CN115312852A

CN115312852A - Polymer solid electrolyte and preparation method and application thereof

Info

Publication number: CN115312852A
Application number: CN202210803120.XA
Authority: CN
Inventors: 韦伟锋; 刘�东; 文建豪; 文建超
Original assignee: Shenzhen Guota Intelligent Machinery Co ltd; Central South University
Current assignee: Shenzhen Guota Intelligent Machinery Co ltd; Central South University
Priority date: 2022-07-07
Filing date: 2022-07-07
Publication date: 2022-11-08

Abstract

The invention discloses a solid polymer electrolyte, a preparation method thereof and application thereof in a secondary battery, wherein the solid polymer electrolyte comprises a polymer matrix and lithium salt, wherein the molecular chain of the polymer matrix comprises 3 components: the alkene monomer containing the boron heterocycle can provide the lithium ion transmission channel, can effectively anchor anions and induce lithium ions to be uniformly deposited, and can generate a high-voltage stable monomer with strong interaction with a high-voltage positive electrode material. The functional monomers in the polymer matrix act synergistically to realize excellent anode and cathode compatibility and high voltage resistance of the electrolyte matrix, and the electrolyte matrix can be applied to automobile power batteries and flexible energy storage devices to realize excellent cycling stability and high safety of solid-state batteries under high voltage and high current density.

Description

Polymer solid electrolyte and preparation method and application thereof

Technical Field

The invention relates to the technical field of lithium secondary batteries, in particular to a polymer solid electrolyte and a preparation method and application thereof.

Background

With the ever-increasing demand for electric vehicles, grid-scale energy storage, and advanced electronics, higher energy density and safe energy storage devices are being forced. Theoretically, the energy density of the battery can be improved by 57% by increasing the capacity of the anode material by one time, the energy density can also be improved by 47% by increasing the capacity of the cathode by ten times, and the energy density of the lithium battery can be greatly improved by using the high-voltage anode material and the lithium metal cathode. However, conventional organic liquid electrolytes often have serious safety problems, and the growth of lithium dendrites and the flammability of the liquid electrolytes are major sources of safety problems of lithium metal batteries.

In order to solve the safety problem of the lithium metal battery, the use of a solid-state battery containing no liquid component has been vigorously developed, and may be classified into an inorganic solid-state electrolyte and a polymer solid-state electrolyte according to their chemical compositions. Inorganic solid electrolytes are difficult to adapt to the volume change of electrodes during the charge-discharge cycle of batteries due to their high brittleness. And the polymer solid electrolyte is hopeful to be applied to automobile power energy storage equipment and wearable equipment due to the advantages of low cost, easiness in processing, good interface performance, flexibility, bending and the like. However, the conventional preparation method and material for the polymer electrolyte often have the problems of high interface impedance, low ionic conductivity, poor electrode interface compatibility, narrow electrochemical window and the like, so that long-term cycling stability at room temperature is difficult to realize when the polymer electrolyte is matched with a high-voltage positive electrode material.

CN109546212B discloses a preparation method of a solid polymer electrolyte and a solid secondary battery thereof, which belong to the field of secondary batteries, the polymer electrolyte comprises a vinyl boron monomer, a vinyl carbonate monomer, a metal salt and a free radical initiator compound, and the metal salt is selected from one or more of alkali metal salt, calcium salt, magnesium salt, zinc salt or aluminum salt; the alkene boron monomer is an organic compound which has a structure of one of formulas 1 to 6, contains at least one vinyl group and has a molecular weight of 2000g/mol or less,

wherein R is ₁ ～R ₉ Is one or more of hydrogen atom, benzene ring, alkyl chain or alkyl chain segment containing benzene ring group, ether oxygen group, ester group, cyanogen group, boron oxygen group or silicon oxygen group or/and phosphorus oxygen group. The solid polymer electrolyte has good room temperature ion conduction capability, but the precursor solution of the polymer electrolyte has low viscosity, poor wettability to a porous support material and an electrode material and weak binding capability with an electrode interface, so that the solid electrolyte obtained by polymerization cannot effectively contact with the electrode material, and an ion transmission path is reduced. In addition, the electrochemical window of the polymer electrolyte is narrow, the polymer electrolyte is decomposed when matched with a high-voltage positive electrode material, the mechanical property is poor, the polymer electrolyte cannot adapt to the volume change of an electrode material in the charge-discharge cycle process, and the polymer electrolyte is difficult to be applied to a power battery.

Therefore, the technical problem to be solved by the technical personnel in the field is how to provide a polymer solid electrolyte with good stability, high conductivity and positive and negative electrode compatibility, and a preparation method and application thereof.

Disclosure of Invention

The invention aims to provide a high-voltage-resistant polymer solid electrolyte with positive and negative electrode compatibility, a preparation method thereof and a solid secondary battery using the polymer electrolyte. The compatibility includes chemical compatibility, electrochemical compatibility, and mechanical compatibility. The polymer solid electrolyte comprises a polymer matrix and lithium salt, wherein the molecular chain of the polymer matrix comprises 3 components: the main monomer which provides the lithium ion transmission channel and is compatible with the negative electrode, the difunctional monomer which provides the lithium ion transmission channel and can effectively anchor negative ions, and the high-voltage stable monomer with high-voltage positive electrode stability are provided. The polymer solid electrolyte membrane has high lithium ion conductivity and excellent high-voltage stability, and can realize long-term circulation stability of a high-voltage cathode material and a lithium metal cathode at room temperature.

In order to achieve the purpose, the invention adopts the following technical scheme:

a polymer solid electrolyte has a structure shown in formula I:

wherein A is an unsaturated nitrile structural unit, B is an alkene carbonate structural unit, and C is an alkene boron monomer structural unit; the mass ratio of x, y and z is (1-20) to (1-10);

R ₁ ～R ₃ each independently selected from one or more of hydrogen atoms, alkyl chains or alkyl chain segments containing benzene ring groups, ether oxygen groups, ester groups, cyanogen groups, boron oxygen groups or silicon oxygen groups or/and phosphorus oxygen groups.

Preferably, the unsaturated nitrile is any one or more of acrylonitrile, fumaric nitrile, 2-butenenitrile, allyl nitrile, propane dinitrile, ethyl ethoxymethylenecyanoacetate, crotononitrile, 3-aminocrotonitrile, cinnamonitrile, 4-cyanostyrene, tetracyanoethylene, 1-oxymalenitrile, diaminomaleonitrile, ethoxymethylenemalononitrile, 3-amino-3- (4-methylpiperazine) acrylonitrile, ethyl 2-cyano-3- (dimethylamino) acrylate, 2-cyano-3,3-bis (methylthio) acrylamide.

Another object of the present invention is to provide the above polymer solid electrolyte, comprising the steps of:

(1) Under the environment with protective atmosphere and the water content and the oxygen content of less than 0.5ppm, mixing unsaturated nitrile monomers, vinyl boron monomers, vinyl carbonate monomers, lithium salt and free radical initiator compounds to obtain precursor solution.

(2) And (2) coating the precursor solution prepared in the step (1) on the surface of a porous support material or a metal negative electrode material for a secondary battery or the surface of a positive active material in an environment with a protective atmosphere and with the water content and the oxygen content of less than 0.5ppm, and carrying out polymerization reaction in a microwave, light, heat or power-on mode to obtain the solid polymer electrolyte.

Preferably, the mass of the lithium salt is 10 to 40wt% of the sum of the mass of the unsaturated nitrile monomer, the mass of the vinyl boron monomer and the mass of the vinyl carbonate monomer.

Preferably, the lithium salt includes any one of lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethyl) sulfonyl imide, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium hexafluorophosphate, lithium perchlorate or lithium hexafluoroarsenate, or a combination of at least two thereof.

The preferable beneficial effects are as follows: the use of different lithium salt species has an effect on the stability of the cycling of high voltage materials, e.g., the use of lithium bis (oxalato) borate can effectively inhibit the corrosion of aluminum foil and electrolyte by electrode materials at high voltages

Preferably, the mass of the free radical initiator compound is 0.05 to 1wt% of the sum of the mass of the unsaturated nitrile monomer, the mass of the vinyl boron monomer and the mass of the vinyl carbonate monomer.

The preferable beneficial effects are as follows: too small amount of the initiator hardly polymerizes the electrolyte, and too large amount of the initiator causes decrease in ionic conductivity of the electrolyte.

Preferably, the radical initiator compound is any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, diethylhexyl peroxydicarbonate, sodium persulfate, ammonium persulfate, or potassium persulfate.

The preferable beneficial effects are as follows: the initiating conditions and mechanisms of different initiators are different, and the listed initiators are common initiator medicines and are low in price. For example: the initiation temperature of azodiisobutyronitrile is low, usually 60 ℃, but gas is generated in the initiation process, which can cause poor interface contact, and the initiation temperature of BPO is high, usually 80 ℃, which has high initiation efficiency and does not generate gas

Preferably, the porous support material comprises porous membranes composed of one or more of polyethylene, polypropylene, polyacrylonitrile, polyvinylidene fluoride, poly (vinylidene fluoride-hexafluoroethylene), polymethyl methacrylate, polyimide, polyetherimide, aramid and cellulose, and porous composite membranes prepared by modifying the surfaces of the polymer substrates with inorganic ceramic particles.

The preferable beneficial effects are as follows: the precursor solution of the electrolyte in the invention has better wettability to most of the porous support materials, can fully fill the porous support materials, provides more transmission channels for lithium ions, and has smaller bulk impedance and interface impedance in example 15.

It is still another object of the present invention to provide a use of the above-mentioned polymer solid electrolyte in a solid secondary battery.

Preferably, the solid-state secondary battery comprises a positive electrode, the above polymer solid-state electrolyte and a negative electrode, wherein the positive electrode and the negative electrode are both the positive electrode and the negative electrode of the existing secondary battery, for example, the positive electrode adopts a nickel-cobalt-manganese ternary active material, the negative electrode adopts a metal lithium sheet, and the solid-state electrolyte adopts the solid-state polymer electrolyte prepared by the above method. In the preparation of the solid-state battery, there are the following ways:

(1) Under the environment with protective atmosphere and water content and oxygen content less than 0.5ppm, the positive electrode, the porous support material and the negative electrode are sequentially placed in the shell, the precursor solution is injected into the inner cavity, and polymerization reaction is carried out for a certain time in a microwave, light, heat or power-on mode after packaging.

(2) The solid electrolyte polymerized in situ in the porous support material is prepared by the solid battery electrolyte method, and then the anode, the solid electrolyte and the cathode are directly assembled into the battery in the environment with protective atmosphere and the water content and the oxygen content of less than 0.5 ppm.

(3) The solid electrolyte polymerized in situ on the surface of the metal cathode of the secondary battery is prepared by adopting the solid battery electrolyte method, and then the battery is directly assembled by using the anode and the metal cathode with the formed solid electrolyte membrane under the environment with protective atmosphere and the water content and the oxygen content of less than 0.5 ppm.

(4) The solid electrolyte which can be used for in-situ polymerization on the surface of the active material of the anode of the secondary battery is prepared by adopting the solid battery electrolyte method, and then the battery is directly assembled by the metal cathode and the active material of the anode which forms the solid electrolyte membrane under the environment with protective atmosphere and the water content and the oxygen content of less than 0.5 ppm.

Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:

(1) The polymer of the invention comprises 3 components in the molecular chain: the main monomer which provides the lithium ion transmission channel and is compatible with the negative electrode, the difunctional monomer which provides the lithium ion transmission channel and can effectively anchor negative ions, and the high-voltage stable monomer with high-voltage positive electrode stability are provided.

(2) The polymer solid electrolyte membrane can be directly polymerized in situ in the pole piece pore of the traditional liquid system, so that the existing pole piece formula, homogenate method, production process and production line equipment in the industry are not changed. The method has small change on the pole piece production process of the existing lithium ion battery production enterprises, and greatly saves the production line modification cost from the production of liquid batteries to the production of solid batteries.

(3) The polymer solid electrolyte membrane has high lithium ion conductivity, excellent high-voltage stability and good electrode interface compatibility, realizes long-term circulation stability of a high-voltage anode material and a lithium metal cathode at room temperature, and can be widely applied to polymer solid secondary batteries.

(4) The precursor solution of the polymer solid electrolyte has extremely low viscosity, has excellent wettability on a porous support material and an electrode, and can greatly reduce the interface impedance of a polymer all-solid battery.

(5) The polymer solid electrolyte has good flexibility, can form strong interaction with the surface of a positive active substance, can effectively adapt to the volume change of an electrode material in the charge-discharge cycle process, and realizes effective contact between the electrode material and the electrolyte in the charge-discharge cycle process.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a graph of electrochemical ac impedance measured at 30 ℃ for a stainless steel/stainless steel symmetric cell assembled using PVNB electrolyte.

Fig. 2 is a linear sweep voltammetry test curve of electrolytes PVB and PVNB electrolyte prepared without adding unsaturated nitrile monomer.

Fig. 3 shows mechanical property measurements of a strip PVB electrolyte and a PVNB electrolyte.

Figure 4 is a test of the wettability of different substrates with PVB and PVNB electrolyte precursor solutions.

Fig. 5 is a high-resolution tem image of positive active materials in PVB and PVNB solid-state batteries after ultrasonic cleaning;

FIG. 6 is an AC impedance spectrum as described in example 11;

FIG. 7 is an AC impedance spectrum as described in example 12;

FIG. 8 is an AC impedance spectrum as described in example 13;

FIG. 9 is a graph showing constant current charge/discharge test performed at 30 ℃ and 0.5C rate for two batteries of example 14;

FIG. 10 is an electrochemical AC impedance spectrum for two solid-state batteries of example 15;

FIG. 11 is a linear sweep voltammetry test chart for two cells of example 16.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The following abbreviations correspond to the Chinese characters respectively:

VC: vinylene carbonate;

B-PEGMA: poly (ethylene glycol) methacrylate with cyclic boronic acid groups;

AN: acrylonitrile;

and (3) LiTFSI: lithium bis (trifluoromethanesulfonyl) imide;

and (3) LiBOB: lithium bis (oxalato) borate;

LiDFOB: lithium difluoro (oxalato) borate;

AIBN: azobisisobutyronitrile;

BPO: benzoyl peroxide;

LFP: lithium iron phosphate;

NCM: nickel-cobalt-manganese ternary cathode material;

NMP: n-methylpyrrolidone.

Example 1

A preparation method of a polymer solid electrolyte comprises the following steps:

(1) In a glove box protected by argon and having the water content and the oxygen content of less than 0.5ppm, mixing monomers VC and AN at a mass ratio of 7:3 to obtain a solution A, then mixing the solution A and B-PEGMA at a mass ratio of 4:1 to obtain a solution B, adding 20 mass percent of LiTFSI and 0.5 mass percent of AIBN of the solution B, and uniformly stirring to obtain a precursor solution alpha.

(2) Injecting the precursor solution alpha prepared in the step (1) into a porous cellulose membrane in a glove box with argon protection and water content and oxygen content of less than 0.5ppm, selecting two stainless steel sheets as blocking electrodes to assemble a button cell, and then placing the cell at 60 ℃ for heating for 24h to carry out in-situ polymerization. By means of electrochemistryThe stainless steel sheet symmetrical battery assembled above is subjected to impedance spectrum test at a workstation as shown in figure 1, and the lithium ion conductivity is 9.24 multiplied by 10 at 25 DEG C ^-4 Scm ^-1 。

Example 2

In a glove box protected by argon and having a water content and an oxygen content of less than 0.5ppm, the precursor solution of example 1 was alpha-injected into a polyethylene separator to assemble a stainless steel/lithium metal battery. For comparison, the solution a in step (1) in example 1 is completely VC solution, the same steps are performed to obtain precursor solution β, stainless steel/lithium metal batteries are assembled using the precursor solution β, and the above two batteries are heated at 60 ℃ for 24 hours to perform in-situ polymerization of the precursor solution, thereby obtaining solid stainless steel/lithium metal batteries. Linear sweep voltammetry tests were performed on both cells as shown in fig. 2, and the PVNB electrolyte decomposition voltage using precursor solution a was measured to be 5.1V, while the PVB electrolyte decomposition voltage using precursor solution β was measured to be 4.75V.

Example 3

The precursor solution alpha prepared in step (1) of example 1 was injected into a polyethylene separator under argon protection in a glove box having a water content and an oxygen content of less than 0.5ppm, and sealed to assemble an NCM/lithium metal battery, using NCM as the positive electrode and a metal lithium sheet as the negative electrode. For comparison, the precursor solution β of example 2 was injected into a polyethylene separator and sealed to assemble an NCM/lithium metal battery, and the above two batteries were heated at 60 ℃ for 24 hours to allow the precursor solution to undergo in-situ polymerization reaction to obtain a solid NCM/lithium metal battery. The constant current charge-discharge test is carried out on the two batteries at 30 ℃ and 0.5C multiplying power, the test voltage interval is 2.8-4.3V, the initial discharge specific capacity of the PVNB electrolyte NCM/lithium metal battery using the precursor solution alpha is 162.3mAh/g, after 100 cycles of circulation, the discharge specific capacity is 79mAh/g, the initial discharge specific capacity of the PVB electrolyte NCM/lithium metal battery using the precursor solution beta is 170.8mAh/g, and after 100 cycles of circulation, the discharge specific capacity is 2mAh/g.

Example 4

LFP is used as a positive electrode, a metal lithium sheet is used as a negative electrode, and in a glove box which is protected by argon and has the water content and the oxygen content of less than 0.5ppm, the precursor solution alpha prepared in the step (1) in the example 1 is injected into a polyethylene diaphragm to be sealed and assembled into the LFP/lithium metal battery. For comparison, the precursor solution β of example 2 was injected into a polyethylene separator and sealed to assemble an LFP/lithium metal battery, and the two batteries were heated at 60 ℃ for 24 hours to polymerize the precursor solution in situ to obtain a solid LFP/lithium metal battery. The constant current charge-discharge test is carried out on the two batteries at 30 ℃ and 5C multiplying power, the test voltage interval is 2.4-4.0V, the initial discharge specific capacity of the PVNB electrolyte LFP/lithium metal battery using the precursor solution alpha is 114.8mAh/g, after 1000 cycles of circulation, the discharge specific capacity is 89.2mAh/g, the initial discharge specific capacity of the PVB electrolyte LFP/lithium metal battery using the precursor solution beta is 113.8mAh/g, and after 1000 cycles of circulation, the discharge specific capacity is 35.2mAh/g.

Example 5

The precursor solution alpha prepared in the step (1) in the example 1 and the precursor solution beta in the example 2 are injected into a polytetrafluoroethylene flat plate, the flat plate is sealed and then is heated at 60 ℃ for 24h to polymerize the precursor solution, and strip-shaped polymer solid electrolytes PVNB and PVB are obtained, wherein the mechanical performance pictures of the two electrolytes are shown in figure 3, and an object with the mass of about 15g is placed at the tail end of the electrolyte, so that the PVNB electrolyte has more excellent flexibility and can effectively adapt to the volume change of an electrode material in the charge-discharge cycle process.

Example 6

The precursor solution α obtained in the step (1) of example 1 and the precursor solution β obtained in example 2 were dropped on a 16 μm polyethylene separator, a 9 μm polyethylene separator, and a compacted density of 3.3gcm, respectively ^-3 The contact angle test is carried out on the NCM electrode sheet of (1), as shown in fig. 4, among the three substrates, the precursor solution α exhibits more excellent wettability, and effective contact between the polymer electrolyte matrix and the electrode material can be realized.

Example 7

The solid-state NCM/lithium metal battery obtained in example 3 was disassembled to obtain an NCM electrode piece, which was immersed in NMP and washed with ultrasonic waves to obtain dispersed NCM particles, and the NCM particles were observed with a high-resolution transmission electron microscope, as shown in fig. 5, it was found that there was no organic matter on the surface of the NCM particles of PVB electrolyte, but a layer of electrolyte was still wrapped in the PVNB electrolyte, indicating that the PVNB electrolyte can form a strong bond with the NCM particles.

Example 8

A metal lithium sheet is selected as an electrode, in a glove box which is protected by argon and has the water content and the oxygen content of less than 0.5ppm, the precursor solution alpha prepared in the step (1) in the embodiment 1 is injected into a polyethylene diaphragm to be sealed and assembled into a lithium metal symmetrical battery, and the lithium metal symmetrical battery is placed at 60 ℃ and heated for 24 hours to enable the precursor to be subjected to in-situ polymerization reaction to form the solid electrolyte. And (3) performing steady-state current polarization test and impedance spectrum test before and after polarization on the lithium metal symmetrical battery by using an electrochemical workstation, and measuring that the transference number of the lithium ions is 0.58.

Example 9

In a glove box protected by argon and having the water content and the oxygen content of less than 0.5ppm, mixing a monomer VC and fumaronitrile at a mass ratio of 7:3 to obtain a solution A, then mixing the solution A and B-PEGMA at a mass ratio of 4:1 to obtain a solution B, adding 20 mass percent of LiTFSI and 0.5 mass percent of AIBN of the solution B, uniformly stirring to obtain a precursor solution, injecting the precursor solution into a polyethylene diaphragm, and assembling the stainless steel/lithium metal battery. And heating the battery at 60 ℃ for 24h to perform in-situ polymerization reaction on the precursor solution to obtain the solid stainless steel/lithium metal battery. The two cells were subjected to a linear sweep voltammetry test with an electrolyte decomposition voltage of 5.4V.

Example 10

In a glove box protected by argon and having the water content and the oxygen content of less than 0.5ppm, mixing monomers VC and 2-butenenitrile in a mass ratio of 6:4 to obtain solution A, then mixing the solution A and B-PEGMA in a mass ratio of 4:1 to obtain solution B, then adding LiTFSI accounting for 20% of the mass of the solution B and AIBN accounting for 0.5% of the mass of the solution B, uniformly stirring to obtain a precursor solution, injecting the precursor solution into a polyethylene diaphragm, and assembling the stainless steel/lithium metal battery. And heating the battery at 60 ℃ for 24h to perform in-situ polymerization reaction on the precursor solution to obtain the solid stainless steel/lithium metal battery. The two cells were subjected to a linear sweep voltammetry test with an electrolyte decomposition voltage of 5.2V.

Example 11

This example differs from example 1 only in that LiTFSI is replaced with LiDFOBThe amount of LiDFOB used was 10% by mass of solution B, and the other conditions and parameters were exactly the same as those in example 1. The AC impedance spectrum was obtained as shown in FIG. 6, and the ionic conductivity was found to be 6.4X 10 at room temperature (25 ℃ C.) ^-4 Scm ^-1 。

Example 12

This example is different from example 11 only in that LiTFSI was replaced with LiBOB, the amount of LiBOB used was 10% by mass of solution B, and other condition parameters were exactly the same as example 1. The obtained AC impedance spectrum is shown in FIG. 7, and the measured ionic conductivity is 7X 10 at room temperature (25 deg.C) ^-4 Scm ^-1 。

Example 13

This example differs from example 1 only in that the amounts of initiator used are 0.05%, 0.1%, 1%, 5% by mass of solution B, respectively, and the other condition parameters are exactly the same as example 1. The measured AC impedance spectrum is shown in FIG. 8, and the measured ionic conductivities at 30 ℃ are respectively 8.2 multiplied by 10 ^-4 Scm ^-1 、7.4×10 ^-4 Scm ^-1 、7.7×10 ^-4 Scm ^-1 、3.2×10 ^-4 Scm ^-1 It can be seen that when the amount of the initiator is too large, rapid polymerization of the monomer is caused to cause a decrease in ionic conductivity of the electrolyte, whereas when the amount of the initiator is small, polymerization cannot occur.

Example 14

An NCM is selected as a positive electrode, a metal lithium sheet is selected as a negative electrode, in a glove box which is protected by argon and has the water content and the oxygen content of less than 0.5ppm, an initiator in the precursor solution alpha prepared in the step (1) in the example 1 is replaced by BPO to obtain a new precursor solution, and the new precursor solution is injected into a polyethylene diaphragm to seal and assemble the NCM/lithium metal battery. And heating the battery at 85 ℃ for 4h, 6h and 8h respectively to perform in-situ polymerization reaction on the precursor solution to obtain the solid NCM/lithium metal battery. The two batteries are subjected to constant current charge-discharge test at 30 ℃ and 0.5C multiplying power, the test voltage interval is 2.8-4.3V, the test result is shown in figure 9, the initial discharge specific capacities of the NCM/lithium metal battery are respectively 127.4mAh/g, 162mAh/g and 71mAh/g, the first-circle coulomb efficiencies are respectively 72.1%, 85.3% and 71%, and the discharge specific capacity of the NCM/lithium metal battery obtained under the heating condition of 85 ℃ and 6h is 68.7mAh/g after 100-circle circulation.

Example 15

The precursor solution α prepared in step (1) of example 1 was injected into a lithium metal symmetrical battery using a polyethylene separator and a cellulose separator, the two batteries were heated at 60 ℃ for 24 hours to perform in-situ polymerization to prepare solid-state batteries, and electrochemical ac impedance spectra were measured on the two solid-state batteries, respectively, as shown in fig. 10, both of which exhibited a small bulk impedance R _b 3.16 Ω and 2.84 Ω, respectively, and excellent interface impedance of 60 Ω and 73 Ω, respectively.

Example 16

When the precursor solutions of examples 11 and 12 were used to assemble stainless steel/lithium metal batteries, and the linear sweep voltammetry tests were performed on both batteries as shown in fig. 11, it was determined that the PVNB electrolyte using LiBOB began to rise in response current around 3.9V and was then maintained below 25 μ a until no significant rise in response current occurred around 5.5V, while the PVNB electrolyte using LiBOB began to rise in response current around 4.4V and was then maintained below 5 μ a until no significant rise in response current around 5.6V occurred.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polymer solid electrolyte is characterized in that the structure is shown as formula I:

2. A polymer solid electrolyte according to claim 1, wherein the unsaturated nitrile is any one or more of acrylonitrile, fumaronitrile, 2-butenenitrile, allylnitrile, propanedinitrile, ethyloxymethylenecyanoacetate, crotononitrile, 3-aminocrotonitrile, cinnamonitrile, 4-cyanostyrene, tetracyanoethylene, 1-oxymalenitrile, diaminomaleonitrile, ethoxymethylenemalononitrile, 3-amino-3- (4-methylpiperazine) acrylonitrile, ethyl 2-cyano-3- (dimethylamino) acrylate, 2-cyano-3,3-bis (methylthio) acrylamide.

3. A method for producing a polymer solid electrolyte according to claim 1 or 2, comprising the steps of:

4. The method according to claim 3, wherein the amount of the lithium salt is 10 to 40wt% of the sum of the amounts of the unsaturated nitrile monomer, the vinyl boron monomer and the vinyl carbonate monomer.

5. The method according to claim 3, wherein the lithium salt comprises any one or a combination of at least two of lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium tetrafluoroborate, lithium dioxalate, lithium difluorooxalate, lithium hexafluorophosphate, lithium perchlorate, and lithium hexafluoroarsenate.

6. The method according to claim 3, wherein the mass of the radical initiator compound is 0.05 to 1wt% of the sum of the mass of the unsaturated nitrile monomer, the mass of the vinyl boron monomer and the mass of the vinyl carbonate monomer.

7. The method according to claim 3, wherein the radical initiator compound is one or a combination of at least two of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, diethylhexyl peroxydicarbonate, sodium persulfate, ammonium persulfate, and potassium persulfate.

8. The method according to claim 3, wherein the porous support material comprises a porous membrane made of one or more of polyethylene, polypropylene, polyacrylonitrile, polyvinylidene fluoride, poly (vinylidene fluoride-hexafluoroethylene), polymethyl methacrylate, polyimide, polyetherimide, aramid, and cellulose, and a porous composite membrane made of inorganic ceramic particles to modify the surface of the polymer matrix.

9. Use of a polymer solid electrolyte as claimed in claim 1 or 2 in a solid secondary battery.

10. Use of a polymer solid electrolyte according to claim 8 in a solid-state secondary battery, wherein the solid-state secondary battery comprises a positive electrode, the polymer solid electrolyte according to claim 1 or 2, and a negative electrode, and the positive electrode and the negative electrode are both the positive electrode and the negative electrode of the existing secondary battery.