CN114512718A - Composite solid electrolyte, preparation method thereof and high-performance all-solid-state battery - Google Patents
Composite solid electrolyte, preparation method thereof and high-performance all-solid-state battery Download PDFInfo
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Abstract
The invention relates to the technical field of all-solid batteries, and discloses a composite solid electrolyte, a preparation method thereof and application thereof in a high-performance all-solid 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 battery at room temperature. The novel lithium alloy filler adopted by the invention has the characteristics of lithium ion conduction, electrochemical lithium supplement, stability to lithium metal, cheap raw materials, simple 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-state batteries. The invention not only improves the performance of the all-solid battery at room temperature, but also reduces the preparation cost of the composite solid electrolyte, and has important significance for the industrial popularization of the all-solid battery.
Description
Technical Field
The invention relates to the technical field of all-solid batteries, in particular to a composite solid electrolyte, a preparation method thereof and a high-performance all-solid battery.
Background
Most of the currently commercialized lithium ion batteries adopt liquid electrolyte as a lithium ion conducting medium inside the battery, and as people demand the increasing safety and energy density of the battery, the disadvantages of the liquid electrolyte become more and more obvious. The reason for this is that the liquid electrolyte still occupies a considerable proportion of the specific gravity of the battery as a whole, and the specific gravity is difficult to be lowered, and the electrochemical window of the organic solvent of the conventional commercial electrolyte limits the upper limit of the voltage used in the battery. The two limit the improvement of the energy density of the lithium ion battery. In addition, during the use of the battery, the side reaction between the liquid electrolyte and the pole piece can cause the irreversible attenuation of the battery capacity. In addition, the organic solvent in the liquid electrolyte has the defects of easy volatilization, flammability, explosiveness and the like, so that the battery has larger potential safety hazard in large-scale and large-capacity use.
Therefore, an all-solid-state battery using a solid electrolyte is one of the best solutions at present, and has a potential for development in terms of realizing a battery having both high energy density and high safety. However, all-solid-state batteries still face many challenges from solid electrolyte to overall battery design, such as severe interface problems of inorganic oxide solid electrolytes, poor processability and easy fragmentation of inorganic oxide solid electrolytes, poor stability of sulfide solid electrolytes to metallic lithium or air, low ionic conductivity of polymers at room temperature, easy gelation of gel electrolytes and difficulty in inhibiting lithium dendrite growth, and the like. Therefore, the development of the 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 being applied to all-solid batteries.
In order to prepare a composite solid electrolyte having a desired conductivity at room temperature, various inorganic fillers are added to a polymer-based solid electrolyte. For example, Al is common scientific literature2O3、TiO2、ZrO2The inert filler can only improve the conductivity by only reducing the crystallinity of the polymer electrolyte through the Lewis acid-base action and can not provide additional lithium ions for the composite solid electrolyte, so that the composite solid electrolyte can not be prepared by the inert filler, and the likeThe performance improvement of the composite solid electrolyte can not reach the practical application standard. For example, CN108155412A discloses a composite solid electrolyte using an NASICON type inorganic oxide represented by LAGP as a filler, but titanium ions and germanium ions in such a composite solid electrolyte are unstable to lithium and are easily reduced in a lithium metal battery to introduce electronic conductance, thereby reducing the ion transport number of the composite solid electrolyte and the charge/discharge efficiency of the solid battery. For example, CN109004271 discloses a composite solid electrolyte with niobium carbide nanosheets as fillers, which can significantly improve the electrochemical window, ionic conductivity, mechanical strength, and the like of PEO, but is mainly applied to inhibiting the shuttling effect of polysulfides in lithium sulfur batteries, and does not discuss the applicability of the electrolyte to lithium ion batteries at normal temperature. In addition, the preparation process of the electrolyte has obviously high 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 time is long and complicated, and the whole process is difficult to realize industrialized popularization. Further, CN109004271 discloses a composite solid electrolyte containing a garnet-type inorganic oxide represented by LLZO as a filler, but the filler in such a composite electrolyte is unstable to air, is not suitable for storage in air, and cannot provide more capacity for an all-solid battery. Furthermore, inorganic oxides such as LAGP, LATP, LLZO, LLTO, and LLZTO contain valuable metals such as germanium, titanium, zirconium, lanthanum, and tantalum, and the calcination process is complicated and the energy consumption is large, so that the composite solid electrolyte using such inorganic oxides as a filler is expensive. In addition, the amount of lithium ions in the above 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 decreased. Therefore, there is a need for a composite solid electrolyte containing a novel filler that has a high lithium ion conductivity at a low cost and sufficiently compensates for lithium ion loss.
Disclosure of Invention
The invention aims to provide a composite solid electrolyte containing a novel filler which has low cost and high lithium ion conductivity and can fully compensate lithium ion loss, improve and improve the conductivity, mechanical property, processability and stability of the solid electrolyte, and prepare an all-solid-state battery with excellent performance at room temperature by using the composite solid electrolyte. The defects of high cost, low energy density, poor room-temperature electrical property, non-ideal rate performance and the like of the all-solid-state battery in the prior art are overcome.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a composite solid electrolyte, the composite solid electrolyte raw material comprising a polymer 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 greater than 25 wt%, based on the total weight of the composite solid electrolyte.
Preferably, the polymer solid electrolyte comprises any one of 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, and polyvinylidene fluoride-hexafluoropropylene; and
electrolyte lithium salt, the lithium salt includes any one of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bistrifluoromethanesulfonylimide and lithium difluorooxalato borate; and the number of the first and second groups,
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 and lithium gallium alloy, or lithium-containing three-component alloys such as aluminum-magnesium-lithium alloy and aluminum-silicon-lithium alloy, or lithium-containing four-component alloys such as aluminum-magnesium-lithium-zinc alloy and aluminum-magnesium-lithium-copper alloy.
In another aspect, the present invention provides a method for preparing the composite solid electrolyte, comprising the steps of:
(1) mixing a polymer electrolyte and electrolyte lithium salt, dissolving the mixture in a solvent, and heating and stirring the mixture 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 mold or a pole piece, and carrying out vacuum drying to obtain the composite solid electrolyte.
Preferably, the addition ratio of the polymer electrolyte to the lithium salt in the step (1) is 10-20: 1, preferably 18: 1; and
the heating temperature of the steps (1) and (2) is 40-80 ℃, preferably 55 ℃; and
the addition amount of the lithium alloy in the step (2) accounts for 5-25 wt.%, preferably 25 wt.% of the total mass of the composite solid electrolyte; and
the solvent in the step (2) is an organic inert solvent stable to the metallic lithium, and comprises at least one of N-methylpyrrolidone, acetonitrile, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, 1, 3-dimethyl-2-imidazolidinone and tetrahydrofuran, and
and (3) based on relative pressure identification, wherein the vacuum drying condition is-50 to-90 KPa, 60 to 120 ℃, preferably-80 KPa,80 ℃.
In another aspect, the invention provides an all-solid-state battery, which comprises the composite solid-state electrolyte or the composite solid-state electrolyte prepared by the preparation method of the composite solid-state electrolyte, a composite positive electrode and a composite negative electrode, wherein the composite electrode plate material contains the same polymer electrolyte and lithium salt as those in the composite electrolyte; the composite cathode or anode material comprises the following components based on the total weight of the composite cathode or anode material:
a positive or negative active material in an amount of 50 to 92 wt.%, preferably 75 to 90 wt.%;
5-30 wt.%, preferably 10-20 wt.% of polymer electrolyte as a binder;
electrolyte lithium salt, the content of which is 2.5-5 wt.%;
an electrically conductive additive in an amount of 2.5 to 15 wt.%, preferably 5 to 10 wt.%.
Preferably, the positive active material is at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium iron phosphate, lithium nickel cobalt manganese, lithium nickel cobalt aluminate and lithium nickel manganese; and
the negative 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 used as the 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 battery core member includes two modes:
(1) taking the composite electrolyte membrane prepared in the mould as an independent solid electrolyte, attaching a composite anode and a composite cathode to two sides of the solid electrolyte membrane, and preparing a battery cell in a laminating or winding way;
(2) in the preparation method of the composite solid electrolyte, the mixed slurry is uniformly coated on the surfaces of the 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 composite layered structure and the negative electrode are laminated to prepare the battery cell.
Preferably, the method for preparing the positive electrode comprises the following steps:
(1) uniformly mixing all the components of the positive electrode according to the preset proportion in the all-solid-state battery, adding the organic solvent in the preparation method of the composite solid electrolyte, and uniformly stirring to obtain slurry;
(2) and uniformly coating the slurry on an aluminum foil, drying, rolling and cutting to obtain the anode.
Preferably, the negative electrode takes copper foil as the negative electrode except the lithium metal, and the preparation method of the pole piece is the same as that of the positive electrode.
The invention also provides the 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 can better solve the interface problem while having certain mechanical strength;
(2) the lithium alloy inorganic filler is easy to prepare and low in cost, and the composite solid electrolyte prepared by the invention has better cost advantage than the conventional composite electrolytes of fillers such as LAGP, LATP, LLZO, LLZTO and the like;
(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-discharge efficiency at room temperature, ideal rate performance and cycle performance.
(5) The composite solid electrolyte provided by the invention comprises a polymer solid electrolyte, electrolyte lithium salt and a lithium alloy inorganic filler.
The polymer solid electrolyte is mainly used as a matrix of the composite solid electrolyte to prevent short circuit caused by direct contact of the positive electrode and the negative electrode, but the poor conductivity causes that the polymer solid electrolyte is difficult to be independently applied to all-solid batteries. Compared with the conventional composite solid electrolyte taking oxide ceramic as a filler, the lithium alloy is adopted as a novel filler, and the prepared composite solid electrolyte has the following obvious advantages: (1) the lithium alloy is used as a direct lithium ion conductor, and the lithium ion conduction performance of the lithium alloy is far higher than that of oxide ceramic solid electrolytes, 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 used as a reaction product of other metals and lithium metal at a low potential, so that the lithium alloy is very stable to a lithium metal negative electrode, and is more suitable for a lithium metal battery compared with a LATP (LatP, LAGP (Latp) filler 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 cost advantage; (4) the lithium alloy filler can dissociate lithium ions, so that the rate performance is improved by increasing the concentration of the lithium ions when the all-solid-state battery needs high-rate charge and discharge, and part of the lithium ions can be dissociated to make up for the loss of active lithium ions when the capacity of the battery is attenuated, thereby improving the cycle performance.
Drawings
The accompanying drawings, which form a part of the specification, are included to provide a further description of the invention and are not intended to constitute an undue description of the invention.
FIG. 1 is a graph comparing electrochemical impedance of two solid electrolytes described in example 1;
FIG. 2 is a graph comparing electrochemical impedance of two solid electrolytes described in example 2;
FIG. 3 is a schematic view of a composite layered structure constructed in example 4;
fig. 4 is a schematic view of an all-solid-state battery according to embodiment 6;
FIG. 5 is a schematic diagram of an all-solid-state battery according to example 6;
FIG. 6 is a graph comparing rate performance of the all-solid-state battery of example 6;
FIG. 7 is a schematic diagram of an all-solid-state battery according to example 7;
FIG. 8 is a graph comparing the cycle performance of the all-solid battery in example 7;
Detailed Description
The technical solution of the present invention is further described in detail below with reference to the specific embodiments, but the scope of the present invention is not limited to the following description, and the specific scope of the present invention shall be subject to the claims.
Example 1: preparation of composite solid electrolyte
Adding a certain amount of PEO and LiDFOB into a mixed solvent of DMF and MDAC (dimethyl formamide-maleic anhydride) 1:1 according to the proportion of EO to Li to be 18:1, wherein the adding amount of PEO is 0.05g/mL in solid-to-liquid ratio, and continuously dissolving and stirring for 12h at 55 ℃ until a uniform viscous liquid is obtained. Then adding a certain amount of aluminum lithium alloy powder, and continuously stirring for 12 hours at 55 ℃ after ultrasonic dispersion to obtain uniformly mixed slurry. And transferring the obtained slurry into a polytetrafluoroethylene mold, standing and cooling to room temperature, reducing the boiling points of the solvents DMF and DMAC in a vacuum heating mode, and evaporating and removing the solvents DMF and DMAC, wherein the vacuum heating process is-70 KPa,80 ℃ and 10 hours. The content of the aluminum-lithium alloy in the obtained composite solid electrolyte after cooling is 5 wt%, and the composite solid electrolyte is cut into a required shape and area and then is sealed in vacuum for later all-solid-state battery preparation.
As shown in fig. 1, the composite solid electrolyte has a lower impedance and higher conductivity than pure PEO electrolyte.
Example 2: preparation of composite solid electrolyte
Adding a certain amount of PEO and PMMA into DMF (dimethyl formamide) solvent according to the ratio of 1:1, wherein the adding amount of PEO and PMMA is 0.05g/mL according to the solid-to-liquid ratio, and continuously dissolving and stirring for 12h at the temperature of 60 ℃ until uniform viscous blending liquid is obtained. Then adding a certain amount of lithium silicon alloy powder and lithium salt LiTFSI, and continuously stirring for 12h at 60 ℃ after ultrasonic dispersion to obtain uniformly mixed slurry, wherein the addition amount of the lithium salt is EO, and Li is 10: 1. The obtained slurry is still subjected to vacuum heating to obtain the composite solid electrolyte, wherein the vacuum heating process is-80 KPa,80 ℃ and 6 hours.
As shown in fig. 2, the impedance of the composite solid electrolyte is lower than that of a pure PEO/PMMA electrolyte, and has higher conductivity.
Example 3: preparation of composite positive electrode
At room temperature, the anode material with active material being lithium iron phosphate is prepared according to LiFePO4After PEO, SP, LiDFOB and NMP in a ratio of 14:3:2:1 are mixed by primary dry grinding, a certain amount of mixed solvent of DMF and NMP in a ratio of 1:1 is added, and the mixture is kept stirred for 20 hours at 55 ℃ to form uniform and stable slurry, wherein the solid content of the obtained slurry is 30 wt%. And then uniformly blade-coating the obtained slurry on two sides of an aluminum foil in a thickness of 200 mu m, carrying out vacuum drying, then carrying out rolling to obtain a composite anode firmly bonded on the aluminum foil, cutting the obtained anode according to the required area and shape, and carrying out vacuum sealing for later all-solid-state battery preparation.
Example 4: construction of composite layered structure of solid electrolyte/composite positive electrode/solid electrolyte
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, the components are mixed in a dry grinding mode according to the proportion of 14:2:3:1, a certain amount of DMF (dimethyl formamide)/DMAC (dimethyl acetamide) mixed solvent is added, the mixture is placed at 55 ℃ and is continuously stirred for 24 hours to form uniform and stable slurry, and the solid content of the obtained slurry is 35 wt%. And then uniformly coating the obtained slurry on two sides (aluminum foil 4) of a current collector in a thickness of 200 mu m, and rolling after vacuum drying to obtain the composite anode 5 firmly bonded on the aluminum foil. Then, the composite solid electrolyte slurry obtained in the example 2 was uniformly poured on the surface of a composite positive electrode, and vacuum heating was performed at-80 KPa,80 ℃, for 6 hours, so that a composite solid electrolyte layer 8 containing lithium-silicon alloy particles 6 and a co-mixed polymer electrolyte 7 (blended by PEO and PMMA) and having a thickness of 100 μm was formed on the surface of the positive electrode. And finally, generating a composite solid electrolyte layer with the same thickness on the other side of the composite positive electrode in the same manner, and finally obtaining a composite laminated structure of solid electrolyte/composite positive electrode/solid electrolyte as shown in fig. 3.
Example 5: preparation of composite negative electrode
The negative electrode material with the active substance being graphite is primarily dry-milled and mixed according to the proportion of the graphite PEO to the LiDFOB to the ratio of 14 to 5 to 1 at room temperature, then a certain amount of mixed solvent of DMF to the THF to the ratio of 3 to 1 is added, and the mixture is continuously stirred for 20 hours at 55 ℃ to form uniform and stable slurry, wherein the solid content of the obtained slurry is 30 wt%. And then uniformly coating the obtained slurry on two sides of a copper foil, drying in vacuum, 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 then sealing in vacuum for subsequent all-solid-state battery preparation. 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 lamination manner in fig. 4, using a metallic lithium sheet as a negative electrode, together with the composite solid electrolyte in example 1 and the composite positive electrode in example 3. And welding an aluminum tab 9 with a positive electrode 10, welding a copper nickel-plated tab 11 with a metal lithium sheet 12, and packaging the welded battery cell by using an aluminum-plastic film 13. In order to ensure that the composite solid electrolyte is in full contact with the positive electrode and the negative electrode, the packaged battery is subjected to external pressure of 5Mpa and then is subjected to vacuum sealing, so that the all-solid-state battery shown in the figure 5 is obtained.
The obtained all-solid-state battery has good rate performance at room temperature based on the capacity exertion of the unit mass of the cathode material. As shown in fig. 6, the obtained all-solid battery can still exert a capacity exceeding 20mAh at a rate of 1C (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 negative electrode in example 5 were laminated to prepare an all-solid battery core member. And welding the aluminum tab with an aluminum foil reserved in the composite laminated structure, welding the copper nickel-plated tab with a metal lithium sheet, and packaging the welded battery cell by using an aluminum-plastic film. In order to ensure that the composite solid electrolyte is in full contact with the positive electrode and the negative electrode, the packaged battery is subjected to vacuum sealing after external pressure of 1Mpa is applied, and the all-solid-state battery shown in the figure 7 is obtained.
The obtained all-solid-state battery has good cycle performance at room temperature based on the capacity exertion of the unit mass of the cathode material. As shown in fig. 8, the capacity retention ratio of the obtained all-solid-state battery after 100 cycles was 90% with respect to the maximum value.
In the invention, PEO is polyoxyethylene, PVDF is polyvinylidene fluoride, PMMA is polymethyl methacrylate, PAN is polyacrylonitrile, PVP is polyvinylpyrrolidone, CHR is epichlorohydrin rubber, PPC is polymethyl ethylene carbonate, PVDF-HFP is polyvinylidene fluoride-hexafluoropropylene;
LiClO4is lithium perchlorate, LiPF6Is lithium hexafluorophosphate, LiAsF6Lithium hexafluoroarsenate, lithium tetrafluoroborate LiBF4, lithium trifluoromethanesulfonate LiOTF, lithium bistrifluoromethanesulfonylimide, and lithium difluorooxalato borate.
Claims (10)
1. A composite solid electrolyte, characterized in that the composite solid electrolyte raw material comprises a polymer 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 greater than 25 wt%, based on the total weight of the composite solid electrolyte.
2. The composite solid electrolyte of claim 1,
the polymer solid electrolyte comprises any one or a blend combination of at least two of polyethylene oxide or a modified substance thereof, polyvinylidene fluoride or a modified substance thereof, polymethyl methacrylate or a modified substance thereof, polyacrylonitrile or a modified substance thereof, polyvinylpyrrolidone or a modified substance thereof, epichlorohydrin rubber or a modified substance thereof, polymethyl ethylene carbonate (PPC) or a modified substance thereof, and polyvinylidene fluoride-hexafluoropropylene; and
electrolyte lithium salt, the lithium salt includes any one of lithium perchlorate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bistrifluoromethanesulfonylimide and lithium difluorooxalato borate; and the number of the first and second groups,
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 and lithium gallium alloy, or lithium-containing three-component alloys such as aluminum-magnesium-lithium alloy and aluminum-silicon-lithium alloy, or lithium-containing four-component alloys such as aluminum-magnesium-lithium-zinc alloy and aluminum-magnesium-lithium-copper alloy.
3. The method for producing a composite solid electrolyte according to claim 1 or 2, characterized by comprising the steps of:
(1) mixing a polymer electrolyte and electrolyte lithium salt, dissolving the mixture in a solvent, and heating and stirring the mixture 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 mold or a pole piece, and carrying out vacuum drying to obtain the composite solid electrolyte.
4. The method for producing a composite solid electrolyte according to claim 3,
adding the polymer electrolyte and the lithium salt in the step (1) according to the ratio of polymer monomer to Li being 10-20: 1, preferably 18: 1; and
the heating temperature of the steps (1) and (2) is 40-80 ℃, preferably 55 ℃; and
the addition amount of the lithium alloy in the step (2) accounts for 5-25 wt.%, preferably 25 wt.% of the total mass of the composite solid electrolyte; and
the solvent in the step (2) is an organic inert solvent stable to the metallic lithium, and comprises at least one of N-methylpyrrolidone, acetonitrile, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, 1, 3-dimethyl-2-imidazolidinone and tetrahydrofuran, and
and (3) based on relative pressure identification, wherein the vacuum drying condition is-50 to-90 KPa, 60 to 120 ℃, preferably-80 KPa,80 ℃.
5. An all-solid battery is characterized by comprising the composite solid electrolyte of claim 1 or 2 or the composite solid electrolyte prepared by the preparation method of the composite solid electrolyte of any one of claims 3 to 4, a composite positive electrode and a composite negative electrode, wherein the composite electrode plate material contains the same polymer electrolyte and lithium salt as those in the composite electrolyte; the composite cathode or anode material comprises the following components based on the total weight of the composite cathode or anode material:
a positive or negative active material in an amount of 50 to 92 wt.%, preferably 75 to 90 wt.%;
5-30 wt.%, preferably 10-20 wt.% of polymer electrolyte as a binder;
electrolyte lithium salt, the content of which is 2.5-5 wt.%;
an electrically conductive additive in an amount of 2.5 to 15 wt.%, preferably 5 to 10 wt.%.
6. The all-solid battery according to claim 5, 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 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 as a binder are the same as those used in claim 2; and
the organic solvent used in the preparation of the all-solid battery is the same as that used in claim 4.
7. The all-solid battery according to claim 5 or 6, wherein the all-solid battery core member includes two modes:
(1) taking the composite electrolyte membrane prepared in the mold of claim 3 as an independent solid electrolyte, attaching a composite anode and a composite cathode to two sides of the solid electrolyte membrane, and preparing a battery cell in a lamination or winding manner;
(2) the method of claim 3, wherein the mixed slurry is uniformly coated on the surfaces of both sides of the positive electrode, and dried to obtain a composite layered structure of solid electrolyte/composite positive electrode/solid electrolyte, and the composite layered structure and the negative electrode are laminated to prepare the battery cell.
8. The all-solid battery according to claim 5, wherein the positive electrode preparation method comprises the steps of:
(1) uniformly mixing the components of the positive electrode according to the preset proportion in the claim 5, adding the organic solvent in the claim 6, and uniformly stirring to obtain slurry;
(2) and uniformly coating the slurry on an aluminum foil, drying, rolling and cutting to obtain the anode.
9. The all-solid battery according to claim 5, wherein the negative electrode is made of copper foil except lithium metal, and the preparation method of the electrode sheet is the same as that of claim 8.
10. Use of the all-solid-state battery according to any one of claims 5 to 9 in a battery with high energy density, high safety and excellent room temperature performance.
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