CN117525575A

CN117525575A - Solid electrolyte and preparation method and application thereof

Info

Publication number: CN117525575A
Application number: CN202410022304.1A
Authority: CN
Inventors: 廖友好; 田震; 李伟善; 朱霨亚
Original assignee: Chaozhou Three Circle Group Co Ltd
Current assignee: Chaozhou Three Circle Group Co Ltd
Priority date: 2024-01-08
Filing date: 2024-01-08
Publication date: 2024-02-06
Anticipated expiration: 2044-01-08
Also published as: CN117525575B

Abstract

The invention relates to the technical field of solid-state batteries, and discloses a solid-state electrolyte, a preparation method and application thereof. A solid state electrolyte comprising the following components: polymer monomer, lithium salt, cross-linking agent, ceramic particles and photoinitiator; the polymer monomer includes a carbonate group-containing monomer, a trifluoromethyl group-containing monomer, and a succinic anhydride group-containing monomer. The polymer/inorganic ceramic composite solid electrolyte provided by the invention has high ionic conductivity, decomposition voltage and mechanical properties; the solid electrolyte is directly generated on the surface of the electrode material through photoinitiated polymerization reaction, so that the contact real area between the solid electrolyte and the electrode is ensured to be larger and more uniform, the ion transmission efficiency between the electrolyte and the electrode is improved, and the interface performance is improved; the solid electrolyte provided by the invention is applied to the preparation of lithium metal batteries, and can enhance the cyclical stability and safety of the lithium metal batteries.

Description

Solid electrolyte and preparation method and application thereof

Technical Field

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

Background

Secondary batteries represented by lithium ion batteries are widely applied to the fields of electronic equipment, electric automobiles, aerospace military industry, energy storage power stations and the like as an important means for storing clean energy, and the demand is still increasing year by year. Among them, lithium metal is considered as one of the most promising negative electrode materials for the next generation lithium battery due to its characteristics of high theoretical specific capacity, lowest redox potential, low mass density, and the like.

Unlike lithium ion intercalation/deintercalation reactions that occur in conventional graphite anodes, lithium metal anodes utilize deposition/exfoliation of lithium to complete charge-discharge cycles. The lithium metal has high reactivity, is easy to generate side reaction with electrolyte, consumes the electrolyte and affects the cycle stability of the battery; and the electric field on the surface of the negative electrode is uneven, so that lithium ions are unevenly deposited, dendrite growth is caused, and potential safety hazards are brought due to the fact that a diaphragm is possibly pierced. Solid state electrolytes are effective strategies to inhibit dendrite growth and improve battery safety. However, the development of solid electrolytes is hindered by the disadvantages of low conductivity, poor interfacial compatibility with electrodes, and the like. Therefore, there is a need to develop a solid electrolyte with high conductivity, good compatibility with electrode interfaces and excellent performance, and promote the development of solid electrolytes and lithium metal batteries.

Disclosure of Invention

The present invention aims to solve at least one of the above technical problems in the prior art. To this end, one of the objects of the present invention is to provide a solid electrolyte; the second object of the present invention is to provide a method for producing such a solid electrolyte; it is a third object of the present invention to provide a lithium metal battery including the solid electrolyte.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the first aspect of the invention provides a solid electrolyte comprising the following components: polymer monomer, lithium salt, cross-linking agent, ceramic particles and photoinitiator;

the polymer monomer includes a carbonate group-containing monomer, a trifluoromethyl group-containing monomer, and a succinic anhydride group-containing monomer.

The basic principle of the invention is explained as follows:

1) The invention uses polymer monomers respectively provided with carbonate groups, trifluoromethyl groups and succinic anhydride groups to prepare polymer electrolyte in the composite solid electrolyte; the carbonate group has the property of high dielectric constant, and can fully dissolve lithium salt; the trifluoromethyl group can improve electrochemical stability and improve the oxidative decomposition potential of the electrolyte; the succinic anhydride group reduces the contact angle between the precursor solution and the negative electrode plate, so that the solution is more fully wetted on the surface of lithium metal; the polymer film formed by mixing the three polymer monomers in a specific proportion has better ion conduction capacity and oxidation resistance; the solid electrolyte formed by three polymer monomers is taken as a polymer electrolyte, wherein the polymer refers to poly (ethylene carbonate-trifluoroethyl methacrylate-octenyl succinic anhydride) (PVTO).

2) The existence of the ceramic particles improves the ionic conductivity of the solid electrolyte, and simultaneously enhances the mechanical property of the solid electrolyte, so that the cycling stability of the battery is improved; when the lithium-containing ceramic particles are selected, the lithium ion transmission capacity is further enhanced, and the lithium ion conductivity of the solid electrolyte can be improved.

3) After the photoinitiator is added, the polymerization degree of the polymer formed by photoinitiation is high, and the polymer has better mechanical strength.

Preferably, in the polymer monomer, the mole percentage of the succinic anhydride group-containing monomer, the carbonate group-containing monomer and the trifluoromethyl group-containing monomer is 1 (8-14): 5-11; further preferably, in the polymer monomer, the mole percentage of the succinic anhydride group-containing monomer, the carbonate group-containing monomer and the trifluoromethyl group-containing monomer is 1 (10-12): 7-9.

Preferably, the carbonate group-containing monomer comprises ethylene carbonate (VEC).

Preferably, the succinic anhydride group-containing monomer comprises Octenyl Succinic Anhydride (OSA).

Preferably, the trifluoromethyl group-containing monomer comprises trifluoroethyl methacrylate (TFEMA).

Preferably, the mass ratio of the polymer monomer to the lithium salt to the cross-linking agent to the ceramic particles is 100 (40-60): 2-6): 6-10;

further preferably, the mass ratio of the polymer monomer to the lithium salt to the crosslinking agent to the ceramic particles is 100 (45-55): 3-5): 7-9.

Preferably, the mass ratio of the sum of the polymer monomer, the lithium salt, the cross-linking agent and the ceramic particles to the photoinitiator is (99-200) 1; further preferably, the mass ratio of the sum of the polymer monomer, the lithium salt, the crosslinking agent and the ceramic particles to the photoinitiator is (150-200): 1.

Preferably, the lithium salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethanesulfonyl) imide, lithium difluorooxalato borate; further preferably, the lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI), and the solid electrolyte has better high voltage resistance effect.

Preferably, the cross-linking agent comprises at least one of trimethylolpropane triacrylate, trimethylolpropane tetraacrylate, ethylene glycol diacrylate, and butanediol methacrylate; further preferably, the crosslinking agent is trimethylolpropane triacrylate.

Preferably, the photoinitiator comprises at least one of benzoin dimethyl ether and 2,4, 6-trimethylbenzoyl phosphorus oxide; further preferably, the photoinitiator is 2,4, 6-trimethylbenzoyl phosphorus dioxide (TPO).

Preferably, the ceramic particles comprise at least one of lithium lanthanum zirconium oxide particles, lithium calcium phosphorus particles, lithium calcium zirconium phosphorus particles, barium titanate particles, boron nitride particles, nano-alumina particles; further preferably, the ceramic particles are lithium calcium zirconium phosphorus particles (Li _1.2 Ca _0.1 Zr _1.9 (PO ₄ ) ₃ ) The lithium ion transmission capacity can be enhanced, and the lithium ion conductivity of the solid electrolyte can be improved.

Preferably, the particle size of the ceramic particles is 2-6 μm; further preferably, the particle diameter of the ceramic particles is 3 to 5 μm.

A second aspect of the present invention provides a method for preparing the solid electrolyte according to the first aspect of the present invention, comprising the steps of:

1) Mixing a polymer monomer, lithium salt, a cross-linking agent and ceramic particles to obtain a precursor;

2) And mixing the precursor with a photoinitiator, and reacting to obtain the solid electrolyte.

Preferably, the specific operation of the step 1) is as follows: mixing polymer monomers according to molar mass ratio, adding lithium salt and cross-linking agent, fully stirring and mixing, adding ceramic particles, and stirring until no precipitate exists, thus forming a precursor.

Preferably, in the step 2), the reaction is performed by photoinitiated polymerization; further preferably, the reaction is carried out by initiating the polymerization reaction with ultraviolet light.

Preferably, in the step 2), the reaction time is 20-40 min; further preferably, the reaction time is 25-35 min; still more preferably, the reaction time is 30 minutes.

A third aspect of the invention provides a lithium metal battery comprising the solid electrolyte of the first aspect of the invention.

Preferably, the positive electrode material of the battery comprises one of 622 type nickel cobalt manganese ternary material, 811 type nickel cobalt manganese ternary material and lithium cobaltate.

Preferably, the negative electrode material of the battery comprises one of metallic lithium, natural graphite and artificial graphite.

Preferably, the type of lithium metal battery includes a button cell battery.

Compared with the prior art, the invention has the beneficial effects that:

1) The polymer/inorganic ceramic composite solid electrolyte provided by the invention has high ionic conductivity and decomposition voltage and better mechanical property through the synergistic effect of the components.

2) The preparation method of the solid electrolyte provided by the invention is an in-situ photopolymerization method, and the solid electrolyte is directly generated on the surface of an electrode material through photoinitiated polymerization reaction. This approach can ensure a larger and more uniform real area of contact between the solid electrolyte and the electrode, helping to improve the ion transport efficiency between the electrolyte and the electrode, and thus improve the interfacial properties.

3) The solid electrolyte provided by the invention is applied to the preparation of lithium metal batteries, and can enhance the cyclical stability and safety of the lithium metal batteries.

Drawings

FIG. 1 is a Fourier transform infrared spectrum of a polymer solid electrolyte and each polymer monomer;

FIG. 2 is an SEM image of a solid electrolyte of example 9;

fig. 3 is an SEM image of the solid electrolyte in comparative example 5;

FIG. 4 is a graph showing the results of the cycle performance test of the batteries corresponding to example 9 and comparative example 5;

FIG. 5 is a Nyquist plot for the impedance test in examples 7-9 and comparative example 5;

FIG. 6 is a graph showing the relationship between ion conductivity and temperature in example 9 and comparative example 5;

fig. 7 is a normal temperature linear potential scanning comparison chart in examples 7 to 9 and comparative example 5.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The starting materials, reagents or apparatus used in the examples and comparative examples were either commercially available from conventional sources or may be obtained by prior art methods unless specifically indicated. Unless otherwise indicated, assays or testing methods are routine in the art.

Example 1

Example 1 the components and contents of the solid electrolyte are shown in table 1:

TABLE 1 example 1 Components and content of solid electrolyte

1) Preparation of a polymer electrolyte precursor: mixing the polymer monomer with lithium salt in a glove box, adding the cross-linking agent, fully stirring and mixing to obtain a uniform solution, adding the ceramic particles, and strongly stirring until no precipitate exists, so as to form a precursor, and storing in the glove box.

2) And (3) adding a photoinitiator into a high-purity argon glove box, uniformly mixing, dropwise adding the mixture onto the surface of the negative electrode plate, uniformly spreading, and starting ultraviolet irradiation for curing for 30min to form the solid electrolyte.

Example 2

Example 2 the components and contents of the solid electrolyte are shown in table 2, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 1.

TABLE 2 example 2 Components and content of solid electrolyte

Example 3

Example 3 the components and contents of the solid electrolyte are shown in table 3, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 1.

TABLE 3 example 3 Components and content of solid electrolyte

Example 4

Example 4 the solid electrolyte was prepared with the components and contents shown in table 4, and was different from example 1 in that the mass ratio of the photoinitiator to the precursor solution was 99:1.

TABLE 4 example 4 Components and content of solid electrolyte

Example 5

Example 5 the solid electrolyte was composed and contained in the composition shown in table 5, and was different from example 2 in that the mass ratio of the photoinitiator to the precursor solution was 99:1.

TABLE 5 example 5 Components and content of solid electrolyte

Example 6

Example 6 the solid electrolyte was prepared with the components and contents shown in table 6, and was different from example 3 in that the mass ratio of the photoinitiator to the precursor solution was 99:1.

TABLE 6 Components and content of solid electrolyte of EXAMPLE 6

Example 7

Example 7 the solid electrolyte was prepared with the components and contents shown in table 7, and was different from example 1 in that the mass ratio of the photoinitiator to the precursor solution was 99.5:0.5.

TABLE 7 Components and content of solid electrolyte of EXAMPLE 7

Example 8

Example 8 the solid electrolyte was prepared with the components and contents shown in table 8, and was different from example 2 in that the mass ratio of the photoinitiator to the precursor solution was 99.5:0.5.

TABLE 8 Components and content of solid electrolyte of EXAMPLE 8

Example 9

Example 9 the solid electrolyte was prepared with the components and contents shown in table 9, and was different from example 3 in that the mass ratio of the photoinitiator to the precursor solution was 99.5:0.5.

TABLE 9 example 9 Components and content of solid electrolyte

Example 10

Example 10 the solid electrolyte was composed of the components and the contents shown in table 10, and was different from example 9 in that the ceramic particles used were lithium lanthanum zirconium oxide particles.

TABLE 10 example 10 Components and content of solid electrolyte

Example 11

Example 11 the solid electrolyte was composed and the contents are shown in table 11, and the difference from example 9 was that the ceramic particles used were lithium zirconium oxide particles.

TABLE 11 Components and content of solid electrolyte of EXAMPLE 11

Example 12

Example 12 the solid electrolyte was composed and the contents are shown in table 12, and the difference from example 9 was that the ceramic particles used were lithium calcium phosphorus particles.

TABLE 12 Components and content of solid electrolyte of EXAMPLE 12

Example 13

Example 13 the components and contents of the solid electrolyte are shown in table 13, and the difference from example 9 is that the ceramic particles used were barium titanate particles.

TABLE 13 example 13 Components and content of solid electrolyte

Example 14

Example 14 the solid electrolyte was different from example 9 in that the ceramic particles used were boron nitride particles, as shown in table 14.

TABLE 14 Components and content of solid electrolyte of EXAMPLE 14

Example 15

Example 15 the solid electrolyte was composed and the contents are shown in table 15, and the difference from example 9 was that the ceramic particles used were nano alumina particles.

TABLE 15 example 15 Components and content of solid electrolyte

Example 16

Example 16 the solid electrolyte was prepared as shown in table 16, except that lithium hexafluorophosphate was used as the lithium salt as in example 9.

TABLE 16 example 16 Components and content of solid electrolyte

Example 17

Example 17 the solid electrolyte was prepared as shown in table 17, except that lithium tetrafluoroborate was used as the lithium salt in example 9.

TABLE 17 example 17 Components and content of solid electrolyte

Example 18

Example 18 the solid state electrolyte was prepared as shown in table 18, except that lithium salt used was lithium bis-fluorosulfonyl imide.

TABLE 18 example 18 Components and content of solid electrolyte

Example 19

Example 19 the solid electrolyte was prepared as shown in table 19, except that lithium salt used was lithium difluorooxalato borate.

TABLE 19 example 19 Components and contents of solid electrolyte

Example 20

Example 20 the solid state electrolyte was prepared with the composition and content shown in table 20, and the difference from example 9 was that the photoinitiator used was benzoin dimethyl ether.

TABLE 20 example 20 Components and content of solid electrolyte

Comparative example 1

Comparative example 1 the components and contents of the solid electrolyte are shown in table 21, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 9.

TABLE 21 comparative example 1 Components and content of solid electrolyte

Comparative example 2

Comparative example 2 the components and contents of the solid electrolyte are shown in table 22, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 9.

Table 22 comparative example 2 components and contents of solid electrolyte

Comparative example 3

Comparative example 3 the components and contents of the solid electrolyte are shown in table 23, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 9.

TABLE 23 comparative example 3 Components and content of solid electrolyte

Comparative example 4

Comparative example 4 the components and contents of the solid electrolyte are shown in table 24, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 9.

TABLE 24 comparative example 4 Components and content of solid electrolyte

Comparative example 5

Comparative example 5 the components and contents of the solid electrolyte are shown in table 25, and the amounts of the polymer monomer, the lithium salt, the crosslinking agent, and the ceramic particles added are different from those of example 9, and the ceramic particles are not added.

Table 25 comparative example 5 components and contents of solid electrolyte

1) Preparation of a polymer electrolyte precursor: mixing the polymer monomer with lithium salt in a glove box, adding the cross-linking agent, fully stirring and mixing to form a uniform solution, forming a precursor and storing in the glove box.

Comparative example 6

Comparative example 6 the components and contents of the solid electrolyte are shown in table 26, and the difference from example 9 is that the mass ratio of the photoinitiator to the precursor solution is 98:2.

TABLE 26 composition and content of solid electrolyte of comparative example 6

Performance test:

1) Infrared testing:

in a glove box, ethylene carbonate, trifluoroethyl methacrylate and octenyl succinic anhydride are mixed according to the proportion in the example 1, a photoinitiator 2,4, 6-trimethylbenzoyl diphenyl oxygen phosphorus (TPO) is added after uniform stirring, the mixture is dropwise added on the surface of a steel sheet after stirring, ultraviolet irradiation is started for curing for 30min, a solid electrolyte is formed, the solid electrolyte is ground into powder, and then infrared testing is carried out.

2) And (3) testing the cycle performance:

LiNi is added to _0.6 Co _0.2 Mn _0.2 O ₂ (NCM 622), polyvinylidene fluoride adhesive (PVDF) and conductive agent acetylene black are dissolved in a proper amount of N-methyl pyrrolidone (NMP) according to the mass ratio of 8:1:1, the slurry is uniformly coated on a current collector aluminum foil, firstly, the current collector aluminum foil is dried for 1h in an oven at 80 ℃, then, the current collector aluminum foil is transferred to 120 ℃ for vacuum drying for 12h, and a pole piece with the diameter of 12mm is prepared for standby after the three times of roller pressing. The prepared NCM622 electrode plate is taken as a positive electrode, the lithium sheet is taken as a negative electrode, a photoinitiator is added into a high-purity argon glove box, the photoinitiator is dripped onto the surface of the lithium sheet and uniformly spread, ultraviolet irradiation is started for curing for 30min, and the 2032 type button cell is assembled by using the solid electrolyte prepared in example 9 and comparative example 5. The battery is placed in a blue charge-discharge tester to be subjected to 0.1C cycle 5 within the voltage range of 3.00-4.35VAnd (3) performing 0 circles of cyclic test.

3) Impedance testing:

and (3) taking a stainless steel sheet as a positive electrode material, assembling the stainless steel sheet and different solid electrolytes into corresponding button half batteries, respectively placing the button half batteries in a PGSTAT-30Autolab multichannel electrochemical station at the temperature of 25, 35, 45, 55, 65 and 75 ℃ for impedance test, wherein the set frequency range is 105-0.1 Hz, and the voltage amplitude is 5mV.

4) Linear potential scan test:

the metal lithium is taken as a negative electrode, a stainless steel sheet is taken as a positive electrode, the metal lithium and different solid electrolytes are assembled into corresponding button-type half batteries, the button-type half batteries are placed on a Su Lijiang electrochemical tester for linear potential scanning test, the scanning potential range is set to be 3.00-6.00V, and the scanning speed is set to be 1 mV s ^-1 。

Ion conductivity calculation formula:

calculating the ionic conductivity by the formula ρ=r×s/L, where L is the electrolyte membrane thickness, measured on the synthesized electrolyte using a micrometer, about 110 μm; s is the area of electrolyte, which is 15.6 mm consistent with the area of the steel sheet for testing ² The method comprises the steps of carrying out a first treatment on the surface of the R is the impedance of the battery body and can be obtained through the intercept in an EIS spectrogram; the calculation results are shown in Table 27.

TABLE 27 ionic conductivity and decomposition Voltage of solid electrolytes

Table 26 shows the ionic conductivity and decomposition voltage of the solid electrolyte. As can be seen from Table 26, the solid electrolyte provided in the present invention in the examples has an ion conductivity as high as 2.6X10 ^-4 S·cm ^-1 Generally higher than the comparative examples. Wherein, when the mass ratio of the polymer monomer, the lithium salt, the cross-linking agent and the ceramic particles is 60:32.5:2.5:5, and the mass ratio of the solid electrolyte precursor solution to the photoinitiator is 99.5:0.5, the ion conductivity of the solid electrolyte is the highest. The data for examples 13-15 are not shown in table 27, but differ from example 9 only in the ceramic particles, the performance test results are only slightly lower than in example 9,examples 9 to 20 provide solid electrolyte having ion conductivities higher than 2.3X10 ^-4 The decomposition voltage is higher than 5.1V. The decomposition voltage of the existing fluorine-containing solid electrolyte is at the level of 4.9-5.3V, the decomposition voltage of the solid electrolyte provided by the invention can generally reach more than 5.1V, the higher the decomposition voltage of the solid electrolyte is, the more stable the solid electrolyte is under high voltage, the decomposition reaction is not easy to occur, the service life of the electrolyte in a battery is prolonged, the risk of accidents or accidents of the battery can be reduced, the safety of the battery is improved, in addition, the high decomposition voltage can provide a larger working voltage window, the battery is allowed to run under higher voltage, and the energy density and the power density of the battery are improved.

Fig. 1 is a fourier transform infrared spectrum of a polymer solid electrolyte and each polymer monomer. As can be seen from FIG. 1, there is a succinic anhydride characteristic peak (1780 cm) ^-1 ，1820cm ^-1 ) and-CF ₃ （650cm ^-1 ) At the same time c=c (1640 cm ^-1 ) The polymerization reaction is reduced, so that all the polymer monomers participate in the addition polymerization reaction, and the polymerization degree is certain, and side reactions caused by incompletely polymerized monomers in the reaction are reduced.

FIG. 2 is an SEM image of a solid electrolyte of example 9; fig. 3 is an SEM image of the solid electrolyte in comparative example 5. As can be seen from fig. 2 and 3, the surface of the solid electrolyte is smoother without the ceramic particles in comparative example 5; in example 9, after the ceramic particles of lithium calcium zirconium phosphorus were doped, the ceramic particles were uniformly distributed on the surface of the solid electrolyte.

Fig. 4 is a graph showing the results of the cycle performance test of the corresponding batteries of example 9 and comparative example 5. As can be seen from fig. 4, the capacity of the lithium metal battery according to example 9 after 50 cycles of 3.00-4.35 v is 126 mAh g ^-1 The capacity retention rate was 80%, which was higher than that of the lithium metal battery corresponding to comparative example 5 (66%), and example 9 was different from the solid electrolyte corresponding to comparative example 5 in that 10% of ceramic particles lithium calcium zirconium phosphorus particles (Li _1.2 Ca _0.1 Zr _1.9 (PO ₄ ) ₃ ) Contrast toIn example 5, no ceramic particles were added, which indicates Li _1.2 Ca _0.1 Zr _1.9 (PO ₄ ) ₃ The introduction of ceramic particles is beneficial to the diffusion of lithium ions in the solid electrolyte, so that the cycle performance of the battery is more excellent.

Fig. 5 is a nyquist plot of impedance tests in examples 7-9 and comparative example 5. As can be seen from FIG. 5, the ionic conductivities of examples 7 to 9 were 0.21 mS.cm, respectively ^-1 、0.2mS·cm ^-1 And 0.26 mS.cm ^-1 The ionic conductivity of comparative example 5 was 0.08 mS.cm ^-1 The solid electrolyte of comparative example 5, which does not contain ceramic particles, has significantly lower ionic conductivity than the solid electrolyte of examples 7 to 9, but reaches a maximum value when the mass of ceramic particles is 10% of the mass of the solid electrolyte, indicating that the ceramic particles can most effectively reduce resistance when uniformly dispersed, provide good ion transport ability inside the electrolyte, and agglomerate to affect battery performance when the mass of ceramic particles is further increased.

FIG. 6 is a graph showing the relationship between ion conductivity and temperature in example 9 and comparative example 5. As can be seen from fig. 6, when the solid electrolyte is doped with ceramic particles (example 9) and undoped ceramic particles (comparative example 5), the ion conductivities are closer to each other due to the influence of temperature, and the ion conductivities of the solid electrolyte in example 9 are higher than those of comparative example 5 after the doped ceramic particles are all reduced with the increase of temperature, which indicates that the doped ceramic particles are beneficial to the improvement of the ion conductivities of the solid electrolyte.

Fig. 7 is a normal temperature linear potential scanning comparison chart in examples 7 to 9 and comparative example 5. As can be seen from fig. 7, in comparative example 5, the decomposition voltage was the lowest, and a larger decomposition current was already present at about 4.75V, compared with examples 7 to 9, indicating that the electrolyte began to decompose. After the ceramic particles are doped, the decomposition voltage of the solid electrolyte is increased, and the service life and the safety of the battery are improved when the solid electrolyte is used for assembling the battery.

Therefore, the polymer/inorganic ceramic composite solid electrolyte provided by the invention has high ionic conductivity, decomposition voltage and mechanical property, and can enable the metal lithium battery to have better cycle performance when being applied to the assembly of the metal lithium battery, and can improve the stability, safety and efficiency of the battery.

Claims

1. A solid electrolyte characterized by comprising the following components: polymer monomer, lithium salt, cross-linking agent, ceramic particles and photoinitiator;

2. The solid electrolyte according to claim 1, wherein the molar percentage of the succinic anhydride group-containing monomer, the carbonate group-containing monomer and the trifluoromethyl group-containing monomer in the polymer monomer is 1 (8-14): 5-11.

3. A solid state electrolyte according to claim 1, wherein the carbonate group-containing monomer comprises ethylene carbonate; the succinic anhydride group-containing monomer includes octenyl succinic anhydride; the trifluoromethyl group-containing monomer comprises trifluoroethyl methacrylate.

4. The solid electrolyte according to claim 1, wherein the mass ratio of the polymer monomer, the lithium salt, the crosslinking agent and the ceramic particles is 100:40-60:2-6:6-10;

and/or the mass ratio of the sum of the polymer monomer, the lithium salt, the cross-linking agent and the ceramic particles to the photoinitiator is (99-200): 1.

5. The solid state electrolyte of claim 1 wherein the lithium salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethylsulfonyl imide, lithium difluorooxalato borate.

6. The solid electrolyte of claim 1 wherein the cross-linking agent comprises at least one of trimethylolpropane triacrylate, trimethylolpropane tetraacrylate, ethylene glycol diacrylate, and butylene methacrylate.

7. A solid state electrolyte as claimed in claim 1 wherein the photoinitiator comprises at least one of benzoin dimethyl ether, 2,4, 6-trimethylbenzoyl phosphorus oxide.

8. The solid state electrolyte of claim 1 wherein the ceramic particles comprise at least one of lithium lanthanum zirconium oxide particles, lithium calcium phosphorus particles, lithium calcium zirconium phosphorus particles, barium titanate particles, boron nitride particles, nano-alumina particles.

9. The method for producing a solid electrolyte according to any one of claims 1 to 8, comprising the steps of:

10. A lithium metal battery comprising the solid electrolyte of any one of claims 1 to 8.