CN114512718B - Composite solid electrolyte, preparation method thereof and high-performance all-solid battery - Google Patents
Composite solid electrolyte, preparation method thereof and high-performance all-solid battery Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0082—Organic polymers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to the technical field of all-solid-state batteries, and discloses a composite solid-state electrolyte, a preparation method thereof and application thereof in a high-performance all-solid-state battery, namely, the composite electrolyte is prepared by adopting novel inorganic filler and polymer electrolyte and is used for improving the performance of the all-solid-state battery at room temperature. The novel lithium alloy filler adopted by the invention has the characteristics of lithium ion conduction, electrochemical lithium supplementation, stability to lithium metal, cheap raw materials, simplicity in preparation and the like, and the prepared composite solid electrolyte has excellent electrochemical performance at room temperature and provides higher capacity and more ideal service life for all-solid batteries. The invention not only improves the performance of the all-solid-state battery at room temperature comprehensively, but also reduces the preparation cost of the composite solid-state electrolyte, and has important significance for the industrialized popularization of the all-solid-state battery.
Description
Technical Field
The invention relates to the technical field of all-solid-state batteries, in particular to a composite solid-state electrolyte, a preparation method thereof and a high-performance all-solid-state battery.
Background
At present, the commercialized lithium ion batteries mostly adopt liquid electrolyte as lithium ion conducting medium in the batteries, and the drawbacks of the liquid electrolyte are more obvious when people have ever-increasing safety and energy density requirements for the batteries. The main reason for this is that the liquid electrolyte still occupies a considerable part of the specific gravity in the whole cell, and the specific gravity is difficult to reduce, and the electrochemical window of the organic solvents of the commonly used commercial electrolytes limits the upper voltage limit of the cell use. Both together limit the rise in energy density of lithium ion batteries. In addition, in the use process of the battery, the side reaction between the liquid electrolyte and the pole piece can cause irreversible attenuation of the battery capacity. In addition, the organic solvent in the liquid electrolyte has the defects of easy volatilization, inflammability, explosiveness and the like, so that the battery has a large potential safety hazard in large-scale and large-capacity use.
Therefore, all-solid-state batteries using solid-state electrolytes are one of the best solutions at present, and have more development potential in realizing batteries having both high energy density and high safety. However, the overall design of all-solid batteries from solid electrolyte to battery still faces many challenges, such as serious interface problems of inorganic oxide solid electrolyte, poor processability and cracking of inorganic oxide solid electrolyte, poor stability of sulfide solid electrolyte to metallic lithium or air, low ionic conductivity at room temperature of polymer, easy shrinkage of gel electrolyte and difficulty in inhibiting lithium dendrite growth, etc. Therefore, the development of a composite solid electrolyte is the only way to integrate the advantages of various solid electrolytes, and the developed composite solid electrolyte has practical significance for application to all-solid batteries.
To prepare a composite solid electrolyte having a desired conductivity at room temperature, various inorganic fillers are added to the polymer-based solid electrolyte. For example, in the common scientific literature, al 2 O 3 、TiO 2 、ZrO 2 The composite solid electrolyte prepared by the inert filler represented by the invention can only improve the conductivity by reducing the crystallinity of the polymer electrolyte under the action of Lewis acid and alkali, and can not provide additional lithium ions for the composite solid electrolyte, so that the performance improvement of the composite solid electrolyte can not reach the practical application standard. For example, CN108155412a discloses a composite solid-state electrolyte using NASICON inorganic oxide as filler represented by LAGP, but titanium ions and germanium ions in the composite solid-state electrolyte are unstable to lithium, and are easily reduced in a metal lithium battery to introduce electron conductance, thereby reducing the ion migration number of the composite solid-state electrolyte and the charge and discharge efficiency of the solid-state battery. For example, CN109004271 discloses a composite solid electrolyte with niobium carbide nano-sheets as filler, which can obviously improve electrochemical window, ionic conductivity, mechanical strength and the like of PEO, but is mainly applied to inhibiting polysulfide penetration in lithium-sulfur batteriesThe shuttle effect does not discuss the applicability of the electrolyte to lithium ion batteries at normal temperature. In addition, the preparation process of the electrolyte is obviously high in time and energy consumption, the hydrofluoric acid etching time is 36-60 hours, the intercalation stripping treatment time is 46-54 hours, the subsequent freeze drying is long and complicated, and the whole process is difficult to realize industrialized popularization. Also, as in CN109004271, a composite solid electrolyte using garnet-type inorganic oxide as a filler represented by LLZO is disclosed, but the filler in such composite dielectric is unstable to air, is not suitable for storage in air, and cannot provide more capacity for all solid-state batteries. Further, since inorganic oxides such as LAGP, LATP, LLZO, LLTO, LLZTO contain valuable metals such as germanium, titanium, zirconium, lanthanum, tantalum, etc., and the calcination process is complicated and the energy consumption is large, the cost of composite solid electrolytes using such inorganic oxides as fillers is high. In addition, the amount of lithium ions in the above-mentioned inorganic oxide filler is small in the composite solid electrolyte, and capacity compensation cannot be performed when the capacity of the all-solid battery is reduced. Thus, there is a need for a composite solid electrolyte containing a novel filler that has a low cost, high lithium ion conductivity, and sufficiently compensates for lithium ion loss.
Disclosure of Invention
The invention aims to provide a composite solid electrolyte containing novel filler with low cost and high lithium ion conduction capability and fully compensating lithium ion loss, which can improve and improve the conductivity, mechanical property, processability and stability of the solid electrolyte and prepare an all-solid battery with excellent performance at room temperature. The defects of high cost, low energy density, poor room temperature electrical property, non-ideal multiplying power performance and the like of the all-solid-state battery in the prior art are solved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a composite solid electrolyte comprising a polymeric solid electrolyte, an electrolyte lithium salt, and a lithium alloy inorganic filler:
wherein the sum of the weights of the lithium salt and lithium alloy filler is not more than 25wt%, based on the total weight of the composite solid electrolyte.
Preferably, the polymer solid electrolyte includes any one or a blend combination of at least two of polyethylene oxide or a modified product thereof, polyvinylidene fluoride or a modified product thereof, polymethyl methacrylate or a modified product thereof, polyacrylonitrile or a modified product thereof, polyvinylpyrrolidone or a modified product thereof, chloroether rubber or a modified product thereof, polymethyl ethylene carbonate PPC or a modified product thereof, polyvinylidene fluoride-hexafluoropropylene; and
an electrolyte lithium salt including any one of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium trifluoromethane sulfonate, lithium bistrifluoromethane sulfonimide, and lithium difluorooxalato borate; the method comprises the steps of,
the lithium alloy inorganic filler comprises at least one of lithium-containing two-component alloys such as aluminum lithium alloy, magnesium lithium alloy, lithium silicon alloy, lithium indium alloy, lithium boron alloy, lithium tin alloy, lithium gallium alloy and the like, or lithium-containing three-component alloys such as aluminum magnesium lithium alloy, aluminum silicon lithium alloy and the like, or lithium-containing four-component alloys such as aluminum magnesium lithium zinc alloy, aluminum magnesium lithium copper alloy and the like.
In another aspect, the present invention provides a method for preparing the above composite solid electrolyte, comprising the steps of:
(1) Mixing polymer electrolyte and electrolyte lithium salt, dissolving in a solvent, heating and stirring until uniform viscous liquid is generated;
(2) Uniformly dispersing the prepared lithium alloy filler in a solvent to prepare slurry, mixing the slurry with the liquid obtained in the step (1), and continuously heating and stirring;
(3) Pouring the mixed slurry obtained in the step (2) on the surface of a die or a pole piece, and carrying out vacuum drying to obtain the composite solid electrolyte.
Preferably, the polymer electrolyte and lithium salt are added in the ratio of polymer monomer to li=10 to 20:1, preferably 18:1 in step (1); and
the heating temperature in the steps (1) and (2) is 40-80 ℃, preferably 55 ℃; and
the lithium alloy in the step (2) accounts for 5-25 wt%, preferably 25wt%, of the total mass of the composite solid electrolyte; and
the solvent in the step (2) is an organic inert solvent stable to metallic lithium and comprises at least one of N-methylpyrrolidone, acetonitrile, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, 1, 3-dimethyl-2-imidazolidinone, tetrahydrofuran and
the vacuum drying condition in the step (3) is-50 to-90 KPa,60 to 120 ℃, preferably-80 KPa,80 ℃ based on the relative pressure mark.
In still another aspect, the invention provides an all-solid-state battery, which contains the above composite solid-state electrolyte or the composite solid-state electrolyte prepared by the above preparation method of the composite solid-state electrolyte, and also contains a composite positive electrode and a composite negative electrode, wherein the composite electrode sheet material contains the same polymer electrolyte and lithium salt as in the composite electrolyte; based on the total weight of the composite positive electrode or negative electrode material, the components thereof comprise:
a positive electrode or negative electrode active material in an amount of 50 to 92wt.%, preferably 75 to 90wt.%;
a polymer electrolyte as a binder in an amount of 5 to 30wt.%, preferably 10 to 20wt.%;
electrolyte lithium salt with a content of 2.5-5 wt.%;
the conductive additive is present in an amount of 2.5 to 15wt.%, preferably 5 to 10wt.%.
Preferably, the positive electrode active material is at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium iron phosphate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, and lithium nickel manganate; and
the negative electrode active material is at least one of metal lithium, graphite, hard carbon, soft carbon, lithium titanate and metal oxide; and
the conductive additive is at least one of conductive carbon black, conductive graphite, carbon nanofiber, carbon nanotube and graphene; and
the electrolyte lithium salt and the polymer electrolyte serving as a binder are the same as the materials used in the composite solid electrolyte; and
the organic solvent used in the preparation of the all-solid battery is the same as the solvent used in the preparation method of the composite solid electrolyte.
Preferably, the all-solid-state battery core member includes two modes:
(1) The composite electrolyte membrane prepared in the mould is used as independent solid electrolyte, the composite anode and the composite cathode are attached to the two sides of the solid electrolyte membrane, and a battery cell is prepared by lamination or winding;
(2) In the preparation method of the composite solid electrolyte, the mixed slurry is uniformly coated on the surfaces of two sides of the positive electrode, the composite layered structure of the solid electrolyte/the composite positive electrode/the solid electrolyte is obtained after drying, and the battery cell is prepared by laminating the composite layered structure and the negative electrode.
Preferably, the positive electrode preparation method includes the steps of:
(1) Uniformly mixing all positive electrode components according to a preset proportion in the all-solid-state battery, adding the organic solvent in the preparation method of the composite solid-state electrolyte, and uniformly stirring to prepare slurry;
(2) And uniformly coating the slurry on an aluminum foil, drying, and rolling and cutting to obtain the used anode.
Preferably, the anode uses copper foil as the anode except metallic lithium, and the preparation method of the electrode plate is the same as that of the anode.
The invention also provides application of the all-solid-state battery in batteries with high energy density, high safety and excellent room temperature performance.
Compared with the prior art, the invention has the following beneficial effects:
(1) The composite solid electrolyte provided by the invention has high conductivity and flexibility, and has certain mechanical strength and can better solve the interface problem;
(2) The lithium alloy inorganic filler is easy to prepare and low in cost, and the prepared composite solid electrolyte has better cost advantage than the conventional composite electrolyte with the filler such as LAGP, LATP, LLZO, LLZTO;
(3) The composite solid electrolyte provided by the invention has stability to metal lithium, and can be more applied to lithium metal batteries than the conventional composite solid electrolyte with fillers such as LAGP, LATP and the like;
(4) The all-solid-state battery prepared by the invention has higher energy density, excellent charge and discharge efficiency at room temperature, ideal multiplying power performance and cycle performance.
(5) The composite solid electrolyte provided by the invention comprises polymer solid electrolyte, electrolyte lithium salt and lithium alloy inorganic filler as raw materials.
The polymer solid electrolyte is mainly used as a matrix of the composite solid electrolyte to prevent the positive electrode and the negative electrode from being in direct contact to short circuit, but the poor conductivity makes the polymer solid electrolyte difficult to be singly applied to all-solid batteries. Compared with the composite solid electrolyte which usually takes oxide ceramic as a filler, the lithium alloy is adopted as a novel filler, and the prepared composite solid electrolyte has obvious advantages: (1) The lithium alloy is used as a lithium ion direct conductor, and the lithium ion conductivity of the lithium alloy is far higher than that of the oxide ceramic solid electrolyte, so that the conductivity of the composite solid electrolyte can be obviously increased by adding a small amount of lithium alloy filler; (2) The lithium alloy can be regarded as a reaction product of other metals and metal lithium under low potential, so the lithium alloy is very stable to a metal lithium anode, and can be more suitable for lithium metal batteries compared with fillers such as LATP, LAGP and the like; (3) Compared with inorganic oxide fillers containing valuable metals such as germanium, titanium, zirconium, lanthanum, tantalum and the like, common lithium alloys such as lithium aluminum alloy, magnesium lithium alloy, lithium silicon alloy and the like have more cost advantages; (4) The lithium alloy filler can dissociate lithium ions, so that the concentration of lithium ions is increased to improve the rate performance when the all-solid-state battery needs high-rate charging and discharging, and partial lithium ions can be dissociated to compensate the loss of active lithium ions when the battery capacity is attenuated, so that the cycle performance is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate and do not constitute an undue definition of the invention.
FIG. 1 is a graph of electrochemical impedance contrast for two solid state electrolytes described in example 1;
FIG. 2 is a graph of electrochemical impedance contrast for the two solid state electrolytes described in example 2;
FIG. 3 is a schematic view of the composite layered structure constructed in example 4;
fig. 4 is a schematic view of the structure of an all-solid-state battery in embodiment 6;
fig. 5 is a physical view of an all-solid battery in example 6;
fig. 6 is a graph showing the ratio performance of the all-solid battery in example 6;
fig. 7 is a physical view of an all-solid battery in example 7;
fig. 8 is a graph showing the cycle performance of the all-solid battery of example 7;
Detailed Description
The technical scheme of the present invention is further described in detail below with reference to specific embodiments, but the scope of the present invention is not limited to the following description, and the claims are in the right of the specific scope of the present invention.
Example 1: preparation of composite solid electrolyte
A quantity of PEO and lidaob was added to a mixed solvent of DMF: mdac=1:1 in a ratio EO: li=18:1, PEO added in a solid to liquid ratio of 0.05g/mL, and left to dissolve and stir continuously at 55 ℃ for 12h until a homogeneous viscous liquid was obtained. And adding a certain amount of aluminum-lithium alloy powder, and continuously stirring at 55 ℃ for 12 hours after ultrasonic dispersion to obtain uniformly mixed slurry. Transferring the obtained slurry into a polytetrafluoroethylene mould, standing and cooling to room temperature, reducing the boiling points of a solvent DMF and DMAC by a vacuum heating mode, and evaporating and removing the solvent DMF and DMAC, wherein the vacuum heating process is-70 KPa,80 ℃ for 10 hours. The aluminum-lithium alloy content in the composite solid electrolyte obtained after cooling is 5wt%, and the composite solid electrolyte is cut into the required shape and area and then vacuum sealed for subsequent preparation of all-solid batteries.
As shown in fig. 1, the impedance of the composite solid state electrolyte has a lower impedance and higher conductivity than the pure PEO electrolyte.
Example 2: preparation of composite solid electrolyte
An amount of PEO and PMMA was added to the solvent DMF at a ratio of 1:1, PEO and PMMA were added at a solid to liquid ratio of 0.05g/mL, and the mixture was placed at 60℃for continuous dissolution stirring for 12h until a uniform viscous blend liquid was obtained. And adding a certain amount of lithium silicon alloy powder and lithium salt LiTFSI, and continuously stirring at 60 ℃ for 12 hours after ultrasonic dispersion to obtain uniformly mixed slurry, wherein the addition amount of the lithium salt is EO: li=10:1. The obtained slurry is still subjected to vacuum heating to obtain the composite solid electrolyte, wherein the vacuum heating process is 80KPa at 80 ℃ below zero for 6 hours.
As shown in fig. 2, the impedance of the composite solid state electrolyte has a lower impedance and higher conductivity than the pure PEO/PMMA electrolyte.
Example 3: preparation of composite anode
The positive electrode material with the active substance of lithium iron phosphate is prepared into LiFePO at room temperature 4 After preliminary dry-grinding and mixing in the ratio of PEO to SP to LiDFOB=14:3:2:1, a certain amount of mixed solvent of DMF and NMP=1:1 was added, and the mixture was placed at 55 ℃ and stirred continuously for 20 hours to form a uniform and stable slurry, wherein the solid content of the obtained slurry was 30wt%. And then uniformly scraping the obtained slurry on two sides of an aluminum foil with the thickness of 200 mu m, vacuum drying, rolling to obtain a composite positive electrode firmly bonded on the aluminum foil, cutting the obtained positive electrode according to the required area and shape, and vacuum sealing for later preparation of all-solid-state batteries.
Example 4: construction of solid electrolyte/composite anode/solid electrolyte composite layered structure
The components of the positive electrode are NCM622 ternary material 1, SP conductive carbon black 2, PEO polymer electrolyte 3 and lithium salt LiDFOB respectively, and the components are primarily dry-ground and mixed according to the proportion of 14:2:3:1, then a certain amount of mixed solvent of DMF and DMAC=1:1 is added, and the mixture is placed at 55 ℃ and continuously stirred for 24 hours to form uniform and stable slurry, wherein the solid content of the slurry is 35wt%. The resulting slurry was then knife coated uniformly at 200 μm thickness on both sides of the current collector (aluminum foil 4), dried in vacuo, and rolled to obtain a composite positive electrode 5 firmly bonded to the aluminum foil. Then the composite solid electrolyte slurry obtained in example 2 was poured uniformly on the surface of a composite positive electrode, and the surface of the positive electrode was heated in vacuum by a process of 80KPa at 80℃for 6 hours to form a composite solid electrolyte layer 8 with a thickness of 100 μm containing lithium silicon alloy particles 6 and polymer electrolyte blend 7 (PEO, PMMA blend). And finally, generating a composite solid electrolyte layer with the same thickness on the other side of the composite positive electrode in the same way, and finally obtaining the composite layered structure of the solid electrolyte/the composite positive electrode/the solid electrolyte shown in figure 3.
Example 5: preparation of composite negative electrode
After preliminary dry-grinding and mixing a negative electrode material with graphite as an active substance according to the proportion of graphite to PEO to LiDFOB=14 to 5 to 1 at room temperature, adding a certain amount of mixed solvent of DMF to THF=3 to 1, and continuously stirring at 55 ℃ for 20 hours to form uniform and stable slurry, wherein the solid content of the obtained slurry is 30wt%. And uniformly scraping the obtained slurry on two sides of a copper foil, vacuum drying, rolling to obtain a composite negative electrode firmly bonded on the copper foil, cutting the obtained negative electrode according to the required area and shape, and vacuum sealing for later preparation of all-solid-state batteries. The surface density of the negative electrode is controlled by the coating thickness of the negative electrode slurry on the surface of the copper foil, and the capacity of the negative electrode plate with the same area is 20% higher than that of the positive electrode plate.
Example 6: preparation of all-solid-state battery
An all-solid battery core member was prepared in a laminated manner of fig. 4 with the composite solid electrolyte in example 1 and the composite positive electrode in example 3 using a metallic lithium sheet as a negative electrode. And welding the aluminum tab 9 with the positive electrode 10, welding the copper nickel-plated tab 11 with the metal lithium sheet 12, and packaging the welded battery cell by using an aluminum plastic film 13. To ensure that the composite solid electrolyte is fully contacted with the anode and the cathode, the packaged battery is vacuumized and sealed after external pressure of 5Mpa is applied, and the all-solid battery in fig. 5 is obtained.
The obtained all-solid-state battery has good rate performance at room temperature based on the capacity exertion of the cathode material per unit mass. As shown in fig. 6, the obtained all-solid battery can still exert a capacity exceeding 20mAh at a 1C rate (corresponding to a specific capacity of 100mAh/g of the positive electrode).
Example 7: preparation of all-solid-state battery
As shown in fig. 3, the composite layered structure in example 4 and the composite anode in example 5 were prepared by lamination to form an all-solid battery core member. And welding the aluminum tab with an aluminum foil reserved in the composite layered structure, welding the copper-nickel-plated tab with a metal lithium sheet, and packaging the welded battery cell by using an aluminum-plastic film. To ensure that the composite solid electrolyte is fully contacted with the anode and the cathode, the packaged battery is vacuumized and sealed after external pressure of 1Mpa is applied, and the all-solid battery in fig. 7 is obtained.
The obtained all-solid-state battery has good cycle performance at room temperature based on the capacity exertion of the cathode material per unit mass. As shown in fig. 8, the capacity of the resulting all-solid battery after 100 cycles was 90% with respect to the maximum retention rate.
In the invention, PEO is polyethylene oxide, PVDF is polyvinylidene fluoride, PMMA is polymethyl methacrylate, PAN is polyacrylonitrile, PVP is polyvinylpyrrolidone, CHR is chloroether rubber, PPC is polymethyl ethylene carbonate, PVDF-HFP is polyvinylidene fluoride-hexafluoropropylene;
LiClO 4 lithium perchlorate, liPF 6 Is lithium hexafluorophosphate, liAsF 6 The lithium hexafluoroarsenate is LiBF4, liOTF, litrifluoromethane sulfonate, liTSI, liDFOB and lithium difluorooxalate borate.
Claims (16)
1. A method for preparing a composite solid electrolyte, comprising the steps of:
(1) Mixing polymer electrolyte and electrolyte lithium salt, dissolving in a solvent, heating and stirring until uniform viscous liquid is generated;
(2) Uniformly dispersing the prepared lithium alloy filler in a solvent to prepare slurry, mixing the slurry with the liquid obtained in the step (1), and continuously heating and stirring;
(3) Pouring the mixed slurry obtained in the step (2) on the surface of a die or a pole piece, and carrying out vacuum drying to obtain a composite solid electrolyte;
the sum of the weights of the lithium salt and lithium alloy filler is not higher than 25wt% based on the total weight of the composite solid electrolyte;
the solvent in the step (2) is an organic inert solvent stable to metallic lithium.
2. The method for producing a composite solid electrolyte according to claim 1, wherein the polymer solid electrolyte comprises any one or a blend combination of at least two of polyethylene oxide or a modified product thereof, polyvinylidene fluoride or a modified product thereof, polymethyl methacrylate or a modified product thereof, polyacrylonitrile or a modified product thereof, polyvinylpyrrolidone or a modified product thereof, epichlorohydrin rubber or a modified product thereof, polymethyl ethylene carbonate PPC or a modified product thereof, polyvinylidene fluoride-hexafluoropropylene; and
the electrolyte lithium salt comprises any one of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium trifluoromethane sulfonate, lithium bistrifluoromethane sulfonyl imide and lithium difluoro oxalate borate; and the lithium alloy filler comprises at least one of a lithium-containing two-component alloy such as an aluminum lithium alloy, a magnesium lithium alloy, a lithium silicon alloy, a lithium indium alloy, a lithium boron alloy, a lithium tin alloy, a lithium gallium alloy and the like, a lithium-containing three-component alloy such as an aluminum magnesium lithium alloy, an aluminum silicon lithium alloy and the like, or a lithium-containing four-component alloy such as an aluminum magnesium lithium zinc alloy, an aluminum magnesium lithium copper alloy and the like.
3. The method for producing a composite solid electrolyte according to claim 1, wherein the polymer electrolyte and the electrolyte lithium salt in step (1) are added in a ratio of polymer monomer: li=10 to 20:1; and
the heating temperature in the steps (1) and (2) is 40-80 ℃; and
the addition amount of the lithium alloy filler in the step (2) accounts for 5-25 wt% of the total mass of the composite solid electrolyte; and
the solvent in the step (2) comprises at least one of N-methylpyrrolidone, acetonitrile, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoric triamide, 1, 3-dimethyl-2-imidazolidinone, tetrahydrofuran, and
and (3) marking based on relative pressure, wherein the vacuum drying condition is-50 to-90 KPa and 60 to 120 ℃.
4. The method for producing a composite solid electrolyte according to claim 3, wherein,
the addition ratio of the polymer electrolyte to the electrolyte lithium salt in the step (1) is according to the polymer monomer to Li=18 to 1.
5. The method for producing a composite solid electrolyte according to claim 3, wherein the heating temperature in steps (1) and (2) is 55 ℃.
6. A method of producing a composite solid electrolyte according to claim 3, wherein the lithium alloy filler in step (2) is added in an amount of 25wt% based on the total mass of the composite solid electrolyte.
7. The method for producing a composite solid electrolyte according to claim 3, wherein the step (3) is based on a relative pressure mark, and the vacuum drying condition is-80 kpa,80 ℃.
8. An all-solid-state battery characterized by comprising the composite solid-state electrolyte prepared by the method for preparing a composite solid-state electrolyte according to any one of claims 2 to 7, and further comprising a composite positive electrode and a composite negative electrode, wherein the composite positive electrode and the composite negative electrode material contain the same polymer electrolyte and the electrolyte lithium salt as in the composite solid-state electrolyte; based on the total weight of the composite positive electrode or negative electrode material, the components thereof comprise:
a positive electrode or negative electrode active material in an amount of 50 to 92wt.%;
a polymer electrolyte as a binder in an amount of 5 to 30wt.%;
electrolyte lithium salt with the content of 2.5-5 wt percent;
conductive additive, its content is 2.5-15 wt%.
9. The all-solid battery according to claim 8, wherein the content of the positive electrode or negative electrode active material is 75 to 90wt.%.
10. The all-solid battery according to claim 8, wherein the polymer electrolyte as a binder is contained in an amount of 10 to 20wt.%.
11. The all-solid battery according to claim 8, wherein the conductive additive is contained in an amount of 5 to 10 wt%.
12. The all-solid battery according to claim 8, wherein the positive electrode active material is at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium iron phosphate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel manganate; and
the negative electrode active material is at least one of metal lithium, graphite, hard carbon, soft carbon, lithium titanate and metal oxide; and
the conductive additive is at least one of conductive carbon black, conductive graphite, carbon nanofiber, carbon nanotube and graphene.
13. The all-solid battery according to any one of claims 8 to 12, wherein the all-solid battery core member includes two modes:
(1) Attaching a composite positive electrode and a composite negative electrode to two sides of a composite solid electrolyte, and preparing a battery cell by lamination or winding;
(2) Uniformly coating the mixed slurry on the surfaces of two sides of the positive electrode, drying to obtain a solid electrolyte/composite positive electrode/solid electrolyte composite layered structure, and preparing a battery cell with the negative electrode in a lamination manner;
wherein, the mixed slurry is:
(1) Mixing polymer electrolyte and electrolyte lithium salt according to the adding proportion of polymer monomer to Li=10-20:1, dissolving in solvent, heating and stirring until uniform viscous liquid is generated;
(2) Uniformly dispersing 5-25-wt% of lithium alloy filler accounting for the total mass of the composite solid electrolyte in a solvent to prepare slurry, mixing the slurry with the liquid obtained in the step (1), and continuously heating and stirring;
the heating temperature in the steps (1) and (2) is 40-80 ℃.
14. The all-solid battery according to claim 8, wherein the positive electrode preparation method comprises the steps of:
(1) Uniformly mixing all the components of the positive electrode, adding the organic solvent, and uniformly stirring to prepare slurry;
based on the total weight of the positive electrode, the components comprise:
a positive electrode active material in an amount of 50 to 92wt.%;
a polymer electrolyte as a binder in an amount of 5 to 30wt.%;
electrolyte lithium salt with the content of 2.5-5 wt percent;
2.5-15 wt% of conductive additive;
(2) And uniformly coating the slurry on an aluminum foil, drying, and rolling and cutting to obtain the anode.
15. The all-solid battery according to claim 14, wherein the negative electrode is made of copper foil as a negative electrode except for metallic lithium.
16. Use of an all-solid-state battery according to any one of claims 8 to 15 in a battery with high energy density, high safety, excellent room temperature performance.
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