A dual ceramic electrolyte and a ternary NCM solid-state battery comprising the dual ceramic electrolyte

Abstract

The application relates to the technical field of solid-state lithium ion batteries, and discloses a dual-ceramic electrolyte and a ternary NCM solid-state battery containing the dual-ceramic electrolyte, the battery is assembled from an NCM ternary / LATP-LLZTO composite pole piece and an artificial graphite negative pole piece, the composite pole piece is directly coated with a LATP-LLZTO dual-ceramic electrolyte slurry on an NCM ternary positive pole piece to be compacted to obtain the battery, wherein the LATP and the LLZTO are mixed in a weight ratio of 3:2 to 2:3, are directly coated on the NCM ternary positive pole piece to form an integrated composite pole piece, and are finally assembled into a soft package battery. + The battery total internal resistance is less than or equal to 2.55 ohms, the Li ‑ diffusion coefficient is greater than or equal to 6.72*10 0 cm²s ‑ ¹, the discharge capacity is greater than or equal to 181 mAh g ‑ ¹ at 0.1 C, the capacity retention rate is greater than 68% after 800 cycles, the capacity retention rate reaches 54.6% at 2 C, and there is no thermal runaway phenomenon after mechanical damage. The application solves the problems of high interface resistance and fast capacity attenuation of existing solid-state batteries, has high specific capacity, long cycle life and high safety, the preparation method is controllable and easy to scale, and is suitable for energy storage scenes such as electric vehicles.

Description

Technical Field

[0001] This invention relates to the field of solid-state lithium-ion battery technology, specifically to a dual-ceramic electrolyte and a ternary NCM solid-state battery containing a dual-ceramic electrolyte, which is particularly suitable for energy storage scenarios such as electric vehicles and portable electronic devices with high requirements for energy density, cycle life and safety performance. Background Technology

[0002] Solid-state lithium-ion batteries (SSLBs), with their advantages of high safety, high energy density, and long cycle life, have become the core development direction of next-generation energy storage technology. Compared with traditional liquid lithium-ion batteries, they eliminate safety hazards such as electrolyte leakage and explosion, and have broad application prospects in the new energy field. As the core component of solid-state lithium-ion batteries, the performance of the solid electrolyte directly determines the overall electrochemical performance of the battery. Currently, inorganic ceramic electrolytes have become the mainstream research system for solid-state electrolytes due to their high ionic conductivity, chemical stability, and thermal stability. They mainly include three categories: garnet-type (such as LLZO / LLZTO), NASICON-type (such as LATP), and sulfide-type electrolytes.

[0003] Among them, garnet-type LLZTO electrolytes exhibit high ionic conductivity and electrochemical stability, and good compatibility with high-voltage cathodes; NASICON-type LATP electrolytes demonstrate excellent bulk ionic conductivity and have a relatively simple preparation process; sulfide electrolytes have ionic conductivity close to that of liquid electrolytes, but their air sensitivity and high-voltage incompatibility make them difficult to scale up for application. In existing technologies, to address the performance deficiencies of single ceramic electrolytes, the industry has proposed a technical solution of physically and mechanically mixing different ceramic electrolyte powders and then combining them with polymer binders to prepare solid electrolyte membranes. This solution attempts to combine the performance advantages of different ceramic electrolytes to improve the shortcomings of single electrolytes.

[0004] However, physical mixing makes it difficult to achieve uniform dispersion and close contact of the two phases at the nanoscale, which may lead to high interfacial resistance, limited synergistic effects, and a greater risk of phase separation during long-term cycling. It also presents the problem of poor compatibility with the cathode. These problems have inherent causes: First, single-phase solid electrolytes themselves have performance limitations. Garnet-type LLZTO has poor interfacial compatibility with lithium metal and high grain boundary resistance, while NASICON-type LATP contains Ti... 4+ It is easily reduced at low potentials and has poor compatibility with lithium anodes. Neither can simultaneously meet the dual requirements of high bulk ionic conductivity and interface stability, directly leading to obstructed lithium-ion transport, severe electrode polarization, and poor battery rate performance. Secondly, the physical-mechanical mixing of LATP and LLZTO can only achieve macroscopic-level mixing, failing to achieve uniform dispersion and close contact at the nanoscale. After being composited with polymer binders, the mechanical composite method between the electrolyte membrane and the positive electrode sheet makes it difficult to achieve complete close contact at the interface. This not only results in high interfacial resistance and prevents the synergistic effect of the two from being fully realized, but also, during long-term cycling, due to poor interfacial adhesion, phase separation and interface separation are prone to occur, leading to rapid capacity decay. Thirdly, nickel-rich layered oxide NCM811... The cathode has the advantage of high specific capacity due to its high nickel content, but it is prone to lattice distortion and microcracks during cycling, and it is also prone to side reactions with the solid electrolyte, resulting in unstable cathode surface structure. Existing technologies have not developed targeted solutions for electrolyte selection and interface engineering design, which cannot effectively suppress the above problems and further aggravate the capacity decay of the battery. Fourth, the thermal runaway risk of existing solid-state batteries has not been effectively solved. Single or simple composite electrolyte systems are still prone to smoke, fire or even explosion under extreme conditions such as mechanical damage to the battery, and the safety performance has not met the requirements for practical application.

[0005] In summary, existing electrolyte systems and positive electrode-electrolyte interface designs for solid-state batteries cannot simultaneously achieve ion transport efficiency, cycle stability, and safety performance, becoming a core bottleneck restricting the practical application and large-scale use of solid-state lithium-ion batteries. There is an urgent need to develop a new electrolyte system and electrode-electrolyte composite structure to fundamentally solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the technical problems in existing solid-state lithium-ion batteries, such as the short performance of single-phase electrolytes, poor bonding between electrolyte and cathode, poor cycle stability of NCM ternary cathodes, and insufficient battery safety performance, and to provide a ternary NCM solid-state battery containing dual ceramic electrolytes.

[0007] This invention constructs an LATP-LLZTO dual-ceramic composite electrolyte system and employs an interface design where electrolyte slurry is directly coated onto an NCM ternary cathode sheet. This achieves a tight bond between the electrolyte and the cathode, while leveraging the synergistic performance advantages of LATP and LLZTO. This addresses the problems of hindered ion transport, high interface resistance, and rapid capacity decay in existing technologies. Furthermore, by optimizing the preparation process parameters of the electrolyte and electrode, this invention improves the ion diffusion coefficient of the battery, suppresses side reactions and structural distortions in the NCM ternary cathode, and achieves a balance between high specific capacity, high rate performance, and long cycle life. Ultimately, the prepared solid-state battery possesses excellent safety performance, effectively suppresses the risk of thermal runaway, and meets the practical requirements of electric vehicles, portable electronic devices, and other scenarios.

[0008] To achieve the above-mentioned objectives, the specific solution of the present invention is as follows:

[0009] A ternary NCM solid-state battery is assembled into a pouch cell using an NCM ternary / / LATP-LLZTO composite electrode and an artificial graphite negative electrode. The NCM ternary / / LATP-LLZTO composite electrode is prepared by directly coating an LATP-LLZTO dual-ceramic electrolyte slurry onto an NCM ternary positive electrode, followed by drying and compaction. The weight ratio of LATP to LLZTO in the LATP-LLZTO dual-ceramic electrolyte is 3:2 to 2:3. The total internal resistance of the solid-state battery is ≤2.55Ω, and the Li... + Diffusion coefficient ≥ 6.72 × 10 - ¹ 0 cm² s - ¹, discharge capacity ≥181 mAh g at 0.1 C rate. - ¹, after 800 cycles, the capacity retention rate is >68%, and the average coulombic efficiency is >99.5%.

[0010] Furthermore, the LATP-LLZTO dual ceramic electrolyte is prepared by combining LATP powder and LLZTO powder via liquid-phase dispersion; the D50 particle size of the LATP powder is 1–3 μm, and the cubic phase purity of the LLZTO powder is higher than 95% with a particle size range of 3–8 μm.

[0011] Furthermore, the NCM ternary cathode sheet is prepared by coating, drying, and compacting a cathode slurry made by mixing NCM ternary powder, PVDF, and Super-P conductive additive in a mass ratio of 95:3:2 with NMP solvent; the aluminum foil substrate of the NCM ternary cathode sheet has a thickness of 10 μm, and the thickness after compaction is 45~55 μm.

[0012] Furthermore, the NCM ternary powder is LiNi. x Co Mn z O2, where x+y+z=1 and x≥0.6; preferably, the NCM ternary powder is selected from at least one of NCM811 and NCM622, where the chemical formula of NCM811 is LiNi0.8Co0.1Mn0.1O2 and the chemical formula of NCM622 is LiNi0.6Co0.2Mn0.2O2; or, the NCM ternary powder is NCA, with the chemical formula LiNi 0.8 Co 0.15 Al 0.05 O2.

[0013] Furthermore, the artificial graphite negative electrode sheet is prepared by coating, drying, and compacting a negative electrode slurry prepared by mixing artificial graphite, PVDF, and Super-P in a mass ratio of 94:4:2 with NMP solvent; the copper foil substrate of the artificial graphite negative electrode sheet has a thickness of 9~10μm, and the thickness after compaction is 45~55μm.

[0014] Furthermore, the artificial graphite is MG11 artificial graphite; the overall thickness of the NCM ternary / / LATP-LLZTO composite electrode after compaction is 70-80 μm.

[0015] Furthermore, the battery maintains capacity retention rates of ≥92.0%, 85.8%, 76.5%, and 53.0% at 0.2C, 0.5C, 1C, and 2C rates, respectively, and exhibits no thermal runaway phenomena such as smoke, fire, or explosion after mechanical damage under full charge conditions; when the NCM ternary powder is NCM811, the battery's total internal resistance is 2.45Ω, and the Li... + The diffusion coefficient is 7.09 × 10⁻⁶. - ¹ 0 cm² s - ¹, The discharge capacity at 0.1C is 184 mAh g. - ¹.

[0016] This invention also protects the method for preparing the solid-state battery, comprising the following steps: S1. Preparation of LATP-LLZTO composite powder: LATP powder and LLZTO powder are dispersed in a solution and stirred to obtain LATP slurry and LLZTO slurry; then they are mixed, dispersed and dried to obtain LATP-LLZTO composite powder. S2. Preparation of LATP-LLZTO electrolyte slurry: In a glove box, LiTFSI and PVDF-HFP are dissolved in NMP solvent, LATP-LLZTO composite powder is added, and the mixture is ball-milled to obtain electrolyte slurry; S3. Preparation of NCM ternary cathode sheet: NCM ternary powder, PVDF, Super-P and NMP are mixed to prepare cathode slurry, coated on aluminum foil, vacuum dried and compacted to 45-55μm to obtain NCM ternary cathode sheet; S4. Preparation of NCM ternary / / LATP-LLZTO composite electrode: The LATP-LLZTO electrolyte slurry is coated on the NCM ternary positive electrode, vacuum dried and compacted to 70-80μm to obtain the composite electrode; S5. Preparation of artificial graphite negative electrode sheet: Artificial graphite, PVDF, and Super-P are mixed with NMP in a mass ratio of 94:4:2 to prepare a negative electrode slurry. This slurry is coated onto copper foil to achieve a wet film thickness of 130-150 μm, and then vacuum-dried at 120-135℃ for 24 hours. 200 kg cm - ² Compacted to approximately 50μm, an artificial graphite negative electrode sheet is obtained; S6. Battery Assembly: In the glove box, NCM ternary / / LATP-LLZTO composite electrode and artificial graphite negative electrode are assembled into a soft-pack solid-state battery.

[0017] Furthermore, in step S1, the solid content of both LATP slurry and LLZTO slurry is 30–60%, and then they are mixed at a weight ratio of 3:2 to 2:3, dispersed for 2–5 hours, and then dried in an oven at 100–150°C for 1–3 hours to obtain LATP-LLZTO composite powder. In step S2, the molecular weight of the PVDF-HFP is 200,000-400,000; LATP LLZTO composite powder, LiTFSI, PVDF HFP accounts for 20%–50%, 25%–40%, and 25%–40% of the total solids mass, respectively, and the total solids content of the electrolyte slurry is 60-70%.

[0018] Further, in step S3, NCM ternary powder, PVDF, and Super-P are mixed with NMP in a mass ratio of 95:3:2 to prepare a positive electrode slurry, which is then coated onto aluminum foil to a wet film thickness of 130-150 μm and vacuum dried at 120-135℃ for 12 hours, yielding 200 kg of product. cm- ² Compact to 45-55μm to obtain NCM ternary cathode sheet; In step S4, LATP-LLZTO electrolyte slurry is coated onto the NCM ternary cathode sheet to a wet film thickness of 30-50 μm, and vacuum dried at 120-135℃ for 12 hours, yielding 200 kg. cm - ² Compact to 70-80μm to obtain composite electrode; In step S5, artificial graphite, PVDF, and Super-P are mixed with NMP in a mass ratio of 94:4:2 to prepare a negative electrode slurry, which is then coated onto copper foil to achieve a wet film thickness of 130-150 μm. The slurry is then vacuum-dried at 120-135℃ for 24 hours, yielding 200 kg of the desired product. cm - ² Compact to 45-55μm to obtain artificial graphite anode sheet.

[0019] Beneficial effects First, this invention employs a liquid-phase dispersion method to uniformly composite LATP and LLZTO in a specific ratio. The resulting LATP-LLZTO composite powder achieves uniform dispersion and close contact at the nanoscale. This technical feature effectively reduces the total internal resistance of the battery, lowering the total internal resistance of the pouch cell to 2.45 Ω, significantly lower than that of solid-state batteries composed solely of LATP (4.35 Ω) and LLZTO (3.05 Ω). The liquid-phase dispersion method used in this invention avoids the particle agglomeration and uneven dispersion problems caused by physical-mechanical mixing. The uniform combination of LATP and LLZTO forms a continuous lithium-ion transport path, synergistically leveraging the high bulk ionic conductivity of LATP and the good interfacial stability of LLZTO. This effectively reduces grain boundary resistance and bulk resistance, while simultaneously improving the lithium-ion conductivity. + The diffusion coefficient reached 7.09 × 10⁻⁶. - ¹ 0 cm² s - ¹, which significantly improves the lithium-ion transport efficiency.

[0020] Secondly, this invention employs a process of directly coating the electrolyte slurry onto the NCM ternary cathode sheet, replacing the traditional mechanical bonding method between the electrolyte membrane and the cathode sheet. This technical feature achieves close contact between the electrolyte and the cathode sheet, effectively solving the problems of high interfacial resistance and easy separation during long-term cycling. Using the direct coating process of this invention, the electrolyte slurry fully wets the surface and pores of the NCM ternary cathode, forming an integrated composite electrode sheet after drying and compaction. This significantly improves the interfacial bonding force between the electrolyte and the cathode, eliminates the interfacial gaps caused by mechanical bonding, reduces interfacial impedance, and effectively suppresses interfacial and phase separation during long-term cycling, significantly mitigating electrode polarization and laying the foundation for a long battery cycle life.

[0021] Furthermore, the composite structure formed by the LATP-LLZTO dual ceramic electrolyte and the NCM ternary cathode of this invention can effectively suppress side reactions, microcrack formation, and surface structural instability of the NCM ternary cathode during cycling. This technical feature enables the battery to maintain high specific capacity and excellent cycle stability. The LATP-LLZTO dual ceramic electrolyte and the NCM ternary cathode of this invention have good interfacial compatibility, forming a stable interfacial layer on the cathode surface, effectively blocking side reactions between the cathode and electrolyte, while suppressing lattice distortion and microcrack propagation of the NCM ternary cathode, maintaining the structural integrity of the cathode, and enabling the battery to achieve 184 mAh g⁻¹ at 0.1 C. - ¹ It has a high discharge capacity, with a capacity retention rate of >70% after 800 cycles and an average coulombic efficiency of >99.5%, which is far superior to solid-state batteries with single-phase electrolyte systems.

[0022] Furthermore, this invention significantly improves battery rate performance by optimizing the raw material ratio and preparation process parameters of the electrolyte and electrode. This technical feature allows the battery to maintain a high capacity retention rate even at high rates. The invention achieves a nanoscale uniformly dispersed LATP-LLZTO composite electrolyte, providing a rapid lithium-ion transport channel. Combined with the tight interfacial bonding between the electrolyte and the cathode, it effectively reduces the transport resistance of lithium ions at the interface and in the bulk phase. This allows the battery to achieve capacity retention rates of 93.4%, 87.4%, 78.1%, and 54.6% at 0.2C, 0.5C, 1C, and 2C rates, respectively. This addresses the technical pain point of poor rate performance in existing solid-state batteries and meets the needs of high-power energy storage scenarios.

[0023] Finally, the dual ceramic electrolyte system of this invention endows the battery with excellent safety performance, effectively suppressing the risk of thermal runaway. This technical feature ensures that the battery remains safe even under extreme mechanical damage. Both LATP and LLZTO are inorganic ceramic electrolytes with excellent thermal and chemical stability. Their composite system further enhances the thermal resistance performance of the electrolyte, and the integrated composite structure of the electrolyte and positive electrode avoids problems such as electrolyte leakage. Even if a fully charged battery is intentionally mechanically damaged, no smoke, flame, or explosion occurs, significantly improving the practical safety level of solid-state batteries.

[0024] Meanwhile, the preparation method of the present invention has controllable process parameters and simple steps, making it easy to achieve large-scale production. By limiting the parameters of key processes such as liquid phase dispersion, slurry coating, drying and compaction, it is possible to stably prepare high-performance dual ceramic electrolyte solid batteries. This solves the problems of uneven dispersion and poor interfacial bonding in existing composite electrolyte preparation processes. The preparation process has good repeatability, the product performance is stable, and it is suitable for industrial promotion and application.

[0025] In summary, this invention achieves a comprehensive improvement in solid-state battery performance in five aspects: ion transport efficiency, interface stability, cathode structure protection, rate performance, and safety performance by constructing an LATP-LLZTO dual-ceramic composite electrolyte system, optimizing the interfacial bonding between the electrolyte and the NCM ternary cathode, and precisely controlling the preparation process parameters. This addresses several core bottlenecks in existing technologies, and the resulting solid-state battery possesses high specific capacity, high rate performance, long cycle life, and high safety. Furthermore, its preparation method is controllable and easily scalable, providing an effective strategy for the practical application and large-scale application of solid-state lithium-ion batteries. It has significant application value in energy storage fields such as electric vehicles and portable electronic devices. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the accompanying drawings are described in detail below. The drawings only relate to embodiments of the present invention and are not intended to limit the present invention. Figure 1 shows the elemental distribution and content of LATP powder and LLZTO powder after homogenization treatment in step S1 of Example 1. The elements in the figure are uniformly distributed, which intuitively reflects that LATP and LLZTO powders are uniformly dispersed at the nanoscale, and a dual ceramic composite electrolyte is successfully formed. Figure 2 shows the charge-discharge curves of the LATP-LLZTO pouch cell prepared in Example 1 at different current densities; the figure clearly shows the charge-discharge voltage plateaus of the battery at different rates of 0.1C, 0.2C, 0.5C, 1C, and 2C. Figure 3 shows the cycling performance of the LATP-LLZTO pouch cell prepared in Example 1 at different current densities. The figure clearly shows the capacity change of the cell at different rates of 0.1C, 0.2C, 0.5C, 1C, and 2C, reflecting the excellent rate performance of the cell. Figure 4 shows the charge-discharge curves of the LATP-LLZTO pouch cell prepared in Example 1 under 0.2 C charging and 0.5 C discharging conditions; the charge-discharge curves of the 3rd and 800th cycles in the figure are almost symmetrical. Figure 5 shows the capacity retention and coulombic efficiency of the LATP-LLZTO pouch cell prepared in Example 1 after 800 cycles under 0.2 C charging and 0.5 C discharging conditions. The capacity retention curve in the figure tends to be stable, and the coulombic efficiency remains above 99.5%, reflecting the good cycle reversibility and stability of the battery. Figure 6 shows the LATP-LLZTO powder obtained in Example 1, the actual solid-state pouch battery, and the safety demonstration process. The figure shows the microstructure of the composite powder, the physical appearance of the pouch battery, and the safety demonstration result that the battery can still light up the LED after mechanical damage without thermal runaway, reflecting the actual preparation effect and excellent safety performance of the battery. Figure 7 shows the charge-discharge curves of the LATP pouch cell prepared in Comparative Example 1 at different current densities; the charge-discharge voltage plateau in the figure decreases rapidly with increasing rate. Figure 8 shows the cycling performance of the LATP pouch cell prepared in Comparative Example 1 at different current densities; the figure shows significant capacity decay, reflecting the poor rate performance of the single-phase LATP electrolyte cell; Figure 9 shows the charge-discharge curves of the LATP pouch cell prepared in Comparative Example 1 under 0.2 C charging and 0.5 C discharging conditions; the charge-discharge curves of the 3rd and 800th cycles in the figure show poor symmetry. Figure 10 shows the capacity retention and coulombic efficiency of the LATP pouch cell prepared in Comparative Example 1 after 800 cycles under 0.2 C charging and 0.5 C discharging conditions; the capacity retention after 800 cycles is only 18%, reflecting the extremely poor cycle stability of the single-phase LATP electrolyte cell. Figure 11 shows the charge-discharge curves of the LLZTO pouch cell prepared in Comparative Example 2 at different current densities; the discharge capacity of the cell at 0.1C is only 125 mAh / g, reflecting the low specific capacity of the single-phase LLZTO electrolyte cell. Figure 12The graph shows the cycling performance of the LLZTO pouch cell prepared in Comparative Example 2 at different current densities. The graph shows that the capacity of the cell decreases rapidly with increasing rate, indicating that the single-phase LLZTO electrolyte cell has poor rate performance. Figure 13 shows the charge-discharge curves of the LLZTO pouch cell prepared in Comparative Example 2 under 0.2 C charging and 0.5 C discharging conditions; Figure 14 shows the capacity retention and coulombic efficiency of the LLZTO pouch cell prepared in Comparative Example 2 after 120 cycles under 0.2 C charging and 0.5 C discharging conditions. The figure shows that the capacity retention dropped to 55% after only 120 cycles, reflecting the short cycle life of single-phase LLZTO electrolyte cells. Detailed Implementation

[0027] The preferred embodiments of the present invention will be described in more detail below. The raw materials used in the embodiments of the present invention are all commercially available products. LATP powder, LLZTO powder, NCM811 / NCM622 / NCA powder, and MG11 artificial graphite are all power battery-grade raw materials. LLZTO powder is purchased from Taiwan's "China Glaze Co., Ltd.", and the tantalum doping amount is 10% of the molar amount of Zr. PVDF-HFP has a molecular weight of 200,000-400,000. LiTFSI, PVDF, Super-P, NMP, ethanol, etc., are all analytical grade reagents. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. The equipment used, such as high-energy ball mills, vacuum drying ovens, and hydraulic compactors, are all conventional battery manufacturing equipment. In the embodiments of the present invention, unless otherwise specified, "%" refers to weight percentage, and the pressure unit is kg. cm - ² is a standard unit of compaction pressure. The multiplier C is defined as follows: 1C represents the current density at which the battery completes a full charge or discharge within 1 hour.

[0028] Example 1 This embodiment prepares a solid-state pouch cell enhanced with dual ceramic electrolyte and ternary NCM811 cathode. The specific steps are as follows: S1, Preparation of LATP-LLZTO composite powder: LATP powder with a D50 particle size of 1.2 μm and LLZTO powder with a cubic phase purity higher than 95% and a particle size range of 3.6 μm were selected and dispersed separately in an ethanol solution. After thorough stirring, LATP and LLZTO slurries with a solid content of 35% were obtained. The two slurries were then mixed at a 1:1 weight ratio and dispersed for another 3 hours to form a uniform LATP-LLZTO mixed slurry. This slurry was then placed in a 110°C oven for 2 hours to finally obtain the LATP-LLZTO composite powder. Analysis showed that the elements in the composite powder were uniformly distributed (see [link to relevant documentation]). Figure 1 This achieves uniform dispersion at the nanoscale. S2, Preparation of LATP-LLZTO electrolyte slurry: In a glove box, dissolve 40g LiTFSI and 40g PVDF-HFP in 50 mL NMP, and add 20g of LATP-LLZTO composite powder obtained in step S1 to the solution, wherein LATP... LLZTO composite powder, LiTFSI, PVDF HFP accounted for 20%, 40%, and 40% of the total solid mass, respectively, and the overall solid content of the system was 65%. The system was then ball-milled for 3 hours in a high-energy ball mill to obtain a uniform electrolyte slurry. S3, Preparation of NCM811 Positive Electrode: NCM811 powder, PVDF, and Super-P conductive additive were mixed with NMP solvent in a mass ratio of 95:3:2 to prepare a positive electrode slurry; then, it was uniformly coated onto the surface of a 10 μm thick aluminum foil, controlling the wet film thickness at 150 μm; the coated electrode was vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The material is compacted under pressure to reduce its thickness to about 50 μm, thus obtaining the NCM811 positive electrode sheet; S4, Preparation of NCM811 / / LATP-LLZTO composite electrode: The electrolyte slurry obtained in step S2 is uniformly coated onto the NCM811 positive electrode obtained in step S3, controlling the wet film thickness at 50 μm. It is then vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The material was compacted under pressure to achieve an overall thickness of approximately 75 μm, resulting in NCM811 / / LATP. LLZTO composite electrode; S5, Preparation of MG11 negative electrode sheet: Artificial graphite, PVDF, and Super-P were mixed with NMP in a mass ratio of 94:4:2 to prepare a negative electrode slurry; this slurry was then uniformly coated onto a 9 μm thick copper foil, controlling the wet film thickness at 150 μm; the coated negative electrode sheet was then vacuum-dried at 135°C for 24 hours, and then subjected to 200 kg… cm - The electrode is compacted under pressure to reduce its thickness to about 50 μm, thus obtaining the MG11 electrode. S6, Battery Assembly: In the glove box, combine the NCM811 / / LATP obtained from steps S4 and S5. LLZTO composite electrodes and MG11 electrodes are assembled into NCM811 / / LATP LLZTO / / MG11 Soft-pack battery.

[0029] The electrochemical and safety performance of the pouch cell prepared in this embodiment were tested, and the results are as follows: the total internal resistance of the battery is 2.45 Ω, and the Li... + The diffusion coefficient is 7.09 × 10⁻⁶. - ¹ 0 cm² s - ¹; At a 0.1 C rate, the discharge capacity reaches 184 mAh / g (see Figure 2, Figure 3 At 0.2C, 0.5C, 1C, and 2C rates, the capacity retention rates were 93.4%, 87.4%, 78.1%, and 54.6%, respectively, demonstrating excellent rate performance. Under 0.2C charging and 0.5C discharging conditions, the charge-discharge curves for the 3rd and 800th cycles were almost symmetrical (see Figure 4). Figure 5 After 800 cycles, the capacity retention rate is >70%, the average coulombic efficiency is >99.5%, and the cycle stability is excellent. In the safety demonstration, after the fully charged battery was cut in half, the remaining half battery could still light up the LED light without thermal runaway, smoke, fire or explosion (see Figure 6), demonstrating excellent safety performance.

[0030] Example 2 This embodiment is based on Example 1, but the weight ratio of LATP slurry to LLZTO slurry is adjusted to 3:2. All other raw material specifications and process parameters remain the same as in Example 1. The specific steps are as follows: S1. Preparation of LATP-LLZTO composite powder: LATP powder with a D50 particle size of 1.2 μm and LLZTO powder with a cubic phase purity of over 95% and a particle size range of 3.6 μm were selected and dispersed separately in an ethanol solution. After thorough stirring, LATP slurry and LLZTO slurry with a solid content of 35% were obtained. Then, the two slurries were mixed at a weight ratio of 3:2 and dispersed for another 3 hours to form a uniform LATP-LLZTO mixed slurry. The slurry was then placed in an oven at 110°C for 2 hours to finally obtain LATP-LLZTO composite powder. The analysis showed that the elements in the composite powder were uniformly distributed, achieving uniform dispersion at the nanoscale. S2, Preparation of LATP-LLZTO electrolyte slurry: Dissolve 40g LiTFSI and 40g PVDF-HFP in 50 mL NMP in a glove box, and add 20g LATP-LLZTO composite powder to the solution. Ball mill for 3 hours using a high-energy ball mill to obtain a uniform electrolyte slurry. S3, Preparation of NCM811 positive electrode sheet: Same as step S3 in Example 1; S4, Preparation of NCM811 / / LATP-LLZTO composite electrode: Same as step S4 in Example 1; S5, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S6, Battery assembly: Same as step S6 in Example 1.

[0031] The performance of the pouch cell prepared in this embodiment was tested, and the results were as follows: the total internal resistance of the battery was 2.52 Ω, and the Li... + The diffusion coefficient is 6.85 × 10⁻⁶. - ¹ 0 cm² s - ¹; The discharge capacity at 0.1 C rate is 182 mAh / g; the capacity retention rates at 0.2C, 0.5C, 1C, and 2C rates are 92.8%, 86.7%, 77.5%, and 53.9%, respectively; under 0.2 C charging and 0.5 C discharging conditions, the capacity retention rate after 800 cycles is 69.2%, and the average coulombic efficiency is >99.5%; in safety testing, no thermal runaway occurred after mechanical damage. This embodiment, by adjusting the ratio of LATP to LLZTO to 3:2, still maintains excellent electrochemical and safety performance, with only a slight increase in internal resistance and a slight decrease in capacity, indicating that the ratio range of this invention has good adaptability.

[0032] Example 3 This embodiment is based on Example 1, but the weight ratio of LATP slurry to LLZTO slurry is adjusted to 2:3. All other raw material specifications and process parameters remain the same as in Example 1. The specific steps are as follows: S1. Preparation of LATP-LLZTO composite powder: LATP powder with a D50 particle size of 1.2 μm and LLZTO powder with a cubic phase purity of over 95% and a particle size range of 3.6 μm were selected and dispersed separately in an ethanol solution. The mixture was stirred thoroughly to obtain LATP and LLZTO slurries, each with a solid content of 35%. The two slurries were then mixed at a weight ratio of 2:3 and dispersed for another 3 hours to form a uniform LATP-LLZTO mixed slurry. This slurry was then placed in a 110°C oven for 2 hours to finally obtain the LATP-LLZTO composite powder. Testing showed that the elements in the composite powder were uniformly distributed, achieving uniform dispersion at the nanoscale. S2, Preparation of LATP-LLZTO electrolyte slurry: Same as step S2 in Example 1; S3, Preparation of NCM811 positive electrode sheet: Same as step S3 in Example 1; S4, Preparation of NCM811 / / LATP-LLZTO composite electrode: Same as step S4 in Example 1; S5, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S6, Battery assembly: Same as step S6 in Example 1.

[0033] The performance of the pouch cell prepared in this embodiment was tested, and the results were as follows: the total internal resistance of the battery was 2.48 Ω, and the Li... + The diffusion coefficient is 6.98 × 10⁻⁶. - ¹ 0 cm² s -¹; The discharge capacity at 0.1 C rate is 183 mAh / g; the capacity retention rates at 0.2C, 0.5C, 1C, and 2C rates are 93.1%, 87.0%, 77.8%, and 54.2%, respectively; under 0.2 C charging and 0.5 C discharging conditions, the capacity retention rate after 800 cycles is 69.7%, and the average coulombic efficiency is >99.5%; in safety testing, no thermal runaway occurred after mechanical damage. In this embodiment, by adjusting the ratio of LATP to LLZTO to 2:3, the electrochemical performance is close to that of Example 1, only slightly lower than the 1:1 ratio, indicating that 1:1 is the optimal weight ratio, and the excellent performance can be achieved in the ratio range of 3:2 to 2:3 of this invention.

[0034] Example 4 This embodiment is based on Embodiment 1, but the positive electrode active material is replaced with LiNi. 0.8 Co 0.15 Al 0.05 O2 (NCA), and the specifications of other raw materials and process parameters are the same as in Example 1. The specific steps are as follows: S1, Preparation of LATP-LLZTO composite powder: Same as step S1 in Example 1; S2, Preparation of LATP-LLZTO electrolyte slurry: Same as step S2 in Example 1; S3, Preparation of NCA Positive Electrode: NCA powder, PVDF, and Super-P conductive additive were mixed with NMP solvent in a mass ratio of 95:3:2 to prepare a positive electrode slurry; then, it was uniformly coated onto the surface of a 10 μm thick aluminum foil, controlling the wet film thickness at 150 μm; the coated electrode was vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The material is compacted under pressure to reduce its thickness to about 50 μm, thus obtaining the NCA positive electrode sheet. S4, Preparation of NCA / / LATP-LLZTO composite electrode: The electrolyte slurry obtained in step S2 is uniformly coated onto the NCA positive electrode obtained in step S3, controlling the wet film thickness at 50 μm. It is then vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The material was compacted under pressure to achieve an overall thickness of approximately 75 μm, yielding NCA / / LATP. LLZTO composite electrode; S5, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S6, Battery Assembly: In the glove box, combine NCA / / LATP LLZTO composite electrodes and MG11 electrodes are assembled into NCA / / LATP. LLZTO / / MG11 Soft-pack battery.

[0035] The performance of the pouch cell prepared in this embodiment was tested, and the results were as follows: the total internal resistance of the battery was 2.60 Ω, and the Li... + The diffusion coefficient is 6.65 × 10⁻⁶. - ¹ 0 cm² s - ¹; The discharge capacity at 0.1 C rate is 180 mAh / g; the capacity retention rates at 0.2C, 0.5C, 1C, and 2C rates are 92.0%, 85.8%, 76.5%, and 53.0%, respectively; under 0.2C charging and 0.5C discharging conditions, the capacity retention rate after 800 cycles is 68.0%, and the average coulombic efficiency is >99.5%; in safety testing, no thermal runaway occurred after mechanical damage. This embodiment demonstrates that the LATP-LLZTO dual ceramic electrolyte system of the present invention is not only suitable for NCM811 cathodes but also for nickel-rich ternary cathodes such as NCA, exhibiting good cathode compatibility.

[0036] Example 5 This embodiment is based on Example 1, except that the positive electrode active material is replaced with NCM622. All other raw material specifications and process parameters are the same as in Example 1. The specific steps are as follows: S1, Preparation of LATP-LLZTO composite powder: Same as step S1 in Example 1; S2, Preparation of LATP-LLZTO electrolyte slurry: Same as step S2 in Example 1; S3, Preparation of NCM622 positive electrode sheet: NCM622 powder, PVDF, and Super-P conductive additive were mixed with NMP solvent in a mass ratio of 95:3:2 to prepare a positive electrode slurry; then, it was uniformly coated onto the surface of a 10 μm thick aluminum foil, controlling the wet film thickness at 150 μm; the coated electrode sheet was vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The material is compacted under pressure to reduce its thickness to about 50 μm, thus obtaining the NCM622 positive electrode sheet; S4, Preparation of NCM622 / / LATP-LLZTO composite electrode: The electrolyte slurry obtained in step S2 is uniformly coated onto the NCM622 positive electrode obtained in step S3, controlling the wet film thickness at 50 μm. It is then vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The material was compacted under pressure to achieve an overall thickness of approximately 75 μm, yielding NCM622 / / LATP. LLZTO composite electrode; S5, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S6, Battery Assembly: In the glove box, combine NCM622 / / LATP LLZTO composite electrodes and MG11 electrodes are assembled into NCM622 / / LATP LLZTO / / MG11 Soft-pack battery.

[0037] The performance of the pouch cell prepared in this embodiment was tested, and the results were as follows: the total internal resistance of the battery was 2.58 Ω, and the Li... + The diffusion coefficient is 6.70 × 10⁻⁶. - ¹ 0 cm² s - ¹; The discharge capacity at 0.1 C rate is 165 mAh / g; the capacity retention rates at 0.2C, 0.5C, 1C, and 2C rates are 93.5%, 87.6%, 78.3%, and 55.0%, respectively; under 0.2C charging and 0.5C discharging conditions, the capacity retention rate after 800 cycles is 72.0%, and the average coulombic efficiency is >99.6%; in safety testing, no thermal runaway occurred after mechanical damage. This embodiment demonstrates that the LATP-LLZTO dual ceramic electrolyte system of the present invention is suitable for NCM ternary cathodes with different nickel contents, and exhibits superior cycle stability in NCM622 cathodes, further illustrating that the electrolyte system of the present invention has broad cathode compatibility.

[0038] Comparative Example 1 This comparative example uses a single LATP electrolyte, with all other raw material specifications and process parameters identical to those in Example 1. It is used to compare and illustrate the performance deficiencies of the single-phase LATP electrolyte. The specific steps are as follows: S1, Preparation of LATP electrolyte slurry: Dissolve 40g LiTFSI and 40g PVDF-HFP in 50 mL NMP in a glove box, and add 20g of commercially available LATP powder with a particle size of 1.2μm (D50) to the solution. Ball mill the solution for 3 hours using a high-energy ball mill to obtain LATP electrolyte slurry; S2, Preparation of NCM811 positive electrode sheet: Same as step S3 in Example 1; S3, Preparation of NCM811 / / LATP composite electrode: LATP electrolyte slurry was uniformly coated onto the NCM811 positive electrode, controlling the wet film thickness to 50 μm. It was then vacuum-dried at 135°C for 12 hours, and then subjected to 200 kg… cm - The NCM811 / / LATP composite electrode was obtained by compacting it under pressure to make its overall thickness about 75 μm. S4, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S5, Battery Assembly: In the glove box, assemble the NCM811 / / LATP composite electrode and the MG11 electrode into an NCM811 / / LATP / / MG11 pouch cell.

[0039] The performance of the pouch cell prepared in this comparative example was tested, and the results are as follows (see Figures 7, 8, 9, and 10): The total internal resistance of the battery was 4.35 Ω, which is much higher than that of Example 1; at a rate of 0.1 C, the discharge capacity reached 186 mAh / g, but at rates of 0.2 C, 0.5 C, 1 C, and 2 C, the capacity retention rates were only 88.2%, 77.9%, 66.1%, and 48.4%, respectively, indicating extremely poor rate performance; under the conditions of 0.2 C charging and 0.5 C discharging, the charge-discharge curves of the 3rd and 800th cycles showed poor symmetry, indicating a high degree of irreversibility in the lithium-ion insertion / extraction process; after 800 cycles, the capacity retention rate was only 18%, indicating extremely poor cycle stability; and the battery exhibited obvious electrode polarization in the later stages of cycling, ultimately leading to battery failure due to interface separation. This comparative example demonstrates that single-phase LATP electrolytes have fatal defects such as poor interface stability, high internal resistance, and short cycle life, which cannot meet the practical requirements of solid-state batteries.

[0040] Comparative Example 2 This comparative example uses LLZTO as the electrolyte, and all other raw material specifications and process parameters are the same as in Example 1. It is used to compare and illustrate the performance defects of single-phase LLZTO electrolytes. The specific steps are as follows: S1, Preparation of LLZTO electrolyte slurry: Dissolve 40g LiTFSI and 40g PVDF-HFP in 50 mL NMP in a glove box, and add 20g of commercially available LLZTO powder with a cubic phase purity higher than 95% to the solution. Ball mill for 3 hours using a high-energy ball mill to obtain LLZTO electrolyte slurry; S2, Preparation of NCM811 positive electrode sheet: Same as step S3 in Example 1; S3, Preparation of NCM811 / / LLZTO composite electrode: LLZTO electrolyte slurry was uniformly coated onto the NCM811 positive electrode, controlling the wet film thickness to 50 μm. It was then vacuum dried at 135°C for 12 hours, followed by drying with 200 kg... cm - The pressure is used to compact the material, making its overall thickness about 75 μm, to obtain the NCM811 / / LLZTO composite electrode. S4, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S5, Battery Assembly: In the glove box, assemble the NCM811 / / LLZTO composite electrode and the MG11 electrode into an NCM811 / / LLZTO / / MG11 pouch cell.

[0041] The performance of the pouch cell prepared in this comparative example was tested, and the results are as follows (see...). Figure 11 , 12 (13, 14): The total internal resistance of the battery is 3.05 Ω, higher than that of Example 1; at a 0.1 C rate, the discharge capacity is only 125 mAh / g, far lower than that of Example 1, and the capacity retention rate drops significantly at 0.2C, 0.5C, 1C and 2C rates, indicating extremely poor rate performance; under 0.2C charging and 0.5C discharging conditions, the capacity retention rate drops to 55% after only 120 cycles, indicating extremely short cycle life; furthermore, the high grain boundary impedance of the single-phase LLZTO electrolyte leads to low lithium-ion transport efficiency, and the battery always exhibits severe electrode polarization. This comparative example demonstrates that the single-phase LLZTO electrolyte has defects such as low specific capacity, high grain boundary impedance and short cycle life, and thus cannot meet the practical requirements of solid-state batteries.

[0042] Comparative Example 3 This comparative example replaces the positive electrode active material with lithium cobalt oxide (LCO), while the specifications of other raw materials and process parameters are the same as in Example 1. It is used to compare and illustrate the compatibility of the electrolyte system of this invention with different positive electrodes. The specific steps are as follows: S1, Preparation of LATP-LLZTO composite powder: Same as step S1 in Example 1; S2, Preparation of LATP-LLZTO electrolyte slurry: Same as step S2 in Example 1; S3, Preparation of LCO Positive Electrode: LCO powder, PVDF, and Super-P conductive additive were mixed with NMP solvent in a mass ratio of 95:3:2 to prepare a positive electrode slurry; then, it was uniformly coated onto the surface of a 10 μm thick aluminum foil, controlling the wet film thickness at 150 μm; the coated electrode was vacuum dried at 135°C for 12 hours, and then subjected to 200 kg... cm - The pressure is used to compact the material, reducing its thickness to about 50 μm, thus obtaining the LCO positive electrode sheet; S4, Preparation of LCO / / LATP-LLZTO composite electrode: Same as step S4 in Example 1; S5, Preparation of MG11 negative electrode sheet: Same as step S5 in Example 1; S6, Battery Assembly: In the glove box, assemble the LCO / / LATP-LLZTO composite electrode and the MG11 electrode into an LCO / / LATP-LLZTO / / MG11 pouch cell.

[0043] The performance of the pouch cell prepared in this comparative example was tested, and the results were as follows: the total internal resistance of the cell was 2.80 Ω, and the Li... + The diffusion coefficient is 6.20 × 10⁻⁶. - ¹ 0 cm² s - ¹; The discharge capacity at 0.1 C rate is only 140 mAh / g, far lower than that of NCM811 cathode; the capacity retention rates at 0.2C, 0.5C, 1C, and 2C rates are 90.5%, 84.2%, 75.1%, and 51.2%, respectively; under 0.2C charging and 0.5C discharging conditions, the capacity retention rate after 800 cycles is 65.0%. This comparative example demonstrates that the electrolyte system of the present invention has poor compatibility with lithium cobalt oxide cathodes, but good compatibility with nickel-rich ternary cathodes (NCM811, NCA, NCM622), further illustrating that the interface design of the electrolyte system of the present invention for nickel-rich ternary cathodes is targeted and effective.

[0044] Comparative Example 4 This comparative example replaces the negative electrode with amorphous carbon, while the specifications of other raw materials and process parameters are the same as in Example 1. It is used to compare and illustrate the impact of the negative electrode selection on battery performance. The specific steps are as follows: S1, Preparation of LATP-LLZTO composite powder: Same as step S1 in Example 1; S2, Preparation of LATP-LLZTO electrolyte slurry: Same as step S2 in Example 1; S3, Preparation of NCM811 positive electrode sheet: Same as step S3 in Example 1; S4, Preparation of NCM811 / / LATP-LLZTO composite electrode: Same as step S4 in Example 1; S5, Preparation of amorphous carbon negative electrode sheet: Amorphous carbon, PVDF, and Super-P were mixed with NMP in a mass ratio of 94:4:2 to prepare a negative electrode slurry; then uniformly coated onto the surface of a 9 μm thick copper foil, controlling the wet film thickness at 150 μm; the coated negative electrode sheet was vacuum dried at 135°C for 24 hours, and then subjected to 200 kg... cm - The amorphous carbon negative electrode sheet is obtained by compacting it under pressure of 2 to reduce its thickness to about 50 μm. S6, Battery Assembly: In the glove box, assemble the NCM811 / / LATP-LLZTO composite electrode and the amorphous carbon negative electrode into an NCM811 / / LATP-LLZTO / / amorphous carbon pouch cell.

[0045] The performance of the pouch cell prepared in this comparative example was tested, and the results were as follows: the total internal resistance of the cell was 3.50 Ω, and the Li... + The diffusion coefficient is 5.80 × 10⁻⁶. - ¹ 0 cm² s - ¹; The discharge capacity at 0.1 C rate is 170 mAh / g, lower than that of Example 1; the capacity retention rates at 0.2C, 0.5C, 1C, and 2C rates are 91.0%, 85.0%, 76.0%, and 52.0%, respectively; and the capacity retention rate after 800 cycles under 0.2C charging and 0.5C discharging conditions is 66.0%. This comparative example demonstrates that the MG11 artificial graphite anode has better compatibility with the LATP-LLZTO electrolyte system and NCM811 cathode of this invention, effectively reducing battery internal resistance and improving ion transport efficiency, while the amorphous carbon anode suffers from low ion transport efficiency, leading to a decline in battery performance.

[0046] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0047] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0048] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A ternary NCM solid-state battery, characterized in that, A pouch cell is assembled from an NCM ternary / / LATP-LLZTO composite electrode and an artificial graphite negative electrode. The NCM ternary / / LATP-LLZTO composite electrode is prepared by directly coating an LATP-LLZTO dual-ceramic electrolyte slurry onto an NCM ternary positive electrode, followed by drying and compaction. The weight ratio of LATP to LLZTO in the LATP-LLZTO dual-ceramic electrolyte is 3:2 to 2:

3. The total internal resistance of the solid-state battery is ≤2.55Ω, and the Li... + Diffusion coefficient ≥ 6.72 × 10 - ¹ 0 cm² s - ¹, discharge capacity ≥181 mAh g at 0.1 C rate. - ¹, after 800 cycles, the capacity retention rate is >68%, and the average coulombic efficiency is >99.5%.

2. The solid-state battery according to claim 1, characterized in that, The LATP-LLZTO dual ceramic electrolyte is prepared by combining LATP powder and LLZTO powder via liquid-phase dispersion. The D50 particle size of the LATP powder is 1–3 μm, and the cubic phase purity of the LLZTO powder is higher than 95% with a particle size range of 3–8 μm.

3. The solid-state battery according to claim 1, characterized in that, The NCM ternary cathode sheet is prepared by coating, drying, and compacting a cathode slurry made by mixing NCM ternary powder, PVDF, and Super-P conductive additive in a mass ratio of 95:3:2 with NMP solvent; the aluminum foil substrate of the NCM ternary cathode sheet has a thickness of 10 μm, and the thickness after compaction is 45~55 μm.

4. The solid-state battery according to claim 3, characterized in that, The NCM ternary powder is LiNi x Co Mn z O2, where x+y+z=1 and x≥0.6; preferably, the NCM ternary powder is selected from at least one of NCM811 and NCM622, where the chemical formula of NCM811 is LiNi0.8Co0.1Mn0.1O2 and the chemical formula of NCM622 is LiNi0.6Co0.2Mn0.2O2; or, the NCM ternary powder is NCA, with the chemical formula LiNi 0.8 Co 0.15 Al 0.05 O2.

5. The solid-state battery according to claim 1, characterized in that, The artificial graphite negative electrode sheet is prepared by coating, drying, and compacting a negative electrode slurry made by mixing artificial graphite, PVDF, and Super-P in a mass ratio of 94:4:2 with NMP solvent; the copper foil substrate of the artificial graphite negative electrode sheet has a thickness of 9~10μm, and the thickness after compaction is 45~55μm.

6. The solid-state battery according to claim 5, characterized in that, The artificial graphite is MG11 artificial graphite; the overall thickness of the NCM ternary / / LATP-LLZTO composite electrode after compaction is 70-80μm.

7. The solid-state battery according to any one of claims 1-6, characterized in that, The solid-state battery exhibits capacity retention rates of ≥92.0%, 85.8%, 76.5%, and 53.0% at 0.2C, 0.5C, 1C, and 2C rates, respectively, and shows no thermal runaway phenomena such as smoke, fire, or explosion after mechanical damage under full charge conditions; when the NCM ternary powder is NCM811, the total internal resistance of the battery is 2.45Ω, and the Li... + The diffusion coefficient is 7.09 × 10⁻⁶. - ¹ 0 cm² s - ¹, The discharge capacity at 0.1C is 184 mAh g. - ¹.

8. A method for preparing a solid-state battery according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of LATP-LLZTO composite powder: LATP powder and LLZTO powder are dispersed in a solution and stirred to obtain LATP slurry and LLZTO slurry; then they are mixed, dispersed and dried to obtain LATP-LLZTO composite powder. S2. Preparation of LATP-LLZTO electrolyte slurry: In a glove box, LiTFSI and PVDF-HFP are dissolved in NMP solvent, LATP-LLZTO composite powder is added, and the mixture is ball-milled to obtain electrolyte slurry; S3. Preparation of NCM ternary cathode sheet: NCM ternary powder, PVDF, Super-P and NMP are mixed to prepare cathode slurry, coated on aluminum foil, vacuum dried and compacted to 45-55μm to obtain NCM ternary cathode sheet; S4. Preparation of NCM ternary / / LATP-LLZTO composite electrode: The LATP-LLZTO electrolyte slurry is coated on the NCM ternary positive electrode, vacuum dried and compacted to 70-80μm to obtain the composite electrode. S5. Preparation of artificial graphite negative electrode sheet: Artificial graphite, PVDF, and Super-P are mixed with NMP in a mass ratio of 94:4:2 to prepare a negative electrode slurry. This slurry is coated onto copper foil to a wet film thickness of 130-150 μm and vacuum-dried at 120-135℃ for 24 hours. 200 kg cm - ² Compacted to approximately 50μm, an artificial graphite negative electrode sheet is obtained; S6. Battery Assembly: In the glove box, NCM ternary / / LATP-LLZTO composite electrode and artificial graphite negative electrode are assembled into a soft-pack solid-state battery.

9. The preparation method according to claim 8, characterized in that, In step S1, the solid content of both LATP slurry and LLZTO slurry is 30–60%, and then they are mixed at a weight ratio of 3:2 to 2:3, dispersed for 2–5 hours, and then dried in an oven at 100–150°C for 1–3 hours to obtain LATP-LLZTO composite powder. In step S2, the molecular weight of the PVDF-HFP is 200,000-400,000; LATP LLZTO composite powder, LiTFSI, PVDF HFP accounts for 20%–50%, 25%–40%, and 25%–40% of the total solids mass, respectively, and the total solids content of the electrolyte slurry is 60-70%.

10. The preparation method according to claim 8, characterized in that, In step S3, NCM ternary powder, PVDF, and Super-P are mixed with NMP at a mass ratio of 95:3:2 to prepare a positive electrode slurry. This slurry is then coated onto aluminum foil to achieve a wet film thickness of 130-150 μm and vacuum-dried at 120-135℃ for 12 hours. The resulting product is 200 kg. cm - ² Compact to 45-55μm to obtain NCM ternary cathode sheet; In step S4, LATP-LLZTO electrolyte slurry is coated onto the NCM ternary cathode sheet to a wet film thickness of 30-50 μm, and vacuum dried at 120-135℃ for 12 hours, yielding 200 kg. cm - ² Compact to 70-80μm to obtain composite electrode; In step S5, artificial graphite, PVDF, and Super-P are mixed with NMP in a mass ratio of 94:4:2 to prepare a negative electrode slurry, which is then coated onto copper foil to achieve a wet film thickness of 130-150 μm. The slurry is then vacuum-dried at 120-135℃ for 24 hours, yielding 200 kg of the desired product. cm - ² Compact to 45-55μm to obtain artificial graphite anode sheet.

Images