WO2019153168A1 - 3d network all-solid-state electrolyte and preparation method therefor, and lithium secondary battery - Google Patents

Abstract

Provided in the present invention is a 3D network organic-inorganic hybrid all-solid-state electrolyte, comprising: a three-dimensional network polymer electrolyte matrix serving as a 3D network organic-inorganic hybrid all-solid-state electrolyte framework; and oxide electrolyte nanoparticles or oxide electrolyte nanoparticle agglomerates and lithium salt which are dispersed in the three-dimensional network polymer electrolyte matrix. The three-dimensional network polymer electrolyte matrix is obtained by a ring-opening polymerization reaction of a reaction monomer having an epoxy group, glycidyl ether-type epoxy resin, a derivative of the glycidyl ether-type epoxy resin, a cross-linking agent and a linear polymer.

Description

[Name of invention made by ISA according to Rule 37.2] A 3D network all solid electrolyte and preparation method thereof and lithium secondary battery Technical field

The invention belongs to the technical field of lithium secondary batteries, and particularly relates to a 3D network organic-inorganic hybrid all-solid electrolyte, a preparation method thereof and a lithium secondary battery.

Background technique

Lithium-ion batteries have high specific energy density, high operating voltage, low self-discharge rate, fast charge and discharge, long service life and no memory effect (J. Power Sources., 2011, 196:8651–8655), making lithium ions The battery is considered to be the best choice for large-scale power batteries. However, the low energy density of the graphite anode leads to the current energy density of the lithium ion battery is usually around 200Wh / kg, which seriously restricts the wide application of lithium ion batteries in electric vehicles. With the acceleration of the commercialization of pure electric vehicles, it is urgent to further increase the energy density (energy density of 300 Wh/kg or more) of lithium ion batteries. The use of metallic lithium as the negative electrode can greatly improve the energy density of the battery, mainly due to the theoretical specific energy density of metallic lithium in the negative electrode material of lithium secondary battery up to 3860 mAh/g, and the use of metallic lithium also makes the current collectorless electrode The preparation is made possible, thereby greatly increasing the energy density of the battery. However, the lithium metal anode is liable to cause safety problems due to the non-uniform deposition of lithium ions in the charge-discharge cycle, which poses a great challenge for the application of lithium metal electrodes (Energ.Environ.Sci., 2013, 7). (2): 513-537). In addition, the currently widely used volatile and flammable liquid organic solvents are currently used as commercial lithium ion battery electrolytes, which are prone to safety problems during cycling (J. Power Sources., 2012, 208: 210–224), The unstable electrochemical performance of organic electrolytes and separators at high voltages makes it difficult to increase the energy density of lithium ion batteries. The use of solid polymer electrolytes to replace traditional organic liquid electrolytes is considered to be an effective way to improve the safety of lithium batteries. In all-solid-state lithium-ion batteries, all solid electrolyte materials do not contain any liquid components and can act directly as electrolytes and membranes (J. Power Sources., 2015, 282: 299–322), and solid electrolytes can Effectively inhibit the growth of lithium dendrites. The basic requirements for solid electrolytes are high ionic conductivity, suitable mechanical strength and a stable electrode interface. All-solid-state lithium-ion batteries have higher energy density than current lithium-ion batteries and are considered to be one of the most promising next-generation high-energy-density lithium battery systems. So far, the preparation of polymer electrolyte materials with high ionic conductivity, low electrode/electrolyte interface impedance, and good mechanical strength is still a huge technical challenge at this stage (Chem. Rev., 2014, 114(23): 11503 -11618). Therefore, the development of a new type of solid electrolyte for high energy density lithium battery systems is expected to significantly increase the energy density and safety of existing lithium ion batteries, and has important practical applications (Nature., 2001, 414: 359-367).

Patentes CN106876784 A and CN106941190 A respectively disclose a PEO-based solid polymer electrolyte membrane and a pomegranate-type LLZO solid oxide electrolyte. CN106876784 A disclosed PEO-based solid polymer electrolyte membrane has problems such as low room temperature ionic conductivity, high temperature mechanical properties and poor thermal stability, and is prone to short circuit, which is difficult to meet practical use requirements. The pomegranate-type LLZO solid oxide electrolyte disclosed in CN106941190 A has high room temperature conductivity, but the thickness of the electrolyte sheet is large and brittle, resulting in high battery interface resistance, greatly reducing the weight energy density and volume energy density of the battery, and making it difficult to prepare a large capacity. Batteries. Therefore, the key problem of the current solid electrolyte is to prepare an organic-inorganic hybrid solid electrolyte membrane which has high lithium ion conductivity, high oxidation resistance potential, mechanical properties and ion conduction characteristics, and can completely inhibit lithium dendrite piercing throughout the life cycle. The realization of the fusion of high mechanical strength and high ionic conductivity solves the problem that the current ionic conductivity and mechanical properties of the electrolyte are difficult to balance.

Summary of the invention

In view of this, the technical problem to be solved by the present invention is to provide a 3D network organic-inorganic hybrid all-solid electrolyte and a preparation method thereof, and a lithium secondary battery, and the 3D network organic-inorganic hybrid solid-state solid provided by the present invention The electrolyte has high electrical conductivity, and it has excellent mechanical properties and flexibility, excellent thermal stability and dimensional stability, and solves the problem that the current ionic conductivity and mechanical properties of the polymer electrolyte are difficult to balance, and the lithium battery is improved. safety.

The invention provides a 3D network organic-inorganic hybrid all solid electrolyte, comprising:

a three-dimensional network polymer electrolyte substrate as a 3D network organic-inorganic hybrid all-solid electrolyte skeleton;

And agglomerates and lithium salts of oxide electrolyte nanoparticles or oxide electrolyte nanoparticles dispersed inside the three-dimensional network polymer electrolyte matrix;

The three-dimensional network polymer electrolyte matrix is obtained by ring-opening polymerization of a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, and a linear polymer.

Preferably, the linear polymer is selected from the group consisting of polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polystyrene, polyvinylidene fluoride-hexafluoropropylene, polyoxypropylene, polyethylene oxide, and polysiloxane. One or more of an alkane, a polyurethane or a polysulfone having a number average molecular weight ranging from 100,000 to 4,000,000.

Preferably, the lithium salt is selected from the group consisting of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate, difluorosulfonamide One or more of lithium amine and lithium difluorooxalate borate.

Preferably, the molar ratio of the lithium salt to the linear polymer is 1: (4 to 50).

Preferably, the reactive monomer having an epoxy group is selected from one or more of glycidyl ether compounds.

Preferably, the glycidyl ether compound is selected from the group consisting of 3-glycidoxypropyltriethoxysilane, polyethylene glycol diglycidyl ether, poly(propylene glycol) diglycidyl ether, and neopentyl glycol One or more of glycidyl ether and poly(dimethylsiloxane) diglycidyl ether.

Preferably, the number average molecular weight of the reactive monomer having an epoxy group is from 300 to 20,000 Da.

Preferably, the number average molecular weight of the reactive monomer having an epoxy group is from 500 to 10,000 Da.

Preferably, the glycidyl ether type epoxy resin and the derivative thereof have a number average molecular weight of 400 to 20,000 Da and an epoxy value of 160 to 290.

Preferably, the glycidyl ether type epoxy resin and derivatives thereof are one or more of E44, E51, E52, E54, E55 and E56D.

Preferably, the crosslinking agent is a compound containing at least one amine group.

Preferably, the crosslinking agent is selected from compounds containing at least one amine group selected from the group consisting of alkanes and derivatives thereof, polyolefins and derivatives thereof, polyalkylene oxides and derivatives thereof, and cellulose and derivatives thereof. Things.

Preferably, the derivative of the alkane is selected from the group consisting of a halogenated product of an alkane, the derivative of the polyolefin is selected from the group consisting of a halogenated product of a polyolefin, and the derivative of the polyalkylene oxide is selected from the group consisting of a halogenated product of a polyalkylene oxide. The polyalkylene oxide is selected from the group consisting of polyethylene oxide or polypropylene oxide.

Preferably, the crosslinking agent is selected from one or more of polyethyleneimine, polypropyleneimine, and polyetheramine.

Preferably, the crosslinking agent has a number average molecular weight of from 230 to 10,000 Da.

Preferably, the mass ratio of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin and the derivative thereof, and the crosslinking agent is (1 to 3): (1 to 3): (4 to 8) ).

Preferably, the oxide electrolyte nanoparticles are selected from the group consisting of Li ₁₄ Zn(GeO ₄ ) ₄ , LiZr ₂ Si ₂ PO ₁₂ , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ One or more of Li ₇ La ₃ Zr ₂ O ₁₂ and Li _6.75 La ₃ Zr _1.75 Ta _0.25 O ₁₂ having a particle diameter of 50 nm to 900 nm, and an agglomerate of the oxide electrolyte nanoparticles having a particle diameter of 1 μm ~5μm.

Preferably, the oxide electrolyte nanoparticles account for 20% by weight to 50% by weight of the sum of the mass of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin, and a derivative thereof and the crosslinking agent. The linear polymer is 5% by weight to 30% by weight based on the sum of the mass of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin, and a derivative thereof and the crosslinking agent.

Preferably, the all-solid electrolyte has a thickness of 20 to 200 μm.

The invention also provides a preparation method of the above all-solid electrolyte, comprising the following steps:

A) mixing a linear polymer, a lithium salt, and a solvent to obtain a mixed solution;

B) mixing a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, an oxide electrolyte nanoparticle, and a solvent to obtain a mixed dispersion;

C) mixing and stirring the mixed solution and the mixed dispersion to obtain a reaction precursor solution;

D) injecting the reaction precursor solution into a mold or coating the surface of the substrate, heating to carry out a reaction, and drying to obtain a 3D network organic-inorganic hybrid all-solid electrolyte;

Steps A) and B) have no order restrictions.

Preferably, the solvent described in the step A) is independently selected from the solvent described in the step B): acetone, cyclohexane, toluene, chloroform, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, N, N-dimethylacetamide or N-methylpyrrolidone.

Preferably, in step D), the temperature at which the reaction is carried out by heating is from 60 to 120 ° C for a period of from 12 to 36 hours.

The present invention also provides a lithium secondary battery comprising the above 3D network organic-inorganic hybrid all-solid electrolyte or the 3D network organic-inorganic hybrid all-solid electrolyte prepared by the above preparation method.

The present invention provides a 3D network organic-inorganic hybrid all-solid electrolyte comprising: a three-dimensional network polymer electrolyte substrate as a 3D network organic-inorganic hybrid all-solid electrolyte skeleton; and a polymer electrolyte substrate dispersed in the three-dimensional network Internal oxide electrolyte nanoparticles or agglomerates of oxide electrolyte nanoparticles and lithium salts; the three-dimensional network polymer electrolyte matrix is composed of a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and derivatives thereof The crosslinking agent and the linear polymer are obtained by ring-opening polymerization. The method of the invention adopts a dense three-dimensional polymer matrix with good performance and high molecular structure as a skeleton, and the oxide electrolyte nanoparticles and the lithium salt are uniformly formed in situ in the polymer electrolyte matrix to prepare a multi-layer lithium ion conductive channel. 3D Network Organic - Inorganic Hybrid Solid Electrolyte. The 3D network organic-inorganic hybrid solid electrolyte structure in the method of the invention effectively combines the advantages of the polymer electrolyte and the inorganic oxide electrolyte, and the crosslinked polymer electrolyte network imparts good flexibility and adhesion to the hybrid electrolyte, inorganic Oxide electrolyte nanoparticles have extremely high hardness and a wide electrochemical stability window, which can effectively inhibit lithium dendrite growth.

The results show that the 3D network hybrid all-solid electrolyte prepared by the method of the invention realizes the organic fusion of ionic conductivity and mechanical properties, and the room temperature ionic conductivity is as high as 3.68×10 ^-5 S cm ^-1 , which is much higher than that of PEO+lithium base. The room temperature conductivity of the solid electrolyte (room temperature ionic conductivity is 1.52 × 10 ^-5 S cm ^-1 ), and the ionic conductivity at 80 ° C is 1.04 × 10 ^-3 S cm ^-1 (PEO + lithium salt-based all-solid electrolyte 80 ° C The ion conductivity is 5.43×10 ^-4 S cm ^-1 ), which is the practical application level. At the same time, it has excellent mechanical properties and flexibility (tensile strength is 10.8Mpa, elastic shape is 125%, and PEO+lithium-based all-solid electrolyte has a tensile strength of only 0.62Mpa), excellent thermal stability and dimensional stability. Sexuality solves the problem that the current ionic conductivity and mechanical properties of polymer electrolytes are difficult to balance, and improves the safety of lithium batteries.

DRAWINGS

1 is a schematic flow chart of a method for preparing a 3D network organic-inorganic hybrid all-solid electrolyte provided by the present invention;

2 is a schematic structural view of a polytetrafluoroethylene mold;

3 is a surface topography diagram of a 3D network organic-inorganic hybrid solid electrolyte membrane prepared in Example 1;

4 is a thermogravimetric (TGA) curve of a 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1;

5 is a mechanical property diagram of a 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1;

6 is a thermal dimensional stability diagram of a 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1;

7 is a graph showing the relationship between ionic conductivity and temperature of a 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1. FIG.

Detailed ways

The invention provides a 3D network organic-inorganic hybrid all solid electrolyte, comprising:

a three-dimensional network polymer electrolyte substrate as a 3D network organic-inorganic hybrid all-solid electrolyte skeleton;

And agglomerates and lithium salts of oxide electrolyte nanoparticles or oxide electrolyte nanoparticles dispersed inside the three-dimensional network polymer electrolyte matrix;

The three-dimensional network polymer electrolyte matrix is obtained by ring-opening polymerization of a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, and a linear polymer.

The 3D network organic-inorganic hybrid all solid electrolyte provided by the present invention comprises a three-dimensional network polymer electrolyte matrix as a 3D network organic-inorganic hybrid all solid electrolyte skeleton.

Wherein the three-dimensional network polymer electrolyte matrix is obtained by ring-opening polymerization of a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, and a linear polymer.

The linear polymer is selected from the group consisting of polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polystyrene, polyvinylidene fluoride-hexafluoropropylene, polyoxypropylene, polyethylene oxide, polysiloxane, polyurethane. Or one or more of polysulfones. The linear polymer has a number average molecular weight ranging from 100,000 to 4,000,000, preferably from 500,000 to 3,000,000, more preferably from 1,000,000 to 2,000,000.

The reactive monomer having an epoxy group is selected from one or more of glycidyl ether compounds. Preferably, the glycidyl ether compound is selected from the group consisting of 3-glycidoxypropyltriethoxylate. One or more of a silane, a polyethylene glycol diglycidyl ether, a poly(propylene glycol) diglycidyl ether, a neopentyl glycol diglycidyl ether, and a poly(dimethylsiloxane) diglycidyl ether .

The number average molecular weight of the reactive monomer having an epoxy group is from 300 to 20,000 Da, preferably from 500 to 10,000 Da, more preferably from 500, 1000, 2000, 3,000 or 6000 Da.

The glycidyl ether type epoxy resin and its derivative have a molecular weight of 400 to 20,000 Da, preferably 500 to 10,000 Da, more preferably 1,000 to 8,000 Da, and an epoxy value of 160 to 290, preferably 180 to 270, more preferably 200. ~250.

Preferably, the glycidyl ether type epoxy resin and derivatives thereof are one or more of E44, E51, E52, E54, E55 and E56D.

The crosslinking agent is selected from compounds containing at least one amine group selected from the group consisting of alkanes and derivatives thereof, polyolefins and derivatives thereof, polyalkylene oxides and derivatives thereof, or cellulose and derivatives thereof.

The crosslinking agent of the present invention is selected from a linear amine compound, a branched amine compound or an amine compound having a hyperbranched structure.

Preferably, the derivative of the alkane is selected from the group consisting of a halogenated product of an alkane, the derivative of the polyolefin is selected from the group consisting of a halogenated product of a polyolefin, and the derivative of the polyalkylene oxide is selected from the group consisting of a halogenated product of a polyalkylene oxide. The polyalkylene oxide is selected from the group consisting of polyethylene oxide or polypropylene oxide. More preferably, the crosslinking agent is selected from one or more of polyethyleneimine, polypropyleneimine, and polyetheramine.

In the present invention, the crosslinking agent has a number average molecular weight of 230 to 10,000 Da, preferably 230, 400, 1000, 2000, 4000 or 5000 Da.

The mass ratio of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin, a derivative thereof, and the crosslinking agent is (1 to 3): (1 to 3): (4 to 8), preferably (1.5 to 2.5): (1.5 to 2.5): (5 to 7).

The linear polymer comprises from 5 wt% to 30 wt%, preferably from 10 wt% to 25 wt%, based on the sum of the mass of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin, and a derivative thereof and the crosslinker. % is more preferably 15% by weight to 20% by weight.

The 3D network organic-inorganic hybrid all-solid electrolyte provided by the present invention further comprises an oxide electrolyte nanoparticle or an agglomerate of the oxide electrolyte nanoparticle dispersed inside the three-dimensional network polymer electrolyte matrix, and a lithium salt.

The lithium salt is an inorganic lithium salt or an organic lithium salt, preferably lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), three One of lithium fluoromethanesulfonate (LiCF ₃ SO ₄ ), lithium trifluoromethanesulfonate (LiTFSI), lithium bisfluorosulfonimide (LiFSI), and lithium difluorooxalate borate (LiDFOB) or A variety.

The molar ratio of the lithium salt to the linear polymer is 1: (4 to 50), preferably 1: (5 to 45), more preferably 1: (10 to 40), still more preferably 1: (20) ~30).

The oxide electrolyte nanoparticles are selected from the group consisting of Li ₁₄ Zn(GeO ₄ ) ₄ , LiZr ₂ Si ₂ PO ₁₂ , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ , Li ₇ One or more of La ₃ Zr ₂ O ₁₂ and Li _6.75 La ₃ Zr _1.75 Ta _0.25 O ₁₂ have a particle diameter of 50 nm to 900 nm, preferably 100 nm to 800 nm, and more preferably 300 to 500 nm.

The oxide electrolyte nanoparticles are 20% by weight to 50% by weight, preferably 25% by weight, based on the sum of the mass of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin, and a derivative thereof and the crosslinking agent. ～45 wt%, more preferably 30 wt% to 40 wt%.

The 3D network organic-inorganic hybrid all-solid electrolyte has a thickness of 20 to 200 μm, preferably 50 to 180 μm, and more preferably 100 to 150 μm.

The invention also provides a preparation method of the above 3D network organic-inorganic hybrid all-solid electrolyte, comprising the following steps:

A) mixing a linear polymer, a lithium salt, and a solvent to obtain a mixed solution;

B) mixing a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, an oxide electrolyte nanoparticle, and a solvent to obtain a mixed dispersion;

C) mixing and stirring the mixed solution and the mixed dispersion to obtain a reaction precursor solution;

D) injecting the reaction precursor solution into a mold or coating the surface of the substrate, heating to carry out a reaction, and drying to obtain a 3D network organic-inorganic hybrid all-solid electrolyte;

Steps A) and B) have no order restrictions.

Specifically, in the present invention, the solvent described in the step A) and the solvent described in the step B) are preferably organic solvents, more preferably aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers and ketones. One or more of the class and other organic solvents. In some embodiments of the invention, the solvent described in step A) is independently selected from the solvent described in step B): acetone, cyclohexane, toluene, chloroform, N,N-dimethylformamide. , acetonitrile, tetrahydrofuran, N,N-dimethylacetamide or N-methylpyrrolidone.

The present invention has no particular limitation on the order of preparation of the mixed solution and the mixed dispersion.

After the mixed solution and the mixed dispersion are obtained, the mixed solution and the mixed dispersion are mixed and stirred to obtain a reaction precursor solution.

The mixing method of the mixed solution and the mixed dispersion is not particularly limited, and the mixed solution may be poured into the mixed dispersion, or the mixed dispersion may be poured into the mixed solution. The stirring time is 2 to 12 h, preferably 4 to 10 h, and more preferably 6 to 8 h.

Wherein, the linear polymer accounts for 5% to 30% by weight of the precursor solution, preferably 10% to 25%, more preferably 15% to 20%.

The reaction precursor solution is injected into a mold or coated on the surface of the substrate, heated to carry out a reaction, and after drying, a 3D network organic-inorganic hybrid all-solid electrolyte is obtained.

In the present invention, the manner in which the precursor solution is formed into an electrolyte membrane is not particularly limited, and the precursor solution may be poured into a mold, preferably a polytetrafluoroethylene mold, the polytetrafluoroethylene. The ethylene mold is preferably a circular mold and preferably has a diameter of 6 to 20 cm, more preferably 10 to 15 cm. The thickness of the precursor solution poured into the mold is preferably 20 to 200 μm, more preferably 50 to 150 μm, still more preferably 70 to 120 μm.

The precursor solution may also be applied to the surface of the substrate. The method for coating is not particularly limited, and may be poured on the surface of the substrate to form a film of a certain thickness, or coated by spraying or spin coating. The thickness of the film formed on the surface of the precursor solution is preferably 20 to 200 μm, more preferably 50 to 150 μm, still more preferably 70 to 120 μm.

Next, the reaction is carried out by heating, and the reaction temperature is preferably 60 to 120 ° C, more preferably 80 to 100 ° C; and the time is preferably 12 to 36 hours, more preferably 16 to 32 hours, still more preferably 20 to 28 hours.

Finally, the heated reaction product is dried to obtain a 3D network organic-inorganic hybrid all-solid electrolyte.

Referring to FIG. 1, FIG. 1 is a schematic flow chart of an all-solid electrolyte of a 3D network organic-inorganic hybrid all-solid electrolyte provided by the present invention. In Fig. 1, the reaction monomer A, the reaction monomer B and the reaction monomer C respectively correspond to a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, and a crosslinking agent; an oxide solid electrolyte The nanoparticles are oxide electrolyte nanoparticles.

The specific process is: mixing a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent and an oxide electrolyte nanoparticle, and mixing the mixture of the lithium salt and the linear polymer Then, a heating reaction is carried out to obtain a 3D network organic-inorganic hybrid all-solid electrolyte (3D-HSPE).

The present invention also provides a lithium secondary battery comprising the above 3D network organic-inorganic hybrid all solid electrolyte.

The method of the invention adopts a dense three-dimensional polymer matrix with good performance and high molecular structure as a skeleton, and the oxide electrolyte nanoparticles and the lithium salt are uniformly formed in situ in the polymer electrolyte matrix to prepare a multi-layer lithium ion conductive channel. 3D network organic-inorganic hybrid solid electrolyte. The 3D network organic-inorganic hybrid solid electrolyte structure in the method of the invention effectively combines the advantages of the polymer electrolyte and the inorganic oxide electrolyte, and the crosslinked polymer electrolyte network imparts good flexibility and adhesion to the hybrid electrolyte, inorganic Oxide electrolyte nanoparticles have extremely high hardness and a wide electrochemical stability window, which can effectively inhibit lithium dendrite growth.

The results show that the 3D network hybrid all-solid electrolyte prepared by the method of the invention realizes the organic fusion of ionic conductivity and mechanical properties, and the room temperature ionic conductivity is as high as 3.68×10 ^-5 S cm ^-1 , which is much higher than that of PEO+lithium base. The room temperature conductivity of the solid electrolyte (room temperature ionic conductivity is 1.52 × 10 ^-5 S cm ^-1 ), and the ionic conductivity at 80 ° C is 1.04 × 10 ^-3 S cm ^-1 (PEO + lithium salt-based all-solid electrolyte 80 ° C The ion conductivity is 5.43×10 ^-4 S cm ^-1 ), which is the practical application level. At the same time, it has excellent mechanical properties and flexibility, excellent thermal stability and dimensional stability, which solves the difficult problem of ionic conductivity and mechanical properties in polymer electrolytes, and improves the safety of lithium batteries.

In order to further understand the present invention, the 3D network organic-inorganic hybrid all-solid electrolyte and the preparation method thereof and the lithium secondary battery provided by the present invention are described below with reference to the embodiments, and the scope of protection of the present invention is not limited by the following examples.

Example 1

The embodiment relates to a method for preparing a 3D network organic-inorganic hybrid solid electrolyte, and the method comprises the following steps:

(1) Add 0.10 g of polyethylene oxide (PEO, Mn = 600,000) to 25 ml of beaker A, then add 2.0 g of acetonitrile dropwise with a pipette, stir for 2 h to completely dissolve, and then add 0.55 g of LiTFSI to continue. Stirring to form a colorless transparent solution;

(2) 0.10 g of polyethylene glycol diglycidyl ether (Mn = 500), 0.06 g of bisphenol A diglycidyl ether epoxy resin E51 (epoxy value 186) and 0.4 were sequentially added to a 25 ml beaker B. g polyetheramine (Mn=2000) was added to the beaker, 2.0 g of acetonitrile was added dropwise with a pipette, and finally 1.2 g of LAGP nanoparticles (particle size: 300±10 nm) were added, and the mixture was stirred for 6 hours to form a white precursor. Mixture.

(3) Pour the solution in beaker A into beaker B, and stir for 6 hours to obtain a mixed reaction precursor mixture; apply the precursor mixture to a Teflon mold at a constant temperature of 80 °C. After 24 hours, a white 3D network organic-inorganic hybrid all-solid electrolyte membrane was obtained; the prepared solid electrolyte membrane was dried and placed in a glove box for use.

In addition, the beaker may be replaced by a container, which is a container that does not react with the reactants or solvent, may be a glass container, or may be stainless steel, or a ceramic container. Different sizes of containers can be selected depending on the size of the reaction. The step of stirring and dissolving can also be summarized as a sub-step of dissolution, which can be a natural dissolution, the purpose of which is to dissolve the components completely.

In the step (3), a polytetrafluoroethylene mold is used, which is a vessel having a groove and a circular bottom surface, and an open vessel. Referring to Figure 2, Figure 2 is a schematic view of the structure of a polytetrafluoroethylene mold. The drying step of the solid electrolyte membrane may be drying, vacuum drying, or natural drying. If it is needed, it can be placed in a glove box or an oven for storage. If it needs to be stored, it needs to be placed in a dry environment.

After measurement, the thickness of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this example was 104 μm, and the measured room temperature conductivity was 3.68×10 ^-5 S cm ^-1 .

The surface topography of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this embodiment is shown in FIG. 3, and FIG. 3 is the surface topography of the 3D network organic-inorganic hybrid solid electrolyte membrane prepared in Example 1. . Wherein (a) is an optical photograph of the surface of the 3D network organic-inorganic hybrid solid electrolyte membrane prepared in Example 1, and (b) is a scan of the 3D network organic-inorganic hybrid solid electrolyte membrane prepared in Example 1. Electron micrograph. As can be seen from FIG. 3, the prepared 3D network organic-inorganic hybrid all solid electrolyte surface exhibits a dense crosslinked network structure, and the oxide electrolyte nanoparticles are uniformly distributed in the polymer matrix.

The thermal weight loss curve of the 3D network organic-inorganic hybrid all solid electrolyte prepared in this example is shown in FIG. 4 . As can be seen from FIG. 4, the initial decomposition temperature of the hybrid solid polymer film is as high as 300 ° C, which shows that the solid electrolyte membrane has excellent thermal stability, which is sufficient for the use requirements on the lithium secondary battery. The thermal decomposition temperature of the reference PEO+LiTFSI is only 150 °C, and it is easy to decompose and decompose at high temperature.

The bending properties of the 3D network organic-inorganic hybrid solid electrolyte prepared in this example are shown in FIG. 5, and FIG. 5 is a mechanical property diagram of the 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1. In Fig. 5, a is a finished view of a 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1, and b is a photo of a 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1 wound on a columnar body. , c is a stress-strain curve of the 3D network organic-inorganic hybrid solid electrolyte prepared in Example 1.

As can be seen from Fig. 5, the solid electrolyte has excellent flexibility and mechanical properties and is less prone to fracture. Lithium secondary batteries may be subjected to certain external forces during assembly and use. Therefore, the mechanical properties of solid electrolytes are an important indicator to determine whether they meet practical applications. In this experiment, the tensile properties and tensile elongation at break of solid electrolytes were determined under certain conditions to characterize the mechanical properties of polymer electrolytes. The solid electrolyte membrane was cut into 10 mm wide and 50 mm long splines, and the tensile strength of the polymer electrolyte membrane was measured by a CMT 6104 universal electronic tensile machine of MTS Industrial Systems, USA, and the tensile rate was 5 mm min ^-1 . The thickness of the sample was measured by the G103 type electronic digital display outer diameter micrometer of Shanghai Measuring Tool Co., Ltd. The 3D network organic-inorganic hybrid solid electrolyte prepared in this example was tested to have a tensile strength of 10.8 MPa and an elastic shape of 125%.

The tensile strength of the PEO+lithium salt-based all-solid electrolyte (see Example 2 for the preparation method) is only 0.62 MPa.

The thermal dimensional stability of the 3D network organic-inorganic hybrid solid electrolyte prepared in this example is shown in Fig. 6, and the solid electrolyte was left at 80 ° C for 3 hours without any shrinkage in size. On the contrary, the PEO+LiTFSI solid electrolyte (see Example 2 for the preparation method) is severely deformed, and the lithium battery safety problem is easily caused by the short circuit. The 3D network organic-inorganic hybrid solid electrolyte has excellent thermal dimensional stability and can greatly improve the safety of lithium batteries.

The ionic conductivity and temperature relationship of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this example is shown in Fig. 7. The room temperature ionic conductivity is 3.68×10 ^-5 S cm ^-1 , which is much higher than Room temperature ionic conductivity (1.52×10 ^-5 S cm ^-1 ) of PEO+LiTFSI-based all-solid electrolyte, ionic conductivity at 80 °C is 1.04×10 ^-3 S cm ^-1 (PEO+lithium-based all-solid electrolyte ( For the preparation method, see Example 2) The ionic conductivity at 80 ° C is only 5.43 × 10 ^-4 S cm ^-1 ), which is the practical application level. The linear relationship between ionic conductivity and temperature indicates that the ionic conductivity changes with temperature in accordance with the mechanism of Arrhenium ion conduction.

Example 2

The present embodiment relates to a method for preparing a PEO+lithium salt-based all-solid electrolyte reference sample, the method comprising the following steps:

(1) 0.72 g of PEO (Mn = 100,000) was added to a 25 ml beaker, then 6.0 g of acetonitrile was added dropwise, and the mixture was completely dissolved by stirring, and then 0.59 g of LiTFSI was weighed and stirred for 6 hours to be uniformly mixed. The above solution is poured into a clean polytetrafluoroethylene mold, left to stand for a period of time, and then placed in a vacuum oven at a constant temperature of 60 ° C for 8 h to obtain a PEO + lithium salt-based all-solid electrolyte, and the obtained PEO-based solid electrolyte membrane Put it in the glove box for later use.

The PEO+lithium salt-based all-solid electrolyte membrane prepared in this example has a thickness of 180 μm and a room temperature conductivity of 1.52×10 ^-5 S cm ^-1 .

Example 3

The embodiment relates to a method for preparing a 3D network organic-inorganic hybrid all-solid electrolyte membrane, and the method comprises the following steps:

(1) Add 0.12g of polyethylene oxide (Mn=1000000) to 25ml of beaker A, then add 2.0g of acetonitrile dropwise with a pipette, stir for 2h to completely dissolve, then add 0.55g of LiTFSI and continue to stir. Colorless transparent solution;

(2) 0.15 g of polyethylene glycol diglycidyl ether (Mn = 1000), 0.05 g of bisphenol A diglycidyl ether epoxy resin E44 (epoxy value 190) and 0.4 were sequentially added to a 25 ml beaker B. g polyetheramine (Mn=1000) was added to the beaker, 2.0 g of acetonitrile was added dropwise with a pipette, and finally 0.3 g of LAGP nanoparticles (particle size: 500±20 nm) was added, and the mixture was stirred for 6 hours to form a white precursor. Mixture.

(3), the solution in the beaker A is poured into the beaker B, and after rapid stirring for 6 hours, a mixed reaction precursor mixture is obtained; the precursor mixture is poured into a polytetrafluoroethylene mold, and the reaction is kept at a constant temperature for 24 hours. Then, a white 3D network organic-inorganic hybrid all-solid electrolyte membrane was obtained; the prepared solid electrolyte membrane was dried and placed in a glove box for use.

The thickness of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this example was 125 μm, and the measured room temperature conductivity was 1.34×10 ^-5 S cm ^-1 .

Example 4

The embodiment relates to a method for preparing a 3D network organic-inorganic hybrid all-solid electrolyte membrane, and the method comprises the following steps:

(1) Add 0.24 g of polyethylene oxide (Mn = 4000000) to 25 ml of beaker A, then add 2.0 g of acetonitrile dropwise with a pipette, stir for 2 h to completely dissolve, and then add 0.64 g of LiTFSI to continue stirring. Colorless transparent solution;

(2) 0.15 g of polyethylene glycol diglycidyl ether (Mn = 2000), 0.05 g of bisphenol A diglycidyl ether epoxy resin E51 (epoxy value 195) and 0.4 were sequentially added to a 25 ml beaker B. g polyetheramine (Mn=2000) was added to the beaker, 2.0 g of acetonitrile was added dropwise with a pipette, and finally 0.6 g of LAGP nanoparticles (particle size: 500±20 nm) was added, and the mixture was stirred for 6 hours to form a white precursor. Mixture.

(3), the solution in the beaker A is poured into the beaker B, and after rapid stirring for 6 hours, a mixed reaction precursor mixture is obtained; the precursor mixture is poured into a polytetrafluoroethylene mold, and the reaction is kept at a constant temperature for 12 hours. Then, a white 3D network organic-inorganic hybrid all-solid electrolyte membrane was obtained; the prepared solid electrolyte membrane was dried and placed in a glove box for use.

The thickness of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this example was 100 μm, and the measured room temperature conductivity was 2.94×10 ^-5 S cm ^-1 .

Example 5

The embodiment relates to a method for preparing a 3D network organic-inorganic hybrid all-solid electrolyte membrane, and the method comprises the following steps:

(1) Add 0.12 g of polyacrylonitrile (Mn=130000) to 25 ml of beaker A, then add 2.0 g of acetonitrile dropwise with a pipette, stir for 2 hours to completely dissolve, then add 0.45 g of LiTFSI and continue stirring. Colorless transparent solution;

(2) 0.15 g of polyethylene glycol diglycidyl ether (Mn = 500), 0.05 g of bisphenol A diglycidyl ether epoxy resin E44 (epoxy value 195) and 0.4 were sequentially added to a 25 ml beaker B. g polyetheramine (Mn=2000) was added to the beaker, 2.0 g of acetonitrile was added dropwise with a pipette, and finally 0.6 g of LLZO nanoparticles (particle size: 900±50 nm) was added, and the mixture was stirred for 6 hours to form a white precursor. Mixture.

(3), the solution in the beaker A is poured into the beaker B, and after rapid stirring for 6 hours, a mixed reaction precursor mixture is obtained; the precursor mixture is poured into a polytetrafluoroethylene mold, and the reaction is kept at a constant temperature for 24 hours. Then, a white 3D network organic-inorganic hybrid all-solid electrolyte membrane was obtained; the prepared solid electrolyte membrane was dried and placed in a glove box for use.

The thickness of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this example was 110 μm, and the measured room temperature conductivity was 6.0×10 ^-6 S cm ⁻¹ .

Example 6

The embodiment relates to a method for preparing a 3D network organic-inorganic hybrid all-solid electrolyte membrane, and the method comprises the following steps:

(1) 0.24 g of polysiloxane (Mn = 100,000) was added to 25 ml of beaker A, and then 2.0 g of N,N-dimethylformamide was added dropwise with a pipette, and the mixture was completely dissolved by stirring for 2 hours. Then adding 0.2 g of LiTFSI and continuing to stir to form a colorless transparent solution;

(2) 0.15 g of polyethylene glycol diglycidyl ether (Mn = 2000), 0.05 g of bisphenol A diglycidyl ether epoxy resin E44 (epoxy value of 165) and 0.4 were sequentially added to a 25 ml beaker B. g polyetheramine (Mn=2000) was added to the beaker, 2.0 g of acetonitrile was added dropwise with a pipette, and finally 0.3 g of LLZO micron particles (particle size: 5±0.5 μm) was added, and the mixture was stirred for 6 hours to form a white precursor. Body mixture.

(3), the solution in the beaker A is poured into the beaker B, and after rapid stirring for 6 hours, a mixed reaction precursor mixture is obtained; the precursor mixture is poured into a polytetrafluoroethylene mold, and the reaction is kept at a constant temperature for 12 hours. Then, a white 3D network organic-inorganic hybrid all-solid electrolyte membrane was obtained; the prepared solid electrolyte membrane was dried and placed in a glove box for use.

The thickness of the 3D network organic-inorganic hybrid all-solid electrolyte prepared in this example was 115 μm, and the measured room temperature conductivity was 2.3×10 ^-6 S cm ^-1 .

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Claims (23)

1. A 3D network organic-inorganic hybrid all-solid electrolyte characterized by comprising:

   a three-dimensional network polymer electrolyte substrate as a 3D network organic-inorganic hybrid all-solid electrolyte skeleton;

   And agglomerates and lithium salts of oxide electrolyte nanoparticles or oxide electrolyte nanoparticles dispersed inside the three-dimensional network polymer electrolyte matrix;

   The three-dimensional network polymer electrolyte matrix is obtained by ring-opening polymerization of a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, and a linear polymer.
2. The all-solid electrolyte according to claim 1, wherein the linear polymer is selected from the group consisting of polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polystyrene, polyvinylidene fluoride-hexafluoropropylene. Or one or more of polyoxypropylene, polyethylene oxide, polysiloxane, polyurethane or polysulfone, wherein the linear polymer has a number average molecular weight ranging from 100,000 to 4,000,000.
3. The all-solid electrolyte according to claim 1, wherein the lithium salt is selected from the group consisting of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, and trifluoromethyl. One or more of lithium sulfonate, lithium bisfluorosulfonimide and lithium difluorooxalate borate.
4. The all-solid electrolyte according to claim 1, wherein a molar ratio of said lithium salt to said linear polymer is 1: (4 to 50).
5. The all-solid electrolyte according to claim 1, wherein the reactive monomer having an epoxy group is one or more selected from the group consisting of glycidyl ether compounds.
6. The all-solid electrolyte according to claim 5, wherein the glycidyl ether compound is selected from the group consisting of 3-glycidoxypropyltriethoxysilane, polyethylene glycol diglycidyl ether, and poly( One or more of propylene glycol) diglycidyl ether, neopentyl glycol diglycidyl ether, and poly(dimethylsiloxane) diglycidyl ether.
7. The all-solid electrolyte according to claim 1, wherein the number average molecular weight of the reactive monomer having an epoxy group is from 300 to 20,000 Da.
8. The all-solid electrolyte according to claim 1, wherein the number average molecular weight of the reactive monomer having an epoxy group is from 500 to 10,000 Da.
9. The all-solid electrolyte according to claim 1, wherein the glycidyl ether type epoxy resin and the derivative thereof have a number average molecular weight of 400 to 20,000 Da and an epoxy value of 160 to 290.
10. The all-solid electrolyte according to claim 1, wherein the glycidyl ether type epoxy resin and derivatives thereof are one or more of E44, E51, E52, E54, E55 and E56D.
11. The all-solid electrolyte according to claim 1, wherein the crosslinking agent is a compound containing at least one amine group.
12. The all-solid electrolyte according to claim 11, wherein the crosslinking agent is selected from the group consisting of compounds containing at least one amine group selected from the group consisting of alkanes and derivatives thereof, polyolefins and derivatives thereof, and polycyclic rings. Oxylkane and its derivatives or cellulose and its derivatives.
13. The all-solid electrolyte according to claim 12, wherein the derivative of the alkane is selected from the group consisting of a halogenated product of an alkane, and the derivative of the polyolefin is selected from the group consisting of a halogenated product of a polyolefin, and a polyalkylene oxide. The derivative is selected from the group consisting of halogenated products of polyalkylene oxides selected from the group consisting of polyethylene oxide or polypropylene oxide.
14. The all-solid electrolyte according to claim 11, wherein the crosslinking agent is one or more selected from the group consisting of polyethyleneimine, polypropyleneimine, and polyetheramine.
15. The all-solid electrolyte according to claim 11, wherein the crosslinking agent has a number average molecular weight of from 230 to 10,000 Da.
16. The all-solid electrolyte according to claim 1, wherein the mass ratio of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin and the derivative thereof, and the crosslinking agent is (1 to 3). ): (1 to 3): (4 to 8).
17. The all-solid electrolyte according to claim 1, wherein the oxide electrolyte nanoparticles are selected from the group consisting of Li ₁₄ Zn(GeO ₄ ) ₄ , LiZr ₂ Si ₂ PO ₁₂ , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , one or more of Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ , Li ₇ La ₃ Zr ₂ O ₁₂ and Li _6.75 La ₃ Zr _1.75 Ta _0.25 O ₁₂ having a particle diameter of 50 nm to 900 nm, said oxidation The agglomerates of the electrolyte nanoparticles have a particle diameter of from 1 μm to 5 μm.
18. The all-solid electrolyte according to claim 1, wherein the oxide electrolyte nanoparticles comprise a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, and a crosslinking agent. And the weight percentage is 20% by weight to 50% by weight, and the linear polymer accounts for 5wt% of the sum of the mass of the reactive monomer having an epoxy group, the glycidyl ether type epoxy resin, and the derivative thereof and the crosslinking agent. % ~ 30wt%.
19. The all-solid electrolyte according to claim 1, wherein the all-solid electrolyte has a thickness of 20 to 200 μm.
20. A method for preparing an all-solid electrolyte according to any one of claims 1 to 19, comprising the steps of:

    A) mixing a linear polymer, a lithium salt, and a solvent to obtain a mixed solution;

    B) mixing a reactive monomer having an epoxy group, a glycidyl ether type epoxy resin and a derivative thereof, a crosslinking agent, an oxide electrolyte nanoparticle, and a solvent to obtain a mixed dispersion;

    C) mixing and stirring the mixed solution and the mixed dispersion to obtain a reaction precursor solution;

    D) injecting the reaction precursor solution into a mold or coating the surface of the substrate, heating to carry out a reaction, and drying to obtain a 3D network organic-inorganic hybrid all-solid electrolyte;

    Steps A) and B) have no order restrictions.
21. The preparation method according to claim 20, wherein the solvent in the step A) is independently selected from the solvent described in the step B): acetone, cyclohexane, toluene, chloroform, N, N-di Methylformamide, acetonitrile, tetrahydrofuran, N,N-dimethylacetamide or N-methylpyrrolidone.
22. The preparation method according to claim 20, wherein in the step D), the temperature at which the reaction is carried out is 60 to 120 ° C for a period of 12 to 36 hours.
23. A lithium secondary battery comprising the 3D network organic-inorganic hybrid solid state electrolyte according to any one of claims 1 to 19 or the preparation method according to any one of claims 20 to 22. 3D network organic-inorganic hybrid all solid electrolyte.

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