Solid electrolyte coating, composite positive electrode, solid-state battery and preparation methods of solid electrolyte coating, composite positive electrode and solid-state battery
By using solid electrolyte coatings made from inorganic solid electrolyte materials and polymer solid electrolyte materials in lithium-ion batteries, the safety risks and high production costs of traditional organic electrolytes are solved, achieving efficient lithium-ion transport and low-cost production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-03-27
AI Technical Summary
In existing lithium-ion batteries, the use of traditional organic electrolytes leads to high safety risks, the gel electrolyte is thick and the improvement of battery energy density is limited, and the production environment is harsh and incompatible with existing lithium battery production equipment, resulting in high production costs.
Using inorganic solid electrolyte materials as the main component and polymer solid electrolyte materials as the auxiliary component, a solid electrolyte coating with a thickness of 10~40μm is prepared and coated on the positive electrode. It is compatible with existing lithium battery production equipment and uses a trace amount of organic electrolyte to assemble solid batteries.
It improves lithium-ion transport capacity, suppresses lithium dendrite growth, reduces production costs, achieves compatibility with existing equipment, and enhances battery performance and safety.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention belongs to the field of new energy lithium-ion battery technology, and relates to a solid electrolyte coating, a composite cathode and a solid battery, and their preparation methods. Background Technology
[0002] With the global proliferation of new energy lithium-ion batteries, their safety has become increasingly important. Traditional lithium-ion batteries use flammable, explosive, corrosive, and thermally unstable organic electrolytes as their sole lithium-ion transport medium, inevitably posing safety risks to the entire battery system and severely limiting its development. Currently, the consensus in industry and academia is that completely replacing organic electrolytes with non-flammable solid electrolytes to prepare all-solid-state batteries can fundamentally solve the safety problems of lithium batteries. Furthermore, because solid electrolytes have a higher electrochemical window, they can be paired with high-capacity positive and negative electrode materials, significantly improving the energy density of lithium batteries.
[0003] However, the development of solid-state batteries is also limited by many technical problems, such as poor contact at the solid-solid interface inside the battery, low conductivity of solid electrolytes, and high production costs. Currently, a more realistic technical approach is to develop semi-solid-state batteries as a transitional product between traditional liquid lithium-ion batteries and future all-solid-state batteries, while also ensuring that they can be produced using existing lithium-ion battery manufacturing equipment to reduce production costs.
[0004] Semi-solid-state batteries use a solid electrolyte combined with an organic electrolyte to replace the traditional separator in battery assembly. This approach improves the ionic conductivity of the solid electrolyte, improves the internal interface of the solid-state battery, reduces internal resistance, and enhances battery performance. Current semi-solid-state battery products mostly use gel solid electrolytes instead of traditional separators. The chemical system of gel electrolytes uses a polymer solid electrolyte as a substrate and absorbs a large amount of organic electrolyte to achieve high lithium-ion conductivity. While this system can improve battery safety to some extent, gel electrolytes are typically thick, and the presence of a large amount of electrolyte limits the improvement in battery energy density. Furthermore, the main component of gel electrolytes is a relatively soft polymer material, which has limited effect on inhibiting lithium dendrite growth. In addition, the preparation of gel electrolytes requires the absence of air due to the presence of lithium salts, making the production environment more demanding and incompatible with existing lithium battery production equipment, significantly increasing battery production costs. Summary of the Invention
[0005] The purpose of this invention is to provide a solid electrolyte coating, a composite cathode, and a solid-state battery, as well as methods for their preparation.
[0006] The present invention provides a solid electrolyte coating comprising a solvent, an inorganic solid electrolyte material, and a polymer solid electrolyte material; The mass ratio of the inorganic solid electrolyte material to the polymer solid electrolyte material is 25-30:1.
[0007] In this invention, the solid electrolyte coating is mainly composed of inorganic solid electrolyte materials, used to replace traditional separators. The active materials in the positive electrode are all common commercial positive electrode materials. The solid battery is compatible with existing lithium battery production equipment.
[0008] In the above-mentioned solid electrolyte coating, the inorganic solid electrolyte material includes garnet-type (LLZO) solid electrolyte material and / or NASICON solid electrolyte material; The polymer solid electrolyte material is selected from at least one of PVDF, PVDF-HFP, PEO, PMMA, and PVC; The solvent is selected from at least one of NMP (N-methylpyrrolidone), CAN (acetonitrile), ACE (acetone), and DMF (N,N-dimethylformamide).
[0009] The present invention also provides a method for preparing the above-mentioned solid electrolyte coating, comprising the following steps: 1) Dissolve the inorganic solid electrolyte material in the solvent, disperse it ultrasonically, and then stir to obtain solution 1; 2) Add the polymer solid electrolyte material to solution 1, stir to dissolve, and obtain solution 2; 3) Disperse the solution 2 by ultrasonication, stir again, and let stand to obtain the slurry of the solid electrolyte coating.
[0010] The present invention also provides a composite positive electrode, comprising a positive electrode sheet and a solid electrolyte coating coated thereon.
[0011] In the aforementioned composite cathode, the thickness of the solid electrolyte coating can be 10~40μm, specifically 30μm; The positive electrode sheet includes a positive electrode active material, a conductive agent, a binder, a solvent, and a current collector; The positive electrode active material is selected from one of lithium iron phosphate (LiFePO4, abbreviated as LFP), nickel-cobalt-manganese ternary materials (abbreviated as NCM), and lithium cobalt oxide (LiCoO2, abbreviated as LCO); The conductive agent is Super P, the binder is PVDF (polyvinylidene fluoride), the solvent is NMP (N-methylpyrrolidone), and the current collector is aluminum foil.
[0012] In this invention, the nickel-cobalt-manganese ternary material (NCM) is composed of nickel, cobalt, and manganese in a certain proportion.
[0013] In the above-mentioned composite positive electrode, the mass ratio of the positive electrode active material, the conductive agent, and the binder can be 93-97:1.2:1-3.
[0014] The present invention also provides a method for preparing the above-mentioned composite positive electrode, comprising the following steps: 1) mixing positive electrode active material, conductive agent, and binder and then pouring the mixture into an appropriate amount of solvent and stirring to obtain a positive electrode slurry; 2) pouring the positive electrode slurry onto the current collector, performing positive electrode coating, and vacuum drying to obtain a positive electrode sheet; 3) pouring the slurry of the solid electrolyte coating as described in claim 1 or 2 onto the positive electrode sheet in step 2), coating the positive electrode sheet with the slurry to obtain a composite positive electrode after wet coating; 4) placing the composite positive electrode after wet coating under vacuum drying to obtain the composite positive electrode sheet.
[0015] In the above preparation method, after step 4), the method further includes step 5), which involves placing the dried composite positive electrode sheet in a hot press for hot pressing at 65~75℃ and 25~35MPa to make the positive electrode layer and the solid electrolyte coating adhere more tightly; specifically, hot pressing can be performed at 70℃ and 30MPa. Step 5) is followed by step 6) cutting the composite positive electrode to the required size.
[0016] The present invention also provides a solid-state battery comprising the above-mentioned composite positive electrode, negative electrode, and electrolyte.
[0017] In this invention, only a trace amount of the electrolyte is needed in the solid-state battery, and the electrolyte wets the negative electrode side interface, specifically 1~3μL.
[0018] The present invention further provides a method for preparing the above-mentioned solid-state battery, comprising the following steps: assembling the above-mentioned composite positive electrode with the negative electrode sheet and the electrolyte wetting interface in a glove box environment by stacking the sheets to obtain the solid-state battery.
[0019] In this invention, the glove box environment is a low-water, low-oxygen environment, which is a conventional environmental condition for stacked assembly.
[0020] The present invention has the following beneficial effects: 1. The solid electrolyte coating of the present invention has a certain viscosity and can be directly coated on the electrode sheet in situ. The presence of inorganic solid electrolyte material can effectively improve the lithium-ion transport capacity of the coating and the ability to suppress lithium dendrite growth. The polymer solid electrolyte material has a relatively soft structure and can adapt to the volume change of the electrode during charging and discharging. The solid electrolyte coating with a thickness of micrometers formed directly on the electrode surface after drying can effectively achieve strong interfacial contact between the coating and the electrode.
[0021] 2. The solid electrolyte coating of the present invention has an extremely high inorganic phase content, which can improve the ionic conductivity of the coating while also giving the coating high strength. It can effectively suppress the growth of lithium dendrites and avoid the risk of short circuit caused by lithium dendrites penetrating the coating and contacting the positive electrode.
[0022] 3. The solid electrolyte coating of the present invention can completely replace the traditional polymer separator, and unlike gel electrolyte, the present invention only requires a very small amount of organic electrolyte to wet the negative electrode side interface to enable the solid battery to have excellent performance.
[0023] 4. The raw materials for the solid electrolyte coating of this invention are all common materials, which can effectively reduce production costs. Using this coating to prepare composite cathodes and solid-state batteries allows for compatibility with existing lithium-ion battery equipment, enabling mass production in a short period. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of a composite cathode with a solid electrolyte coating.
[0025] Figure 2 This is a schematic diagram of a solid-state button cell.
[0026] Figure 3 This is a performance diagram of a solid-state lithium-ion battery. Figure 3 The numbers 1 through 4 represent the number of cycles. Detailed Implementation
[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0028] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0029] The present invention provides a solid electrolyte coating comprising a solvent, an inorganic solid electrolyte material, and a polymer solid electrolyte material; The mass ratio of the inorganic solid electrolyte material to the polymer solid electrolyte material is 25-30:1.
[0030] Furthermore, the inorganic solid electrolyte material includes garnet-type (LLZO) solid electrolyte material and / or NASICON solid electrolyte material; The polymer solid electrolyte material is selected from at least one of PVDF, PVDF-HFP, PEO, PMMA, and PVC; The solvent is selected from at least one of NMP (N-methylpyrrolidone), CAN (acetonitrile), ACE (acetone), and DMF (N,N-dimethylformamide).
[0031] The present invention also provides a method for preparing the above-mentioned solid electrolyte coating, comprising the following steps: 1) Dissolve the inorganic solid electrolyte material in the solvent, disperse it ultrasonically, and then stir to obtain solution 1; 2) Add the polymer solid electrolyte material to solution 1, stir to dissolve, and obtain solution 2; 3) Disperse the solution 2 by ultrasonication, stir again, and let stand to obtain the slurry of the solid electrolyte coating.
[0032] The present invention also provides a composite positive electrode, comprising a positive electrode sheet and a solid electrolyte coating coated thereon. The thickness of the solid electrolyte coating may be 10~40 μm.
[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: A solid electrolyte coating: The coating material comprises polyethylene oxide (PVDF), tantalum-doped lithium lanthanum zirconium oxide (commercially purchased from Hefei Kejing Materials Technology Co., Ltd., LLZTO conductive powder material, abbreviated as LLZTO), and solvent NMP. The mass ratio of LLZTO / PVDF is 25 / 1.
[0034] Preparation method: Step 1: First, dissolve LLZTO in NMP solvent, ultrasonically disperse for 0.5 h, and then magnetically stir for 4 h to obtain solution 1; Step 2: Place PVDF in solution 1 and stir for 2 h to obtain solution 2; Step 3: Ultrasonically disperse solution 2 for 1 h, continue to magnetically stir for 10 h, and then let it stand for 12 h to obtain coating slurry.
[0035] Preparation of composite cathodes: Composite cathodes include common commercially available cathode sheets and solid electrolyte coatings, such as... Figure 1 As shown.
[0036] Preparation method: Step 1: Thoroughly dry-mix the positive electrode active material lithium iron phosphate (LFP), conductive agent conductive carbon black, and binder (PVDF) at a mass ratio of 95:1.2:2, then pour the mixture into an appropriate amount of solvent (NMP) and stir magnetically to obtain a positive electrode slurry; Step 2: Pour the positive electrode slurry from Step 1 onto an aluminum foil current collector, place it in a coating machine, start the coating machine to coat the positive electrode, and then vacuum dry at 100℃ for 12 hours to obtain a positive electrode sheet; Step 3: Pour the obtained solid electrolyte coating slurry onto the positive electrode sheet from Step 2, and start the coating machine to evenly coat the slurry. The coating is applied to the positive electrode sheet, and the coating thickness is adjusted to 30μm by adjusting the height of the coating machine blade, while ensuring that the coating can completely and uniformly cover the positive electrode layer; Step 4: The composite positive electrode after wet coating is placed in a vacuum oven at 100℃ and vacuum dried to obtain a composite positive electrode sheet for solid-state batteries; Step 5: The dried composite positive electrode sheet is placed in a hot press and hot-pressed at 70℃ and 30MPa to make the positive electrode layer and the solid electrolyte coating adhere more tightly; Step 6: The composite positive electrode is cut to the required size according to the needs to obtain the final LFP composite positive electrode sheet.
[0037] Preparation of negative electrode sheet: Step 1: Dissolve CMC in deionized water and stir for 1 hour to form a CMC solution; Step 2: Dry mix graphite and conductive carbon black thoroughly and add them to the CMC solution, stir for 10 hours; Step 3: Add SBR solution to the solution obtained in Step 2; Step 4: Coat the graphite negative electrode slurry obtained in Step 3 onto the current collector, vacuum dry it, and then cut it to obtain the graphite negative electrode sheet.
[0038] Solid-state battery fabrication: In a low-water, low-oxygen glove box environment, a composite positive electrode is combined with a graphite negative electrode and a small amount of electrolyte (specifically 1 μL) to wet the interface. A coin cell solid-state battery is then assembled using a stacking method. Figure 2 As shown.
[0039] Example 2: A solid electrolyte coating: The coating material comprises polyethylene oxide (PEO), lithium lanthanum titanium oxide (LLTO), and solvent acetonitrile. The mass ratio of LLTO / PEO is 27 / 1.
[0040] Preparation method: Step 1: First, dissolve LLTO in acetonitrile solvent, ultrasonically disperse for 1 hour, and then magnetically stir for 2 hours to obtain solution 1; Step 2: Place PEO in solution 1 and stir for 6 hours to obtain solution 2; Step 3: Ultrasonically disperse solution 2 for 1 hour, continue to magnetically stir for 10 hours, and then let it stand for 12 hours to obtain coating slurry.
[0041] Preparation of composite cathodes: Composite cathodes include common commercial cathode sheets and solid electrolyte coatings.
[0042] Preparation method: Step 1: Thoroughly dry-mix the positive electrode active material lithium cobalt oxide (LCO), conductive agent conductive carbon black, and binder (PVDF) at a certain mass ratio of 95:1.2:2, then pour the mixture into an appropriate amount of solvent (NMP) and magnetically stir to obtain a positive electrode slurry; Step 2: Pour the positive electrode slurry from Step 1 onto an aluminum foil current collector, place it in a coating machine, start the coating machine to coat the positive electrode, with a doctor blade height of 40 μm, and then vacuum dry at 100℃ for 12 h to obtain a positive electrode sheet; Step 3: Pour the obtained solid electrolyte coating slurry onto the positive electrode sheet from Step 2, and start the coating machine. The coating machine evenly coats the slurry onto the positive electrode sheet. The coating thickness is adjusted by adjusting the height of the coating machine's scraper, while ensuring that the coating can completely and evenly cover the positive electrode layer. Step four: The composite positive electrode after wet coating is placed in a vacuum oven and dried at 100°C to obtain a composite positive electrode sheet for solid-state batteries. Step five: The dried composite positive electrode sheet is placed in a hot press and hot-pressed at 80°C and 10MPa to ensure that the positive electrode layer and the solid electrolyte coating can adhere more tightly. Step six: The composite positive electrode is cut to the required size to obtain the final LFP composite positive electrode sheet.
[0043] Preparation of negative electrode sheet: Step 1: Dissolve CMC in deionized water and stir for 1 hour to form a CMC solution; Step 2: Dry mix graphite and conductive carbon black thoroughly and add them to the CMC solution, stir for 10 hours; Step 3: Add SBR solution to the solution obtained in Step 2; Step 4: Coat the graphite negative electrode slurry obtained in Step 3 onto the current collector, vacuum dry it, and then cut it to obtain the graphite negative electrode sheet.
[0044] Solid-state battery fabrication: In a low-water, low-oxygen glove box environment, a composite positive electrode is combined with a graphite negative electrode and a small amount of electrolyte to wet the interface. No separator is required, and button solid-state batteries are assembled by stacking.
[0045] Performance tests were performed on the button solid-state battery prepared in Example 1 of the present invention: voltage-specific capacity determination. The button battery was tested at room temperature (25℃) with a specific current of 0.33C / 0.33C and a voltage range of 2.5~3.65V. The first discharge capacity reached 143mAh / g. Figure 3 As shown.
Claims
1. A solid electrolyte coating, characterized in that, It is made from solvents, inorganic solid electrolyte materials, and polymer solid electrolyte materials; The mass ratio of the inorganic solid electrolyte material to the polymer solid electrolyte material is 25-30:
1.
2. The solid electrolyte coating according to claim 1, characterized in that, The inorganic solid electrolyte material includes garnet-type solid electrolyte material and / or NASICON solid electrolyte material; The polymer solid electrolyte material is selected from at least one of PVDF, PVDF-HFP, PEO, PMMA, and PVC; The solvent is selected from at least one of NMP, ACN, ACE and DMF.
3. The method for preparing the solid electrolyte coating according to claim 1 or 2, characterized in that, Includes the following steps: 1) Dissolve the inorganic solid electrolyte material in the solvent, disperse it ultrasonically, and then stir to obtain solution 1; 2) Add the polymer solid electrolyte material to solution 1, stir to dissolve, and obtain solution 2; 3) Disperse the solution 2 by ultrasonication, stir again, and let stand to obtain the slurry of the solid electrolyte coating.
4. A composite positive electrode, characterized in that, Includes a positive electrode sheet and a solid electrolyte coating as described in claim 1 or 2 coated on the positive electrode sheet.
5. The composite positive electrode according to claim 4, characterized in that, The thickness of the solid electrolyte coating is 10~40μm; The positive electrode sheet includes a positive electrode active material, a conductive agent, a binder, a solvent, and a current collector; The positive electrode active material is selected from one of lithium iron phosphate, nickel-cobalt-manganese ternary materials, and LiCoO2; The conductive agent is Super P, the binder is PVDF, the solvent is NMP, and the current collector is aluminum foil.
6. The composite positive electrode according to claim 5, characterized in that, The mass ratio of the positive electrode active material, the conductive agent, and the binder is 93-97:1.2:1-3.
7. The method for preparing the composite cathode according to any one of claims 4-6, characterized in that, Includes the following steps: 1) Mix the positive electrode active material, conductive agent, and binder, then pour the mixture into an appropriate amount of solvent and stir to obtain a positive electrode slurry; 2) Pour the positive electrode slurry onto the current collector, perform positive electrode coating, and vacuum dry to obtain a positive electrode sheet; 3) Pour the slurry of the solid electrolyte coating according to claim 1 or 2 onto the positive electrode sheet in step 2), coat the positive electrode sheet with the slurry, and obtain a composite positive electrode after wet coating; 4) Place the composite positive electrode after wet coating in a vacuum dryer to obtain the composite positive electrode sheet.
8. The preparation method according to claim 7, characterized in that, Step 4) is followed by: Step 5) placing the dried composite positive electrode sheet in a hot press for hot pressing at 65~75℃ and 25~35MPa. Step 5) is followed by step 6) cutting the composite positive electrode to the required size.
9. A solid-state battery, characterized in that, It comprises the composite positive electrode, negative electrode, and electrolyte as described in any one of claims 4-6.
10. The method for preparing the solid-state battery according to claim 9, comprising the following steps: assembling the composite positive electrode according to any one of claims 4-6, together with the negative electrode sheet and the electrolyte wetting interface, in a glove box environment by stacking, thereby obtaining the solid-state battery.