Solid-state battery unit and preparation method of solid-state battery containing composite multifunctional electrolyte layer

Abstract

The invention discloses a preparation method of a solid-state battery unit and a solid-state battery containing a composite multifunctional electrolyte layer, multifunctional integration of a single-layer electrolyte is realized through a composite material system, and compared with a traditional PE / PP diaphragm system, the proportion of an inorganic material in the composite electrolyte layer is greater than 90%, and the composite electrolyte layer has excellent high-temperature resistance and can be used for preparing a solid-state battery. And the structural integrity is kept when the battery is possibly subjected to thermal runaway. The localized adding mode of the ionic liquid and the conductive salt is optimized, and high-temperature degradation is avoided; the manufacturing process is simplified, tight interface contact between the electrolyte layer and the electrode is ensured, and impedance is reduced. Compared with a traditional liquid lithium ion battery, the solid-state battery prepared by the invention has the liquid content of less than 1%, and has high safety and cycle performance. The problems that an electrolyte layer in a traditional solid-state battery is single in function (for example, only ion conduction is concerned), the interface impedance is large, the thermal stability is poor, and the mechanical strength is insufficient are mainly solved, and the comprehensive performance and safety of the battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state lithium-ion battery manufacturing, and in particular relates to a method for preparing a solid-state battery cell and a solid-state battery containing a composite multifunctional electrolyte layer. Background Art

[0002] Traditional lithium-ion batteries use flammable liquid electrolytes, which pose a risk of fire and explosion, especially in the event of thermal runaway or mechanical damage (such as needle puncture, collision and extrusion). Solid-state batteries use solid electrolytes, which have higher thermal stability and are non-flammable, greatly improving the inherent safety of the battery. This is crucial for scenarios such as electric vehicles, aerospace, and energy storage systems that have extremely high safety requirements. Solid-state batteries are regarded as a key technology in the "post-lithium-ion era" and an important tool for achieving electrification and carbon neutrality goals. Many global technology giants, car companies, and energy companies are increasing their investment to compete for dominance in solid-state battery technology, and their research and development level has become an important indicator for measuring a country's energy technology competitiveness.

[0003] Although solid-state batteries have been developed over decades, practical applications still face the following challenges:

[0004] 1. Interface problem: The physical contact between the rigid oxide electrolyte and the electrode is poor, resulting in high interface impedance and low ion migration efficiency.

[0005] 2. Thermal management defects: Local heat accumulation during the charging and discharging process can easily cause lithium dendrites, while traditional electrolytes have low thermal conductivity and heat cannot diffuse quickly.

[0006] 3. Insufficient safety: The electrolyte layer itself lacks an active fire prevention mechanism. When a short circuit occurs in the battery, the instantaneous current can reach several thousand ampere-hours and the temperature generated can reach several thousand degrees. The chain reaction cannot be blocked in the event of thermal runaway.

[0007] 4. Poor mechanical properties: Pure oxide electrolytes are brittle and prone to cracking and failure during battery cycling.

[0008] At present, although there are technical solutions that can partially solve the problem, there are still limitations:

[0009] 1. Single functional modification: For example, adding flame retardants (such as APP) only improves fire resistance but sacrifices ionic conductivity; adding flexible polymers (such as PVDF) enhances interfacial adhesion but reduces thermal stability.

[0010] 2. Direct mixing of ionic liquids: Although it improves interfacial ion conduction, it is easy to decompose at high temperatures and has poor compatibility with some solvents.

[0011] There is an urgent need for an integrated multifunctional electrolyte layer that can synergistically solve the problems of thermal management, flame retardancy and mechanical stability while ensuring high ionic conductivity (>10-3S / cm). Summary of the Invention

[0012] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a solid-state battery cell and a method for preparing a solid-state battery containing a composite multifunctional electrolyte layer, wherein the solid-state battery cell has high ionic conductivity, high flame retardancy, mechanical stability, and good thermal management performance.

[0013] To achieve the above objectives, the present invention provides a solid-state battery cell, comprising a composite negative electrode sheet, a positive electrode sheet, and a separator, wherein the separator separates the composite negative electrode sheet and the positive electrode sheet, and the composite negative electrode sheet and the positive electrode sheet are clamped at both end surfaces of the separator;

[0014] The composite negative electrode sheet comprises a negative electrode substrate, an ionic liquid layer, a negative electrode active material layer, and a composite electrolyte slurry layer. The negative electrode substrate is provided with the negative electrode active material layer, the composite electrolyte slurry layer is provided on the negative electrode active material layer, and the ionic liquid layer is provided outside the composite electrolyte slurry layer.

[0015] The positive electrode sheet comprises a positive electrode substrate and a positive electrode active coating, wherein the positive electrode active coating is arranged on the surface of the positive electrode substrate.

[0016] As a further improvement of the present invention, it also includes an insulating rubber frame, in which the positive electrode sheet is installed; the thickness of the positive electrode sheet is less than or equal to the thickness of the insulating rubber frame, and a notch is provided on the insulating rubber frame, and the positive electrode tab connected to the positive electrode sheet passes through the notch so that the end face of the positive electrode tab is not higher than the insulating rubber frame; the insulating rubber frame is provided on the composite negative electrode sheet or is sleeved on the outside of the positive electrode sheet or is fixed on the isolation film, ultimately forming a stacked structure of the composite negative electrode sheet, the isolation film, and the positive electrode sheet installed in the insulating rubber frame.

[0017] The insulating rubber frame is not a complete frame but leaves a gap at the positive electrode tab to ensure the overall flatness of the battery cell (the positive electrode tab will not be too thick to affect the subsequent hot pressing). The insulating rubber frame is prepared as a single layer, saving steps. The clever point is that the thickness of the frame glue is exactly the same as the positive electrode sheet. The positive electrode sheet is embedded in the frame glue to form a complete plane with no height difference. The positive and negative electrodes are completely flat after the interlayer is combined and can be stacked arbitrarily. Of course, setting the insulating rubber frame on the composite negative electrode sheet is the best choice because it makes the manufacturing process simpler and more convenient. After the insulating rubber frame is set on the composite negative electrode sheet, the isolation membrane is located inside the insulating rubber frame to separate the positive electrode sheet and the composite negative electrode sheet.

[0018] The negative electrode substrate is a conductive material, and copper foil can be selected; the thickness of the composite electrolyte slurry layer is 10-50μm; the positive electrode sheet includes a positive electrode substrate and a positive electrode active coating, and the positive electrode active coating is arranged on the surface of the positive electrode substrate; the positive electrode substrate is a conductive material, and aluminum foil can be selected.

[0019] As a further improvement of the present invention, a negative electrode tab is installed on the composite negative electrode sheet, a positive electrode tab is installed on the positive electrode sheet, and a notch is provided on the insulating rubber frame, and the positive electrode tab is installed in the notch.

[0020] As a further improvement of the present invention, the negative electrode collector of the negative electrode sheet extends with a negative electrode tab; the positive electrode collector of the positive electrode sheet extends with a positive electrode tab; and the connection between the positive electrode tab and the positive electrode sheet is affixed with insulating glue or insulating coating.

[0021] As a further improvement of the present invention, the positive electrode sheet, the negative electrode sheet, and the separator form a laminate structure to form a bare cell. The laminate structure is preferably a Z-type (alternating stacking directions) or symmetrical structure to optimize the ion transport path and spatial uniformity. The separator is an insulating microporous film, preferably PP or PE.

[0022] The present invention also discloses a method for preparing a solid-state battery containing a composite multifunctional electrolyte layer, comprising the following steps:

[0023] S100, preparation of negative electrode sheet:

[0024] S110, dispersing the binder in the electrolyte solvent, and after dissolving, adding 85-92 parts by mass of the electrolyte material, 0.5-4 parts by mass of the high thermal conductivity material, 0.5-4 parts by mass of the failure suppression material, and 2-7 parts by mass of the flame retardant material, and mixing them thoroughly to obtain a composite electrolyte slurry;

[0025] S120, taking out the following components according to the mass ratio and mixing them, and stirring them at high speed until they are evenly dispersed to prepare a negative electrode active material containing a negative electrode active material: 85-95 active material silicon-carbon negative electrode (gram capacity 1200 mAh / g), 2-6 conductive agent, 0.2-2 single-walled carbon nanotubes, and 2-8 binder; then adding a negative electrode solvent (water can be used) to prepare a negative electrode active material slurry; the conductive agent is a conductive material, which can be one of conductive carbon black, carbon nanotubes, graphene, or any combination thereof;

[0026] S130, uniformly coating the negative electrode active material on the surface of the negative electrode substrate and drying to obtain a negative electrode sheet; then coating the surface of the negative electrode sheet with a composite electrolyte slurry to obtain a composite negative electrode sheet having a composite electrolyte slurry layer, wherein the composite electrolyte slurry layer has a thickness of 10-50 μm;

[0027] S200, Preparation of positive electrode sheet

[0028] S210, taking out the positive electrode active material, the conductive agent, and PVDF in a mass ratio of 94-98:0.5-2:1-3, stirring and uniformly dispersing them to prepare a mixture containing the positive electrode active material; the conductive agent is a conductive material, which can be one of conductive carbon black, carbon nanotubes, graphene, or any combination thereof;

[0029] S220, dispersing the mixture prepared in S210 in a cathode solvent to prepare a cathode active material;

[0030] S230, coating the positive electrode active material prepared in S220 on the surface of the positive electrode substrate to form a positive electrode active coating, and then compacting the coating by roller pressing equipment after drying, with a compaction density of 3.2-3.6 g / cm 3 , obtaining a positive electrode sheet blank;

[0031] S240, die-cutting the obtained positive electrode sheet blank to prepare a single positive electrode sheet;

[0032] The electrolyte solvent and the cathode solvent may both be NMP (N-methylpyrrolidone), and of course, they may be replaced by one or any combination of γ-valerolactone (GVL), sulfolane derivatives, propylene carbonate (PC), etc.

[0033] S300, battery preparation

[0034] S310, lamination assembly

[0035] The ionic liquid is coated on the surface of the positive electrode sheet or the composite negative electrode sheet to form an ionic liquid layer; the coating method can be printing or spraying;

[0036] The positive electrode sheet, the negative electrode sheet, and the isolation membrane are stacked in sequence to form a laminate structure to constitute a single solid-state battery unit; the single solid-state battery unit is repeatedly stacked to a set number of layers to complete the preparation of the solid-state battery cell; the solid-state battery cell is subjected to battery formation to obtain a solid-state battery.

[0037] As a further improvement of the present invention, in S110, the binder content in the composite electrolyte slurry is 1-6 wt%, and the electrolyte material content is ≥80 wt%.

[0038] As a further improvement of the present invention, in S120, the negative electrode active material is selected from one of graphite, silicon carbon, pure silicon, lithium metal or any combination thereof.

[0039] As a further improvement of the present invention, the positive electrode active material in S210 is a lithium oxide containing nickel, cobalt, and manganese, wherein the weight percentage of nickel is greater than 80%. Positive electrode active materials include NCM811, NCM83, NCM90 (NCM9055), NCA, NCMA, etc. Of course, any one or any combination thereof may be selected.

[0040] As a further improvement of the present invention, the binder is selected from polyvinylidene fluoride (PVDF), polyvinyl fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyacrylic acid (PAA), sodium carboxymethyl cellulose (CMC), polyacrylate copolymer (SBR), polyethylene oxide (PEO), polyacrylamide (PAM), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), nitrile rubber (NBR), hydrogenated rubber (SEBS), hydrogenated nitrile rubber (HNBR), water glass (sodium silicate / potassium silicate), gelled silicate cement (Geopolymer), aluminum hydroxide (Al(OH)3) / alumina gel, aluminum phosphate (AlPO4) / polyphosphate, lithium phosphate (Li3PO4), sodium borate, lithium borate glass (such as Li2O-B2O3 system) or any combination thereof;

[0041] The electrolyte material is selected from Li 1+x Al x Ti 2-x (PO4)3(x=0-0.6,LATP),Ta-doped LLZO(Li 7- x La3Zr 2-x Ta x O 12 (x=0-0.6,LLZTO),Nb-doped LLZO(Li 7-x La3Zr 2-x Nb x O 12 (x=0-0.6,LLZNO), Ga-doped LLZO(Li 7-3x Ga x La3Zr2O 12 (x=0-0.6,LLGZO),Li 7-3x Al x La3Zr2O 12 (x=0–0.4), Li7La 3- x Sr x Zr2O 12 (x=0–0.6), Li7La 3-x Ba x Zr2O 12 (x=0–0.6), Li 7-3x Al x La3Zr 2-γ Ta γ O 12 (x,y=0–0.4), Li 7-3x Ga x La3Zr 2-γ Nb γ O12 , Li 1+x Al x Ge 2-x (PO4)3(x=0-0.6,LAGP),Li 1+x Ta2P 1-x Si x O8(x=0-1,LTPSO),Li 1+x Zr2Si x P 3-x O 12 (0≤x≤3);Li 2-x La (1+x) / 3 Nb2O6F(x=0–0.8), Li 2-x La (1+x) / 3 One or any combination of Ta2O6F (x = 0-0.8); high thermal conductivity material selected from one or any combination of silicon nitride (Si3N4), aluminum nitride (AlN), silicon carbide (SiC), aluminum oxide (Al2O3), gallium nitride (GaN), boron nitride (BN), magnesium oxide (MgO), titanium carbide (TiC);

[0042] The failure inhibition material is selected from one of sodium chloride (NaCl), sodium nitrate (NaNO3), sodium carbonate (Na2CO3), calcium chloride (CaCl2), calcium nitrate (Ca(NO3)2), calcium acetate (Ca(CH3COO)2), calcium hydroxide (Ca(OH)2), strontium nitrate (Sr(NO3)2), strontium chloride (SrCl2), copper (II) sulfate (CuSO4), copper (II) chloride (CuCl2), copper (II) nitrate (Cu(NO3)2), sodium metaaluminate (NaAlO2), ferroaluminum FeAl(SO4)2·12H2O, magnesium hydroxide (Mg(OH)2), aluminum hydroxide, barium titanate (BTO), polyethylene glycol (PEG), and borax decahydrate (Na2B4O7·10H2O), or any combination thereof;

[0043] The flame retardant material is selected from potassium aluminum sulfate, AlK(SO4)2·12H2O, silicon oxide (SiO2), melamine (C3H6N6), melamine formaldehyde resin (Melamine Formaldehyde Resin), melamine phosphate (Melamine Phosphate), melamine cyanurate (melamine cyanurate), melamine borate (Melamine Borate), aminotriammonium polyphosphate (Ammonium Polyphosphate, APP), cyanuric acid (Cyanuric Acid), hydrazone and hydrazine compounds, triphenylphosphate (Triphenylphosphate, TPP), melamine phosphate (Melamine Phosphate), melamine polyphosphate (Melamine Polyphosphate), sodium acetate trihydrate (CH3COONa·3H2O) or any combination thereof.

[0044] As a further improvement of the present invention, S300 further includes:

[0045] S320, first hot pressing

[0046] The laminated solid-state battery cells are placed in a vacuum hot press for the first hot pressing process; the hot pressing temperature is 60-80°C and the pressure is 20-40 MPa; the pressure is 20-40 MPa and the time is 5-10 minutes; the process is carried out in an inert atmosphere or vacuum conditions to prevent the material from absorbing moisture or oxidizing;

[0047] S330, tab welding

[0048] After the first hot pressing is completed, the bare battery cell is removed from the hot pressing mold and the tab welding is performed;

[0049] S340, second hot pressing

[0050] Place the battery cell back into the hot pressing equipment for a second hot pressing; hot pressing temperature: 60-90°C; pressure: 30-80 MPa; time: 3-8 minutes;

[0051] S350, aluminum-plastic package

[0052] Place the shaped battery cell into a prefabricated aluminum-plastic film shell and then perform heat sealing operation; heat sealing temperature: 130-150℃; vacuum degree: <10Pa; pressure: ≥0.2MPa; time: 3-6 seconds / side;

[0053] S360, static aging

[0054] Place the battery cells in a dry environment for aging for 12–24 hours at room temperature or a constant temperature of 30°C. Humidity requirement: RH < 1%, or under nitrogen protection.

[0055] As a further improvement of the present invention, in S120, the adhesive is prepared by mixing the following components according to a mass ratio: 2-5% of the adhesive SBR and 0.4-3% of the adhesive PAA.

[0056] As a further improvement of the present invention, in S110, the binder includes HNBR, PVDF, and PAN, and the mass ratio of the three is 7-9:0.5-2:0.5-2; the binder is dissolved in the electrolyte solvent, and the solid content is 5%-15%.

[0057] As a further improvement of the present invention, in S110, the binder is HNBR and PAN, and the mass ratio of the two is 7-9:1-4; the binder is added to the electrolyte solvent to form a solution system with a mass fraction of 10%-20%, and is fully stirred until the binder is completely dissolved.

[0058] As a further improvement of the present invention, in S110, solid electrolyte powders LLZTO, aluminum nitride, aluminum oxide, sodium aluminate, BTO, and melamine cyanurate are taken out and evenly mixed according to the following mass ratio: LLZTO = 80-90, high thermal conductivity material aluminum nitride = 0.5-2, aluminum oxide = 3-6, sodium aluminate = 0.5-2, BTO = 0.5-2, melamine cyanurate = 3-5; a composite electrolyte slurry having a viscosity of 75000-85000 mPa·s and a solid content greater than or equal to 70% is obtained.

[0059] As a further improvement of the present invention, in S110, the solid electrolyte powder Li 2-x La (1+x) / 3 Nb2O6F, aluminum nitride (AlN), aluminum oxide, sodium metaaluminate, BTO, and amino ammonium tripolyphosphate are taken out and mixed uniformly according to the following weight ratio:

[0060] Solid electrolyte powder Li 2-x La (1+x) / 3 Nb2O6F=80-92, aluminum nitride (AlN)=0.5-2, aluminum oxide=3-6, sodium metaaluminate=0.5-2, BTO=0.5-2, amino ammonium tripolyphosphate=3-5;

[0061] Finally, a composite electrolyte slurry with a viscosity of 75000-90000 cP and a solid content of 80% was obtained.

[0062] As a further improvement of the present invention, in S120, the negative electrode active material uses deionized water as the negative electrode solvent, the solid content of the slurry is 42%-48%, and the slurry viscosity is controlled at 3000-5000 mPa·s.

[0063] As a further improvement of the present invention, in S130, the negative electrode active material is evenly coated on the surface of the negative electrode substrate by double-sided coating. After coating, it is pre-dried at 80-120°C for 10-30 minutes, and then thoroughly dried at 120-160°C under a vacuum environment for 4-12 hours to remove residual moisture. After drying, it is roller-pressed, and the negative electrode compaction density is 1.4-1.7 g / cm 3 , and obtain a composite negative electrode sheet.

[0064] As a further improvement of the present invention, in S310, the lithium salt is first dissolved in the ionic liquid, and the lithium salt concentration is 1-2 mol / L; the ionic liquid is selected from 1-ethyl-3-methylimidazolium ion (EMIM + , 1-ethyl-3-methylimidazolium), 1-butyl-3-methylimidazolium ion (BMIM + , 1-butyl-3-methylimidazolium), N-methyl-N-propylpyrrolidinium (PYR 13 + ), bis(trifluoromethylsulfonyl)imide (TFSI-, bis(trifluoromethanesulfonyl)imide), EMIM-TFSI, BMIM-PF6 or any combination thereof; the lithium salt is selected from one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(cyanomethyl)sulfonylimide (LiFSI), lithium nitrate, and lithium bis(oxalatoborate) (LiBOB) or any combination thereof.

[0065] As a further improvement of the present invention, in S310, LiFSI / Pyr 13 The FSI ionic liquid is printed on the surface of the composite negative electrode sheet, and the printing amount per unit area is controlled to be 3%-6% of the mass of the composite electrolyte layer per unit area.

[0066] As a further improvement of the present invention, the drying of S230 adopts low-temperature pre-drying and high-temperature final drying, pre-drying at 80-120°C for 10 minutes, and then final drying at 120-170°C for 20 minutes, and the residual moisture is controlled to be less than 300ppm.

[0067] The beneficial effects of the present invention are:

[0068] The solid-state battery of the present invention comprises a positive electrode active material end having a positive electrode active material; a negative electrode active material end having a negative electrode active material; and a composite electrolyte system located between the positive electrode active material end and the negative electrode active material end, which allows lithium ions to move between the positive electrode active material end and the negative electrode active material end to perform an electrochemical reaction of charge and discharge. The solid-solid interface is provided with a trace amount of ionic liquid to reduce impedance.

[0069] The composite electrolyte layer of the present invention comprises a binder, an oxide electrolyte material, a high thermal conductivity material, a failure suppression material, and a flame retardant material. The binder provides adhesion, the oxide electrolyte provides ion transport, the thermal conductivity material promptly dissipates heat generated by the battery cell, the failure suppression material reacts with heat and absorbs energy from the high-energy positive and negative electrodes, and the flame retardant material further prevents the battery cell from exploding. The interconnected composite electrolyte layers effectively enhance battery safety.

[0070] The present invention realizes the multifunctional integration of a single-layer electrolyte through a composite material system (adhesive + oxide electrolyte + high thermal conductivity + failure inhibition material + flame retardant). Compared with the traditional PE / PP diaphragm system, the inorganic material in the composite electrolyte layer of the present invention accounts for more than 90%, has excellent high temperature resistance, and maintains structural integrity when the battery may experience thermal runaway. The present invention optimizes the localized addition method of ionic liquids and conductive salts to avoid high-temperature degradation; simplifies the manufacturing process, ensures close interfacial contact between the electrolyte layer and the electrode, and reduces impedance. Compared with traditional liquid lithium-ion batteries, the solid-state battery prepared by the present invention has a liquid content of less than 1%, and has both high safety and cycle performance.

[0071] This invention addresses the challenges of traditional solid-state batteries, such as the single-function electrolyte layer (e.g., focusing solely on ion conduction), high interfacial impedance, poor thermal stability, and insufficient mechanical strength. By integrating multiple functions into the electrolyte layer, which combines adhesion, thermal conductivity, flame retardancy, failure suppression, and ion conduction, the design improves the battery's overall performance and safety. This invention is particularly suitable for power batteries and energy storage applications requiring high energy density and high safety requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 This is a schematic flow chart of the preparation method of Example 1;

[0073] Figure 2 This is a photo of the composite negative electrode sheet in Example 1;

[0074] Figure 3 Schematic diagram of the structure of the negative electrode sheet, the positive electrode sheet, and a single solid-state battery unit in Example 1;

[0075] Figure 4 This is a photo of the needle penetration test of the solid-state battery in Example 1;

[0076] Figure 5 The curves of voltage and temperature variation over time in the solid-state battery acupuncture test in Example 1 are as follows;

[0077] Figure 6 This is the long cycle capacity retention curve of the solid-state battery in Example 1;

[0078] Figure 7 This is a schematic structural diagram of the negative electrode sheet, the positive electrode sheet, and a single solid-state battery unit in Example 2;

[0079] Figure 8 This is a photo of the needle penetration test of the solid-state battery in Example 2;

[0080] Figure 9 The curves of voltage and temperature variation over time in the solid-state battery acupuncture test in Example 2;

[0081] Figure 10 This is the long cycle capacity retention curve of the solid-state battery in Example 2;

[0082] 1-composite negative electrode sheet; 2-negative electrode tab; 3-insulating rubber frame; 4-notch; 5-positive electrode sheet; 6-positive electrode tab; 7-insulating rubber; 8-single solid-state battery cell. DETAILED DESCRIPTION

[0083] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0084] Example 1

[0085] See also Figure 1 The method for preparing a solid-state battery containing a composite multifunctional electrolyte layer of this embodiment comprises the following steps:

[0086] S100, preparation of negative electrode sheet:

[0087] S110, dissolve the binder HNBR, PVDF, and PAN in NMP in a weight ratio of 8:1:1, with a solid content of 10%; after the above colloid is dissolved, add the following weight ratios in sequence: 88 solid electrolyte powder Li 7-x La3Zr 2- x Ta x O 12(x=0.6, LLZTO), 1 high thermal conductivity material aluminum nitride (AlN), 5 aluminum oxide, 1 sodium aluminate (failure inhibition material powder), 1 BTO (barium titanate-based ferroelectric material), 4 MCA (flame retardant material powder, melamine cyanurate) are mixed uniformly to prepare a composite electrolyte slurry with a viscosity greater than or equal to 80000 mPa·s and a solid content greater than or equal to 70% (preferably the solid content of the composite electrolyte slurry is 78%); the stirring speed is 1000-2000 rpm when the binder is dissolved; the stirring time is 2-4 hours; the temperature is kept constant at 25-30°C during stirring to ensure the stability of the slurry; after adding the electrolyte slurry, the stirring speed is 3000-5000 rpm; the stirring time is 6-12 hours; and finally, the powder particle size distribution in the electrolyte slurry is uniform, all of which are 1-2 μm;

[0088] S120, taking out the following components according to the weight ratio and mixing them, and stirring them at high speed until they are evenly dispersed to prepare a negative electrode active material containing a negative electrode active substance:

[0089] 92% active material silicon carbon anode (gram capacity 1200mAh / g), 3% conductive agent (conductive carbon black), 0.5% single-walled carbon nanotubes, 3% binder SBR, 1.5% binder PAA; the silicon carbon particle size Dv50 is 2.5μm, using water as the solvent to prepare the negative electrode active material slurry, the solid content of the slurry is 45%;

[0090] The negative electrode active material slurry uses deionized water as the dispersion medium, with a solids content of preferably 42%-48%, more preferably 45%. This provides good rheological properties and is suitable for double-sided coating processes. To improve coating consistency, the viscosity of the negative electrode active material slurry is preferably controlled between 3000-5000 mPa·s (measured at 25°C and 50 rpm).

[0091] S130, the negative electrode active material slurry is evenly coated on both sides of the copper foil current collector by double-sided coating. The copper foil thickness is 5-8μm. After coating, it is pre-dried at 80-120℃ for 10-30 minutes, and then thoroughly dried at 120-160℃ under vacuum for 4-12 hours to remove residual moisture, finally obtaining a dense and uniform negative electrode sheet. Then, the composite electrolyte slurry is evenly coated on both sides of the negative electrode sheet by extrusion, and after drying, it is rolled to obtain a composite negative electrode sheet 1. The finished product is shown in FIG. Figure 2 The coating speed is 5-40 m / s, the drying temperature is 60-160°C, and the drying time is 30-60 min. The roller pressing pressure is 50-150 tons; more preferably, the roller pressing pressure is 120-150 tons. After roller pressing, the negative electrode compaction density of the composite negative electrode sheet is 1.4-1.7 g / cm3.

[0092] S140, 1.2 mol / L LiFSI / Pyr 13The FSI ionic liquid is printed on the surface of the composite negative electrode sheet by micro-gravure printing; the lithium salt concentration in the ionic liquid is 1-2 mol / L; during the ionic liquid printing process, the printing speed is 5-10 m / s, and the humidity is controlled at -40-60 dew point, more preferably, the ambient humidity is controlled at -50 to 60 dew point;

[0093] S150. Use a screen printer to print an insulating rubber frame 3 with a width of 1-5 mm (preferably 3 mm) around the composite negative electrode sheet. The silicone can be selected from room temperature vulcanized elastic silicone rubber (RTV), thermal conductive silicone, three-proof coated silicone, etc. In theory, as long as the positive electrode sheet can be installed and insulated, there are no special requirements for the material. Preferably, it is room temperature vulcanized elastic silicone rubber, which has good adhesion, flexibility and high temperature resistance. The insulating rubber frame 3 uses a 40-120 mesh screen and is formed by one or more superpositions in an intermittent printing mode. Its positioning accuracy is controlled within the range of ±0.2mm to ensure the sealing effect and electrolyte retention performance during the subsequent stacking or lamination process. The thickness of the insulating rubber frame 3 is consistent with the thickness of the positive electrode sheet. Specifically, the insulating rubber frame 3 is single-sided and has a notch 4. The width of the notch 4 is the same as the width of the positive electrode ear.

[0094] The insulating rubber frame 3 is provided with a notch 4, preferably located at a position corresponding to the positive electrode tab. The width of the notch is preferably consistent with the width of the positive electrode tab, so as to facilitate smooth extraction of the positive electrode tab after the battery cell is stacked and prevent the insulating rubber frame 3 from interfering with the conductive path. More preferably, the length of the notch is slightly larger than the width of the positive electrode tab, by 0.01-0.05 mm, to facilitate tolerance control and positioning consistency.

[0095] The edge of the notch 4 can be an arc transition structure to prevent stress concentration; the corners of the insulating rubber frame 3 can be designed to be rounded R = 0.5 ~ 1mm to prevent tearing.

[0096] S160. A composite negative electrode sheet 1 with an insulating rubber frame 3 attached to one side is prepared by laser die-cutting a composite negative electrode sheet; the composite negative electrode sheet 1 with a single-sided rubber frame structure is cut by a laser die-cutting process, and the laser die-cutting parameters are preferably: power 1030W, cutting speed 300-1000mm / s, and cutting accuracy is controlled within ±0.1mm to ensure that the edge of the electrode sheet is flat and the size is consistent, without affecting the lamination positioning. An automatic positioning system is set during the laser cutting process to prevent the rubber frame from being misplaced or burned. A bottom film protection method is used to prevent laser ablation of the electrode surface; simultaneous laser marking can be performed for QR code identification to improve traceability management;

[0097] S170, see Figure 3 , a negative electrode tab 2 is installed on the composite negative electrode sheet 1 to complete the preparation of the negative electrode sheet, wherein the negative electrode tab 2 is located at the center position of one side of the electrode sheet 1; further, as Figure 3As shown, the negative electrode tab 2 is arranged at the center position of a single side edge of the composite negative electrode sheet 1, that is, within the range of ±1mm of the midpoint of the corresponding side length, so as to facilitate the uniform arrangement of the tabs in the battery cell module and improve the consistency of subsequent welding or lead-out.

[0098] S200, Preparation of positive electrode sheet

[0099] S210, the ternary material NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2) as a positive electrode active material, the positive electrode active material, conductive carbon black, and PVDF are taken out according to a weight ratio of 97.5:1:1.5, and are uniformly dispersed by high-speed stirring to prepare a mixture containing the positive electrode active material, wherein the particle size Dv50 of the positive electrode active material is 4 μm; the molecular weight of PVDF is 400,000-900,000; the positive electrode active material is stirred by high-speed dispersion (preferably at a speed of 3000-6000 rpm) for 30-90 minutes to uniformly disperse the positive electrode active material, the conductive agent, and the binder;

[0100] S220, using NMP (N-methylpyrrolidone) as a solvent to prepare a positive electrode active material from the mixture prepared in S210, wherein the solid content of the positive electrode active material is 58-62%, preferably controlled at 60%, to ensure that the slurry has good fluidity and coating properties;

[0101] S230, evenly coating the positive electrode active material prepared in S220 on both sides of the aluminum foil to form a positive electrode active coating, drying, and rolling compaction to obtain a positive electrode sheet blank;

[0102] Use the "low temperature pre-drying + high temperature final drying" mode, such as: 90℃ for 10 minutes + 120℃ for 20 minutes; finally dry in a vacuum oven for 4 to 12 hours, and control the residual moisture to <300ppm. The dried positive electrode sheet is compacted by roller pressing equipment, and the preferred compaction density is 3.2-3.6g / cm 3 The rolling temperature is controlled at 50-80°C, and the roll gap is adjusted within a range of 60-100μm to improve the volumetric energy density and mechanical stability of the electrode. The result is a densely structured and evenly distributed positive electrode sheet for subsequent cell assembly.

[0103] S240, die-cutting the obtained positive electrode sheet blank; the percentage of the overhang area to the total area of ​​the negative electrode sheet, wherein the width of the overhang area of ​​the edge of the negative electrode sheet close to the positive electrode sheet insulation layer is 2 mm, and the width of the overhang area of ​​the edge of the other side is 1 mm; preparing a single positive electrode sheet 5 (see Figure 3 , Figure 1The area ratio of overhang is (300÷W)%, where W is the width of the negative electrode sheet (unit: mm).

[0104] S250, see Figure 3 , install the positive electrode tab 6 on the single positive electrode sheet 5 to complete the preparation of the positive electrode sheet. The positive electrode tab 6 is located at the center of one side of the single positive electrode sheet 5; the positive electrode tab 6 is set at the center of one side edge of the positive electrode sheet 5, that is, within the range of ±0.1mm from the midpoint of the length direction of the side, to facilitate the consistency of the tab arrangement in the subsequent battery cell stack structure and standardization of the welding process.

[0105] Insulating glue 7 is attached to the tab of the electrode piece 5. In order to improve the insulation of the tab and the interlayer pressure resistance, a section of insulating glue 7 is attached to the positive tab 6 area of ​​the positive electrode piece 5. The insulating glue 7 is preferably a high-temperature resistant polyimide (PI) tape or a flame-retardant silicone tape, which has good electrical insulation, heat resistance and adhesion properties. The length of the insulating glue 7 is consistent with the width of the positive tab 6, preferably 2-6mm, and further preferably the width is 3±0.2mm, more preferably the tab width±0.2mm, and the tape width is 3mm, which is used to cover the interface area between the positive tab and the composite negative electrode piece to prevent electrode short circuit or mechanical wear. Preferably, the thickness of the insulating glue 7 is 0.1-0.5mm; more preferably, the thickness is 0.1-0.2mm; while playing an insulating role, it will not affect the subsequent solid-state battery hot pressing process;

[0106] The bare cell is formed by lamination, such as Figure 3 As shown, the positive electrode sheet 5 is completely embedded in the insulating frame glue 3;

[0107] S300, battery preparation

[0108] S310, lamination assembly

[0109] See also Figure 3 , the positive electrode sheet, the negative electrode sheet, and the isolation membrane are stacked in sequence through a laminating device to form a laminated structure to constitute a bare battery cell. The laminated structure is preferably a Z-type (alternating stacking direction) or a symmetrical structure to optimize the ion transmission path and spatial uniformity. The isolation membrane is an insulating microporous film, and the material is mainly PP and PE. In the battery cell structure, each positive electrode sheet 5 is completely embedded in the insulating rubber frame 3 provided on the negative electrode sheet to achieve insulation isolation of the internal space boundary of the battery cell, improve packaging stability and interface compatibility; completing the above steps to obtain a single solid-state battery cell 8 (including one positive, one negative and a composite electrolyte layer); repeatedly stacking a single solid-state battery cell 8 to a set number of layers can complete the preparation of the solid-state battery cell; the isolation membrane separates the composite negative electrode sheet and the positive electrode sheet. After completing the electrode stacking, the battery cell is subjected to the following multi-step packaging treatment to ensure interface density, structural stability and electrochemical performance:

[0110] In order to reduce the short circuit problem during the subsequent hot pressing process of the battery cell, after the solid-state battery cell is prepared, it is grasped by a special jig / auxiliary robot and placed in a hot press; more preferably, except for the insulating frame glue 3 and the positive electrode tab 6, there is no glue in other positions in the solid-state battery cell.

[0111] S320, first hot pressing (pre-pressing)

[0112] The laminated solid-state cells are placed in a vacuum hot press for the first hot pressing process to improve interlayer contact and reduce interfacial porosity. Hot pressing is performed at a temperature of 60-80°C and a pressure of 20-40 MPa for 5-10 minutes. This process is performed in an inert atmosphere or under vacuum to prevent moisture absorption and oxidation. This helps form a dense interface between the composite solid electrolyte and the electrode, improving the consistency of the ion conduction path.

[0113] S330, tab welding

[0114] After the first hot pressing step, the bare cell is removed from the hot pressing mold and the tabs are welded. Tab materials: nickel ribbon (negative) / aluminum ribbon (positive). Laser welding or ultrasonic welding is preferred; the laser power or ultrasonic amplitude should be adjusted according to the tab thickness. The welds should be uniform and free of cold joints. After welding, the solder joint strength and conductivity should be inspected, and resistance testing should be performed as necessary.

[0115] S340, second hot pressing

[0116] After the tabs are welded, the cell is placed back into the hot press for a second hot press. This ensures a tighter bond between the tab solder joints and the electrode sheet, while also finalizing the cell structure. The hot press temperature is 60-90°C, the pressure is 30-80 MPa, and the time is 3-8 minutes. This step further strengthens the interfacial adhesion and prevents misalignment of the material layers during subsequent packaging.

[0117] S350, aluminum-plastic package

[0118] Place the shaped battery cell into a prefabricated aluminum-plastic film shell, accurately position the battery cell in the center of the shell, and leave the tab lead end in the packaging area to ensure that the entire core is positioned stably in the packaging cavity. After the battery cell is sealed in the aluminum-plastic film, perform a three-side heat sealing operation (both sides and the top). First, seal the edges on both sides using a vacuum heat sealer to ensure that there is no residual gas; finally, seal the top and use a buffer material (such as PI tape, hot melt adhesive) in the root area of ​​the tab to enhance the sealing. Aluminum-plastic film structure: three-layer composite film (outer layer nylon, middle layer aluminum foil, inner layer PP); pre-form a groove structure through a hot pressing mold or a male-female mold structure to facilitate the insertion of the battery cell;

[0119] Heat sealing temperature: 130-150℃; vacuum degree: <10Pa; pressure: ≥0.2MPa; time: 3-6 seconds / side; ensure that there are no bubbles, wrinkles or empty seals at the edge of the aluminum-plastic film. After the overall molding, weigh, appearance, size and sealing inspection shall be carried out.

[0120] S360, static aging

[0121] Place the battery cells in a dry environment for aging to relieve material stress. The aging time is 12–24 hours at room temperature or a constant temperature of 30°C. The humidity requirement is RH < 1%, or under nitrogen atmosphere. This can further improve yield and reduce anomalies (such as voltage anomalies, leakage, and internal short circuits) during subsequent formation.

[0122] S370, battery formation

[0123] The rested battery cells are placed in a battery formation cabinet under a constant temperature environment, and multi-stage current-controlled constant current and constant voltage charging and discharging cycles are carried out to achieve the first lithiation of the battery cell materials.

[0124] Formation temperature: 45±2℃;

[0125] First stage charging: charging at 0.1C constant current to the set voltage (e.g. 4.35V);

[0126] Constant voltage charging: switch to constant voltage 4.2V until the current drops to 0.02C;

[0127] Static absorption stage: After constant pressure is completed, let it stand for 2 hours;

[0128] Discharge stage: 0.1C constant current discharge to the lower limit voltage (such as 2.3V);

[0129] 2–3 more cycles can be performed to stabilize the electrochemical interface and improve the utilization of active materials;

[0130] After formation is completed, the battery cells are moved into a standard temperature-controlled test cabinet for capacity testing to evaluate cell performance and are classified into different grades based on capacity consistency.

[0131] The capacity division temperature during the entire process is: 25±2℃; charging: 0.5C constant current charging to 4.35V + constant voltage charging to 0.05C; discharging: 0.5C constant current discharge to 2.3V; capacity division test acquisition parameters: initial capacity (mAh), internal resistance (mΩ), open circuit voltage (OCV), and rate response.

[0132] Example 2

[0133] This embodiment is carried out with reference to the first embodiment, except that the tabs are arranged on the same side and the composite electrolyte slurry formula is changed, as shown below.

[0134] Preparation of composite electrolyte slurry

[0135] The binder HNBR and PAN were added to NMP in a mass ratio of 8:2 to form a solution system with a mass fraction of 15%, and stirred thoroughly until the binder was completely dissolved. Subsequently, solid electrolyte powder Li 2-x La (1+x) / 3 Nb2O6F (x = 0.75, LLNOF), high thermal conductivity filler aluminum nitride (AlN), aluminum oxide, failure-inhibiting materials sodium metaaluminate, barium titanate (BTO), and flame retardant material ammonium tripolyphosphate (APP) are mixed uniformly. The mass ratio of these powders is: LLZTO = 88, AlN = 1, aluminum oxide = 5, sodium metaaluminate = 1, BTO = 1, and MCA = 4. The resulting composite electrolyte slurry has a viscosity of 85,000 cP and a solids content of 80%.

[0136] The rest of the process is the same as that of Example 1;

[0137] See also Figure 7 The positive electrode tab 6 and the negative electrode tab 2 are both located at the center of a single side of their respective electrode sheets, and all tabs are uniformly extended to one side, forming a single-sided tab structure. To improve the tab insulation and mechanical stability, insulating adhesive 7 is applied to the base of the tab. Preferably, it is polyimide tape with a width of 3-6 mm (preferably 3 mm) and a length consistent with the tab width. The adhesive at the tab serves to prevent short circuits. The width restriction is only to prevent short circuits. In theory, there is no width restriction as long as it can prevent short circuits.

[0138] More specifically, the positive electrode tab and the negative electrode tab are both arranged on the same side and in the same direction.

[0139] The tab spacing is preferably 25 mm, and the tab length is controlled at 1530 mm to avoid subsequent welding overlap.

[0140] A buffer thermal bridge structure can be set between the tab aggregation end and the external connection lead end to slow down the temperature rise.

[0141] The single-sided tab arrangement has higher requirements for alignment, and preferably an automatic optical recognition system is used for alignment and lamination.

[0142] The consistent direction of the tab leads facilitates subsequent module assembly / modular automatic welding, thereby improving assembly efficiency.

[0143] The insulating rubber frame 3 structure can be closed along three sides of the non-positive pole ear side, and a lead-out channel is reserved on the positive pole ear side.

[0144] It is preferred to provide a local protruding structure or a flexible buffer layer on the concentrated side of the positive electrode tabs to alleviate stress concentration in the lead-out area.

[0145] In Example 1 and Example 2, the packaging material selection is:

[0146] The laminated structure of aluminum-plastic film (aluminum foil layer, polymer layer, etc.), thickness range (such as 20-50μm aluminum layer), high barrier properties and chemical resistance.

[0147] Packaging process: After the electrode lamination is completed, the vacuum hot pressing packaging step is performed to seal the all-solid-state electrolyte structure.

[0148] Package structure details:

[0149] A sealing ring / isolation groove is designed at the tab lead-out point to prevent short circuit and mechanical damage.

[0150] Preferably, the solder joints are protected (epoxy coating, tape covering, etc.).

[0151] The detailed parameters of the solid-state batteries prepared in Example 1 and Example 2 are shown in the following table.

[0152] Example capacity length width thickness Energy density Internal resistance Example 1 40Ah 370mm 80mm 38mm 335Wh / Kg 10mΩ Example 2 57Ah 260mm 160mm 40mm 330Wh / Kg 10mΩ .

[0153] The solid-state battery cells prepared in Example 1 and Example 2 were subjected to acupuncture and cycle performance tests, and the specific implementation steps are as follows.

[0154] Acupuncture pass rate test:

[0155] After fully charging the battery using a constant current and constant voltage method, pierce the battery with a 3.00mm diameter, high-temperature-resistant steel needle (the needle tip should have a conical angle of 45°-60°, and the needle surface should be smooth and free of rust, oxide layers, and oil stains) at a speed of 80mm±5mm / s, perpendicular to the battery plate. The puncture point should be close to the geometric center of the surface to be punctured (the needle should remain in the battery). Observe for one hour to determine whether the battery cell will catch fire. If so, the cell will not pass the puncture test. If not, the cell will pass the puncture test.

[0156] The battery is charged and discharged using the constant current constant voltage (CC-CV) mode, with the rate set to 1C (i.e., a current that is 1 times the rated capacity of the battery). The specific charging process is as follows:

[0157] Charging phase: The battery is charged at a constant current of 1C until the battery voltage reaches the set cut-off voltage (e.g. 4.2V). After reaching the cut-off voltage, it switches to the constant voltage charging phase, where the voltage is maintained at 4.2V and the charging current is gradually reduced until the current drops to 0.05C, at which point charging is complete.

[0158] Discharge phase: After charging is completed, the battery is immediately discharged at a constant current of 1C until the battery voltage drops to the set cut-off voltage (for example, 2.3V), and the discharge ends.

[0159] Cycling: The above charge-discharge process constitutes a complete cycle, which is repeated multiple times to evaluate the battery's capacity retention and cycle stability. During the test, the ambient temperature is maintained at 25±1°C. The automated battery testing system collects voltage, current, and capacity data to plot charge-discharge curves and capacity decay curves.

[0160] The acupuncture test of the solid-state battery prepared in Example 1 is as follows Figure 4 As shown, after the steel needle stayed there for 1 hour, the battery did not catch fire, smoke, or explode, and successfully passed the puncture test.

[0161] Example 1 Changes of voltage and temperature over time during acupuncture experiment Figure 5 As shown, the moment the needle penetrated, the battery cell experienced a transient voltage drop, indicating an internal short circuit. After 60 minutes, the voltage had dropped to 4.03V. Impressively, the battery temperature only rose slowly from room temperature (27°C) to 44°C during the one-hour needle penetration test, demonstrating the excellent safety of solid-state batteries.

[0162] The long cycle test of the solid-state battery prepared in Example 1 is as follows Figure 6 As shown in the figure, at a rate of 1C / 1C (1C=40A), the capacity retention rate of the battery was 99% after 570 cycles, with no obvious attenuation.

[0163] The acupuncture test of the solid-state battery prepared in Example 2 is as follows Figure 8 As shown, after the steel needle stayed for 1 hour, the battery cell did not catch fire, smoke or explode, and it can also pass the needle puncture test.

[0164] Example 2: Changes of voltage and temperature over time during acupuncture experiment Figure 9 As shown, the moment the needle penetrates, the battery cell experiences a transient voltage drop, indicating an internal short circuit. After 60 minutes, the voltage drops to 4.07V. During the one-hour needle penetration test, the battery temperature slowly rises from room temperature (26°C) to 40°C.

[0165] The long cycle test of the solid-state battery prepared in Example 2 is as follows Figure 10 As shown in the figure, at a rate of 1C / 1C (1C=57A), the capacity retention rate of the battery was 99% after 550 cycles, with no obvious attenuation.

[0166] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which this application belongs.

[0167] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A solid-state battery cell, characterized in that: It includes a composite negative electrode sheet, a positive electrode sheet, and a separator. The separator separates the composite negative electrode sheet and the positive electrode sheet. The composite negative electrode sheet and the positive electrode sheet are clamped at both end surfaces of the separator. The composite negative electrode sheet comprises a negative electrode substrate, an ionic liquid layer, a negative electrode active material layer, and a composite electrolyte slurry layer. The negative electrode substrate is provided with the negative electrode active material layer, the composite electrolyte slurry layer is provided on the negative electrode active material layer, and the ionic liquid layer is provided outside the composite electrolyte slurry layer. The positive electrode sheet comprises a positive electrode substrate and a positive electrode active coating, wherein the positive electrode active coating is arranged on the surface of the positive electrode substrate.

2. The solid-state battery cell according to claim 1, wherein It also includes an insulating rubber frame, in which the positive electrode sheet is installed; the thickness of the positive electrode sheet is less than or equal to the thickness of the insulating rubber frame, and a notch is provided on the insulating rubber frame. The positive electrode tab connected to the positive electrode sheet passes through the notch so that the end face of the positive electrode tab is not higher than the insulating rubber frame; the insulating rubber frame is provided on the composite negative electrode sheet or is sleeved on the outside of the positive electrode sheet or fixed on the isolation film, ultimately forming a stacked structure of the composite negative electrode sheet, the isolation film, and the positive electrode sheet installed in the insulating rubber frame.

3. A method for preparing a solid-state battery containing a composite multifunctional electrolyte layer, characterized in that: The steps include: S100, preparation of negative electrode sheet: S110, dispersing the binder in the electrolyte solvent, and after dissolving, adding 85-92 parts by mass of the electrolyte material, 0.5-4 parts by mass of the high thermal conductivity material, 0.5-4 parts by mass of the failure suppression material, and 2-7 parts by mass of the flame retardant material, and mixing them thoroughly to obtain a composite electrolyte slurry; S120, taking out the following components according to the mass ratio and mixing them, and stirring them at high speed until they are evenly dispersed to prepare a negative electrode active material containing a negative electrode active material: 85-95 active material silicon-carbon negative electrode, 2-6 conductive agent, 0.2-2 single-walled carbon nanotubes, and 2-8 binder; then adding a negative electrode solvent to prepare a negative electrode active material slurry; S130, uniformly coating the negative electrode active material on the surface of the negative electrode substrate, and drying to obtain a negative electrode sheet; then coating the composite electrolyte slurry on the surface of the negative electrode sheet to obtain a composite negative electrode sheet having a composite electrolyte slurry layer; S200, Preparation of positive electrode sheet S210, taking out the positive electrode active material, the conductive agent, and the PVDF according to a mass ratio of 94-98:0.5-2:1-3, stirring and uniformly dispersing them to prepare a mixture containing the positive electrode active material; S220, dispersing the mixture prepared in S210 in a cathode solvent to prepare a cathode active material; S230, evenly coating the positive electrode active material prepared in S220 on the surface of the positive electrode substrate to form a positive electrode active coating to obtain a positive electrode sheet blank; S240, die-cutting the obtained positive electrode sheet blank to prepare a single positive electrode sheet; S300, battery preparation S310, lamination assembly Coating the ionic liquid on the surface of the positive electrode sheet or the composite negative electrode sheet to form an ionic liquid layer; The positive electrode sheet, the negative electrode sheet, and the isolation membrane are stacked in sequence to form a laminate structure, constituting a single solid-state battery unit in claim 1 or 2; the single solid-state battery unit is repeatedly stacked to a set number of layers to complete the preparation of the solid-state battery cell; the solid-state battery cell is subjected to battery formation to obtain a solid-state battery.

4. The preparation method according to claim 3, wherein In S110, the binder content in the composite electrolyte slurry is 1-6 wt%, and the electrolyte material content is ≥80 wt%.

5. The preparation method according to claim 3, wherein In S120, the negative electrode active material is selected from one of graphite, silicon carbon, pure silicon, lithium metal or any combination thereof.

6. The preparation method according to claim 3, wherein The positive electrode active material in S210 is a lithium oxide containing nickel, cobalt and manganese, wherein the weight percentage of nickel is greater than 80%.

7. The preparation method according to claim 3, wherein The binder is selected from polyvinylidene fluoride (PVDF), polyvinyl fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyacrylic acid (PAA), sodium carboxymethyl cellulose (CMC), polyacrylate copolymer (SBR), polyethylene oxide (PEO), polyacrylamide (PAM), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), nitrile rubber (NBR), hydrogenated rubber (SEBS), hydrogenated nitrile rubber (HNBR), water glass (sodium silicate / potassium silicate), gelled silicate cement (Geopolymer), aluminum hydroxide (Al(OH)3) / alumina gel, aluminum phosphate (AlPO4) / polyphosphate, lithium phosphate (Li3PO4), sodium borate, lithium borate glass (such as Li2O–B2O3 system) or any combination thereof; The electrolyte material is selected from Li 1+x Al x Ti 2-x (PO4)3(x=0-0.6,LATP),Ta-doped LLZO(Li 7-x La3Zr 2- x Ta x O 12 (x=0-0.6,LLZTO),Nb-doped LLZO(Li 7-x La3Zr 2-x Nb x O 12 (x=0-0.6,LLZNO), Ga-doped LLZO(Li 7-3x Ga x La3Zr2O 12 (x=0-0.6,LLGZO),Li 7-3x Al x La3Zr2O 12 (x=0–0.4), Li7La 3-x Sr x Zr2O 12 (x=0–0.6), Li7La 3-x Ba x Zr2O 12 (x=0–0.6), Li 7-3x Al x La3Zr 2-γ Ta γ O 12 (x,y=0–0.4), Li 7- 3x Ga x La3Zr 2-γ Nb γ O 12 , Li 1+x Al x Ge 2-x (PO4)3(x=0-0.6,LAGP),Li 1+x Ta2P 1-x Si x O8(x=0-1,LTPSO),Li 1+x Zr2Si x P 3-x O 12 (0≤x≤3);Li 2-x La (1+x) / 3 Nb2O6F(x=0–0.8), Li 2-x La (1+x) / 3 One or any combination of Ta2O6F (x = 0–0.8); The high thermal conductivity material is selected from one of silicon nitride (Si3N4), aluminum nitride (AlN), silicon carbide (SiC), aluminum oxide (Al2O3), gallium nitride (GaN), boron nitride (BN), magnesium oxide (MgO), titanium carbide (TiC) or any combination thereof; The failure inhibition material is selected from one of sodium chloride (NaCl), sodium nitrate (NaNO3), sodium carbonate (Na2CO3), calcium chloride (CaCl2), calcium nitrate (Ca(NO3)2), calcium acetate (Ca(CH3COO)2), calcium hydroxide (Ca(OH)2), strontium nitrate (Sr(NO3)2), strontium chloride (SrCl2), copper (II) sulfate (CuSO4), copper (II) chloride (CuCl2), copper (II) nitrate (Cu(NO3)2), sodium metaaluminate (NaAlO2), ferroaluminum FeAl(SO4)2·12H2O, magnesium hydroxide (Mg(OH)2), aluminum hydroxide, barium titanate (BTO), polyethylene glycol (PEG), and borax decahydrate (Na2B4O7·10H2O), or any combination thereof; The flame retardant material is selected from potassium aluminum sulfate, AlK(SO4)2·12H2O, silicon oxide (SiO2), melamine (C3H6N6), melamine formaldehyde resin (Melamine Formaldehyde Resin), melamine phosphate (Melamine Phosphate), melamine cyanurate (melamine cyanurate), melamine borate (Melamine Borate), aminotriammonium polyphosphate (Ammonium Polyphosphate, APP), cyanuric acid (Cyanuric Acid), hydrazone and hydrazine compounds, triphenylphosphate (Triphenylphosphate, TPP), melamine phosphate (Melamine Phosphate), melamine polyphosphate (Melamine Polyphosphate), sodium acetate trihydrate (CH3COONa·3H2O) or any combination thereof.

8. The preparation method according to claim 3, wherein The S300 also includes: S320, first hot pressing The laminated solid-state battery cells are placed in a vacuum hot press for the first hot pressing process; the hot pressing temperature is 60-80°C and the pressure is 20-40 MPa; the pressure is 20-40 MPa and the time is 5-10 minutes; the process is carried out in an inert atmosphere or vacuum conditions to prevent the material from absorbing moisture or oxidizing; S340, second hot pressing Place the battery cell back into the hot pressing equipment for a second hot pressing; hot pressing temperature: 60-90°C; pressure: 30-80 MPa; time: 3-8 minutes; S350, aluminum-plastic package Place the shaped battery cell into a prefabricated aluminum-plastic film shell and then perform heat sealing operation; heat sealing temperature: 130-150℃; vacuum degree: <10Pa; pressure: ≥0.2MPa; time: 3-6 seconds / side; S360, static aging Place the battery cells in a dry environment for aging for 12–24 hours at room temperature or 30°C. Humidity requirement: RH < 1%, or under nitrogen protection.

9. The preparation method according to any one of claims 3 to 8, wherein In S120, the adhesive is prepared by mixing the following components according to a mass ratio: 2-5% of the adhesive SBR and 0.4-3% of the adhesive PAA.

10. The preparation method according to any one of claims 3 to 8, characterized in that: In S110, the binder includes HNBR, PVDF, and PAN, and the mass ratio of the three is 7-9:0.5-2:0.5-2; the binder is dissolved in an electrolyte solvent, and the solid content is 5%-15%.

11. The preparation method according to any one of claims 3 to 8, characterized in that: In S110, the binder is HNBR and PAN, and the mass ratio of the two is 7-9:1-4; the binder is added to the electrolyte solvent to form a solution system with a mass fraction of 10%-20%, and is fully stirred until the binder is completely dissolved.

12. The preparation method according to any one of claims 3 to 8, characterized in that: In S110, solid electrolyte powders LLZTO, aluminum nitride, aluminum oxide, sodium aluminate, BTO, and melamine cyanurate are taken out and evenly mixed according to the following mass ratio: LLZTO = 80-90, high thermal conductivity material aluminum nitride = 0.5-2, aluminum oxide = 3-6, sodium aluminate = 0.5-2, BTO = 0.5-2, melamine cyanurate = 3-5; a composite electrolyte slurry with a viscosity of 75000-85000 mPa·s and a solid content greater than or equal to 70% is obtained.

13. The preparation method according to any one of claims 3 to 8, characterized in that: In S110, the solid electrolyte powder Li 2-x La (1+x) / 3 Nb2O6F, aluminum nitride (AlN), aluminum oxide, sodium metaaluminate, BTO, and amino ammonium tripolyphosphate are taken out and mixed uniformly according to the following weight ratio: Solid electrolyte powder Li 2-x La (1+x) / 3 Nb2O6F=80-92, aluminum nitride (AlN)=0.5-2, aluminum oxide=3-6, sodium metaaluminate=0.5-2, BTO=0.5-2, amino ammonium tripolyphosphate=3-5; Finally, a composite electrolyte slurry with a viscosity of 75000-90000 cP and a solid content of 80% was obtained.

14. The preparation method according to any one of claims 3 to 8, characterized in that: In S130, the negative electrode active material is evenly coated on the surface of the negative electrode substrate by double-sided coating. After coating, it is pre-dried at 80-120°C for 10-30 minutes, and then thoroughly dried at 120-160°C under vacuum for 4-12 hours to remove residual moisture. After drying, it is roller-pressed, and the negative electrode compaction density is 1.4-1.7g / cm 3 , and obtain a composite negative electrode sheet.

15. The preparation method according to any one of claims 3 to 8, characterized in that: In S310, the lithium salt is first dissolved in the ionic liquid, and the lithium salt concentration is 1-2 mol / L; the ionic liquid is selected from 1-ethyl-3-methylimidazolium ion (EMIM + , 1-ethyl-3-methylimidazolium), 1-butyl-3-methylimidazolium ion (BMIM + , 1-butyl-3-methylimidazolium), N-methyl-N-propylpyrrolidinium (PYR 13 + ), bis(trifluoromethylsulfonyl)imide (TFSI - , bis(trifluoromethanesulfonyl)imide), EMIM-TFSI, BMIM-PF6 or any combination thereof; the lithium salt is selected from one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(cyanomethyl)sulfonylimide (LiFSI), lithium nitrate, and lithium bis(oxalatoborate) (LiBOB) or any combination thereof.

16. The preparation method according to any one of claims 3 to 8, characterized in that: In S310, LiFSI / Pyr 13 The FSI ionic liquid is printed on the surface of the composite negative electrode sheet, and the printing amount per unit area is controlled to be 3%-6% of the mass of the composite electrolyte layer per unit area.

17. The preparation method according to any one of claims 3 to 8, characterized in that: S230 is dried by low-temperature pre-drying followed by high-temperature final drying, pre-drying at 80-120℃ for 10 minutes, and then final drying at 120-170℃ for 20 minutes, controlling the residual moisture to <300ppm.

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