a muffle furnace to obtain a three-dimensional LLZTO skeleton. Step S3, prepare composite electrolyte solution Polypropylene carbonate (PPC) and lithium salt are dispersed in a second solvent and mixed uniformly to obtain a composite electrolyte solution; Step S4: Prepare an all-solid composite solid electrolyte membrane. The composite electrolyte solution was drop-coated onto the LLZTO framework. After it was completely wetted, the second solvent was evaporated by vacuum drying to obtain an all-solid composite solid electrolyte membrane.

[0020] In step S1, the first solvent is anhydrous ethanol; in the inorganic filler slurry, the mass ratio of butyl benzyl phthalate, polyvinyl butyral, anhydrous ethanol and LLZTO filler is 6:4:50:40.

[0021] In step S2, "the inorganic filler slurry is coated into a 100µm precursor film using a blade coating process" specifically includes the following steps: The inorganic filler slurry was coated onto a polyethylene terephthalate matrix using a doctor blade to form a 100 µm precursor film.

[0022] In step S2, drying, rolling, and slicing all employ conventional techniques in the art. It should be noted that the size of the "slices" is determined according to actual usage requirements; for example, when used for button batteries, they are cut into 16mm diameter round slices; when used for pouch batteries, they are cut into 4cm × 6cm square slices.

[0023] In step S2, the high-temperature rapid firing conditions in the muffle furnace are 1200℃ and the sintering time is 5min.

[0024] In step S3, the lithium salt is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium difluorooxalate borate, and lithium dioxalate borate. The molecular weight of the PPC is 50,000 Da.

[0025] In step S3, the second solvent is anhydrous acetonitrile; in the composite electrolyte solution, the mass ratio of polypropylene carbonate to lithium salt is 5:1; the mass-volume ratio of polypropylene carbonate to anhydrous acetonitrile is (1-2)g:10mL, that is, 1-2g of polypropylene carbonate is added to every 10mL of anhydrous acetonitrile.

[0026] In step S4, "vacuum drying" specifically means: vacuum drying at 50℃ and -0.09MPa for 6 hours.

[0027] This embodiment also provides an all-solid composite solid electrolyte membrane, which is prepared by the above-described method for preparing all-solid composite solid electrolyte membranes, and the thickness of the all-solid composite solid electrolyte membrane is 30-100µm.

[0028] This embodiment also provides an application of the all-solid composite solid electrolyte membrane as described above, used as an electrolyte membrane for lithium-ion batteries.

[0029] Example 1 This embodiment provides a method for preparing an all-solid composite solid electrolyte membrane, including the following steps: (1) Preparation of inorganic fillers 0.6 g of butyl benzyl phthalate (BBP), 0.4 g of polyvinyl butyral (PVB), and 5 g of anhydrous ethanol solvent were stirred until a homogeneous mixture was obtained. Then, 4 g of Li was added. 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO) powder was ultrasonically dispersed and then magnetically stirred for 12 hours to obtain an inorganic slurry.

[0030] (2) Preparation of LLZTO framework An appropriate amount of inorganic slurry was spread evenly on a polyethylene terephthalate (PET) matrix film. The inorganic filler slurry was then coated into a precursor film using a blade coating process. The blade coating rate was 1.5 m / min and the blade gap was 100 μm. After the coating was completed, the film was dried, rolled, and peeled off. The resulting slices were 16 mm in diameter and then sintered in a muffle furnace at 1200 °C for 5 min to obtain a three-dimensional LLZTO porous framework.

[0031] (3) Preparation of composite electrolyte solution 1g of polypropylene carbonate (PPC) crystals and 0.25g of lithium salt (LiTFSI) were dispersed in 10ml of anhydrous acetonitrile solvent. The mixture was heated and stirred in a water bath until the crystals were completely dissolved. The mixture was then stirred at room temperature for 6 hours to obtain a composite electrolyte solution.

[0032] (4) Preparation of all-solid composite solid electrolyte membrane The composite electrolyte solution was applied in small amounts and repeatedly to the surface of the LLZTO three-dimensional skeleton using a pipette. After complete wetting, it was dried in a vacuum oven at 50°C and -0.09MPa for 6 hours to allow the anhydrous acetonitrile solvent to evaporate, resulting in an all-solid composite solid electrolyte membrane with a thickness of approximately 32µm.

[0033] Example 2 This embodiment provides a method for preparing an all-solid composite solid electrolyte membrane, including the following steps: (1) Preparation of inorganic fillers 0.6g of butyl benzyl phthalate (BBP), 0.4g of polyvinyl butyral (PVB) and 5g of anhydrous ethanol solvent were stirred evenly to obtain a mixture. 4g of LLZTO powder was added and ultrasonically dispersed, followed by magnetic stirring for 12h to obtain an inorganic slurry.

[0034] (2) Preparation of LLZTO framework An appropriate amount of inorganic slurry was spread evenly on a polyethylene terephthalate (PET) matrix film. The inorganic filler slurry was then coated into a precursor film using a blade coating process. The blade coating rate was 1.5 m / min and the blade gap was 100 µm. After the coating was completed, the film was dried, rolled, and peeled off. The resulting slices were 16 mm in diameter and then sintered in a muffle furnace at 1200 °C for 5 min to obtain a three-dimensional LLZTO porous framework.

[0035] (3) Preparation of composite electrolyte solution 1g of polypropylene carbonate (PPC) crystals and 0.25g of lithium salt (LiTFSI) were dispersed in 6.7ml of anhydrous acetonitrile solvent. The mixture was heated and stirred in a water bath until the crystals were completely dissolved. The mixture was then stirred at room temperature for 6 hours to obtain a composite electrolyte solution.

[0036] (4) Preparation of all-solid composite solid electrolyte membrane The composite electrolyte solution was applied in small amounts multiple times to the surface of the LLZTO three-dimensional skeleton using a pipette. After complete wetting, the substrate was dried in a vacuum oven at 50°C and -0.09 MPa for 6 hours to allow the anhydrous acetonitrile solvent to evaporate, resulting in an all-solid composite solid electrolyte membrane with a thickness of approximately 35 µm.

[0037] Example 3 This embodiment provides a method for preparing an all-solid composite solid electrolyte membrane, including the following steps: (1) Preparation of inorganic fillers 0.6g of butyl benzyl phthalate (BBP), 0.4g of polyvinyl butyral (PVB) and 5g of anhydrous ethanol solvent were stirred evenly to obtain a mixture. 4g of LLZTO powder was added and ultrasonically dispersed, followed by magnetic stirring for 12h to obtain an inorganic slurry.

[0038] (2) Preparation of LLZTO framework An appropriate amount of inorganic slurry was spread evenly on a polyethylene terephthalate (PET) matrix film. The inorganic filler slurry was then coated into a precursor film using a blade coating process. The blade coating rate was 1.5 m / min and the blade gap was 100 μm. After the coating was completed, the film was dried, rolled, and peeled off. The resulting slices were 16 mm in diameter and then sintered in a muffle furnace at 1200 °C for 5 min to obtain a three-dimensional LLZTO porous framework.

[0039] (3) Preparation of composite electrolyte solution 1g of polypropylene carbonate (PPC) crystals and 0.25g of lithium salt (LiTFSI) were dispersed in 5ml of anhydrous acetonitrile solvent. The mixture was heated and stirred in a water bath until the crystals were completely dissolved. The mixture was then stirred at room temperature for 6 hours to obtain a composite electrolyte solution.

[0040] (4) Preparation of all-solid composite solid electrolyte membrane The composite electrolyte solution was applied in small amounts and repeatedly to the surface of the LLZTO three-dimensional skeleton using a pipette. After complete wetting, it was dried in a vacuum oven at 50°C and -0.09MPa for 6 hours to allow the anhydrous acetonitrile solvent to evaporate, resulting in an all-solid composite solid electrolyte membrane with a thickness of approximately 40µm.

[0041] Samples from Examples 1-3 were subjected to relevant performance tests. The test process and results are as follows: Figure 1 A macroscopic photograph of the sample obtained in Example 1 is shown.

[0042] Figure 2 as well as Figure 3 Scanning electron microscope (SEM) images of the surface and cross-section of the sample obtained in Example 1 are shown. Figure 2 It can be seen that the sample surface is flat and relatively dense, from Figure 3 It can be seen that the pores of the three-dimensional LLZTO porous framework are effectively filled by PPC, forming a continuous ion transport network.

[0043] Figures 4-6 The Nyquist plots of the ionic conductivity of the samples obtained in Examples 1-3 within the temperature range of 15-55℃ are shown. Ionic conductivity was measured as follows: the sample was sandwiched between two polished stainless steel substrates to form a blocking electrode. The all-solid-state composite solid electrolyte membrane sample within the blocking electrode was subjected to AC impedance analysis at different temperatures using an electrochemical workstation in a constant temperature chamber to obtain the corresponding ionic conductivity at each temperature. Figure 4 It can be seen that the ionic conductivity of the sample obtained in Example 1 is 1.71 mS·cm at a temperature of 30℃. -1 ;from Figure 5It can be seen that the ionic conductivity of the sample obtained in Example 2 is 1.3 mS·cm at a temperature of 30℃. -1 ;from Figure 6 It can be seen that the ionic conductivity of the sample obtained in Example 3 is 0.98 mS·cm at a temperature of 30℃. -1 .

[0044] Figure 7 Electrochemical stability window test graphs of the samples obtained in Examples 1-3 are shown, where the 10% P-3D curve corresponds to the sample obtained in Example 2, the 15% P-3D curve corresponds to the sample obtained in Example 1, and the 20% P-3D curve corresponds to the sample obtained in Example 3. Figure 7 As can be seen, Example 1 exhibits a stable window of approximately 4.9V, which stems from the excellent oxidation stability of its internal 3D-LLZTO framework and the low monomer residue resulting from a suitable PPC concentration, thus contributing to its high-voltage stability. The results indicate that this electrolyte has good compatibility with high-voltage cathode materials such as LiFePO4 (LFP), which is beneficial for improving the energy density of solid-state lithium batteries. In contrast, Example 2, due to its low PPC content, high polymer residue, and incomplete filling of framework pores, resulted in discontinuous lithium-ion transport paths, leading to oxidation current at approximately 4.6V. Notably, Example 3, due to its excessively high PPC content, struggled to fully penetrate the framework, resulting in a thicker pure polymer layer on the surface. This surface layer decomposed before the highly oxidation-stable LLZTO framework under high voltage, thus limiting the overall electrochemical window. This also indirectly confirms the crucial role of the three-dimensional LLZTO framework in improving electrochemical stability.

[0045] Figure 8 The cycling performance of the lithium-ion symmetric battery prepared from the sample obtained in Example 1 is shown in the graph, where the horizontal axis represents cycle time and the vertical axis represents voltage. From Figure 8 It can be seen that the sample obtained in Example 1 is at 0.1 mA·cm -2 The stable cycling performance exceeds 2400 hours, which demonstrates its excellent long-term cycling stability and good performance even at high current densities.

[0046] Figure 9 The cycling performance of the LFP-Li full cell prepared from the sample obtained in Example 1 is shown in the graph, where the horizontal axis represents the number of cycles and the vertical axis represents the specific capacity. From Figure 9 It can be seen that at a 0.5C rate, the initial cycle discharge specific capacity is 142.9 mAh·g. -1 It remained at 117.12 mAh·g after 200 cycles. -1The capacity retention rate reached 81.96%, and the average coulombic efficiency was higher than 95.5%. These results indicate that the battery assembled from the sample obtained in Example 1 has good long-term cycle stability and can significantly suppress lithium dendrite growth and interface degradation.

[0047] In summary, compared to traditional single-filler all-solid-state composite solid-state electrolytes based on SSLMB, the all-solid-state composite solid-state electrolyte of this application, based on a three-dimensional LLZTO porous framework and a dual continuous-phase all-solid-state composite solid-state electrolyte, achieves a synergistic effect from structure to performance, constructs lithium-ion transport channels, and reduces Li-ion degradation. + The resistance generated during transport due to the incompatibility between the filler and the polymer interface increases the resistance of Li. + Transport efficiency. Simultaneously, the synergistic effect of the biodegradable polymer matrix and active inorganic filler significantly improves the interfacial compatibility between the electrode and electrolyte, enhancing the cycling stability of SSLMB.

[0048] The embodiments of the invention have been described above with reference to the accompanying drawings. However, the invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the invention without departing from the spirit and scope of the claims, and all of these forms are within the scope of protection of the invention.

Claims

1. A method for preparing an all-solid-state composite solid electrolyte membrane, characterized in that, Includes the following steps: Step S1, Preparation of inorganic filler The butyl benzyl phthalate, polyvinyl butyral and the first solvent were stirred evenly to obtain a mixture. Then, LLZTO filler was added, ultrasonically dispersed and magnetically stirred to obtain an inorganic filler slurry. Step S2, prepare the LLZTO framework The inorganic filler slurry was coated into a 100µm precursor film using a scraping process. After drying and rolling, the film was sliced ​​and then subjected to high-temperature rapid firing in a muffle furnace to obtain a three-dimensional LLZTO skeleton. Step S3, prepare composite electrolyte solution PPC and lithium salt are dispersed in a second solvent and mixed uniformly to obtain a composite electrolyte solution; Step S4: Prepare an all-solid composite solid electrolyte membrane. The composite electrolyte solution was drop-coated onto the LLZTO framework. After it was completely wetted, the second solvent was evaporated by vacuum drying to obtain an all-solid composite solid electrolyte membrane.

2. The method for preparing the all-solid composite solid electrolyte membrane according to claim 1, characterized in that, In step S1, the first solvent is anhydrous ethanol; in the inorganic filler slurry, the mass ratio of butyl benzyl phthalate, polyvinyl butyral, anhydrous ethanol and LLZTO filler is 6:4:50:

40.

3. The method for preparing the all-solid composite solid electrolyte membrane according to claim 1, characterized in that, In step S2, "the inorganic filler slurry is coated into a 100µm precursor film using a blade coating process" specifically includes the following steps: The inorganic filler slurry was coated onto a polyethylene terephthalate matrix using a doctor blade to form a 100 µm precursor film.

4. The method for preparing the all-solid composite solid electrolyte membrane according to claim 1, characterized in that, In step S2, the high-temperature rapid firing conditions in the muffle furnace are 1200℃ and the sintering time is 5min.

5. The method for preparing the all-solid composite solid electrolyte membrane according to claim 1, characterized in that, In step S3, the lithium salt is selected from at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium hexafluorophosphate, lithium difluorooxalate borate, and lithium dioxalate borate.

6. The method for preparing the all-solid composite solid electrolyte membrane according to claim 1, characterized in that, In step S3, the molecular weight of the PPC is 50000 Da; the second solvent is anhydrous acetonitrile; in the composite electrolyte solution, the mass ratio of polypropylene carbonate to lithium salt is 5:1, and the mass-volume ratio of polypropylene carbonate to anhydrous acetonitrile is (1-2) g:10 mL.

7. The method for preparing the all-solid composite solid electrolyte membrane according to claim 1, characterized in that, In step S4, "vacuum drying" specifically means: vacuum drying at 50℃ and -0.09MPa for 6 hours.

8. An all-solid composite solid electrolyte membrane, prepared by the preparation method of the all-solid composite solid electrolyte membrane according to any one of claims 1-7, wherein the thickness of the all-solid composite solid electrolyte membrane is 30-100µm.

9. An application of the all-solid composite solid electrolyte membrane as described in claim 8, characterized in that, Solid electrolyte membrane used as a lithium-ion battery.

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