Modified composite solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a modified composite solid electrolyte as well as a preparation method and application thereof, the modified composite solid electrolyte comprises a polyethylene oxide matrix and an inorganic electrolyte dispersed in the matrix, the inorganic electrolyte is selected from garnet type Li6. 4La3Zr1. 4Ta0. 6O12 (LLZTO) nanoparticles, and the inorganic electrolyte is selected from the group consisting of Li6. 4La3Zr1. 4Ta0. 6O12 (LLZTO) nanoparticles. And an amphiphilic block copolymer is also arranged between the inorganic electrolyte and the matrix. The amphiphilic block copolymer poly (polyethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis (trifluoromethylsulfonyl) imide) is utilized to improve the compatibility of an inorganic phase-organic phase interface, inhibit agglomeration of LLZTO nanoparticles and promote uniform distribution of the LLZTO nanoparticles in a PEO matrix; and meanwhile, as an ion transmission bridge of lithium ions between the polymer and the LLZTO, multi-channel transmission of the lithium ions is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing composite electrolytes for lithium-ion batteries, and more specifically, relates to a modified composite solid electrolyte, a preparation method thereof, and applications thereof. Background Art

[0002] Traditional liquid lithium metal batteries have the problem of uncontrollable lithium dendrite growth, which can easily cause safety problems such as battery short circuit, fire and even explosion, limiting the widespread application of lithium metal batteries. Solid electrolytes have excellent mechanical properties and non-flammability, and have higher safety and energy density than liquid electrolytes. Therefore, all-solid-state lithium metal batteries are widely considered to be the key to the next generation of high-energy density battery technology. Solid electrolytes are generally divided into three categories: solid inorganic electrolytes, solid polymer electrolytes and solid composite electrolytes. Among them, the most representative solid inorganic electrolyte is garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO), which has high room temperature ionic conductivity (>10 -4 S cm -1 ) and electrochemical stability, but its disadvantages are high brittleness and high solid-solid contact resistance. Solid polymer electrolytes usually have good flexibility and good interfacial contact. Polymer electrolytes based on polyethylene oxide (PEO) are the most widely studied polymer electrolytes. The ether oxygen groups give PEO a strong ability to dissociate lithium salts. At the same time, PEO has high flexibility and good compatibility with lithium metal. However, its room temperature crystallinity leads to low ionic conductivity, which cannot meet commercial needs. Solid composite electrolytes refer to the preparation of composite electrolytes by blending inorganic electrolytes with polymers. Taking the garnet-type composite solid electrolyte of LLZTO and PEO as an example, LLZTO can not only enhance the segmental motion of PEO, but its surface Lewis acid sites can also adsorb anions to promote lithium salt dissociation, which can enhance the transmission of lithium ions in the polymer phase; at the same time, the synergistic transmission of PEO and LLZTO can increase more ion transmission paths. Therefore, the composite solid electrolyte has both high ionic conductivity and excellent mechanical properties.

[0003] Studies have shown that the higher the LLZTO content in the garnet-type composite solid electrolyte, the stronger the ion conductivity. However, the compatibility between the polymer matrix and the inorganic filler is poor, which leads to serious agglomeration of LLZTO. The agglomeration phenomenon will cause uneven distribution of LLZTO in PEO, resulting in uneven lithium ion deposition and initiating dendrite growth. At the same time, the interfacial contact area between the polymer phase and the inorganic phase will also be greatly reduced, reducing the lithium ion transmission channel.

[0004] Therefore, how to improve the inorganic-organic interface incompatibility problem in garnet-type composite solid electrolytes and prepare composite electrolytes with high conductivity, high mechanical properties and long cycle life is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a modified composite solid electrolyte, a preparation method and application thereof, so as to solve the technical problem of inorganic-organic interface incompatibility in the prior art garnet-type composite solid electrolyte.

[0006] Based on this, the technical solution of the present invention is as follows:

[0007] A modified composite solid electrolyte comprising a polyethylene oxide matrix and an inorganic electrolyte dispersed in the matrix, wherein the inorganic electrolyte is selected from garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO) nanoparticles, the inorganic electrolyte and the matrix also include an amphiphilic block copolymer.

[0008] According to an embodiment of the present invention, the amphiphilic block copolymer includes a polyether block and a polyionic liquid block. Specifically, the polyether block is, for example, selected from polyethylene glycol acrylate; specifically, the polyionic liquid block is, for example, selected from poly (1-(2-acryloylethyl)-3-methylimidazolium bis (trifluoromethylsulfonyl imide). Exemplarily, the amphiphilic block copolymer is selected from poly (polyethylene glycol acrylate) -co- (1-(2-acryloylethyl)-3-methylimidazolium bis (trifluoromethylsulfonyl imide).

[0009] According to an embodiment of the present invention, the modified composite solid electrolyte further comprises a lithium salt, which is one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and lithium perchlorate.

[0010] According to an embodiment of the present invention, in the modified composite solid electrolyte, the mass ratio of the LLZTO nanoparticles to the amphiphilic block copolymer is (1-5):1, for example, 1:1, 1:2, 1:3, 1:4, or 1:5. Preferably, the mass ratio of the LLZTO nanoparticles to poly(polyethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) is (1-5):1, for example, 1:1, 1:2, 1:3, 1:4, or 1:5.

[0011] According to an embodiment of the present invention, in the modified composite solid electrolyte, the mass ratio of the LLZTO nanoparticles to polyethylene oxide is 1:(1.4-10), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0012] According to an embodiment of the present invention, in the modified composite solid electrolyte, the mass ratio of the lithium salt to polyethylene oxide is 1:(1-10), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0013] The present invention also provides a method for preparing the modified composite solid electrolyte, the method comprising the following steps:

[0014] (1) Garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 (LLZTO) nanoparticles and an amphiphilic block copolymer are mixed in a solvent; the resulting mixture is then mixed with polyethylene oxide and a lithium salt to obtain a slurry;

[0015] (2) forming a film from the slurry obtained in step (1) to obtain the modified composite solid electrolyte.

[0016] According to an embodiment of the present invention, the amphiphilic block copolymer includes a polyether block and a polyionic liquid block. Specifically, the polyether block is, for example, selected from polyethylene glycol acrylate; specifically, the polyionic liquid block is, for example, selected from poly (1-(2-acryloylethyl)-3-methylimidazolium bis (trifluoromethylsulfonyl imide). Exemplarily, the amphiphilic block copolymer is selected from poly (polyethylene glycol acrylate) -co- (1-(2-acryloylethyl)-3-methylimidazolium bis (trifluoromethylsulfonyl imide).

[0017] According to an embodiment of the present invention, in step (1), the mass ratio of the LLZTO nanoparticles to the amphiphilic block copolymer is (1-5):1, for example, 1:1, 1:2, 1:3, 1:4 or 1:5.

[0018] According to an embodiment of the present invention, in step (1), the mass ratio of the LLZTO nanoparticles to polyethylene oxide is 1:(1.4-10), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0019] According to an embodiment of the present invention, in step (1), the solvent is selected from one or more of acetonitrile, tetrahydrofuran and 1,3-dioxane.

[0020] According to an embodiment of the present invention, in step (1), the lithium salt is one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and lithium perchlorate.

[0021] According to an embodiment of the present invention, in step (1), the mass ratio of the lithium salt to the polyethylene oxide is 1:(1-10), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0022] According to an embodiment of the present invention, in step (1), in step (1), the garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The nanoparticles and the amphiphilic block copolymer are mixed in the solvent for 6 to 12 hours.

[0023] According to an embodiment of the present invention, in step (1), the mixture is mixed with polyethylene oxide and lithium salt for 6 to 12 hours.

[0024] In step (1) of the present invention, the mixing temperature is not particularly limited, as long as the raw materials are mixed uniformly.

[0025] According to an embodiment of the present invention, in step (2), the slurry obtained in step (1) is poured into a polytetrafluoroethylene mold, the solvent is dried, and hot-pressed to prepare the modified composite solid electrolyte. For example, hot-pressing is performed using a flat vulcanizer.

[0026] Preferably, the drying temperature is 50-80°C.

[0027] According to an embodiment of the present invention, the hot pressing temperature is 60-100°C, the pressure during hot pressing is 1MPa-10MPa, for example, 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa or 10MPa, and the hot pressing time is 1-10min.

[0028] According to an embodiment of the present invention, the thickness of the modified composite solid electrolyte is 80-200 μm.

[0029] According to another aspect of the present invention, there is provided a use of the modified composite solid electrolyte in a lithium ion battery.

[0030] According to another aspect of the present invention, a lithium-ion battery is provided, which includes a positive electrode, a negative electrode and the modified composite solid electrolyte.

[0031] Beneficial effects of the present invention:

[0032] (1) The modified composite solid electrolyte of the present invention includes LLZTO nanoparticles dispersed in a PEO matrix. The electrolyte with such a structure improves the electrical conductivity while maintaining its flexible structure.

[0033] (2) The present invention utilizes an amphiphilic block copolymer (exemplarily poly(ethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide)) to improve the compatibility of the inorganic-organic phase interface, inhibit the agglomeration of LLZTO nanoparticles, and promote their uniform distribution in the PEO matrix.

[0034] (3) The present invention uses the electrostatic interaction between the polyionic liquid block in the amphiphilic block copolymer (exemplarily poly (polyethylene glycol acrylate) -co- (1- (2-acryloylethyl) -3-methylimidazolium bis trifluoromethylsulfonyl imide)) and the surface of the LLZTO nanoparticles to form a Li + It provides a fast transmission channel, further enhancing the ionic conductivity of the modified composite solid electrolyte. At the same time, the flexibility of PEO gives the composite electrolyte better flexibility, reducing the interface impedance between the solid electrolyte and the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a scanning electron microscope image of the modified composite solid electrolyte prepared in Example 1 of the present invention.

[0036] Figure 2 3 is a temperature-dependent conductivity diagram of the modified composite solid electrolyte prepared in Example 1 of the present invention.

[0037] Figure 3 This is a DC polarization curve of the modified composite solid electrolyte prepared in Example 1 of the present invention.

[0038] Figure 4 3 is a stress-strain curve diagram of the modified composite solid electrolyte prepared in Example 1 of the present invention.

[0039] Figure 5 This is a critical current density diagram of a lithium-lithium symmetrical battery (lithium / electrolyte / lithium battery) assembled with the modified composite solid electrolyte prepared in Example 1 of the present invention.

[0040] Figure 6 This is a scanning electron microscope image of the composite solid electrolyte prepared in Comparative Example 1 of the present invention.

[0041] Figure 7 This is a critical current density diagram of a lithium-lithium symmetrical battery (lithium / electrolyte / lithium battery) assembled with the composite solid electrolyte prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0043] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0044] Example 1

[0045] (1) 0.6 g of LLZTO nanoparticles and 0.2 g of poly(ethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) were dispersed in acetonitrile solvent and stirred for 6 h. Then, 1.2 g of polyethylene oxide and 0.86 g of lithium bis(trifluoromethylsulfonyl)imide were added and stirred for another 6 h to obtain a composite electrolyte slurry.

[0046] (2) injecting the composite electrolyte slurry obtained in step (1) into a polytetrafluoroethylene mold and drying at 60° C. for 12 hours to preliminarily obtain a composite electrolyte membrane;

[0047] (3) The composite electrolyte membrane obtained in step (2) was hot-pressed in a flat vulcanizer at 80° C. and 5 MPa for 1 minute to obtain a dense, flexible, modified composite solid electrolyte membrane with a thickness of 200 μm.

[0048] Figure 1 This is a scanning electron microscope image of the prepared modified composite solid electrolyte. Figure 1 It can be seen that LLZTO nanoparticles are dispersed very evenly in the modified composite solid electrolyte membrane, with a particle size of about 10-20 nm and no obvious agglomeration phenomenon, proving that poly(polyethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) effectively promotes the compatibility of inorganic particles (i.e., LLZTO nanoparticles) and polymers (i.e., PEO).

[0049] Figure 2 This is the temperature-dependent conductivity curve of the prepared modified composite solid electrolyte. Figure 2 It can be seen that the lithium ion conductivity of the electrolyte membrane is 5.6×10 -5 S cm -1 .

[0050] Figure 3This is the DC polarization curve of the prepared modified composite solid electrolyte. The illustration in the figure is the electrochemical impedance spectrum of the lithium-lithium symmetric battery (lithium / electrolyte / lithium battery) before and after polarization. According to the curve, the lithium ion migration number of the electrolyte membrane can be calculated to be 0.41. Since the lithium ion migration number of pure PEO is <0.2, it proves that the polymer and inorganic particles achieve synergistic transmission.

[0051] Figure 4 is a stress-strain curve diagram of the modified composite solid electrolyte prepared in this embodiment, Figure 4 It can be seen that the fracture growth rate of the electrolyte membrane is 3209%, and the maximum stress can reach 3.68 MPa, which proves that the modified composite solid electrolyte of the present invention has excellent flexibility and puncture resistance.

[0052] Figure 5 This is a critical current test of a lithium-lithium symmetrical battery (lithium / electrolyte / lithium battery) assembled using the modified composite solid electrolyte prepared in this embodiment. Figure 5 It can be seen that the critical current density of the lithium-lithium symmetrical battery assembled using the electrolyte of the present invention is 0.5 mA cm -2 , demonstrating the uniformity of lithium ion deposition in the composite solid-state electrolyte.

[0053] Example 2

[0054] (1) 0.2 g of LLZTO nanoparticles and 0.2 g of poly(ethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) were dispersed in acetonitrile and stirred for 6 h. Then, 1.6 g of polyethylene oxide and 0.4 g of lithium bis(trifluoromethylsulfonyl)imide were added and stirred for another 6 h to obtain a composite electrolyte slurry.

[0055] (2) injecting the composite electrolyte slurry obtained in step (1) into a polytetrafluoroethylene mold and drying at 60° C. for 12 hours to preliminarily obtain a composite electrolyte membrane;

[0056] (3) Hot pressing was performed at 90°C and 8 MPa for 2 minutes to obtain an electrolyte membrane with a thickness of 120 μm.

[0057] The lithium ion conductivity of the electrolyte membrane is 3.6×10 -5 S cm -1 , the lithium ion migration number is 0.32.

[0058] Example 3

[0059] (1) 0.6 g of LLZTO nanoparticles and 0.2 g of poly(ethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethyl)methylsulfonyl imide) were dispersed in tetrahydrofuran and stirred for 8 h. Then, 1.2 g of polyethylene oxide and 0.86 g of lithium bis(trifluoromethyl)sulfonyl imide were added and stirred for another 8 h to obtain a composite electrolyte slurry.

[0060] (2) injecting the composite electrolyte slurry obtained in step (1) into a polytetrafluoroethylene mold and drying at 60° C. for 12 hours to preliminarily obtain a composite electrolyte membrane;

[0061] (3) Hot pressing was performed at 80°C and 5 MPa for 1 minute to obtain an electrolyte membrane with a thickness of 200 μm.

[0062] The lithium ion conductivity of the electrolyte membrane is 4.8×10 -5 S cm -1 , the lithium ion migration number is 0.38.

[0063] Example 4

[0064] (1) 0.6 g of LLZTO nanoparticles and 0.2 g of poly(ethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethyl)methylsulfonyl imide) were dispersed in tetrahydrofuran and stirred for 8 h. Then, 1.2 g of polyethylene oxide and 0.86 g of lithium bis(oxalatoborate) were added and stirred for another 8 h to obtain a composite electrolyte slurry.

[0065] (2) injecting the composite electrolyte slurry obtained in step (1) into a polytetrafluoroethylene mold and drying at 60° C. for 12 hours to preliminarily obtain a composite electrolyte membrane;

[0066] (3) Hot pressing was performed at 100°C and 10 MPa for 1 minute to obtain an electrolyte membrane with a thickness of 100 μm.

[0067] The lithium ion conductivity of the electrolyte membrane is 3.1×10 -5 S cm -1 , the lithium ion migration number is 0.45.

[0068] Example 5

[0069] (1) 0.6 g of LLZTO nanoparticles and 0.2 g of poly(ethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethyl)methylsulfonyl imide) were dispersed in 1,3-dioxane and stirred for 8 h. Then, 1.2 g of polyethylene oxide and 0.16 g of lithium perchlorate were added and stirred for another 8 h to obtain a composite electrolyte slurry.

[0070] (2) injecting the composite electrolyte slurry obtained in step (1) into a polytetrafluoroethylene mold and drying at 80° C. for 10 hours to preliminarily obtain a composite electrolyte membrane;

[0071] (3) Hot pressing was performed at 100°C and 10 MPa for 3 minutes to obtain an electrolyte membrane with a thickness of 80 μm.

[0072] The lithium ion conductivity of the electrolyte membrane is 5.5×10 -5 S cm -1 , the lithium ion migration number is 0.48.

[0073] Comparative Example 1

[0074] A preparation method of a garnet-based composite electrolyte comprises the following steps:

[0075] (1) 0.6 g of LLZTO nanoparticles, 1.2 g of polyethylene oxide, and 0.86 g of lithium bis(trifluoromethylsulfonyl)imide were dissolved in tetrahydrofuran and stirred for 8 h to obtain a composite electrolyte slurry.

[0076] (2) injecting the composite electrolyte slurry obtained in step (1) into a polytetrafluoroethylene mold and drying at 60° C. for 12 hours to preliminarily obtain a composite electrolyte membrane;

[0077] (3) Hot pressing was performed at 100°C and 10 MPa for 1 minute to obtain an electrolyte membrane with a thickness of 100 μm.

[0078] Figure 6 This is a scanning electron microscope image of the composite solid electrolyte prepared in this comparative example. It can be seen that the LLZTO nanoparticles showed obvious agglomeration in the composite electrolyte membrane, proving that in the absence of the addition of poly(polyethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), the compatibility of the inorganic particles and the polymer is very poor.

[0079] Figure 7 This is the critical current test of the lithium-lithium symmetrical battery (lithium / electrolyte / lithium battery) assembled with the composite solid electrolyte prepared in this comparative example (the assembly method is the same as in Example 1). The critical current density of the lithium-lithium symmetrical battery assembled with this electrolyte is 0.3 mA cm -2 It may be that the uneven distribution of agglomerated LLZTO in PEO leads to a large concentration polarization of lithium ions during the deposition process, resulting in the massive growth of lithium dendrites.

[0080] The above is an exemplary description of the embodiments of the present invention. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A modified composite solid electrolyte, characterized in that: It includes a polyethylene oxide matrix and an inorganic electrolyte dispersed in the matrix, wherein the inorganic electrolyte is selected from garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The nanoparticles further include an amphiphilic block copolymer between the inorganic electrolyte and the matrix.

2. The modified composite solid electrolyte according to claim 1, characterized in that The amphiphilic block copolymer includes a polyether block and a polyionic liquid block; The polyether block is selected from polyethylene glycol acrylate; The polyionic liquid block is selected from poly 1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Preferably, the amphiphilic block copolymer is selected from poly(polyethylene glycol acrylate)-co-(1-(2-acryloylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide).

3. The modified composite solid electrolyte according to claim 1, characterized in that The modified composite solid electrolyte also includes lithium salt. Preferably, the lithium salt is one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and lithium perchlorate.

4. The modified composite solid electrolyte according to claim 1, characterized in that In the modified composite solid electrolyte, the garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The mass ratio of the nanoparticles to the amphiphilic block copolymer is (1-5):

1.

5. The modified composite solid electrolyte according to claim 1, characterized in that In the modified composite solid electrolyte, the garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The mass ratio of the nanoparticles to the polyethylene oxide is 1:(1.4-10). Preferably, in the modified composite solid electrolyte, the mass ratio of the lithium salt to polyethylene oxide is 1:(1-10).

6. The method for preparing the modified composite solid electrolyte according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: (1) Garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 Nanoparticles and amphiphilic block copolymers are mixed in a solvent; the resulting mixture is then mixed with polyethylene oxide and lithium salt to obtain a slurry; (2) forming a film from the slurry obtained in step (1) to obtain the modified composite solid electrolyte.

7. The method according to claim 6, characterized in that In step (1), the solvent is selected from one or more of acetonitrile, tetrahydrofuran and 1,3-dioxane.

8. The method according to claim 6, characterized in that In step (1), the garnet-type Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The nanoparticles and the amphiphilic block copolymer are mixed in the solvent for 6 to 12 hours. And / or, in step (1), the mixture is mixed with polyethylene oxide and lithium salt for 6 to 12 hours.

9. The method according to claim 6, characterized in that In step (2), the slurry obtained in step (1) is poured into a polytetrafluoroethylene mold, the solvent is dried, and hot-pressed to prepare the modified composite solid electrolyte; Preferably, the hot pressing temperature is 60-100° C., the pressure during hot pressing is 1 MPa-10 MPa, and the hot pressing time is 1-10 min. Preferably, the thickness of the modified composite solid electrolyte is 80-200 μm.

10. Use of the modified composite solid electrolyte according to any one of claims 1 to 5 in lithium-ion batteries. Preferably, a lithium-ion battery comprises a positive electrode, a negative electrode and the modified composite solid electrolyte according to any one of claims 1 to 5.

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