CN117059879A

CN117059879A - Multilayer composite solid electrolyte membrane, preparation method and application thereof, and all-solid battery

Info

Publication number: CN117059879A
Application number: CN202310802983.XA
Authority: CN
Inventors: 余天玮; 邵宗普; 刘亚飞; 陈彦彬
Original assignee: Beijing Easpring Material Technology Co Ltd
Current assignee: Beijing Easpring Material Technology Co Ltd
Priority date: 2023-06-30
Filing date: 2023-06-30
Publication date: 2023-11-14

Abstract

The invention relates to the technical field of solid lithium batteries, and discloses a multilayer composite solid electrolyte membrane, a preparation method and application thereof, and an all-solid battery. The solid electrolyte membrane comprises electrolyte containing sulfide and LiX ¹ A first stabilizing film layer, a first blended transition film layer, a sulfide electrolyte film layer containing a sulfide electrolyte, a first binder and an oxide electrolyte, a second blended transition film layer and a second stabilizing film layer; the first blending transition membrane layer, the second blending transition membrane layer and the second stabilizing membrane layer respectively contain sulfide electrolyte and LiX ¹ A first binder and an oxide electrolyte; along sulfurIn the direction from the oxide electrolyte membrane layer to the first stable membrane layer or the second stable membrane layer, liX ¹ Is an increasing trend in content presentation. LiX in the solid electrolyte membrane ¹ The content of (2) is distributed in a gradient manner, so that the cycle life of the solid-state battery comprising the solid electrolyte membrane is remarkably prolonged.

Description

Multilayer composite solid electrolyte membrane, preparation method and application thereof, and all-solid battery

Technical Field

The invention relates to the technical field of solid lithium batteries, in particular to a multilayer composite solid electrolyte membrane, a preparation method and application thereof and an all-solid battery.

Background

Traditional liquid lithium ion batteries have limited energy density and present potential safety hazards. The solid-state battery has the advantages of high theoretical energy density, wide temperature resistant range and good safety, and is considered as a very promising energy storage technology. High-safety high-specific energy all-solid-state batteries are an inevitable trend in technical development. The power battery industry has a tendency of over-rapid development and unbalanced supply and demand relation in recent years, and the problems of shortage of power battery materials, serious overflow price and the like are continuously emerging. In order to continuously compete with the traditional fuel vehicles in the market, the new energy vehicles must reach a level equivalent to the fuel vehicles in the aspects of endurance mileage, cost and the like, and the development of new system power batteries is urgent. Solid-state batteries using nonflammable inorganic solid-state electrolytes are considered to be capable of fundamentally solving the safety problem of new energy automobiles, and are an important development direction in the field of power batteries. The solid-state battery has the following advantages:

(1) Completely eliminates the potential safety hazards of fire, explosion and the like of the battery which are unavoidable by the organic electrolyte.

(2) The lithium metal negative electrode is hopeful to be safely used, and the energy density can reach more than 400 Wh/kg.

Therefore, it is important to develop a solid-state battery core key material with high energy density and high safety and to develop key interface regulation and control research. And the selection of a proper solid electrolyte and positive and negative electrode materials with high specific capacity is the key for realizing the high specific energy all-solid-state battery. The development of solid electrolytes with high ionic conductivity, high electrochemical stability, and low cost has become one of the main research directions for developing new all-solid-state batteries (ASSLB)

The energy density of most all-solid-state lithium batteries is far lower than expected, which is largely due to the high thickness and high weight of the electrolyte layer. Currently, there is a need forThe hard inorganic solid electrolyte powder is pressed into a sheet shape having a thickness of from several hundreds of micrometers to-1 mm to avoid cracking of the solid electrolyte layer. Thin solid electrolyte layers are critical for assembling high energy density batteries. In order to achieve high energy and power densities, it is often desirable to have>10 ^-4 S/cm solid electrolyte membrane (micron-sized) with high ionic conductivity. However, current methods of producing such solid electrolyte membranes present significant challenges. For example, the process cost of the method using vacuum radio frequency sputtering is too high, and the methods such as Atomic Layer Deposition (ALD), pulse Layer Deposition (PLD), and Chemical Vapor Deposition (CVD) are also more time consuming and less scalable than the roll-to-roll process. The development of inorganic solid electrolyte membranes is more challenging than flexible polymer electrolytes because inorganic solid electrolytes are mechanically less flexible, have poor air/humidity stability, and are prone to chemical side reactions with polar solvents and polymer binders. To overcome these challenges, various viable methods have been developed, including slurry coating methods, solution infiltration methods, dry film techniques, and the like.

The full-solid film lithium battery with the solid electrolyte/solid composite electrode film and the thickness of micron level has the advantages of high safety, long service life, high integration and the like. However, the low energy density of thin film lithium batteries is a major bottleneck limiting their wide application, and the battery material systems currently developed are relatively single (mostly LiCoO ₂ LiPON/Li system). If the novel electrode and electrolyte materials used for the traditional lithium ion battery can be applied to the thin film lithium battery, the device performance is expected to be improved from the material to meet the practical requirements.

Ion transport and interface problems in solid state batteries have been the focus of research and are critical to the wide range of applications for solid state batteries. The development of an inorganic solid electrolyte membrane having good ion transport ability and high interface stability is important for realizing an all-solid battery of high energy density, and in addition to the intrinsic properties of the solid electrolyte membrane, the interface problem of the solid battery is not neglected. In addition, the current sulfide solid-state electrolyte has a limited electrochemical stability window, cannot be matched with a positive electrode active material and a metal lithium negative electrode, and needs to be subjected to interface modification to realize a solid-state battery with high energy density stable cycle. The solid electrolyte membrane of the lithium metal battery in the prior art cannot better achieve the low porosity, high compaction density, high ion conductivity, high electrochemical stability on metal lithium and good thermal stability.

Disclosure of Invention

The invention aims to solve the problems that the electrochemical stability window of the existing single-layer sulfide solid electrolyte membrane is limited, the electrolyte cannot be matched with a high specific energy electrode material to realize good microscopic and macroscopic contact, side reactions possibly existing in electrolyte or electrode components, the preparation process of the electrode material matched with sulfide electrolyte is complex, and the like, and provides a multi-layer composite solid electrolyte membrane, a preparation method thereof and an all-solid-state battery, wherein the composite solid electrolyte membrane comprises a multi-layer membrane layer structure which is formed by sequentially laminating LiX in the solid electrolyte membrane ¹ The content of the electrolyte is distributed in a gradient manner, so that side reactions between the solvent and the electrolyte or electrode components are effectively avoided, the contact performance between the solid electrolyte membrane and the anode and the cathode is improved, and the cycle life of the solid battery comprising the solid electrolyte membrane is obviously prolonged.

In order to achieve the above object, a first aspect of the present invention provides a multilayer composite solid electrolyte membrane, characterized in that the solid electrolyte membrane includes a first stable membrane layer 1, a first blended transition membrane layer 2, a sulfide electrolyte membrane layer 3, a second blended transition membrane layer 4, and a second stable membrane layer 5, which are laminated in this order;

The first stable film layer 1 comprises S-SSEs and LiX containing sulfide electrolyte ¹ A first binder, an oxide electrolyte, and a positive electrode component;

the first blended transition membrane layer 2, the second blended transition membrane layer 4, and the second stabilizing membrane layer 5 each independently comprise a sulfide-containing electrolyte S-SSEs and LiX ¹ A first binder, and an oxide electrolyte;

the sulfide electrolyte membrane layer 3 includes sulfide electrolyte S-SSEs, a first binder, and an oxide electrolyte;

wherein X is ¹ Is halogen, preferably X ¹ F is the same as F;

in the direction from the sulfide electrolyte membrane layer 3 to the first stable membrane layer 1, liX ¹ Content presentation trend of (2);

in the direction from the sulfide electrolyte membrane layer 3 to the second stable membrane layer 5, liX ¹ Is an increasing trend in content presentation.

The second aspect of the present invention provides a method for producing a multilayer composite solid electrolyte membrane, characterized by comprising the steps of:

s1, anode component, sulfide electrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte to obtain a first stable film precursor 1;

s2, sulfide electrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte to obtain a first mixed transition membrane precursor 2;

S3, mixing sulfide electrolyte S-SSEs, a first binder and oxide electrolyte to obtain sulfide electrolyte membrane precursors 3;

s4, sulfide electrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte to obtain a second blended transition film precursor 4;

s5, sulfide electrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte to obtain a second stable film precursor 5;

wherein X is ¹ Is halogen, preferably X ¹ F is the same as F;

s6, sequentially compounding the first stable film precursor 1, the first blending transition film precursor 2, the sulfide electrolyte 3, the second blending transition film precursor 4 and the second stable film precursor 5 in sequence to obtain a multilayer composite solid electrolyte film;

wherein, liX in each step ¹ In such an amount that, in the direction from the sulfide electrolyte membrane layer 3 to the first stable membrane layer 1, liX ¹ Content presentation trend of (2); in the direction from the sulfide electrolyte membrane layer 3 to the second stable membrane layer 5, liX ¹ Is an increasing trend in content presentation.

The third aspect of the present invention provides a multilayer composite solid electrolyte membrane produced by the above production method.

A fourth aspect of the present invention provides an all-solid battery, wherein the all-solid battery comprises a positive electrode, a negative electrode and the above multilayer composite solid electrolyte membrane, wherein a current collector of the positive electrode is located at one side of the first stable film layer 1, and the negative electrode is located at one side of the second stable film layer 5.

Through the technical scheme, the multilayer composite solid electrolyte membrane, the preparation method and application thereof and the solid battery provided by the invention have the following beneficial effects:

the multilayer composite solid electrolyte membrane provided by the invention comprises a plurality of film structures which are sequentially stacked, and each film structure independently comprises sulfide electrolyte and optionally LiX ¹ And the compound LiX in each film layer structure ¹ In a gradient distribution, in particular, in the center-to-surface direction of the multilayer composite solid electrolyte membrane, liX ¹ The content of (2) tends to increase so that the multi-layer composite solid electrolyte membrane forms a uniform progressive halogen chemical environment; due to the compound LiX ¹ LiX with uniform gradient distribution of interface passivation characteristics ¹ The side reaction between the solvent and the electrolyte or electrode components can be effectively avoided, and the high-energy-density electrode can be stably matched for charge and discharge circulation.

Further, the average particle size of sulfide electrolyte S-SSEs in the membrane layer structure of the multilayer composite solid electrolyte membrane provided by the invention changes in a gradient manner, specifically, the average particle size of sulfide electrolyte S-SSEs gradually decreases in the direction from the center to the surface of the multilayer composite solid electrolyte membrane, the sulfide electrolyte S-SSEs in the multilayer composite solid electrolyte membrane are uniformly distributed, and interface particles of each membrane layer are well contacted, so that the LiX-containing effect in the blending transition membrane layer and the stabilizing layer can be realized ¹ The S-SSEs of the sulfide electrolyte component are uniformly dispersed, so that the effective contact sites of the multi-layer composite solid electrolyte membrane and anode and cathode materials are obviously increased, and the interface brought by the uniform progressive halogen chemical environment is fully exertedProtection and passivation.

The multilayer composite solid electrolyte membrane provided by the invention adopts a sulfide solid electrolyte system with high ionic conductivity, and realizes high electrochemical stability of high specific energy anode oxide and cathode metallic lithium through different membrane layer chemical components and physical particle size distribution design, thereby effectively prolonging the cycle life of the all-solid-state lithium battery.

Drawings

FIG. 1 is a schematic view of a multilayer composite solid electrolyte membrane of the present invention;

fig. 2 is a schematic view of electrochemical cycle performance of a solid-state battery assembled by the multilayer composite solid electrolyte membrane of example 1 and comparative example 1.

Description of the reference numerals

1-a first stabilizing film layer; 2-a first blend transition membrane layer; a 3-sulfide electrolyte membrane layer; 4-a second blend transition membrane layer; 5-a second stabilizing film layer.

Detailed Description

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.

The first aspect of the invention provides a multilayer composite solid electrolyte membrane, which is characterized by comprising a first stable membrane layer 1, a first blending transition membrane layer 2, a sulfide electrolyte membrane layer 3, a second blending transition membrane layer 4 and a second stable membrane layer 5 which are sequentially laminated;

the first blended transition membrane layer 2, the second blended transition membrane layer 4, and the second stabilizing membrane layer 5 each independently comprise a blend comprising a sulfideElectrolytes S-SSEs and LiX ¹ A first binder, and an oxide electrolyte;

wherein X is ¹ Is halogen, preferably X ¹ F is the same as F;

In the present invention, the multilayer composite solid electrolyte membrane comprises a plurality of membrane structures which are sequentially stacked, and each membrane structure independently comprises a sulfide electrolyte and optionally LiX ¹ And the compound LiX in each film layer structure ¹ In a gradient distribution, in particular, in the center-to-surface direction of the multilayer composite solid electrolyte membrane, liX ¹ The content of (2) tends to increase so that the multi-layer composite solid electrolyte membrane forms a uniform progressive halogen chemical environment; due to LiX ¹ The halogen atoms in the catalyst have larger electronegativity and stronger ionic bond energy and are not easy to be decomposed by oxidation reduction, so that LiX ¹ Has interface passivation characteristics. Gradient distributed LiX ¹ The method can effectively avoid side reaction between the solvent and the electrolyte or electrode components, is favorable for protecting the inner layer solid electrolyte from oxidative degradation, and can be stably matched with the high-energy-density electrode to carry out charge and discharge circulation.

In the present invention, in order to further improve the lithium ion transport rate and membrane interface stability of the solid electrolyte membrane, preferably, X ¹ F.

According to the invention, the sulfide electrolyte S-SSEs is selected from the group consisting of compounds of formula I, li _4-x Ge _1-x P _x S ₄ (thio-LISICON)、Li ₁₀ GeP ₂ S ₁₂ 、Li ₁₀ SnP ₂ S ₁₂ 、Li ₂ S-P ₂ S ₅ 、Li ₂ S-SiS ₂ 、Li ₂ S-B ₂ S ₃ At least one of, liSiPSCl, liSiPSBr and LiSiPSI, wherein x is more than or equal to 0 and less than or equal to 2;

Li _6-a PS _5-a Cl _1+a-b X ² _b a formula I;

wherein X is ² Is at least one of Cl, br or I, preferably X ² Is at least one of Cl or Br, a is more than or equal to 0 and less than or equal to 3, and b is more than or equal to 0 and less than or equal to 3.

According to the invention, liX is based on the total molar amount of the blend in the first stabilizing film layer 1 ¹ The molar content of (2) is 20mol% to 40mol%;

LiX based on the total molar amount of blend in the first blend transition film layer 2 ¹ The molar content of (2) is 0.5mol% to 20mol%.

In the invention, liX in the first stable film layer 1 and the first blending transition film layer 2 is controlled ¹ When the molar content of (b) satisfies the above range, occurrence of side reactions between the oxide positive electrode material and the sulfide electrolyte material component can be effectively avoided, so that the cycle life of the solid-state battery including the solid electrolyte membrane is remarkably improved.

Further, liX based on the total molar amount of the blend in the first stabilizing film layer 1 ¹ The molar content of (2) is 30mol% to 35mol%;

LiX based on the total molar amount of blend in the first blend transition film layer 2 ¹ The molar content of (2) is 10mol% to 15mol%.

According to the invention, liX is based on the total molar amount of blend in the second blend transition film layer 4 ¹ The molar content of (2) is 0.5mol% to 20mol%;

LiX based on the total molar amount of blend in the second stabilizing film layer 5 ¹ The molar content of (2) is 20mol% to 40mol%.

In the invention, liX in the second blending transition film layer 4 and the second stable film layer 5 is controlled ¹ When the molar content of (b) satisfies the above range, occurrence of side reactions between the metallic lithium anode material and the sulfide electrolyte material component can be effectively avoided.

Further, liX based on the total molar amount of blend in the second blend transition film layer 4 ¹ The molar content of (2) is 10mol% to 15mol%;

LiX based on the total molar amount of blend in the second stabilizing film layer 5 ¹ The molar content of (2) is 30mol% to 35mol%.

According to the invention, the average particle size of the sulfide electrolyte S-SSEs decreases in the direction from the sulfide electrolyte membrane layer 3 to the first stable membrane layer 1;

the average particle size of the sulfide electrolyte S-SSEs tends to decrease in the direction from the sulfide electrolyte membrane layer 3 to the second stable membrane layer 5.

In the invention, the average particle size of sulfide electrolyte S-SSEs in each membrane layer structure of the multilayer composite solid electrolyte membrane is in gradient change, in particular, the average particle size of sulfide electrolyte S-SSEs in the direction from the center to the surface of the multilayer composite solid electrolyte membrane is gradually decreased, the sulfide electrolyte S-SSEs in the multilayer composite solid electrolyte membrane are uniformly distributed, and interface particles of each membrane layer are in good contact, so that the LiX1 in a transition membrane layer and a stable layer can be mixed ¹ The S-SSEs of the sulfide electrolyte component are uniformly dispersed, so that the effective contact sites of the multi-layer composite solid electrolyte membrane and anode and cathode materials are obviously increased, and the interface protection and passivation effects caused by the uniform progressive halogen chemical environment are fully exerted. Specifically, in the present invention, the sulfide electrolyte S-SSEs in the sulfide electrolyte membrane layer 3 are micron-sized particles, and the sulfide electrolyte S-SSEs in the first blending transition membrane layer 2 and the second blending transition membrane layer 4 are each independently submicron-sized particles; the sulfide electrolyte S-SSEs in the first and second stabilizing films 1 and 5 are each independently nano-sized particles.

According to the invention, the sulfide electrolyte S-SSEs in the first stable film layer 1 has an average particle diameter of 50-400nm.

According to the invention, the sulfide electrolyte S-SSEs in the first blended transition membrane layer 2 has an average particle diameter of 0.4-1 μm.

According to the present invention, the sulfide electrolyte S-SSEs in the sulfide electrolyte membrane layer 3 has an average particle diameter of 1 to 10. Mu.m.

According to the invention, the sulfide electrolyte S-SSEs in the second blended transition membrane layer 4 has an average particle diameter of 0.4-1 μm.

According to the invention, the sulfide electrolyte S-SSEs in the second stabilizing film layer 5 has an average particle diameter of 50-400nm.

In the invention, further, when the average grain diameter of sulfide electrolyte S-SSEs in each film layer meets the range, the effective contact sites of the multi-layer composite solid electrolyte film and the anode and cathode materials are obviously increased, so that the interface protection and passivation effects caused by uniform progressive halogen chemical environment are fully exerted.

In the invention, sulfide electrolytes S-SSEs with different average particle diameters are obtained through crushing, and specifically, crushing equipment such as a crusher, a stirring mill, a sand mill, an air flow mill and the like is adopted to crush the sulfide electrolytes S-SSEs to a crusher with a target particle size range.

Further, the average particle size of the sulfide electrolyte S-SSEs in the first stable film layer 1 is 200-400nm.

Further, the sulfide electrolyte S-SSEs in the first blending transition film layer 2 has an average particle diameter of 0.4-0.8 μm.

Further, the sulfide electrolyte S-SSEs in the sulfide electrolyte membrane layer 3 has an average particle diameter of 1 to 3 μm.

Further, the average particle diameter of sulfide electrolyte S-SSEs in the second blending transition film layer 4 is 0.4-0.8 μm.

Further, the average particle diameter of sulfide electrolyte S-SSEs in the second stable film layer 5 is 200-400nm.

According to the present invention, the thickness of the multilayer composite solid electrolyte membrane is 10 to 500. Mu.m, preferably 10 to 100. Mu.m, more preferably 6 to 15. Mu.m.

According to the invention, the thickness of the first stabilizing film layer 1 is 0.5-1 μm, preferably 0.6-0.9 μm, more preferably 0.7-0.8 μm.

According to the invention, the thickness of the first doped transition membrane layer 2 is 0.5-1 μm, preferably 0.6-0.9 μm, more preferably 0.7-0.8 μm.

According to the present invention, the thickness of the sulfide electrolyte membrane layer 3 is 4 to 11. Mu.m, preferably 6 to 9. Mu.m, more preferably 7 to 8. Mu.m.

According to the invention, the thickness of the second blend transition film layer 4 is 0.5 to 1 μm, preferably 0.6 to 0.9 μm, more preferably 0.7 to 0.8 μm.

According to the invention, the thickness of the second stabilizing film layer 5 is 0.5-1 μm, preferably 0.6-0.9 μm, more preferably 0.7-0.8 μm.

According to the present invention, the first stabilizing film layer 1 includes 9.4 to 39.76 parts by weight of the blend, 0.05 to 2 parts by weight of the first binder, 0.01 to 0.4 parts by weight of the oxide electrolyte, and 60 to 90 parts by weight of the positive electrode component.

In the invention, when the content of each component in the first stable film layer 1 is controlled to meet the above range, the positive electrode material and the electrolyte material can be fully and uniformly mixed, so that the first stable film layer can realize good lithium ion conductivity.

Further, the first stabilizing film layer 1 includes 18.8 to 29.82 parts by weight of the blend, 0.1 to 1.5 parts by weight of the first binder, 0.02 to 0.3 parts by weight of the oxide electrolyte, and 70 to 80 parts by weight of the positive electrode material.

According to the invention, the first blended transition film layer 2 comprises 94-99.4 parts by weight of blend, 0.5-5 parts by weight of binder and 0.1-1 parts by weight of oxide electrolyte.

According to the present invention, the sulfide electrolyte membrane layer 3 includes 94 to 99.4 parts by weight of sulfide electrolyte S-SSEs, 0.5 to 5 parts by weight of binder, and 0.1 to 1 part by weight of oxide electrolyte.

According to the invention, the second blended transition film layer 4 comprises 94-99.4 parts by weight of blend, 0.5-5 parts by weight of binder and 0.1-1 parts by weight of oxide electrolyte.

According to the present invention, the second stabilizing film layer 5 includes 94 to 99.4 parts by weight of the blend, 0.5 to 5 parts by weight of the binder, and 0.1 to 1 part by weight of the oxide electrolyte.

In the invention, when the compositions in the first blending transition film layer 2, the sulfide electrolyte film layer 3, the second blending transition film layer 4 and the second stabilizing film layer 5 are controlled to respectively and independently meet the above ranges, the occurrence of side reaction between the components of the oxide positive electrode material and the sulfide electrolyte material can be effectively avoided, the introduction of the first binder is beneficial to the film formation of the material in the subsequent process, and the introduction of the oxide electrolyte is beneficial to the fiberization film formation as the inorganic solid electrolyte with high hardness.

In the invention, a certain amount of oxide electrolyte is added into the first stable film layer 1, the first blending transition film layer 2, the sulfide electrolyte film layer 3, the second blending transition film layer 4 and the second stable film layer 5, so that each film layer can be ensured to have enough strength to meet the requirement of subsequent processing.

Further, the first blending transition film layer 2 comprises 96-99 parts by weight of blend, 0.5-2 parts by weight of binder and 0.5-1 part by weight of oxide electrolyte.

Further, the sulfide electrolyte membrane layer 3 includes 96 to 99 parts by weight of sulfide electrolyte S-SSEs, 0.5 to 2 parts by weight of binder, and 0.5 to 1 part by weight of oxide electrolyte.

Further, the sulfide electrolyte membrane layer 4 includes 96 to 99 parts by weight of the blend, 0.5 to 2 parts by weight of the binder, and 0.5 to 1 part by weight of the oxide electrolyte.

Further, the second stabilizing film layer 5 includes 96 to 99 parts by weight of the blend, 0.5 to 2 parts by weight of the binder, and 0.5 to 1 part by weight of the oxide electrolyte.

According to the present invention, the first binder is at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a (vinylidene fluoride-hexafluoropropylene) copolymer (PVDF-HFP), polyethylene oxide (PEO), polyacrylonitrile (PAN), and Styrene Butadiene Rubber (SBR).

According to the invention, the first binder has an average particle size of 10-1000 μm.

According to the invention, the number average molecular weight of the first binder is greater than or equal to 100,000g/mol, and the compression ratio is 1-10000:1.

In the invention, when the average particle size and/or the number average molecular weight and the compression ratio of the first binder are controlled to meet the above ranges, the first binder can be more easily fibrillated under the action of shearing force, the diameter and the mechanical strength of the fiber yarn obtained after the first binder is fibrillated can be more easily met the requirements of an ultrathin electrolyte membrane, and the prepared electrolyte membrane is thinner and has stronger toughness.

Further, according to the present invention, the first binder has an average particle diameter of 300 to 600 μm.

Further, the number average molecular weight of the first binder is more than or equal to 3,000,000g/mol, and the compression ratio is 3000-5000:1.

According to the present invention, the oxide electrolyte is selected from at least one of Lithium Lanthanum Zirconium Oxide (LLZO), lithium Lanthanum Zirconium Tantalum Oxide (LLZTO), lithium Aluminum Titanium Phosphate (LATP), and Lithium Aluminum Germanium Phosphate (LAGP); preferably selected from Lithium Lanthanum Zirconium Oxide (LLZO) and/or garnet structured Lithium Lanthanum Zirconium Tantalum Oxide (LLZTO).

In the present invention, the composition of the positive electrode component is not particularly limited, and a positive electrode component conventional in the art may be employed, preferably the positive electrode component includes a positive electrode active material, a conductive agent, a lithium salt, and a second binder;

Wherein the mass of the positive electrode active material, the conductive agent, the lithium salt and the second binder is 65-98:0.5-10:0.5-10:1-15.

Further, the mass of the positive electrode active material, the conductive agent, the lithium salt and the second binder is 70-92:1-5:1-5:2-10.

In the present invention, the kind of the positive electrode active material is not particularly limited, and a positive electrode active material of a kind conventional in the art may be used, specifically, a multi-element positive electrode material, for example, a material selected from lithium cobalt oxide LiCoO ₂ (LCO), lithium manganate (LiMnO) ₂ ) Lithium nickel manganese (LiNi) _1-α Mn _α O ₂ ，0<α<1) Lithium nickel cobalt manganate (LiNi) _β Co _γ Mn _δ O ₂ Beta + gamma + delta = 1, beta, gamma and delta are all greater than 0) and lithium nickel cobalt aluminate (liniκco _λ Al _μ O ₂ At least one of κ+λ+μ=1, with κ, λ and μ all greater than 0);the positive electrode active material is an olivine positive electrode material, for example, selected from lithium iron phosphate (LiFePO) ₄ ) Lithium iron manganese phosphate (LiFeMnPO) ₄ ) And lithium manganese phosphate (LiMnPO) ₄ ) At least one of (a) and (b); the positive electrode active material is lithium-rich manganese-based material [ sigma Li ] ₂ MnO ₃ ·(1-σ)LiNi _ω Co _γ Mn _δ O ₂ ，0<σ<1, ω+γ+δ=1, ω, γ and δ are each greater than 0]。

In the present invention, the kind of the conductive agent is not particularly limited, and a conductive agent of a kind conventional in the art, for example, at least one selected from Super P, acetylene black, graphite, KS-6, carbon nanotubes, graphene and carbon fibers may be used.

In the present invention, the kind of the lithium salt is not particularly limited, and a lithium salt of a conventional kind in the art, for example, a material selected from lithium perchlorate (LiClO) ₄ ) Lithium tetrafluoroborate (LiBF) ₄ ) Lithium hexafluoroarsenate (LiAsF) ₆ ) Lithium hexafluorophosphate (LiPF) ₆ ) At least one of lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiLiFSI), lithium bis (oxalato) borate (LiBOB), and lithium bis (oxalato) borate (LiDFOB).

In the present invention, the kind of the second binder is not particularly limited, and binders which are conventional in the art, for example, the second binder is selected from small molecular organic substances and/or high molecular polymers, may be used. In the present invention, the kind of the high molecular polymer is not particularly limited, and a high molecular polymer binder of a conventional kind in the art, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a (vinylidene fluoride-hexafluoropropylene) copolymer (PVDF-HFP), polyethylene oxide (PEO), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polypropylene carbonate (PPC), polyethylene carbonate (PEC), polycaprolactone (PCL), and Styrene Butadiene Rubber (SBR), may be used.

In the present invention, the type of the small molecular organic substance is not particularly limited, and a small molecular organic substance which is generally used in the art and can be used as a binder may be used, for example, at least one selected from the group consisting of an acrylic acid ester compound and/or a vinyl ester compound, preferably polyethylene glycol dimethyl ether (PEGDME), triethylene glycol dimethyl ether (teggme), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), triethylene glycol dimethacrylate (TEGDMA) and trimethylolpropane triacrylate (TMPTA).

In the present invention, when a small molecular organic matter is selected as the second binder, the binder further includes an initiator, and the initiator is used in an amount of 0.1wt% to 5wt%, preferably 0.5wt% to 2wt%, based on the amount of the second binder. In the present invention, the initiator is selected from azo-type initiators and/or peroxide-type initiators, preferably at least one selected from azobisisobutyronitrile, azobisisoheptonitrile and dimethyl azobisisobutyrate, dibenzoyl peroxide, t-butyl dibenzoyl peroxide and methyl ethyl ketone peroxide.

In one specific embodiment of the present invention, the mass ratio of the small molecular organic matter to the high molecular polymer is 0:100-100:0. and both are not 0 at the same time.

In a preferred embodiment of the present invention, the mass ratio of the small molecule organic matter to the high molecule polymer is 20-80:80-20.

According to the present invention, the porosity of the multilayer composite solid electrolyte membrane is 1% -20%.

In the present invention, the multilayer composite solid electrolyte membrane has the above-described specific porosity, so that the multilayer composite solid electrolyte membrane and the solid lithium battery made of the same have more excellent performance.

Further, the porosity of the multilayer composite solid electrolyte membrane is 7% -10%.

According to the present invention, the multilayer composite solid electrolyte membrane has a compacted density of 2g/cm ³ 6g/cm ³ 。

In the present invention, the multilayer composite solid electrolyte membrane has the above specific compacted density so that the multilayer composite solid electrolyte membrane and the solid lithium battery made of the same have more excellent performance.

Further, the multilayer composite solid electrolyte membrane had a compacted density of 3g/cm ³ 5.5g/cm ³ 。

According to the present invention, the peel strength of the multilayer composite solid electrolyte membrane was 300 800N/m.

In the present invention, the multilayer composite solid electrolyte membrane has the above-described specific peel strength, so that the multilayer composite solid electrolyte membrane and the solid lithium battery made of the same have more excellent performance.

Further, the peel strength of the multilayer composite solid electrolyte membrane is 400-700N/m.

According to the invention, the ionic conductivity of the multilayer composite solid electrolyte membrane is more than or equal to 10 ^-4 S/cm, preferably 5X 10 ^-4 S/cm-5×10 ^-3 S/cm。

wherein X is ¹ Is halogen, preferably X ¹ F is the same as F;

The composition and specific kind of the raw materials for preparing the multilayer composite solid electrolyte membrane according to the second aspect of the present invention are identical to those described in the first aspect of the present invention, and in order to avoid repetition, the present invention is not described in detail in this second aspect, and those skilled in the art should not understand the limitation of the present invention.

In the invention, different film layers are prepared through distribution, and are sequentially compounded according to a specific sequence, so that the LiX of the first aspect of the invention is obtained ¹ The content of the solid electrolyte membrane is distributed in a gradient manner in the multilayer composite solid electrolyte membrane.

In one embodiment of the present invention, in step S6, the compounding method includes: the first stable film precursor 1, the first blended transition film precursor 2, the sulfide electrolyte 3, the second blended transition film precursor 4 and the second stable film precursor 5 are sequentially coated and dried.

In the invention, when the coating mode is adopted for compounding, the method further comprises the following steps:

(1) Sulfide electrolyte S-SSEs and LiX ¹ Dispersing the first binder, the oxide electrolyte and the positive electrode component in an organic solvent to obtain slurry, coating the slurry on a base film, drying, and stripping the base film to obtain a first stable film precursor 1;

(2) Sulfide electrolyte S-SSEs and LiX ¹ Dispersing the first binder and the oxide electrolyte in an organic solvent to obtain slurry, coating the slurry on a base film, drying, and stripping the base film to obtain a first blending transition film precursor 2;

(3) Dispersing sulfide electrolyte S-SSEs, a first binder and oxide electrolyte in an organic solvent to obtain slurry, coating the slurry on a base film, drying, and stripping the base film to obtain a sulfide electrolyte film precursor 3;

(4) Will sulfide electrolyte S-SSEs, liX ¹ Dispersing the first binder and the oxide electrolyte in an organic solvent to obtain slurry, coating the slurry on a base film, drying, and stripping the base film to obtain a second blending transition film precursor 4;

(5) Sulfide electrolyte S-SSEs and LiX ¹ Dispersing the first binder and the oxide electrolyte in an organic solvent to obtain slurry, coating the slurry on a base film, drying, and stripping the base film to obtain a second stable film precursor 5;

(6) Sequentially laminating a first stable film precursor 1, a first blending transition film precursor 2, a sulfide electrolyte 3, a second blending transition film precursor 4 and a second stable film precursor 5 in sequence, tabletting, and co-extruding to obtain the multilayer composite solid electrolyte film.

In the present invention, the coating method is not particularly limited, and a coating method conventional in the art, such as knife coating, may be used.

In the present invention, the kind of the organic solvent is not particularly limited, and an organic solvent which is conventional in the art, such as toluene, may be used.

According to the present invention, the conditions for drying in each step include: the drying temperature is 60-200 ℃ and the drying time is 0.5-5h.

In another embodiment of the present invention, in step S6, the compounding method includes: the first stable film precursor 1, the first blended transition film precursor 2, the sulfide electrolyte 3, the second blended transition film precursor 4, and the second stable film precursor 5 are sequentially laminated in this order, and then co-extrusion is performed.

In the present invention, when the compounding is performed by adopting a coextrusion mode, the method further comprises:

(i) The positive electrode component, oxide electrolyte, first binder, sulfide electrolyte S-SSEs and LiX ¹ Mixing and tabletting to obtain a first stable film precursor 1;

(ii) Sulfide electrolyte S-SSEs and LiX ¹ A first adhesiveMixing with oxide electrolyte, tabletting to obtain a first blending transition film precursor 2;

(iii) Mixing sulfide electrolyte S-SSEs, a first binder and oxide electrolyte, and tabletting to obtain sulfide electrolyte membrane precursor 3;

(iv) Sulfide electrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte, and tabletting to obtain a second blended transition film precursor 4;

(v) Sulfide electrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte, and tabletting to obtain a second stable film precursor 5;

(vi) Sequentially laminating a first stable film precursor 1, a first blending transition film precursor 2, a sulfide electrolyte 3, a second blending transition film precursor 4 and a second stable film precursor 5 in sequence, tabletting, and co-extruding to obtain the multilayer composite solid electrolyte film.

According to the invention, the coextrusion is a monolithic hot press, the hot press temperature being 40-100 ℃.

In the present invention, the mode of mixing is not particularly limited, and mixing may be performed by using a device conventional in the art, for example, a grinder, a ball mill, an air mill, screw extrusion, or the like.

In the present invention, the method of the integral heat press is not particularly limited, and the integral heat press may be performed by using a device conventional in the art, for example, a heat roller, a heat platen, or the like.

A fourth aspect of the present invention provides the use of a multilayer composite solid electrolyte membrane as described above in a solid state battery.

In the invention, when the multilayer composite solid electrolyte membrane is used in an all-solid-state battery, the prepared multilayer composite solid electrolyte membrane has a thin thickness, and meanwhile, the extremely low content of the binder fully ensures the contact among inorganic electrolyte particles, so that the influence of the binder on the lithium ion conductivity of the electrolyte is avoided, and the prepared diaphragm has high ion conductivity and a wide electrochemical window, so that the all-solid-state battery can realize better cycle stability.

In the invention, after the multilayer composite solid electrolyte membrane and a metal lithium electrode are assembled into a CNT// solid electrolyte membrane// Li mold battery, linear volt-ampere scanning is carried out, and the positive sweep peak potential of the multilayer composite solid electrolyte membrane is more than or equal to 4V; the area of the integrated current is less than or equal to 5 multiplied by 10 ^-3 AV/cm ² The method comprises the steps of carrying out a first treatment on the surface of the The cut-off current density is less than or equal to 0.01A/cm ² The method comprises the steps of carrying out a first treatment on the surface of the The peak potential of the lithium metal is less than or equal to 0.5V; the area of the integrated current is less than or equal to 1 multiplied by 10 ^-3 AV/cm ² The method comprises the steps of carrying out a first treatment on the surface of the The cut-off current density is less than or equal to 0.01A/cm ² 。

In the invention, the multilayer composite solid electrolyte membrane is assembled into a lithium symmetrical battery, the battery cycle and the critical current density are tested, the battery cycle stabilization time is more than or equal to 800 hours, the cycle stabilized lithium deintercalation polarization potential is less than or equal to 1V, and the critical current density is 0.1-1mA/cm ² 。

A fifth aspect of the present invention provides an all-solid battery, wherein the solid battery comprises a positive electrode, a negative electrode and the above-mentioned multilayer composite solid electrolyte membrane, wherein a current collector of the positive electrode is located at one side of the first stabilizing membrane layer 1, and the negative electrode is located at one side of the second stabilizing membrane layer 5.

In the invention, the current collector is aluminum foil, preferably mesh aluminum foil and/or carbon-coated aluminum foil.

In the present invention, the negative electrode is preferably a lithium-containing negative electrode.

The present invention will be described in detail by examples.

Example 1

The embodiment provides a preparation method of a multilayer composite co-extrusion solid electrolyte membrane matched with a high specific energy electrode, which comprises the following steps:

(i) 80 parts by weight of the positive electrode component and 19 parts by weight of 30 LiF.70Li ₆ PS ₅ The Cl (d50=500 nm) blend, 0.5 parts by weight of the first binder PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1), 0.5 parts by weight LLZTO (d50=1 μm), was placed in a mortar and mixed with the mortar until a dough mixture was formed. Then, the film was placed between stainless steel sheets and flattened to obtain a first stable film precursor 1. Wherein the positive electrode in the positive electrode componentThe mass ratio of the active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the binder polyethylene oxide is 83:5:3:9.

(ii) 99 parts by weight of the mixture had a composition of 10 LiF.90 Li ₆ PS ₅ Cl (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar, and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a first blended transition film precursor 2.

(iii) 99 parts by weight of Li ₆ PS ₅ Cl (d50=5 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar, and mixed with the mortar until a dough-like mixture was formed. Then, the mixture was placed between stainless steel sheets and flattened to obtain a sulfide electrolyte membrane precursor 3.

(iv) 99 parts by weight of the mixture had a composition of 10 LiF.90 Li ₆ PS ₅ Cl (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar, and mixed with the mortar until a dough-like mixture was formed. Then placing the mixture between stainless steel thin plates, and flattening the mixture to obtain a second blended transition film precursor 4.

(v) 99 parts by weight of 30LiF 70Li ₆ PS ₅ Cl (d50=500 nm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar, and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a second stable film precursor 5.

(vi) As shown in fig. 1, a first stable film precursor 1, a first blend transition film precursor 2, a sulfide electrolyte precursor 3, a second blend transition film precursor 4 and a second stable film precursor 5 are stacked in the order of 1-2-3-4-5 and then preliminarily flattened, and repeatedly and step-by-step co-extrusion-rolling and compounding are performed by a hot roll press at a hot-pressing temperature of 120 ℃ to obtain a multilayer composite co-extrusion solid electrolyte film A1 with a thickness of 30 μm.

The solid lithium metal battery cycle performance measurement was performed on the above-obtained multilayer composite solid electrolyte membrane A1:

by LiCoO ₂ Is positive electrode with a loading of 36mg/cm ² And taking lithium metal as a negative electrode, and performing charge and discharge test under the test voltage range of 2.6-4.3V.

By LiCoO ₂ 36mg/cm of positive electrode material ² The multilayer composite solid electrolyte membrane A1 and the lithium sheet are assembled into a battery, and as can be obtained from FIG. 2, the multilayer composite solid electrolyte membrane A1 can be matched with a metal lithium negative electrode at normal temperature, and a positive electrode can normally exert normal specific capacity of 140mAh/g. The battery can be stably cycled for more than 80 circles, and good cycle stability performance is exhibited.

Example 2

(i) The same as in example 1, except that: by using 30 LiF.70Li of equal mass _5.5 PS _4.5 Cl _1.5 (d50=500 nm) substitution of 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives the first stable film precursor 1.

(ii) The same as in example 1, except that: 15 LiF.85Li with equal mass _5.5 PS _4.5 Cl _1.5 (d50=1 μm) substitution of 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A first blended transition film precursor 2 is produced.

(iii) The same as in example 1, except that: by equal mass of Li _5.5 PS _4.5 Cl _1.5 (d50=5 μm) substitution of Li ₆ PS ₅ Cl (d50=5 μm) to prepare a sulfide electrolyte membrane precursor 3.

(iv) The same as in example 1, except that: 15 LiF.85Li with equal mass _5.5 PS _4.5 Cl _1.5 (d50=1 μm) substitution of 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A second blended transition film precursor 4 is produced.

(v) The same as in example 1, except that: the composition of 99% is 30 LiF.70Li by equal mass _5.5 PS _4.5 Cl _1.5 (d50=500 nm) substitution of 30LiF70Li ₆ PS ₅ Cl (d50=500 nm) gives a second stable film precursor 5.

(vi) The same as in example 1, except that: a multilayer composite solid electrolyte film A2 having a thickness of 25 μm was obtained.

Example 3

(i) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₆ PS ₅ Cl _0.5 Br _0.5 (d50=500 nm) substitution of 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives the first stable film precursor 1.

(ii) The same as in example 1, except that: 15 LiF.85Li with equal mass ₆ PS ₅ Cl _0.5 Br _0.5 (d50=1 μm) substitution of 10lif.90li ₆ PS ₅ Cl (d50=1 μm) to give the first blended transition film precursor 2.

(iii) The same as in example 1, except that: by equal mass of Li ₆ PS ₅ Cl _0.5 Br _0.5 (d50=5 μm) substitution of Li ₆ PS ₅ Cl (d50=5 μm) to obtain a sulfide electrolyte membrane precursor 3.

(iv) The same as in example 1, except that: 15 LiF.85Li with equal mass ₆ PS ₅ Cl _0.5 Br _0.5 (d50=1 μm) substitution of 10lif.90li ₆ PS ₅ Cl (d50=1 μm) to give the first blended transition film precursor 4.

(v) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₆ PS ₅ Cl _0.5 Br _0.5 (d50=500 nm) substitution of 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives a second stable film precursor 5.

(vi) The same as in example 1, except that: a multilayer composite solid electrolyte film A3 having a thickness of 25 μm was obtained.

Example 4

(i) 80 parts by weight of positive electrode component, 18 parts by weight of 30 LiF.70Li ₃ PS ₄ (d50=500 nm), 1 part by weight of the first binder PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1), 1 part by weight of LLZTO (d50=1 μm), was placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then, the film was placed between stainless steel sheets and flattened to obtain a first stable film precursor 1. Wherein, the mass ratio of the positive electrode active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the adhesive polyethylene oxide in the positive electrode component is 85:5:3:7.

(ii) 98 parts by weight of the powder had a composition of 10 LiF.90 Li ₃ PS ₄ (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 1 part by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a first blended transition film precursor 2.

(iii) 98 parts by weight of Li ₃ PS ₄ (d50=5 μm), 1 part by weight of LLZTO (d50=1 μm) and 1 part by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then, the mixture was placed between stainless steel sheets and flattened to obtain a sulfide electrolyte membrane precursor 3.

(iv) 98 parts by weight of the powder had a composition of 10 LiF.90 Li ₃ PS ₄ (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 1 part by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placing the mixture between stainless steel thin plates, and flattening the mixture to obtain a second blended transition film precursor 4.

(v) 98 parts by weight of the powder had a composition of 30 LiF.70Li ₃ PS ₄ (d50=500 nm), 1 part by weight of LLZTO (d50=1 μm) and 1 part by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placing the film between stainless steel sheets, flattening to obtain a second stable film And a body 5.

(vi) The same as in example 1, except that: a multilayer composite solid electrolyte film A4 having a thickness of 30 μm was obtained.

Example 5

(i) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₁₀ GeP ₂ S ₁₂ (d50=500 nm) substitution of 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives the first stable film precursor 1.

(ii) The same as in example 1, except that: by using 10 LiF.90Li of equal mass ₁₀ GeP ₂ S ₁₂ (d50=1 μm) substitution of 10lif.90li ₆ PS ₅ Cl (d50=1 μm) to give the second blended transition film precursor 2.

(iii) The same as in example 1, except that: by equal mass of Li ₁₀ GeP ₂ S ₁₂ (d50=10μm) substitution of Li ₆ PS ₅ Cl (d50=5 μm) to obtain a sulfide electrolyte membrane precursor 3.

(iv) The same as in example 1, except that: by using 10 LiF.90Li of equal mass ₁₀ GeP ₂ S ₁₂ (d50=1 μm) substitution of 10lif.90li ₆ PS ₅ Cl (d50=1 μm) to give a second blended transition film precursor 4.

(v) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₁₀ GeP ₂ S ₁₂ (d50=300 nm) substitution of 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives a second stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film A5 was produced.

Example 6

(i) 70 parts by weight of a positive electrode component, 29 parts by weight of 35 LiF.65Li ₃ PS ₄ (d50=500 nm), 0.5 parts by weight of a first viscosityThe binder PVDF (number average molecular weight 500,000g/mol, d50=150 μm, compression ratio 100:1), 0.5 parts by weight LLZTO (d50=1 μm) was placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then, the film was placed between stainless steel sheets and flattened to obtain a first stable film precursor 1. Wherein, the mass ratio of the positive electrode active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the adhesive polyethylene oxide in the positive electrode component is 85:4:4:7.

(ii) 99 parts by weight of 15 LiF.85Li ₃ PS ₄ (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PVDF (number average molecular weight 500,000g/mol, d50=150 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a first blended transition film precursor 2.

(iii) 99 parts by weight of Li ₃ PS ₄ (d50=5 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PVDF (number average molecular weight 500,000g/mol, d50=150 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then, the mixture was placed between stainless steel sheets and flattened to obtain a sulfide electrolyte membrane precursor 3.

(iv) 99 parts by weight of 15 LiF.85Li ₃ PS ₄ (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PVDF (number average molecular weight 500,000g/mol, d50=150 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placing the film blank between stainless steel sheets, and flattening to obtain the single electrolyte layer film blank precursor 4.

(v) 99 parts by weight of 35 LiF.65Li ₃ PS ₄ (d50=500 nm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PVDF (number average molecular weight 500,000g/mol, d50=150 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a second stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film A6 was produced.

Example 7

(i) 80 parts by weight of positive electrode component, 19 parts by weight of 35 LiF.65Li ₁₀ GeP ₂ S ₁₂ (d50=500 nm), 0.5 parts by weight of PEO (number average molecular weight 1,200,000g/mol, d50=50 μm compression ratio 100:1), 0.5 parts by weight of LLZTO (d50=1 μm) were placed in a mortar and mixed with the mortar until a dough mixture was formed. Then, the film was placed between stainless steel sheets and flattened to obtain a first stable film precursor 1. Wherein, the mass ratio of the positive electrode active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the adhesive polyethylene oxide in the positive electrode component is 83:4:4:9.

(ii) 99 parts by weight of 15 LiF.85Li ₁₀ GeP ₂ S ₁₂ (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PEO (number average molecular weight 1,200,000g/mol, d50=50 μm compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a first blended transition film precursor 2.

(iii) 99 parts by weight of Li ₁₀ GeP ₂ S ₁₂ (d50=5 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PEO (number average molecular weight 1,200,000g/mol, d50=50 μm compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then, the mixture was placed between stainless steel sheets and flattened to obtain a sulfide electrolyte membrane precursor 3.

(iv) 99 parts by weight of 15 LiF.85Li ₁₀ GeP ₂ S ₁₂ (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PEO (number average molecular weight 1,200,000g/mol, d50=50 μm, compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placing the mixture between stainless steel thin plates, and flattening the mixture to obtain a second blended transition film precursor 4.

(v) 99 parts by weight of 35 LiF.65Li ₁₀ GeP ₂ S ₁₂ (d50=500 nm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PEO (number average molecular weight 1,200,000g/mol, d50=50 μm compression ratio 100:1) were placed in a mortar and mixed with the mortar until a dough-like mixture was formed. Then placed between stainless steel sheets and flattened to give a second stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film A7 was obtained.

Example 8

This comparative example provides a wet-prepared multilayer inorganic solid electrolyte Li ₆ PS ₅ The preparation method of the Cl diaphragm comprises the following steps:

(i) 81 parts by weight of positive electrode component, 13 parts by weight of 30 LiF.70Li ₆ PS ₅ Cl (d50=500 nm), 5 parts by weight of the first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1), 1 part by weight of LLZTO (d50=1 μm) was added to the toluene solvent to disperse the homogenate. Then, the slurry was formed into a film on a polyester film (PET) base film by blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100℃for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 1. Wherein, the mass ratio of the positive electrode active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the adhesive polyethylene oxide in the positive electrode component is 85:4:4:7.

(ii) 94 parts by weight of 10 LiF.90Li ₆ PS ₅ Cl (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) base film by blade coating with a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 2.

(iii) 94 parts by weight of Li ₆ PS ₅ Cl (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse the homogenate, and then the slurry was applied to a polyester film (PET) base film by blade coatingThe film was formed on the substrate to a thickness of 700. Mu.m, then transferred to a vacuum oven, dried at 100℃for 12 hours, and taken out to peel off the PET base film, thereby obtaining a first stable film precursor 3.

(iv) 94 parts by weight of 10 LiF.90Li ₆ PS ₅ Cl (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) base film by blade coating with a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 4.

(v) 94 parts by weight of 30LiF 70Li ₆ PS ₅ Cl (d50=500 nm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film A8 was obtained.

Example 9

This comparative example provides a wet process for preparing a multi-layered inorganic solid electrolyte Li matching a metallic lithium negative electrode _5.5 PS _4.5 Cl _1.5 The preparation method of the diaphragm comprises the following steps:

(i) 82 parts by weight of a positive electrode component, 12 parts by weight of 30 LiF.70Li _5.5 PS _4.5 Cl _1.5 (d50=500 nm), 5 parts by weight of the first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1), 1 part by weight of LLZTO (d50=1 μm) was added to the toluene solvent to disperse the homogenate. Then, the slurry was formed into a film on a polyester film (PET) base film by blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100℃for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 1. Wherein, the positive electrode active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the lithium salt LiFSI in the positive electrode componentThe mass ratio of the binder polyethylene oxide is 83:3:5:9.

(ii) 94 parts by weight of 15 LiF.85Li _5.5 PS _4.5 Cl _1.5 (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, then the slurry was formed on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, then transferred to a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 2.

(iii) 94 parts by weight of Li _5.5 PS _4.5 Cl _1.5 (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, then the slurry was formed on a polyester film (PET) base film by doctor blade coating to a thickness of 700 μm, then transferred to a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 3.

(iv) 94 parts by weight of 10 LiF.90Li _5.5 PS _4.5 Cl _1.5 (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 4.

(v) 94 parts by weight of 35 LiF.75Li _5.5 PS _4.5 Cl _1.5 (d50=500 nm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film A9 was obtained.

Example 10

This comparative example provides a wet-prepared multilayer inorganic solid electrolyte Li ₆ PS ₅ Cl _0.5 Br _0.5 The preparation method of the diaphragm comprises the following steps:

(i) 85 parts by weight of a positive electrode component, 15 parts by weight of 30 LiF.70Li ₆ PS ₅ Cl _0.5 Br _0.5 (d50=500 nm), 5 parts by weight of the first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1), 1 part by weight of LLZTO (d50=1 μm) was added to the toluene solvent to disperse the homogenate. Then, the slurry was formed into a film on a polyester film (PET) base film by blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100℃for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 1. Wherein, the mass ratio of the positive electrode active material (LCO), the conductive agent acetylene black, the lithium salt LiFSI and the adhesive polyethylene oxide in the positive electrode component is 83:5:3:9.

(ii) 94% of 10 LiF.90Li ₆ PS ₅ Cl _0.5 Br _0.5 (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, then the slurry was formed on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, then transferred to a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 2.

(iii) 94 parts by weight of Li ₆ PS ₅ Cl _0.5 Br _0.5 (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, then the slurry was formed on a polyester film (PET) base film by doctor blade coating to a thickness of 700 μm, then transferred to a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 3.

(iv) 94 parts by weight of 15 LiF.85Li ₆ PS ₅ Cl _0.5 Br _0.5 (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 4.

(v) 94 parts by weight of 30LiF 70Li ₆ PS ₅ Cl _0.5 Br _0.5 (d50=500 nm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,000,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) base film by doctor blade coating to a thickness of 100 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out, and the PET base film was peeled off to obtain a first stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film a10 was obtained.

Example 11

The comparative example provides a method for preparing a multilayer composite co-extruded solid electrolyte membrane without particle size gradient distribution:

(i) The same as in example 1, except that: 30LiF 70Li ₆ PS ₅ The particle diameter d50=5 μm of Cl gives the first stable film precursor 1.

(ii) The same as in example 1, except that: 10 LiF.90Li ₆ PS ₅ The particle size d50=5 μm of Cl gives the second blended transition film precursor 2.

(iii) As in example 1, a sulfide electrolyte membrane precursor 3 was obtained.

(iv) The same as in example 1, except that: 10 LiF.90Li ₆ PS ₅ The particle size d50=5 μm of Cl gives the second blended transition film precursor 4.

(v) The same as in example 1, except that: 30LiF 70Li ₆ PS ₅ The particle size d50=5 μm of Cl gives the second stable film precursor 5.

(vi) The same as in example 1, except that: a multilayer composite solid electrolyte film A11 having a thickness of 50 μm was obtained.

Example 12

(i) The same as in example 1, except that: by using 35 LiF.65Li of equal mass ₆ PS ₅ Cl (d50=500 nm) replaces 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives the first stable film precursor 1.

(ii) The same as in example 1, except that: 15 LiF.85Li with equal mass ₆ PS ₅ Cl (d50=1 μm) replaces 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A first blended transition film precursor 2 is produced.

(iv) The same as in example 1, except that: by using 13 LiF.87Li of equal mass ₆ PS ₅ Cl (d50=1 μm) replaces 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A second blended transition film precursor 4 is produced.

(v) The same as in example 1, except that: the composition of 99% is 35 LiF.65Li by equal mass ₆ PS ₅ Cl (d50=500 nm) replaces 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives a second stable film precursor 5.

(vi) The same as in example 1, except that: a multilayer composite solid electrolyte film A12 having a thickness of 30 μm was obtained.

Example 13

The method according to example 1 is preferably other than a multilayer composite solid electrolyte membrane, specifically:

(i) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₆ PS ₅ Cl (d50=5 μm) replaces 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives the first stable film precursor 1.

(ii) The same as in example 1, except that: by using 10 LiF.90Li of equal mass ₆ PS ₅ Cl (d50=3 μm) replaces 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A first blended transition film precursor 2 is produced.

(iii) The same as in example 1, except that: by equal mass of Li ₆ PS ₅ Cl (d50=1 μm) to replace Li ₆ PS ₅ Cl (d50=5 μm) to prepare a sulfide electrolyte membrane precursor 3.

(iv) The same as in example 1, except that: by using 10 LiF.90Li of equal mass ₆ PS ₅ Cl (d50=3 μm) replaces 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A second blended transition film precursor 4 is produced.

(v) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₆ PS ₅ Cl (d50=5 μm) replaces 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives a second stable film precursor 5.

(vi) The same as in example 1, except that: a multilayer composite solid electrolyte film A13 having a thickness of 60 μm was obtained.

Comparative example 1

Inorganic solid electrolyte Li provided in this comparative example ₆ PS ₅ The Cl film was prepared in a manner different from that of example 1 in that the solid electrolyte film contained only a single electrolyte layer film, 99 parts by weight of Li ₆ PS ₅ Cl (d50=1 μm), 0.5 parts by weight of LLZTO (d50=1 μm) and 0.5 parts by weight of PTFE (molecular weight 1000000g/mol, d50=100 μm, compression ratio 100:1) were placed in a mortar, and mixed with the mortar until a dough-like mixture was formed. Then placing the film blank between stainless steel sheets, and flattening to obtain the single electrolyte layer film blank precursor.

The single electrolyte layer film blank precursor is compacted, and the solid electrolyte film D1 with the thickness of 30 mu m is prepared by repeatedly and step-by-step co-extrusion and rolling by a hot roll squeezer.

The solid lithium metal battery cycle performance measurement is carried out on the obtained multilayer composite solid electrolyte membrane:

by LiCoO ₂ Is positive electrode with a loading of 36mg/cm ² Lithium metal as negative electrodeAnd the test voltage range is 2.6-4.3V, and the charge and discharge test is carried out.

By LiCoO ₂ 36mg/cm of positive electrode material ² The sulfide composite solid electrolyte membrane and the lithium sheet are assembled into a battery, and can be obtained from the figure 2, the prepared sulfide composite electrolyte can be matched with a high-load positive electrode at normal temperature, the positive electrode can exert normal specific capacity of 124mAh/g, the battery circulates for 80 circles, and the capacity is only 20mAh/g.

Comparative example 2

Inorganic solid electrolyte Li provided in this comparative example ₆ PS ₅ A preparation method of Cl film.

(i) The same as in example 1, except that: by using 10 LiF.90Li of equal mass ₆ PS ₅ Cl (d50=500 nm) replaces 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives the first stable film precursor 1.

(ii) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₆ PS ₅ Cl (d50=1 μm) replaces 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A first blended transition film precursor 2 is produced.

(iii) A sulfide electrolyte membrane precursor 3 was produced in the same manner as in example 1.

(iv) The same as in example 1, except that: by using 30 LiF.70Li of equal mass ₆ PS ₅ Cl (d50=1 μm) replaces 10lif.90li ₆ PS ₅ Cl (d50=1 μm). A second blended transition film precursor 4 is produced.

(v) The same as in example 1, except that: the composition of 99% is 10 LiF.90Li by equal mass ₆ PS ₅ Cl (d50=500 nm) replaces 30 lif.70li ₆ PS ₅ Cl (d50=500 nm) gives a second stable film precursor 5.

(vi) As in example 1, a multilayer composite solid electrolyte film D2 having a thickness of 30 μm was produced.

Comparative example 3

(i) In the same manner as in example 1, a first stable film precursor 1 was obtained.

(ii) Unlike example 1, the first blend transition film precursor 2 was not provided.

(iv) Unlike example 1, the first blend transition film precursor 4 was not provided.

(v) A second stable film precursor 5 was obtained in the same manner as in example 1.

(vi) The same as in example 1, except that: the first stable film precursor 1, the sulfide electrolyte 3 and the second stable film precursor 5 are stacked in the order of 1-3-5 and then are primarily flattened, and a hot roller press is used for repeatedly and step-by-step co-extrusion rolling and compounding, wherein the hot pressing temperature is 120 ℃, and the multilayer composite co-extrusion solid electrolyte film D3 with the thickness of 20 mu m is prepared.

Comparative example 4

Inorganic solid electrolyte Li provided in this comparative example ₆ PS ₅ The Cl film was prepared differently from example 8 in that the solid electrolyte film contained only a single electrolyte layer film. 94 parts by weight of Li ₆ PS ₅ Cl (d50=1 μm), 1 part by weight of LLZTO (d50=1 μm) and 5 parts by weight of a first binder NBR (1,200,000 g/mol, d50=50 μm compression ratio 100:1) were added to a toluene solvent to disperse homogenate, and then the slurry was formed into a film on a polyester film (PET) by blade coating with a thickness of 150 μm, and then transferred into a vacuum oven, dried at 100 ℃ for 12 hours, and taken out to obtain a single layer film D4.

(1) Intrinsic contact performance of composite solid electrolyte membrane

The porosity, the compacted density, and the peel strength between the composite solid electrolyte membrane and the metallic lithium anode layer of the composite solid electrolyte membranes prepared in examples and comparative examples were tested, and the results are shown in table 1.

TABLE 1

By comparing the contact performance indexes, examples 1-7 and 11-13, and comparative examples 1-3 all showed similar contact performance indexes, indicating that the multilayer film prepared by the dry method is equivalent to the single-layer film and the secondary multilayer film in particle physical contact, and the loss of contact performance of the whole film is not reduced due to the increase of the film layers; it can be seen that examples 8 to 10 all show similar contact performance indexes as compared with comparative example 4, indicating that the multilayer film produced by the liquid phase method is comparable in physical contact with particles as compared with the single layer film, and that no loss of contact performance of the whole film is reduced due to the increase of the film layers.

(2) Electrochemical stability test for metallic lithium:

(2-1) the composite solid electrolyte membranes obtained in examples and comparative examples were subjected to linear voltammetric scan test by assembling CNT// SSE// Li mold cells and performing negative scan from open circuit voltage to-0.6V at a voltage step of 0.1 mV/s.

(2-2) the composite solid electrolyte membranes prepared in examples and comparative examples were subjected to a lithium symmetric battery cycle test and a critical current density test.

The results are shown in Table 2.

TABLE 2

By comparing the peak potential position, the curve integration area, the cutoff current density and the lithium symmetric battery stability cycle time, the lithium deintercalation polarization potential and the critical current density can be compared with the electrochemical stability response of different electrolyte membranes to metal lithium, and the indexes of the embodiment are found to be better than those of the comparative example, so that the multi-layer composite solid electrolyte membrane with halogen gradient prepared by the invention preferably has a granularity gradient, a wider electrochemical reduction window, higher electrochemical stability to metal lithium and better solid-solid fixation performance.

Further, when the average particle size of the sulfide solid electrolyte in the multilayer composite solid electrolyte membrane has the gradient distribution, the solid electrolyte membrane has a wider electrochemical reduction window, higher electrochemical stability to metallic lithium and better solid-solid contact performance.

(3) Oxidation stability test:

the composite solid electrolyte membranes prepared in examples and comparative examples were subjected to linear voltammetric scan test by assembling CNT// SSE// Li die cells and performing forward scan from open circuit voltage to 5V at a voltage step of 0.1mV/s, and the results are shown in table 3.

TABLE 3 Table 3

By comparing the peak potential position, curve integration area and cut-off current density, the oxidation potential stability response of different electrolyte membrane electrodes can be compared, and the indexes of the embodiment are superior to those of the comparative example. The multi-layer composite solid electrolyte membrane prepared by the method has wider electrochemical reduction window, higher oxidation stability and better solid-solid contact performance.

Further, when the average particle size of the sulfide solid electrolyte in the multilayer composite solid electrolyte membrane has the gradient distribution, the solid electrolyte membrane has a wider electrochemical reduction window, higher oxidation stability and better solid-solid connection performance.

(4) Ion conductivity testing:

the sulfide multilayer composite solid electrolyte membranes (excluding the first stable membrane layer 1) prepared in examples and comparative examples were subjected to an ion conductivity test, and the test results are shown in table 4.

The test method is as follows:

the conductivity of the multilayer composite solid electrolyte membrane was measured by an ac impedance method. Before measurement, a block cell was assembled in a glove box filled with argon, a composite solid electrolyte membrane (SSEs) was punched into a wafer with a diameter of 10mm, and then sandwiched between two Stainless Steel (SS) electrodes to assemble a stainless steel/composite solid electrolyte membrane/stainless steel (SS/SSEs/SS) measurement system. The alternating current impedance spectrum test is carried out by an electrochemical workstation, and in the test process, the alternating current perturbation amplitude is set to be 5mV, and the scanning frequency range is 100KHz-7MHz. The temperature of the system was measured at 25 ℃.

TABLE 4 Table 4

By comparing the examples with the comparative examples, all the samples exhibited similar ion conductivities of ≡0.1mS/cm, indicating that each of the multilayer films prepared by the dry method was comparable in ion conductivity to the single-layer film and the sub-multilayer film, and that excessive decrease in ion conductivity of the whole film due to increase of the film layers or introduction of fluorine components did not occur.

Further, by conducting the ion conductivity test of examples 1 to 3, the ion conductivities of the sulfide composite electrolyte membranes produced from the selected target polymers were all more than 10 ^-3 S/cm。

The ionic conductivity of the sulfide composite electrolyte membranes prepared from the selected target polymers by the ionic conductivity test of examples 4-7 were all close to 10 ^-3 S/cm。

The sulfide composite electrolyte membranes prepared from the selected target polymers each had an ionic conductivity exceeding 10 by the ionic conductivity test performed in examples 8 to 13 ^-4 S/cm, the wet film forming process proves to be more unfavorable for the ion conductivity of the multilayer composite film material than the dry film forming process. The multi-layer composite membrane material without the particle size gradient has poor contact performance and low ionic conductivity level. The interface ion transmission of the composite electrolyte membrane with too high fluorine proportion is poor, and the ionic conductivity is poorLower.

(5) Solid state battery test:

as can be seen from the cycle data of the solid state batteries of comparative example 1 and comparative example 1 (as shown in fig. 2), the multilayer co-extruded composite solid state electrolyte membrane designed by the invention has higher initial discharge specific capacity and more excellent cycle performance, and the potential of the multilayer composite electrolyte membrane in application in full batteries is proved.

In conclusion, the multilayer coextrusion composite electrolyte membrane prepared by the invention has the advantages of high oxidation stability, high reduction stability to metal lithium and the like. In addition, the multilayer co-extrusion composite electrolyte membrane prepared by the invention is equivalent to an unmodified electrolyte membrane in the aspects of porosity, compaction density and ion conductivity, so that the multilayer co-extrusion composite electrolyte membrane prepared by the invention can effectively prolong the cycle life of an all-solid-state lithium battery and has practical application value.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. The multilayer composite solid electrolyte membrane is characterized by comprising a first stable membrane layer 1, a first blending transition membrane layer 2, a sulfide electrolyte membrane layer 3, a second blending transition membrane layer 4 and a second stable membrane layer 5 which are sequentially laminated;

Wherein X is ¹ Is halogen, preferably X ¹ F.

2. The multilayer composite solid electrolyte membrane of claim 1 wherein the sulfide electrolyte S-SSEs is selected from the group consisting of compounds of formula I, li _4-x Ge _1-x P _x S ₄ 、Li ₁₀ GeP ₂ S ₁₂ 、Li ₁₀ SnP ₂ S ₁₂ 、Li ₂ S-P ₂ S ₅ 、Li ₂ S-SiS ₂ 、Li ₂ S-B ₂ S ₃ At least one of, liSiPSCl, liSiPSBr and LiSiPSI, wherein x is more than or equal to 0 and less than or equal to 2;

Li _6-a PS _5-a Cl _1+a-b X ² _b a formula I;

3. The multilayer composite solid electrolyte membrane according to claim 1 or 2, wherein LiX is based on the total molar amount of the blend in the first stable membrane layer 1 ¹ The molar content of (2) is 20mol% to 40mol%;

preferably, liX is based on the total molar amount of blend in the first blend transition film layer 2 ¹ The molar content of (2) is 0.5mol% to 20mol%;

preferably, liX is based on the total molar amount of blend in the second blend transition film layer 4 ¹ The molar content of (2) is 0.5mol% to 20mol%;

preferably, the second stabilizing film layer 5 based on the total molar amount of the blend, liX ¹ The molar content of (2) is 20mol% to 40mol%.

4. The multilayer composite solid electrolyte membrane according to any one of claims 1 to 3, wherein the average particle size of the sulfide electrolyte S-SSEs is in a decreasing trend along the direction from the sulfide electrolyte membrane layer 3 to the first stable membrane layer 1;

5. The multilayer composite solid electrolyte membrane according to claim 4, wherein, preferably, the sulfide electrolyte S-SSEs in the first stable membrane layer 1 has an average particle diameter of 50 to 400nm;

preferably, the sulfide electrolyte S-SSEs in the first blending transition film layer 2 has an average particle diameter of 0.4-1 μm;

preferably, the sulfide electrolyte S-SSEs in the sulfide electrolyte membrane layer 3 has an average particle diameter of 1 to 10 μm;

preferably, the sulfide electrolyte S-SSEs in the second blending transition film layer 4 has an average particle diameter of 0.4-1 μm;

preferably, the sulfide electrolyte S-SSEs in the second stable film layer 5 has an average particle diameter of 50-400nm.

6. The multilayer composite solid electrolyte membrane according to any one of claims 1 to 5, wherein the thickness of the multilayer composite solid electrolyte membrane is 10 to 500 μm, preferably 10 to 100 μm, more preferably 6 to 15 μm;

Preferably, the thickness of the first stable film layer 1 is 0.5-1 μm;

preferably, the thickness of the first blending transition film layer 2 is 0.5-1 μm;

preferably, the thickness of the sulfide electrolyte membrane layer 3 is 4 to 11 μm;

preferably, the thickness of the second blending transition film layer 4 is 0.5-1 μm;

preferably, the thickness of the second stable film layer 5 is 0.5-1 μm.

7. The multilayer composite solid electrolyte membrane according to any one of claims 1 to 6, wherein the first stabilizing membrane layer 1 comprises 9.4 to 39.76 parts by weight of the blend, 0.05 to 2 parts by weight of the first binder, 0.01 to 0.4 parts by weight of the oxide electrolyte, and 60 to 90 parts by weight of the positive electrode component;

preferably, the first blending transition film layer 2 comprises 94 to 99.4 weight parts of blend, 0.5 to 5 weight parts of first binder and 0.1 to 1 weight parts of oxide electrolyte;

preferably, the sulfide electrolyte membrane layer 3 includes 94 to 99.4 parts by weight of sulfide electrolyte S-SSEs, 0.5 to 5 parts by weight of first binder, and 0.1 to 1 part by weight of oxide electrolyte;

preferably, the second blending transition film layer 4 comprises 94-99.4 parts by weight of blend, 0.5-5 parts by weight of first binder and 0.1-1 parts by weight of oxide electrolyte;

Preferably, the second stabilizing film layer 5 includes 94 to 99.4 parts by weight of the blend, 0.5 to 5 parts by weight of the first binder, and 0.1 to 1 part by weight of the oxide electrolyte.

8. The multilayer composite solid electrolyte membrane according to any one of claims 1 to 7, wherein the first binder is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, (vinylidene fluoride hexafluoropropylene) copolymer, polyethylene oxide, polyacrylonitrile, and styrene butadiene rubber;

preferably, the oxide electrolyte is selected from at least one of lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, titanium aluminum lithium phosphate, and germanium aluminum lithium phosphate; lithium lanthanum zirconium oxygen and/or garnet structured lithium lanthanum zirconium tantalum oxygen are preferred;

preferably, the first binder has an average particle size of 10 to 1000 μm;

preferably, the number average molecular weight of the first binder is 100,000g/mol or more, and the compression ratio is 1-10000:1.

9. The multilayer composite solid electrolyte membrane according to claim 7 or 8, wherein the positive electrode component comprises a positive electrode active material, a conductive agent, a lithium salt, and a second binder;

wherein the mass of the positive electrode active material, the conductive agent, the lithium salt and the second binder is 65-98:0.5-10:0.5-10:1-15;

Preferably, the positive electrode active material is selected from at least one of lithium cobaltate, lithium manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium iron manganese phosphate, lithium manganese phosphate, and lithium-rich manganese-based material;

preferably, the second binder is selected from small molecule organic matter and/or high molecular polymer.

10. The multilayer composite solid electrolyte membrane according to any one of claims 1 to 9, wherein the porosity of the multilayer composite solid electrolyte membrane is 1% to 20%;

preferably, the multilayer composite solid electrolyte membrane has a compacted density of 2g/cm ³ 6g/cm ³ ；

Preferably, the peel strength of the multilayer composite solid electrolyte membrane is 300 800N/m;

preferably, the ionic conductivity of the multilayer composite solid electrolyte membrane is more than or equal to 10 ^-4 S/cm。

11. A method of preparing a multilayer composite solid electrolyte membrane, the method comprising the steps of:

s4, electrifying sulfideElectrolyte S-SSEs and LiX ¹ Mixing the first binder and the oxide electrolyte to obtain a second blended transition film precursor 4;

wherein X is ¹ Is halogen; preferably X ¹ F is the same as F;

12. The preparation method according to claim 11, wherein in step S6, the compounding method comprises: coating and drying the first stable film precursor 1, the first blending transition film precursor 2, the sulfide electrolyte 3, the second blending transition film precursor 4 and the second stable film precursor 5 in sequence;

Alternatively, the compounding method includes: the first stable film precursor 1, the first blended transition film precursor 2, the sulfide electrolyte 3, the second blended transition film precursor 4, and the second stable film precursor 5 are sequentially laminated in this order, and then co-extrusion is performed.

13. The production method according to claim 12, wherein the conditions of drying include: the drying temperature is 60-200 ℃ and the drying time is 0.5-5h;

preferably, the coextrusion is a monolithic hot press, the hot press temperature being 40-100 ℃.

14. A multilayer composite solid electrolyte membrane produced by the production method according to any one of claims 10 to 13.

15. Use of the multilayer composite solid electrolyte membrane according to any one of claims 1 to 9 and 14 in a solid state battery.

16. An all-solid battery characterized in that the solid battery comprises a positive electrode, a negative electrode and the multilayer composite solid electrolyte membrane according to any one of claims 1 to 9 and 14, wherein a current collector of the positive electrode is located on one side of the first stabilizing membrane layer 1 and the negative electrode is located on one side of the second stabilizing membrane layer 5.