CN111816916A - Composite solid-state electrolyte membrane, preparation method thereof, and lithium ion battery - Google Patents

Abstract

The invention provides a composite solid electrolyte membrane, a preparation method thereof and a lithium ion battery, and provides the composite solid electrolyte membrane which comprises a polymer electrolyte and inorganic electrolyte fibers dispersed in the polymer electrolyte, wherein an included angle theta between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane satisfies the following requirements: theta is more than or equal to 0 degree and less than or equal to 30 degrees. The composite solid electrolyte membrane improves the ionic conductivity and the mechanical strength of the composite solid electrolyte membrane by designing the material composition and the structure.

Description

Composite solid-state electrolyte membrane, preparation method thereof, and lithium ion battery

technical field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a composite solid-state electrolyte membrane, a preparation method thereof, and a lithium ion battery.

Background technique

All-solid-state batteries replace the flammable electrolyte in traditional lithium-ion batteries with non-flammable solid electrolytes, which fundamentally avoids potential safety hazards. Secondly, the good mechanical properties of the solid electrolyte can effectively inhibit the growth of lithium dendrites in the negative electrode, greatly reducing the risk of short circuit caused by dendrite puncture, making it possible to use metal lithium as a negative electrode material for lithium ion batteries, thereby effectively improving lithium ion batteries. energy density. With many advantages such as high safety performance and long cycle life, all-solid-state lithium-ion batteries have gradually become a hot spot of research and development in the field of new chemical power sources.

It can be said that the comprehensive performance improvement of solid electrolyte has become a key link in the development of all-solid-state lithium-ion batteries. Solid electrolytes are mainly divided into polymer electrolytes and inorganic electrolytes, and inorganic electrolytes are mainly divided into two categories: sulfide electrolytes and oxide electrolytes. Each of these types of solid electrolytes has advantages and disadvantages. For example, polymer electrolytes are flexible, which is beneficial to the interfacial contact of solid-state batteries, and is easy to be mass-produced into electrolyte membranes, but their ionic conductivity is low and cannot withstand high pressures. Sulfide electrolytes have high ionic conductivity, but are extremely unstable in air, and have high interfacial impedance with positive and negative electrode materials for lithium batteries. Oxide electrolytes have high ionic conductivity, but are not flexible, and the interface contact is difficult to ensure that they are processed into membranes. Therefore, a single type of solid electrolyte cannot meet the current needs of solid-state batteries for electrolyte membranes.

One of the effective solutions is to composite a variety of electrolytes into composite electrolyte membranes. For example, polymer electrolytes can be composited with oxide electrolytes, or polymer electrolytes can be composited with sulfide electrolytes to obtain both flexibility and high ionic conductivity. rate of composite electrolyte membrane. It is also possible to mix polymer electrolytes with oxide electrolyte powders, or mix polymer electrolytes with sulfide electrolyte powders, so that oxide or sulfide powders are dispersed in the polymer in a discrete state to obtain high ionic conductivity. Flexible composite electrolyte membrane. However, oxide electrolytes and sulfide electrolytes with high ionic conductivity cannot effectively form lithium ion conductive paths. Therefore, the improvement of the ionic conductivity of the composite electrolyte prepared by the above method is limited, and the mechanical properties of the composite electrolyte by the discretely distributed powder are limited. The increase in strength is also very limited. At present, those skilled in the art have studied the preparation of oxide electrolytes or sulfide electrolytes into fibers, and then compounded with polymer electrolytes, in order to improve the ionic conductivity and mechanical strength of the composite electrolytes. However, the ionic conductivity and mechanical strength obtained by the existing research still cannot meet the current requirements for the electrolyte membrane of lithium-ion batteries.

Therefore, providing a polymer electrolyte membrane with high ionic conductivity and mechanical strength has become one of the topics that have been paid attention to and pursued in the development of the all-solid-state lithium battery industry.

SUMMARY OF THE INVENTION

The invention provides a composite solid-state electrolyte membrane, which improves the ionic conductivity and mechanical strength of the composite solid-state electrolyte membrane by designing the material composition and structure.

The present invention also provides a method for preparing the composite solid-state electrolyte membrane, which is simple to operate and beneficial to industrialized production, and the composite solid-state electrolyte membrane with high mechanical strength and ionic conductivity can be prepared by using the method of the present invention.

The present invention also provides a lithium ion battery, which has better rate performance and cycle performance than the existing composite solid-state electrolyte membrane.

The technical scheme proposed by the present invention is:

In a first aspect, the present invention provides a composite solid electrolyte membrane, comprising a polymer electrolyte, and inorganic electrolyte fibers dispersed in the polymer electrolyte, and the inorganic electrolyte fibers account for 20-20 mass fraction of the composite solid electrolyte membrane. 90%;

The angle θ between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane satisfies:

0°≤θ≤30°;

Preferably, the included angle θ=0° between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane.

The composite solid electrolyte membrane of the present invention improves the ionic conductivity and mechanical strength of the composite solid electrolyte membrane by designing the material composition and structure.

In a specific embodiment of the present invention, the inorganic electrolyte fiber may be a hollow fiber or a solid fiber, or a mixture of the two kinds of fibers.

Specifically, the inner diameter of the inorganic electrolyte hollow fiber is about 10-2000nm, such as 50-200nm, 100-300nm, 300-500nm, 1000-2000nm, 500-1500nm, 800-1600nm, 1400-1800nm, 1200-1500nm, 250-700nm, 300-900nm;

The outer diameter of the inorganic electrolyte hollow fiber may be 50-4000nm, 100-300nm, 700-1000nm, 100-700nm, 200-400nm, 100-200nm, 300-500nm, 300-500nm, 1000-2000nm, 2000-4000nm , 3000-3500nm, 1500-3500nm;

The thickness of the inorganic electrolyte hollow fiber may be 15-2000nm, such as 60-200nm, 100-200nm, 300-500nm, 400-600nm, 500-800nm, 700-1000nm, 1400-1800nm, 1200-1500nm, 100-700nm , 200-400nm;

The diameter of the solid fibers is about 0.05-1000 μm, such as 0.1-1 μm, 0.5-20 μm, 1-10 μm, 10-100 μm, 50-200 μm, 100-300 μm, 300-500 μm, 150-400 μm, 500-1000 μm, 800 -1000μm.

In a specific embodiment of the present invention, the polymer electrolyte may be a lithium-conducting polymer or a non-conducting lithium polymer, or a mixture of the two, which is not limited in the present invention. The lithium conducting polymer can be selected from polyether, polyphosphazene, polycarbonate, polyacrylate, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, nitrile rubber and polyvinyl chloride One or more of; the non-conductive lithium polymer can be selected from polyethylene, polypropylene, polyethylene terephthalate, polyurethane, polycaprolactone, silicone rubber, styrene butadiene rubber, polystyrene One or more of ethylene, polytetrafluoroethylene, polyimide, polyetheretherketone, and epoxy resin.

In a specific embodiment of the present invention, the polymer electrolyte further includes a plasticizer, the mass fraction of the plasticizer is not more than 10% based on the mass of the composite solid electrolyte membrane, and the plasticizer The agent is selected from at least one of small molecular organic plasticizers and ionic liquids with an average molecular weight of 40-800; and/or the polymer electrolyte also includes lithium salts, based on the mass of the composite solid electrolyte membrane, The mass fraction of the lithium salt is not more than 10%.

Wherein, the organic plasticizer with an average molecular weight of 40-800 can be selected from ester, fluoroester or fluoroether plasticizers, for example, can be selected from ethylene carbonate (EC), propylene carbonate ( PC), butylene carbonate, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), fluorodimethyl carbonate, fluoromethyl ethyl carbonate, dimethyl carbonate (DMC), carbonic acid Diethyl (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), methyl formate, ethyl formate, propyl formate, Butyl formate, methyl acetate, ethyl acetate (EA), propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, butyric acid ethyl ester, propyl butyrate, butyl butyrate, methyl trifluoroacetate, methyl difluoroacetate, methyl fluoroacetate, ethyl trifluoroacetate, ethyl difluoroacetate, ethyl fluoroacetate, γ-butyl Lactone (GBL), γ-valerolactone, δ-valerolactone, ethylene glycol dimethyl ether (DME), triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, fluoroether F-EPE , one or more of fluoroether D2, fluoroether (HFPM), fluoroether (MFE), fluoroether (EME), and can also be selected from acetonitrile (AN), malononitrile, glutaronitrile (GN), adiponitrile (ADN), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxane (DOL), 1,4-dioxane (DOX), sulfolane, dimethyl One or more of sulfoxide (DMSO), dichloromethane and dichloroethane;

The ionic liquid is selected from 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, N-ethylpyridine bis(trifluoromethanesulfonyl)imide, N-ethylpyridine hexafluorophosphate, N-ethylpyridine tetrafluoroborate, tributylmethylammonium bis(trifluoromethanesulfonyl) Imide salt, N-methoxyethyl-N-methyldiethylammonium tetrafluoroborate, tributylhexylphosphine bis(trifluoromethanesulfonyl)imide salt, tetrabutylphosphine bis(trifluoroborate) Fluoromethanesulfonyl)imide salt, tributylethylphosphine bis(trifluoromethanesulfonyl)imide salt and N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt one or more of;

Adding an appropriate amount of lithium salt to the composite electrolyte membrane can further improve its lithium ion conductivity, and can use conventional lithium salts in the field, for example, can be selected from lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), high chloride Lithium oxide (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium hexafluoroantimonate (LiSbF ₆ ), lithium difluorophosphate (LiPF ₂ O ₂ ), 4,5-dicyano-2-trifluoro Lithium methylimidazolate (LiDTI), lithium bis(oxalato)borate (LiBOB), lithium bis(malonate)borate (LiBMB), lithium difluorooxalate borate (LiDFOB), lithium bis(difluoromalonate)borate ( LiBDFMB), (malonate oxalate) lithium borate (LiMOB), (difluoromalonate oxalate) lithium borate (LiDFMOB), tris (oxalate) lithium phosphate (LiTOP), tris (difluoromalonate) lithium phosphate ( LiTDFMP), Lithium Tetrafluorooxalate Phosphate (LiTFOP), Lithium Difluorobisoxalate Phosphate (LiDFOP), Lithium Bis(fluorosulfonyl)imide (LiFSI), Lithium Bistrifluoromethanesulfonimide (LiTFSI), Lithium sulfonyl)(trifluoromethanesulfonyl)imide (LiN(SO ₂ F)(SO ₂ CF ₃ )), lithium nitrate (LiNO ₃ ), lithium fluoride (LiF), LiN(SO ₂ R _F ) ₂ One or more of LiN(SO ₂ F)(SO ₂ R _F ), wherein R _F =C _n F _2n+1 , and n is an integer of 2-10.

In the second aspect, the present invention proposes a method for preparing the composite solid electrolyte membrane, comprising the following steps:

The inorganic electrolyte powder and the organic polymer are prepared into a spinning dope, and then coaxial electrospinning is performed to obtain a composite fiber bundle that is aligned in a direction, and then the composite fiber bundle is calcined at a temperature of 300-1200° C. Inorganic electrolyte fiber bundles. The purpose of calcination is on the one hand to remove organic polymers and on the other hand to sinter the fibers.

Specifically, the electrospinning machine used in the present invention adopts the intelligent version TL-Pro-BM electrospinning machine of Shenzhen Tongli Micro Nano Technology Co., Ltd., and is equipped with a cage-like yarn take-up. As long as the parameters of electrospinning are set within a reasonable range, composite fibers can be obtained. For example, the diameter of the spinning needle tube can be controlled to be about 0.05-1000 μm, the voltage can be about 10-50kV, the receiving distance is about 10-50cm, and the cage-shaped receiving The rotating speed of the silk device is 1000-3000r/min.

After the organic electrolyte is melted, it is filled into the voids of the inorganic electrolyte fiber bundles, cooled and formed, and then cut along the direction perpendicular to the inorganic electrolyte fiber bundles to obtain a composite solid electrolyte film.

In a specific embodiment of the present invention, the inorganic electrolyte fibers may be hollow fibers or solid fibers, or a mixture of the two.

It is well known to those skilled in the art that some solvent can also be added to the spinning dope. If it is a hollow fiber, the spinning dope with the solvent added can be introduced into the outer tube, air or only solvent can be introduced into the inner tube, and then the electrospinning solution Oriented coaxial electrospinning was performed on the device. The solvent may be selected from water, N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), methanol, ethanol, acetonitrile, acetone , at least one of formic acid, acetic acid, trifluoroethanol, hexafluoroisopropanol, dichloromethane, chloroform, and tetrahydrofuran. The outer tube and inner tube solvent may be the same or different. The present invention is not particularly limited to this.

Specifically, the inner diameter of the inorganic electrolyte hollow fiber is about 10-2000nm, such as 50-200nm, 100-300nm, 300-500nm, 1000-2000nm, 500-1500nm, 800-1600nm, 1400-1800nm, 1200-1500nm, 250-700nm, 300-900nm;

The outer diameter of the inorganic electrolyte hollow fiber may be 50-4000nm, 100-300nm, 700-1000nm, 100-700nm, 200-400nm, 100-200nm, 300-500nm, 300-500nm, 1000-2000nm, 2000-4000nm , 3000-3500nm, 1500-3500nm;

The thickness of the inorganic electrolyte hollow fiber is not less than 15nm, such as 60-200nm, 100-200nm, 300-500nm, 400-600nm, 500-800nm, 700-1000nm, 1400-1800nm, 1200-1500nm, 100-700nm, 200nm -400nm;

The diameter of the solid fibers is about 0.05-1000 μm, such as 0.1-1 μm, 0.5-20 μm, 1-10 μm, 10-100 μm, 50-200 μm, 100-300 μm, 300-500 μm, 150-400 μm, 500-1000 μm, 800 -1000μm.

In principle, the particle size of the inorganic electrolyte powder only needs to be conducive to spinning, and the particle size of the powder should also be smaller than the size of the composite fiber. Therefore, the particle size of the inorganic electrolyte powder can be controlled to be about 10-900 nm, such as 200- 500nm.

The inorganic electrolyte powder is selected from conventional inorganic electrolyte materials in the art, for example, can be selected from lithium silicate, lithium phosphate, lithium sulfate, lithium borate, sulfide electrolyte powder, perovskite type electrolyte powder, Garnet type electrolyte powder, NASICON One or more of LISICON type electrolyte powder, LISICON type electrolyte powder and glassy electrolyte powder.

Specifically, the sulfide electrolyte can be selected from Li ₂ SP ₂ S ₅ , Li ₃ PS ₄ , Li ₇ P ₃ S ₁₁ or Li ₆ PS ₅ X (X can be selected from one of F, Cl, Br, and I). one or more); Li ₂ SP ₂ S ₅ can be 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ or 80Li ₂ S-20P ₂ S ₅ ;

The perovskite electrolyte can be selected from Li _3z La _2/3-z TiO ₃ , where 0<z<2/3;

The Garnet type electrolyte can be selected from Li _7-a La ₃ Zr _{2-a Ma} O ₁₂ with a garnet structure, wherein M can be selected from one or more of Ta, Nb or W, 0≤a ≤2;

The NASICON type solid electrolyte can be selected from Li _1+x+y Al _x (Tim Zrn _Ger ) _2-x Si _y P _3-y O ₁₂ , wherein _0≤x≤2 , _0≤y≤3 , 0≤m≤1, 0≤n≤1, 0≤r≤1, m+n+r=1; or Li _1+2x Zr _2-x Ca _x (PO ₄ ) ₃ , where 0.1≤x≤0.4;

The LISICON type electrolyte may be selected from Li _4-x Ge _1-x P _x S ₄ (X=0.4 or X=0.6);

_{The glassy electrolyte may be selected from aLi2O.bAl2O3.cLa2O3.dTiO2.eZrO2.fSnO2.gZnO2.hCeO2.iB2O3.jP2O5.kSO3 . _ _ _ _ _ _} mCO ₂ ·nSiO ₂ ·pLiF·qLiCl·rLiBr·sLiI, where 0<a<1, 0≤b<1, 0≤c<1, 0≤d<1, 0≤e<1, 0≤f<1 , 0≤g<1, 0≤h<1, 0≤i<1, 0≤j<1, 0≤k<1, 0≤m<1, 0≤n<1, 0≤p<1, 0 ≤q<1, 0≤r<1, 0≤s<1, and a+b+c+d+e+f+g+h+i+j+k+m+n+p+q+r+ s=1, and b, i, j, k, n are not 0 at the same time.

The organic polymer is selected from polyglycolic acid, polylactic acid, polycaprolactone, aliphatic polyester copolymer, polyphosphazene, polydioxane, polyamide, polycarbonate, polyurethane, polyethylene oxide , one or more of polyvinyl alcohol, polyvinyl acetal, polyacrylic acid, polyacrylate, nitrile rubber, polyacrylamide, polyvinylpyrrolidone and hydroxypropyl cellulose.

The polymer electrolyte is a polymer electrolyte commonly used in the art, for example, it can be selected from polyethylene oxide (PEO), PEO-based copolymers, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride- One or more of hexafluoropropylene copolymer (PVDF-HFP), polycarbonate and polyacrylate. The above-mentioned polymer electrolytes can be obtained commercially or prepared by polymerization of monomers. In order to further improve the mechanical strength of the polymer electrolyte, it can be made to have a certain degree of cross-linking through cross-linking, and the cross-linking can be achieved by means of conventional methods in the art, for example, adding a certain amount of cross-linking agent or ultraviolet radiation. When the polymer electrolyte has a certain degree of cross-linking, such as 5-35%, the composite electrolyte membrane can have certain mechanical strength and flexibility.

The preparation method of the composite solid electrolyte membrane of the present invention has simple operation and is beneficial to industrial production. By adopting the method of the invention, a composite solid electrolyte membrane with high mechanical strength and high ionic conductivity can be prepared.

In a third aspect, the present invention provides a lithium-ion battery, which is prepared by using the above-mentioned composite solid-state electrolyte membrane, and is an all-solid-state lithium battery. The materials of the positive electrode and the negative electrode of the lithium ion battery are not limited. For example, the positive electrode active material can be one or a mixture of several, such as a lithium nickel cobalt manganese oxide system, a lithium iron phosphate system, and a lithium vanadium iron phosphate. system, lithium vanadium phosphate system, lithium cobaltate system, lithium nickelate system, lithium-rich manganese system base oxide, lithium nickel cobalt aluminum system oxide and lithium manganate system one or more mixtures, the negative electrode material can be One or a combination of graphite anode materials, silicon oxide anode materials, other types of silicon-based anode materials, hard carbon anode materials, soft carbon anode materials, and tin-based anode materials.

Compared with the existing composite solid electrolyte membrane, the lithium ion battery of the present invention has better rate discharge performance and cycle life.

Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

Description of drawings

1a and FIG. 1b are schematic diagrams of preparing a composite solid electrolyte membrane by oriented inorganic electrolyte fibers according to an embodiment of the present invention. The difference between FIG. 1a and FIG. 1b lies in the orderly arrangement of the inorganic electrolyte fibers. In FIG. 1a, θ=0°; 0°<θ≤30° in Fig. 1b, Fig. 1c is a schematic diagram of preparing a composite solid electrolyte membrane from non-oriented inorganic electrolyte fibers of a comparative example of the present invention,

Among them, 1-aligned inorganic electrolyte fibers, 2-polymer electrolyte, 3-polymer electrolyte/inorganic electrolyte fiber composite, 4-composite solid electrolyte membrane;

Figures 2a, 2b, and 2c are SEM images of the composite solid electrolyte membranes of Figures 1a, 1b, and 1c, respectively.

Detailed ways

The embodiments of the present invention are described in detail below, and the embodiments are exemplary and intended to explain the present invention, but should not be construed as a limitation of the present invention.

As shown in Figure 1 and Figure 2, Figure 1a and Figure 1b are schematic diagrams of preparing a composite solid electrolyte membrane by oriented inorganic electrolyte fibers according to an embodiment of the present invention. The difference between Figure 1a and Figure 1b is the orderly arrangement of the inorganic electrolyte fibers, In Fig. 1a, θ=0°; in Fig. 1b, 0°<θ≤30°, and Fig. 1c is a schematic diagram of preparing a composite solid electrolyte membrane from non-oriented inorganic electrolyte fibers of a comparative example of the present invention.

Describe the present invention in detail below by specific embodiment:

Example 1

Embodiment 1 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 5 parts by weight of Li ₆ PS ₅ Cl (with an average particle size of about 10 nm), 1 part by weight of polyethylene oxide (with an average molecular weight of about 12 million), and 94 parts by weight of acetonitrile were prepared into a spinning dope.

(2) Electrospinning the spinning dope by using a cage-like take-up device to obtain a directional composite solid fiber bundle with a diameter of about 500 nm, wherein the spinning parameters are set as follows: the diameter of the spinning needle tube is about 500 nm, and the voltage is about 500 nm. It is 50kV, the receiving distance is about 50cm, and the speed of the cage-like wire take-up device is 2000r/min.

As shown in Figures 1a and 2a, the oriented solid fibers were observed by scanning electron microscope (SEM), and all the fibers were nearly parallel.

(3) The composite solid fiber bundle was then calcined at a temperature of 550° C. for 6 h to obtain an inorganic electrolyte fiber bundle.

(4) Polyvinyl carbonate (average molecular weight 450,000) was melted and kneaded uniformly at 95°C, filled with a vacuum infusion machine between the inorganic electrolyte fiber bundles, then cooled and solidified, and then cut into thin films with a precision cutting machine , the included angle between the cutting direction and the length direction of the fiber bundle is 90°, that is, the included angle θ=0° between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane, and the composite solid electrolyte membrane is obtained.

Example 2

Embodiment 2 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 8 parts by weight of Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ (average particle size of about 100 nm), 1 part by weight of polyvinyl alcohol (average molecular weight of about 400,000), and 84 parts by weight of water were prepared for spinning stock solution.

(2) Electrospinning the spinning dope with a cage-like take-up device to obtain a directional composite solid fiber bundle with a diameter of about 800 nm, wherein the spinning parameters are set as follows: the diameter of the spinning needle tube is about 800 nm, and the voltage is about 800 nm. It is 40kV, the receiving distance is about 40cm, and the speed of the cage-like wire take-up device is 1000r/min.

As shown in Figures 1b and 2b, the oriented solid fibers were observed by scanning electron microscope (SEM), and all the fibers were nearly parallel.

(3) The composite solid fiber bundle was then calcined at a temperature of 1200° C. for 8 hours to obtain an inorganic electrolyte fiber bundle.

(4) Polyethylene oxide (average molecular weight 12 million) was melted and kneaded uniformly at 82°C, filled with a vacuum infusion machine between the inorganic electrolyte fiber bundles, then cooled and solidified, and then cut into thin films with a precision cutting machine, The included angle between the cutting direction and the length direction of the fiber bundle is 90°, that is, the included angle θ=0° between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane, and the composite solid electrolyte membrane is obtained.

Example 3

Embodiment 3 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 16 parts by weight of Li ₇ La ₃ Zr ₂ O ₁₂ (average particle size of about 800 nm), 14 parts by weight of polyvinylidene fluoride alcohol (with an average molecular weight of about 900,000), and 70 parts by weight of NMP were prepared into a spinning dope .

(2) Electrospinning the spinning dope with a cage-like take-up device to obtain a directional composite solid fiber bundle with a diameter of about 2000 nm, wherein the spinning parameters are set as follows: the diameter of the spinning needle tube is about 2000 nm, the voltage is about 2000 nm It is 45kV, the receiving distance is about 50cm, and the speed of the cage-like wire take-up device is 2000r/min.

(3) The composite solid fiber bundle was then calcined at a temperature of 1200° C. for 5 hours to obtain an inorganic electrolyte fiber bundle.

(4) Polyvinyl carbonate (average molecular weight 450,000) was melted and kneaded uniformly at 95°C, filled with a vacuum infusion machine between the inorganic electrolyte fiber bundles, then cooled and solidified, and then cut into thin films with a precision cutting machine , the included angle between the cutting direction and the length direction of the fiber bundle is 60°, that is, the included angle θ=30° between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane, and the composite solid electrolyte membrane is obtained.

Example 4

Embodiment 4 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 4 parts by weight of lithium sulfate (average particle size is about 200 nm), 4 parts by weight of lithium borate (average particle size is about 120 nm), 8 parts by weight of polyvinyl formal (average molecular weight is about 300,000), 84 parts by weight Parts by weight of ethanol are prepared into spinning stock solution.

(2) Electrospinning the spinning dope by using a cage-like take-up device to obtain a directional composite solid fiber bundle with a diameter of about 1000 nm, wherein the spinning parameters are set as follows: the diameter of the spinning needle is about 1000 nm, and the voltage is about 1000 nm. It is 45kV, the receiving distance is about 45cm, and the speed of the cage-like wire take-up device is 2000r/min.

(3) The composite solid fiber bundle was then calcined at a temperature of 1000° C. for 4 hours to obtain an inorganic electrolyte fiber bundle.

(4) 50 parts by weight of polyethylene (average molecular weight: 2 million) and 50 parts by weight of polypropylene (average molecular weight: 1.2 million) were melted and kneaded uniformly at 188° C. and then filled between the inorganic electrolyte fiber bundles with a vacuum infusion machine. Cool and solidify, and then use a precision cutting machine to cut it into thin films. The angle between the cutting direction and the length direction of the fiber bundle is 90°, that is, the angle θ=0° between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane. Composite solid electrolyte membrane.

Example 5

Embodiment 5 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 20 parts by weight of Li ₇ La ₃ Zr ₂ O ₁₂ (average particle size of about 250 nm), 10 parts by weight of polyacrylic acid (average molecular weight of about 1.2 million), and 70 parts by weight of water were prepared into a spinning dope.

(2) The spinning dope is injected into the outer tube using a cage-like yarn take-up device, and ethanol is injected into the inner tube to perform electrospinning. The spinning parameters are set as follows: the diameter of the outer tube is about 2000 nm, and the diameter of the inner tube is about 2000 nm. is 500 nm, the voltage is about 90 kV, and the receiving distance is about 80 cm, to obtain an oriented composite hollow fiber bundle with an outer diameter of about 2000 nm and an inner diameter of about 500 nm.

(3) The composite solid fiber bundle was then calcined at a temperature of 1050° C. for 6 hours to obtain an inorganic electrolyte fiber bundle.

(4) 80 parts by weight of polyethylene carbonate (average molecular weight: 450,000) and 20 parts by weight of LiTFSI were melted and kneaded uniformly at 95° C. and then filled between the inorganic electrolyte fiber bundles with a vacuum infusion machine, then cooled and solidified, and then used The precision cutting machine cuts it into thin films, and the angle between the cutting direction and the length direction of the fiber bundle is 90°, that is, the angle θ=0° between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane, and the composite solid electrolyte membrane is obtained.

Example 6

Embodiment 6 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 30 parts by weight of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ (average particle size of about 400 nm), 10 parts by weight of polyvinylpyrrolidone (average molecular weight of about 1 million), and 60 parts by weight of water are prepared for spinning stock solution.

(2) The spinning dope is injected into the outer tube by using a cage-like yarn take-up device, and ethanol is injected into the inner tube to perform electrospinning. The spinning parameters are set as follows: the diameter of the outer tube is about 2200 nm, and the diameter of the inner tube is about 2200 nm. is 900 nm, the voltage is about 80 kV, and the receiving distance is about 70 cm, to obtain a directional composite hollow fiber bundle with an outer diameter of about 2200 nm and an inner diameter of about 900 nm.

(3) Then, the composite solid fiber bundle was calcined at a temperature of 1100° C. for 2 h to obtain an inorganic electrolyte fiber bundle.

(4) 85 parts by weight of polyvinylidene fluoride (average molecular weight: 1 million), 10 parts by weight of LiDFOB and 5 parts by weight of succinonitrile were melted and kneaded uniformly at 200° C. and then filled between the inorganic electrolyte fiber bundles with a vacuum infusion machine , then cooled and solidified, and then cut into thin films with a precision cutting machine. The angle between the cutting direction and the length direction of the fiber bundle is 90°, that is, the angle between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane is θ=0° , a composite solid electrolyte membrane was obtained.

Example 7

Embodiment 7 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 16 parts by weight of Li ₁₀ GeP ₂ S ₁₂ (average particle size of about 300 nm), 10 parts by weight of nitrile rubber (average molecular weight of about 600,000), and 74 parts by weight of xylene were prepared into a spinning dope.

(2) The spinning dope is injected into the outer tube by using a cage-like yarn take-up device, and nitrogen gas is introduced into the inner tube to perform electrospinning. The spinning parameters are set as follows: the diameter of the outer tube is about 2500 nm, and the diameter of the inner tube is about 2500 nm. About 1200nm, the voltage is about 70kV, the receiving distance is about 50cm, and the oriented composite hollow fiber bundle with the outer diameter of about 2500nm and the inner diameter of about 1200nm is obtained.

(3) The composite solid fiber bundle was then calcined at a temperature of 650° C. for 4 hours to obtain an inorganic electrolyte fiber bundle.

(4) 93 parts by weight of nitrile rubber (average molecular weight 800,000), 2 parts by weight of LiTDI and 5 parts by weight of succinonitrile are melted and kneaded uniformly at 180° C. and then filled between the inorganic electrolyte fiber bundles with a vacuum infusion machine, Then it is cooled and solidified, and then cut into thin films with a precision cutting machine. The angle between the cutting direction and the length direction of the fiber bundle is 90°, that is, the angle θ=0° between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane. A composite solid electrolyte membrane was obtained.

Example 8

Embodiment 8 proposes a composite solid-state electrolyte membrane, which is prepared by the following method:

(1) 10 parts by weight of lithium borate (average particle size of about 20 nm), 4 parts by weight of polyethylene oxide (average molecular weight of about 7 million), and 84 parts by weight of acetonitrile are prepared into a spinning dope.

(2) The spinning dope is injected into the outer tube using a cage-like yarn take-up device, and ethanol is injected into the inner tube to perform electrospinning. The spinning parameters are set as follows: the diameter of the outer tube is about 50 nm, and the diameter of the inner tube is about 50 nm. It is 10nm, the voltage is about 65kV, the receiving distance is about 40cm, and the oriented composite hollow fiber bundle with the outer diameter of about 50nm and the inner diameter of about 10nm is obtained.

(3) The composite solid fiber bundle was then calcined at a temperature of 800° C. for 3 hours to obtain an inorganic electrolyte fiber bundle.

(4) 80 parts by weight of polyethylene oxide (average molecular weight: 12 million), 10 parts by weight of LiFSI, 5 parts by weight of tetraethylene glycol dimethyl ether and 5 parts by weight of tetrabutylphosphine bis(trifluoromethanesulfonyl)imide The salt is melted and kneaded uniformly at 78 °C, and then filled between the inorganic electrolyte fiber bundles with a vacuum infusion machine, then cooled and solidified, and then cut into thin films with a precision cutting machine. The angle between the cutting direction and the length direction of the fiber bundles is 90° , that is, the included angle θ=0° between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane, and the composite solid electrolyte membrane is obtained.

Comparative Example 1

A composite solid-state electrolyte membrane is proposed in Comparative Example 1. The only difference between Comparative Example 1 and Example 1 is that a flat yarn take-up is used in step (2) of Comparative Example 1, and the spinning parameters are set as follows: the diameter of the spinning needle tube is approximately 0.5μm, the voltage is about 50kV, and the receiving distance is about 50cm.

As shown in Figures 1c and 2c, the obtained aligned solid fibers were observed by scanning electron microscopy (SEM), and all fibers were disordered.

Comparative Example 2

A composite solid electrolyte membrane is proposed in Comparative Example 2. The difference between Comparative Example 2 and Example 2 is only that in step (2) of Comparative Example 2, a flat wire take-up device is used instead of a cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

Comparative Example 3

A composite solid electrolyte membrane is proposed in Comparative Example 3. The difference between Comparative Example 3 and Example 3 is only that in step (2) of Comparative Example 3, a flat wire take-up device is used instead of a cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

Comparative Example 4

A composite solid electrolyte membrane is proposed in Comparative Example 4. The difference between Comparative Example 4 and Example 4 is only that in step (2) of Comparative Example 4, a flat wire take-up device is used instead of a cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

Comparative Example 5

A composite solid-state electrolyte membrane is proposed in Comparative Example 5. The difference between Comparative Example 5 and Example 5 is only that in step (2) of Comparative Example 5, a flat wire take-up device is used to replace the cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

Comparative Example 6

A composite solid electrolyte membrane is proposed in Comparative Example 6. The only difference between Comparative Example 6 and Example 6 is that in step (2) of Comparative Example 6, a flat wire take-up device is used to replace the cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

Comparative Example 7

A composite solid-state electrolyte membrane is proposed in Comparative Example 7. The difference between Comparative Example 7 and Example 7 is only that in step (2) of Comparative Example 7, a flat wire take-up device is used to replace the cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

Comparative Example 8

A composite solid electrolyte membrane is proposed in Comparative Example 8. The difference between Comparative Example 8 and Example 8 is only that in step (2) of Comparative Example 8, a flat wire take-up device is used to replace the cage-shaped wire take-up device to prepare disordered arrays. Fiber, other preparation methods and steps are the same.

The following methods were used to measure the ionic conductivity and tensile strength of the composite solid electrolyte membranes of Examples 1-8 and Comparative Examples 1-8, respectively. The results are shown in Table 1.

Ionic Conductivity Test

The composite solid electrolyte membrane is punched into a composite solid electrolyte membrane disc with a radius of r=8mm by a punching machine, and then a stainless steel disc (SS) with a radius of r=8mm is placed on both sides of the composite solid electrolyte membrane disc. It was hermetically assembled into a SS/composite solid electrolyte membrane/SS symmetrical blocking cell. The above-mentioned symmetrical blocking battery was tested for AC impedance (EIS) with an electrochemical workstation. Test conditions: the amplitude was 10mV, the frequency was 10-10 ⁶ Hz, and the temperature was 25°C. Before the test, the battery should be kept at the test temperature for 1h. The battery is stable, the impedance spectrum is obtained and the bulk resistance R _b can be obtained by data fitting. The conductivity of the composite solid electrolyte membrane can be calculated according to the following formula (1):

δ=d/(R _b S) Formula (1)

Among them, δ is the conductivity of the composite solid electrolyte membrane, R _b is the bulk resistance obtained by fitting the impedance spectrum data, d is the thickness of the composite solid electrolyte membrane, S is the electrode area, and S=πr ² .

Tensile Strength

The tensile strength test method refers to the national standard GB13022-1991 plastics-film tensile properties test method, and the tensile test machine is used for testing.

Table 1 Performance test of composite solid electrolyte membrane of each embodiment and comparative example

Ionic conductivity (ms/cm) Tensile strength (MPa) Example 1 0.91 14.4 Example 2 0.78 12.5 Example 3 0.83 13.6 Example 4 0.84 29.0 Example 5 0.95 11.2 Example 6 0.97 12.7 Example 7 0.85 18.8 Example 8 1.01 11.9 Comparative Example 1 0.25 4.2 Comparative Example 2 0.20 3.6 Comparative Example 3 0.23 4.1 Comparative Example 4 0.28 9.3 Comparative Example 5 0.53 7.8 Comparative Example 6 0.57 8.3 Comparative Example 7 0.46 7.1 Comparative Example 8 0.62 5.0

As shown in Table 1, the room temperature ionic conductivity and tensile strength of the composite solid electrolyte membranes prepared in each example of the present invention are significantly higher than those of the composite solid electrolyte membranes at room temperature and tensile strength of each comparative example.

Using the following methods, the composite solid electrolyte membranes of the comparative examples of each embodiment are prepared to prepare lithium ion batteries:

(1) Preparation of positive electrode sheet

Referring to the current general lithium-ion battery production method, 97 parts by mass of nickel-cobalt-manganese ternary cathode material (Ningbo Rongbaixin Energy Technology Co., Ltd. nickel-cobalt manganate lithium, NCM811, specific capacity 191mAh/g), 1 part by mass acetylene black conductive agent, 0.5 parts by mass of carbon nanotube conductive agent, 1.5 parts by mass of PVDF binder and 50 parts by mass of solvent NMP were passed through a double planetary stirrer under vacuum at 30 r/min revolution and 2000 r/min rotation. Conditional stirring for 4 hours, dispersed into a uniform slurry, coated on a 9 μm thick aluminum foil current collector, then dried at 130 ° C, rolled under a pressure of 35 tons, and cut to obtain a positive pole piece. The areal density was 16 mg/cm ² and the compacted density was 3.45 g/cm ³ .

In the present invention, the above-mentioned fixed positive electrode sheet is used for the convenience of comparing the performance of the lithium ion battery. Technicians can completely adjust the formula of the positive electrode sheet according to the specific situation. Those skilled in the art can also change the types of positive electrode materials and other conditions, such as replacing the nickel-cobalt-manganese ternary positive electrode material with other commonly used lithium-ion battery positive electrode materials such as lithium iron phosphate, lithium manganate, and lithium cobaltate, or these positive electrode materials. the mix of.

(2) Preparation of negative pole piece

Referring to the current general production method of lithium-ion batteries, 97 parts of graphite anode material (artificial graphite of Beitray New Energy Technology Co., Ltd., model S360-L2-H, specific capacity 357mAh/g), 1.5 parts of carbon black Conductive agent, 1.0 part by mass of SBR binder, 0.5 part by mass of carboxymethyl cellulose and 100 parts by mass of solvent water, were stirred by a double planetary mixer under vacuum at 30r/min revolution and 1500r/min rotation for 4h , dispersed into a uniform slurry, and coated on the surface of 6μm copper foil, then dried at 110 ° C, rolled under a pressure of 40 tons, and finally cut into negative pole pieces of the required size, wherein the surface of the negative pole piece The density was 9.4 mg/cm ² and the pole piece compacted density was 1.78 g/cm ³ .

In order to facilitate the comparison of battery performance, the present invention uses the above-mentioned fixed negative electrode sheet. Technicians can completely adjust the formula of the above-mentioned negative pole pieces according to the specific situation, and can also change the type of negative electrode material, such as graphite negative electrode material, silicon oxide negative electrode material, other types of silicon-based negative electrode material, hard carbon negative electrode material, soft carbon Negative electrode materials, tin-based negative electrode materials, etc. and their mixtures in any proportion to prepare negative electrode pieces. Considering that the metal lithium negative electrode often used in the next-generation battery technology is sensitive to moisture, technicians can also directly use pure metal lithium foil, metal lithium alloy foil, pure metal lithium foil + copper foil composite foil, metal lithium foil The composite foil composed of alloy foil + copper foil, the composite foil composed of pure metal lithium foil + foam copper, and the composite foil composed of metal lithium alloy foil + foam copper are used as negative pole pieces, and there is no need to pass The above-mentioned conventional method for preparing the negative electrode slurry and recoating prepares the negative electrode pole piece.

The positive pole piece and the negative pole piece prepared by the above method, the composite solid electrolyte membrane prepared by each embodiment of the present invention and the comparative example, the positive pole tab (aluminum tab of Lianyungang Delixin Electronic Technology Co., Ltd.), the negative pole tab (Nickel tabs of Lianyungang Delixin Electronic Technology Co., Ltd.) Lithium-ion batteries are prepared by winding or stacking through the conventional preparation process of lithium-ion batteries.

The following methods were used to measure the normal temperature rate performance and normal temperature cycle performance of the lithium ion batteries of Examples 1-8 and Comparative Examples 1-8, respectively. The results are shown in Table 2.

Room temperature rate performance

Use a battery charge-discharge tester to conduct a charge-discharge test at 25°C. The charge-discharge system is as follows: 0.2C constant current charge to 4.25V, then 4.25V constant voltage charge until the current decreases to 0.02C, and after standing for 5 minutes , 0.2C constant current discharge to 2.5V, record discharge capacity Q _0.2c ; after standing for 5min, 0.2C constant current charge to 4.25V, turn to 4.25V constant voltage charge until the current reduces to 0.02C, after standing for 5min , 3C constant current discharge to 2.5V, record discharge capacity Q _3c , 3C discharge capacity retention rate η=Q _3c /Q _0.2c ×100%.

Normal temperature cycle performance

Use a battery charge-discharge tester to test the battery at 25°C for charge-discharge cycle. The battery is discharged to 2.5V with a constant current of 0.5C, which is 1 cycle, and the number of cycles of the battery charge-discharge tester is set to 5000 times.

Table 2 Lithium-ion battery performance test of each embodiment and comparative example

Room temperature rate performance cycle life Example 1 83.1 1533 Example 2 81.4 1464 Example 3 82.0 1440 Example 4 83.8 1405 Example 5 85.7 1538 Example 6 86.3 1626 Example 7 86.2 1651 Example 8 87.1 1729 Comparative Example 1 64.2 810 Comparative Example 2 63.0 763 Comparative Example 3 66.7 904 Comparative Example 4 65.9 813 Comparative Example 5 73.8 1012 Comparative Example 6 73.1 1030 Comparative Example 7 73.7 1058 Comparative Example 8 74.3 1096

As shown in Table 2, the normal temperature rate performance and normal temperature cycle life of the lithium ion batteries prepared by using the composite solid electrolyte membranes of the various embodiments of the present invention are significantly improved compared with the lithium ion batteries of each comparative example.

In conclusion, the composite solid electrolyte membrane of the present invention improves the ionic conductivity and mechanical strength of the composite solid electrolyte membrane by designing the material composition and structure. Compared with the existing composite solid electrolyte membrane, the lithium ion battery of the present invention has better rate performance and cycle performance.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (10)

1. A composite solid electrolyte membrane, comprising a polymer electrolyte, and inorganic electrolyte fibers dispersed in the polymer electrolyte, the inorganic electrolyte fibers constituting 20 to 90% by mass of the composite solid electrolyte membrane;

the included angle theta between the length direction of the inorganic electrolyte fiber and the thickness direction of the composite solid electrolyte membrane satisfies the following condition:

0°≤θ≤30°；

preferably, the angle θ between the length direction of the inorganic electrolyte fibers and the thickness direction of the composite solid electrolyte membrane is 0 °.

2. The composite solid electrolyte membrane according to claim 1, the inorganic electrolyte fibers being hollow fibers and/or solid fibers.

3. The composite solid electrolyte membrane according to claim 2, wherein the inner diameter of the hollow fiber is 10 to 2000nm, the outer diameter of the inorganic electrolyte hollow fiber is 50 to 4000nm, and the thickness of the inorganic electrolyte hollow fiber is 15 to 2000 nm; and/or

The diameter of the solid fiber is 0.05-1000 μm.

4. The composite solid electrolyte membrane according to any one of claims 1 to 3, wherein the polymer electrolyte is a lithium-conducting polymer selected from one or more of polyethers, polyphosphazenes, polycarbonates, polyacrylates, polyvinylidene fluorides, vinylidene fluoride-hexafluoropropylene copolymers, polyacrylonitriles, nitrile rubbers, and polyvinyl chlorides; or

The polymer electrolyte is a lithium-nonconductive polymer, and the lithium-nonconductive polymer is one or more selected from polyethylene, polypropylene, polyethylene terephthalate, polyurethane, polycaprolactone, silicone rubber, styrene-butadiene rubber, polystyrene, polytetrafluoroethylene, polyimide, polyether ether ketone and epoxy resin.

5. The composite solid electrolyte membrane according to claim 4, further comprising a plasticizer in the polymer electrolyte, wherein a mass fraction of the plasticizer is not more than 10% based on the mass of the composite solid electrolyte membrane, and the plasticizer is selected from at least one of an organic plasticizer having an average molecular weight of 40 to 800 and an ionic liquid; and/or

The polymer electrolyte also comprises a lithium salt, and the mass fraction of the lithium salt is not more than 10% based on the mass of the composite solid electrolyte membrane.

6. The composite solid electrolyte membrane according to claim 5, wherein the organic plasticizer having an average molecular weight of 40 to 800 is selected from ester, fluoro-ester or fluoro-ether plasticizers, and/or

The ionic liquid is selected from 1-butyl-2, 3-dimethyl imidazole bis (trifluoromethanesulfonyl) imide salt, 1-butyl-2, 3-dimethyl imidazole tetrafluoroborate, N-ethyl pyridine bis (trifluoromethanesulfonyl) imide salt, N-ethyl pyridine hexafluorophosphate and N-ethyl pyridine tetrafluoroborate, one or more of tributylmethylammonium bis (trifluoromethanesulfonyl) imide salt, N-methoxyethyl-N-methyldiethylammonium tetrafluoroborate, tributylhexylphosphine bis (trifluoromethanesulfonyl) imide salt, tetrabutylphosphine bis (trifluoromethanesulfonyl) imide salt, tributylethylphosphine bis (trifluoromethanesulfonyl) imide salt, and N-butyl-N-methylpyrrolidine bis (trifluoromethanesulfonyl) imide salt; and/or

The lithium salt is selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, lithium difluorophosphate, lithium 4, 5-dicyano-2-trifluoromethylimidazolium, lithium bis (oxalato) borate, lithium bis (malonato) borate, lithium difluorooxalato borate, lithium bis (difluoromalonato) borate, lithium (malonato oxalato) borate, lithium difluoromalonato oxalato oxalate borate, lithium tris (oxalato) phosphate, lithium tris (difluoromalonato) phosphate, lithium tetrafluorooxalato phosphate, lithium difluorodioxaoxalato phosphate, lithium bis (fluorosulfonyl) imide, lithium bistrifluoromethanesulfonylimide, (fluorosulfonyl) (trifluoromethanesulfonyl) (triflate)) Lithium imide, lithium nitrate, lithium fluoride, LiN (SO)₂R_F)₂And LiN (SO)₂F)(SO₂R_F) Wherein R is_F＝C_nF_2n+1And n is an integer of 2 to 10.

7. The method for producing a composite solid electrolyte membrane according to any one of claims 1 to 6, characterized by comprising the steps of:

preparing inorganic electrolyte powder and an organic polymer into spinning solution, then carrying out coaxial electrostatic spinning to obtain composite fiber bundles arranged in an oriented manner, and then calcining the composite fiber bundles at the temperature of 300-1200 ℃ for 0.5-12h to obtain inorganic electrolyte fiber bundles;

and after melting the polymer electrolyte, filling the polymer electrolyte into the gaps of the inorganic electrolyte fiber bundles, cooling and forming, and cutting along the direction vertical to the inorganic electrolyte fiber bundles to obtain the composite solid electrolyte film.

8. The method according to claim 7, wherein the spinning dope is subjected to coaxial electrospinning so that the fibers constituting the inorganic electrolyte fiber bundle are hollow fibers and/or solid fibers; and the number of the first and second electrodes,

the inner diameter of the inorganic electrolyte hollow fiber is 10-2000nm, the outer diameter of the inorganic electrolyte hollow fiber is 50-4000nm, and the thickness of the inorganic electrolyte hollow fiber is not less than 15 nm; and/or

The diameter of the solid fiber is 0.05-1000 μm.

9. The method according to claim 7, wherein the inorganic electrolyte powder has a particle size of 10 to 900nm, and is selected from one or more of lithium silicate, lithium phosphate, lithium sulfate, lithium borate, sulfide electrolyte powder, perovskite electrolyte powder, Garnet type electrolyte powder, NASICON type electrolyte powder, LISICON type electrolyte powder, and glassy electrolyte powder;

the organic polymer is selected from one or more of polyglycolic acid, polylactic acid, polycaprolactone, aliphatic polyester copolymer, polyphosphazene, poly (p-dioxanone), polyamide, polycarbonate, polyurethane, polyethylene oxide, polyvinyl alcohol, polyvinyl acetal, polyacrylic acid, polyacrylate, nitrile rubber, polyacrylamide, polyvinylpyrrolidone and hydroxypropyl cellulose.

10. A lithium ion battery prepared using the composite solid electrolyte membrane according to any one of claims 1 to 7.

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