Solid-state battery and method of manufacturing the same

Abstract

The application belongs to the field of batteries, and specifically discloses a solid-state battery and a preparation method thereof. In the solid-state battery, on the positive electrode side, a positive electrode active material layer is tightly attached to a first electrolyte layer mainly composed of a halide electrolyte, and on the negative electrode side, a negative electrode active material layer is tightly attached to a second electrolyte layer mainly composed of a sulfide electrolyte. The two electrolyte layers are prepared by in-situ polymerization, which can significantly reduce the solid-solid interface impedance between the electrode and the electrolyte, simultaneously solve the two bottlenecks of ion transport and interface side reaction, and achieve the purposes of improving the initial efficiency and the cycle performance of the solid-state battery.

Description

Technical Field

[0001] This invention belongs to the field of batteries, specifically relating to a solid-state battery and its preparation method. Background Technology

[0002] Current solid-state battery cell fabrication typically involves separately preparing the positive and negative electrodes and electrolyte materials, following a stacked assembly process to achieve integrated operation. The positive electrode is usually prepared by mixing the positive active material, solid electrolyte, conductive agent, and binder into a slurry, coating it onto a current collector, and then drying it. The negative electrode is often made directly from lithium metal foil, composite lithium foil, or carbon / silicon-based materials. The key solid electrolyte layer preparation methods include: sulfide or halide ceramics are formed into dense sheets through cold isostatic pressing or hot sintering; polymer-based electrolytes are formed by solution casting or by directly using a precursor solution. Subsequently, under an inert atmosphere, the positive electrode, solid electrolyte layer, and negative electrode are stacked sequentially in a "sandwich" structure, and high temperature and pressure are applied through precision rolling or hot pressing processes to eliminate interlayer gaps and enhance interfacial contact, forming a mechanically integrated battery cell prototype.

[0003] Although the existing manufacturing technology path for all-solid-state battery cells is clear, its core processes still have defects, which seriously restrict the industrialization process. For example, whether by high-pressure rolling or hot pressing, it is difficult to achieve a truly tight and conformal contact between the electrode and the electrolyte at the microscale, resulting in extremely high interfacial charge transfer resistance. Therefore, solid-solid interface resistance is a fundamental problem, which seriously affects the rate performance and power density of the battery. Summary of the Invention

[0004] In view of the problem that the high solid-solid interface impedance of solid-state batteries affects their electrical performance, the present invention will provide a solid-state battery and a method for preparing the same.

[0005] To achieve the above objectives, the following technical solutions are specifically included: On one hand, the present invention provides a solid-state battery, comprising a positive electrode current collector, a positive electrode active material layer located on at least one side surface of the positive electrode current collector, a first electrolyte layer, a second electrolyte layer, a negative electrode current collector, and a negative electrode active material layer located on at least one side surface of the negative electrode current collector, wherein the first electrolyte layer is disposed on the positive electrode active material layer, and the second electrolyte layer is disposed on the negative electrode active material layer. The first electrolyte layer is obtained by in-situ polymerization of the following raw material components in parts by weight: 50-90 parts of halide electrolyte, 1-40 parts of sulfide electrolyte, 1-20 parts of polymer monomer, 1-10 parts of lithium salt, 0-2 parts of initiator, 0-10 parts of polymer, and 0-10 parts of additives. The second electrolyte layer is obtained by in-situ polymerization of the following raw material components in parts by weight: 50-90 parts of sulfide electrolyte, 1-40 parts of halide electrolyte, 1-20 parts of polymer monomer, 1-10 parts of lithium salt, 0-2 parts of initiator, 0-10 parts of polymer, and 0-10 parts of additives.

[0006] In the solid-state battery of this invention, on the positive electrode side, the positive electrode active material layer is closely bonded to a first electrolyte layer mainly composed of a halide electrolyte, which can enhance high-voltage interface passivation, reduce interfacial side reactions between the positive electrode and the electrolyte, significantly improve the interfacial stability of the positive electrode and the electrolyte, and reduce interfacial impedance. On the negative electrode side, the negative electrode active material layer is closely bonded to a second electrolyte layer mainly composed of a sulfide electrolyte, which can fully utilize its high lithium-ion conductivity and reduce the interfacial impedance between the negative electrode and the electrolyte. At the same time, the first electrolyte layer and the second electrolyte layer are obtained by in-situ polymerization of raw materials including polymeric monomers. The in-situ polymerization process realizes nanoscale interfacial modification of the positive electrode active material layer, the first electrolyte layer, the second electrolyte layer, and the positive electrode active material layer, making the contact between each layer tighter, so as to achieve efficient lithium conduction and high stability between layers. This simultaneously solves the two major bottlenecks of ion transport and interfacial side reactions, further reduces interfacial impedance, and comprehensively achieves the goal of improving the battery performance of the solid-state battery.

[0007] Preferably, the first electrolyte layer and the second electrolyte layer are located between the positive electrode active material layer and the negative electrode active material layer, and the first electrolyte layer covers the positive electrode active material layer, and the second electrolyte layer covers the negative electrode active material layer.

[0008] Preferably, the solid-state battery includes a positive current collector, positive active material layers on both sides of the positive current collector, a negative current collector, and negative active material layers on both sides of the negative current collector. The positive active material layers on both sides of the positive current collector are respectively covered with the first electrolyte layer, and the negative active material layers on both sides of the negative current collector are respectively covered with the second electrolyte layer.

[0009] Preferably, the sulfide electrolytes in the first electrolyte layer and the second electrolyte layer are each independently selected from Li2S-P2S5 and Li7P3S. 11 Li6PS5Cl, Li 5.5 PS5Cl 1.5 Li6PS5Br, Li6PS5I, Li 11 Si2PS 12 Li 10 Sn2PS 12 and Li 10 Ge2P2S 12At least one of the above-mentioned sulfide electrolytes. Using the above-mentioned sulfide electrolyte can improve the interfacial stability of the solid-state battery, which is more conducive to improving the performance of the battery.

[0010] Preferably, the halide electrolytes in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of Li3YCl6, Li2ZrCl6, Li3InCl6, Li2InCl5Br, Li3YBr3Cl3, Li3ScCl6, Li3HoCl6, Li3PBr6, Li3SbBr6, and LiCrBr4. Using the aforementioned halide electrolytes can improve the interfacial ion transport effect of the solid-state battery, which is more conducive to improving the battery's performance.

[0011] Preferably, the monomers in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of acrylate compounds, styrene and its derivatives, and crosslinking agents. The monomers can be polymerized through thermal or photoinitiation. The polymers obtained after in-situ polymerization can effectively improve the interfacial contact between the solid electrolyte and the electrode, enhance the mechanical strength of the electrolyte, and suppress dendrite formation, thereby improving battery performance. Styrene compounds include styrene and its derivatives; acrylate compounds are compounds comprising acrylate groups and / or methacrylate groups.

[0012] More preferably, the acrylate compound includes at least one of polyethylene glycol diacrylate, methacrylate, methyl methacrylate, ethyl methacrylate, trifluoroethyl acrylate, pentafluoropropyl acrylate, hexafluorobutyl acrylate, butyl acrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate.

[0013] More preferably, the styrene compounds include at least one of styrene, methylstyrene, 4-fluorostyrene, p-methylstyrene, m-methoxystyrene, methyl p-vinylbenzoate, p-cyanostrene, p-nitrostyrene, divinylbenzene, and p-mercaptostyrene.

[0014] More preferably, the polymer monomers in the first electrolyte layer and the second electrolyte layer each independently include acrylate compounds and styrene compounds, and the mass ratio of acrylate compounds to styrene compounds is (0.05-1):(1-20).

[0015] Preferably, the lithium salts in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium dioxalate borate, lithium trifluoromethanesulfonate, lithium tetrachloroaluminate, lithium 4,5-dicyano-2-trifluoromethylimidazolium, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, and lithium nitrate. The presence of lithium salts in both electrolyte layers further enhances ion transport efficiency at the interface, thereby improving battery performance.

[0016] Preferably, the polymers in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of the following: vinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, styrene-ethylene-butene-styrene copolymer, butadiene-styrene copolymer, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, cellulose, polystyrene, polymethacrylate, polyvinyl chloride, polyamide, polyimide, polyetherimide, polyethylene, polypropylene, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-butadiene rubber, nitrile rubber, cis-butadiene rubber, butadiene rubber, sodium carboxymethyl cellulose, polyphenylene sulfide, and polyetheretherketone. The polymers may optionally include binders and polymer electrolytes, which further improves the interlayer bonding strength and conductivity, and further enhances the interlayer structural stability and battery performance.

[0017] Preferably, the additives in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of ionic liquids, alumina nanoparticles, magnesium oxide nanoparticles, zirconium oxide nanoparticles, silicon oxide nanoparticles, titanium oxide nanoparticles, zinc oxide nanoparticles, lithium fluoride, magnesium fluoride, zinc fluoride, lithium chloride, lithium bromide, and lithium iodide. The role of the additives is to further improve the solid-solid interface contact in the solid-state battery and reduce the interface impedance.

[0018] More preferably, the ionic liquid includes at least one of imidazole, pyridine, quaternary ammonium, quaternary phosphorus, pyrrolidine, and piperidine ionic liquids.

[0019] Preferably, the initiators in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, potassium persulfate, ammonium persulfate, 2-hydroxy-2-methyl-1-phenylpropanone, methyl benzoylformate, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone.

[0020] Preferably, the solid-state battery satisfies the following relationship: M3≥M1; and or, M4≥M2; In the formula, M1 is the area of ​​the positive electrode active material layer, M2 is the area of ​​the first electrolyte layer, M3 is the area of ​​the negative electrode active material layer, and M4 is the area of ​​the second electrolyte layer. When the above relationship is satisfied, solid-state batteries are more advantageous in balancing stacking alignment and overall electrochemical performance.

[0021] Preferably, the solid-state battery satisfies the following relationship: 1%≤(M2-M1) / M2×100%≤10%; And or, 1%≤(M4-M3) / M4×100%≤10%.

[0022] Setting a 1%-10% coating margin at the edge of the electrolyte layer relative to the active material layer can balance the interface coating effect, the alignment of the layers, and the overall electrochemical performance.

[0023] In one embodiment, M1, M2, M3, and M4 are each independently selected from 20-50cm. -2 .

[0024] It should be noted that when a solid-state battery contains multiple layers (two or more) of positive electrode active material layer, first electrolyte layer, negative electrode active material layer, and second electrolyte layer, when constructing the above relationship, M1, M2, M3, and M4 correspond to the area of ​​a single layer of positive electrode active material layer, first electrolyte layer, negative electrode active material layer, and second electrolyte layer, respectively. For example, in a preferred embodiment of the present invention, a first positive electrode active material layer and a second positive electrode active material layer are respectively disposed on both sides of the positive electrode current collector. When calculating M1, the area of ​​the first positive electrode active material layer or the second positive electrode active material layer is used. A similar situation exists for the negative electrode.

[0025] In one embodiment, the solid-state battery includes a positive current collector, positive active material layers located on both sides of the positive current collector, a negative current collector, and negative active material layers located on both sides of the negative current collector. The positive active material layers located on both sides of the positive current collector are respectively covered with a first electrolyte layer of the same area, and the negative active material layers located on both sides of the negative current collector are respectively covered with a second electrolyte layer of the same area.

[0026] Preferably, the positive electrode active material layer comprises the following components in weight percentage: 70%-95% positive electrode active material, 1%-10% conductive agent, 1%-10% binder, and 0-15% electrolyte.

[0027] More preferably, the positive electrode active material includes at least one of lithium cobalt oxide, lithium nickel cobalt oxide, lithium-rich manganese-based oxide, lithium manganese oxide, lithium nickel manganese oxide, ternary lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium manganese iron phosphate, lithium iron phosphate, and lithium sulfide.

[0028] Preferably, the negative electrode active material layer comprises the following components in weight percentage: 70%-95% negative electrode active material, 1%-10% conductive agent, 1%-10% binder, and 0-15% electrolyte.

[0029] More preferably, the negative electrode active material includes at least one of lithium metal, lithium metal alloy, hard carbon, molybdenum disulfide, lithium niobate, lithium titanate, lithium titanyl niobate, graphite, silicon, silicon oxide, silicon carbon, or silicon oxide carbon.

[0030] More preferably, the binders in the positive electrode active material layer and the negative electrode active material layer are each independently selected from at least one of carboxymethyl cellulose, sodium carboxymethyl cellulose, styrene-butadiene emulsion, and polyvinylidene fluoride (PVDF).

[0031] More preferably, the conductive agents in the positive electrode active material layer and the negative electrode active material layer are each independently selected from at least one of conductive carbon black and carbon nanotubes (CNTs).

[0032] More preferably, the electrolytes in the positive electrode active material layer and the negative electrode active material layer are each independently selected from at least one of sulfide electrolytes and halide electrolytes.

[0033] On the other hand, the present invention also provides a method for preparing the solid-state battery, comprising the following steps: S1. A slurry coated with a positive electrode active material layer on at least one side of the positive electrode current collector is dried and pressed to form a positive electrode active material layer on the positive electrode current collector. S2. The slurry for coating the first electrolyte layer onto the positive electrode active material layer is dried to form the first electrolyte layer precursor layer on the positive electrode active material layer, thus obtaining the positive electrode side component. S3. A slurry coated with a negative electrode active material layer on at least one side of the negative electrode current collector is dried and pressed to form a negative electrode active material layer on the negative electrode current collector. S4. The slurry that coats the negative electrode active material layer with the second electrolyte layer is dried to form the second electrolyte precursor layer on the negative electrode active material layer, thus obtaining the negative electrode side component. S5. Stack the positive electrode side component and the negative electrode side component to obtain a composite component; S6. Multiple composite components are alternately stacked and then cured to obtain a solid-state battery cell. The cell is then encapsulated to obtain a solid-state battery.

[0034] The slurry for the positive electrode active material layer, the slurry for the negative electrode active material layer, the slurry for the first electrolyte layer, and the slurry for the second electrolyte layer are respectively mixtures of raw materials and organic solvents for the positive electrode active material layer, the negative electrode active material layer, the first electrolyte layer, and the second electrolyte layer. The organic solvents contained in the above slurries are each independently selected from at least one of n-hexane, N-methyl-2-pyrrolidone (NMP), and toluene.

[0035] Preferably, in step S6, the curing temperature is 70-150°C.

[0036] More preferably, in step S6, the curing process includes a heating prepolymerization process and a hot-press polymerization process in sequence. The heating prepolymerization temperature is 70-100℃, the hot-press polymerization temperature is 100-150℃, and the hot-press polymerization pressure is 300-500MPa.

[0037] Compared with the prior art, the present invention has the following beneficial effects: In the solid-state battery of the present invention, on the positive electrode side, the positive electrode active material layer is closely bonded to the first electrolyte layer mainly composed of halide electrolyte; on the negative electrode side, the negative electrode active material layer is closely bonded to the second electrolyte layer mainly composed of sulfide electrolyte. Moreover, the two electrolyte layers are prepared by in-situ polymerization, which can significantly reduce the solid-solid interface impedance between the electrode and the electrolyte, and simultaneously solve the two major bottlenecks of ion transport and interfacial side reactions, thereby achieving the goal of improving the first efficiency and cycle performance of the solid-state battery. Detailed Implementation

[0038] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0039] Example 1 A method for preparing a solid-state battery includes the following steps: S1. Mix NCM811 positive electrode active material, Super-P conductive carbon black, Li3InCl6, and PVDF binder in a mass ratio of 90:4:3:3, and then disperse them in an appropriate amount of NMP (65wt% solid content) to obtain a slurry for the positive electrode active material layer. Coat the obtained slurry evenly on both sides of an aluminum foil. After drying, calendering, and vacuum drying, a first positive electrode active material layer and a second positive electrode active material layer are formed on both sides of the positive electrode current collector, respectively, to obtain a positive electrode sheet. The dimensions of the first positive electrode active material layer and the second negative electrode active material layer are the same. Measure the dimensions of the first positive electrode active material layer using a micrometer and calculate the area M1 of a single first positive electrode active material layer.

[0040] S2. By weight, 10 parts of styrene monomer, 0.5 parts of polyethylene glycol diacrylate monomer, 670 parts of Li3InCl, 5 parts of Li6PS5Cl, 5 parts of LiTFSI, and 0.05 parts of AIBN are added to 300 parts of n-hexane solvent and mixed evenly to obtain a slurry for the first electrolyte layer. The slurry for the first electrolyte layer is coated onto the first positive electrode active material layer and the second positive electrode active material layer on both sides of the positive electrode sheet, completely covering the surfaces of the first positive electrode active material layer and the second positive electrode active material layer, respectively. After drying, a first electrolyte precursor layer is formed on the first positive electrode active material layer and the second positive electrode active material layer, respectively. The coating area is controlled during the coating process to ensure that the dimensions of the first electrolyte precursor layers on both sides are the same, thus obtaining the positive electrode side component. Here, a micrometer is used to measure the dimensions of the single-layer first electrolyte precursor layer and calculate its area. Compared to the first electrolyte precursor layer, the thickness of the first electrolyte layer obtained after polymerization of the first electrolyte precursor layer will be slightly reduced, while its area will remain basically unchanged; therefore, the area of ​​the first electrolyte precursor layer can be equal to the area of ​​the first electrolyte layer; in this embodiment, the thickness of the first electrolyte precursor layer is 10 μm, the area of ​​the first electrolyte layer is denoted as M2, and M2 is slightly larger than M1.

[0041] S3. A mixture of silicon carbide (anode active material), Super-P conductive carbon black, Li6PS5Cl, and nitrile rubber in a mass ratio of 80:5:12:3 is prepared and dispersed in an appropriate amount of toluene (50wt% solid content) to obtain a slurry for the anode active material layer. The resulting slurry is uniformly coated on both sides of a copper foil. After drying, calendering, and vacuum drying, a first and second anode active material layer are formed on both sides of the anode current collector, respectively, to obtain the anode sheet. The first and second anode active material layers have the same dimensions. The area M3 of the first anode active material layer is measured.

[0042] S4. By weight, take 10 parts of styrene monomer, 0.5 parts of polyethylene glycol diacrylate monomer, 65 parts of Li3InCl, 70 parts of Li6PS5Cl, 5 parts of LiTFSI, and 0.05 parts of AIBN and add them to 300 parts of n-hexane solvent. After uniform mixing, a slurry for the second electrolyte layer is obtained. The slurry of the second electrolyte layer completely covers the surfaces of the first and second negative electrode active material layers, respectively. After drying, a second electrolyte precursor layer is formed on the first and second negative electrode active material layers, respectively. The coating area is controlled during the coating process to ensure that the dimensions of the second electrolyte precursor layers on both sides are the same, thus obtaining the negative electrode side component. The dimensions of a single second electrolyte precursor layer are measured with a micrometer, and its area is calculated. Compared to the second electrolyte precursor layer, the thickness of the second electrolyte layer obtained by polymerizing the second electrolyte precursor layer will be slightly reduced, while its area will remain basically unchanged; therefore, the area of ​​the second electrolyte precursor layer can be equated with the area of ​​the second electrolyte layer; in this embodiment, the thickness of the second electrolyte precursor layer is 30 μm, and the area of ​​the second electrolyte layer is denoted as M4.

[0043] S5. The above-mentioned positive electrode side component and negative electrode side component are stacked to obtain a composite component; multiple composite components are stacked alternately; then placed at 60°C for 4 hours to allow the monomers in the first electrolyte precursor layer and the second electrolyte precursor layer to polymerize. Then, hot pressing is performed at a pressure of 400MPa and a temperature of 100°C to further polymerize the monomers inside the two electrolyte precursor layers, forming a dense first electrolyte layer and a dense second electrolyte layer, which are tightly bonded to their respective electrode plates to obtain a solid-state battery cell. The cell is then encapsulated to obtain a solid-state battery; the thickness of the single-layer positive electrode active material layer is 60μm and its compaction density is 3.5g / cm³. 3 The thickness of the single-layer negative electrode active material layer is 35 μm and its compaction density is 1.5 g / cm³. 3 The compaction densities of the first and second electrolyte layers are 2.0 g / cm³. 3 1.6g / cm 3 .

[0044] Example 2 The difference between this embodiment and Embodiment 1 is that the styrene monomer is replaced with an equal amount of 4-fluorostyrene monomer, as detailed in Table 1. The rest are the same.

[0045] Example 3 The difference between this embodiment and Embodiment 1 is that Li6PS5Cl is replaced with an equal amount of Li 10 Ge2P2S 12 See Table 1 for details; the rest are the same.

[0046] Examples 4-8 Compared with Example 1, the difference is that the amount of the two polymer monomers in the first electrolyte layer and the second electrolyte layer will be changed, as detailed in Table 1, the rest are the same.

[0047] Examples 9-14 Compared with Example 1, the difference is that the amount of the two electrolytes in the first electrolyte layer and / or the second electrolyte layer will be changed, as detailed in Table 1, otherwise the same.

[0048] Example 15 Compared with Example 1, the difference is that the halide electrolyte of the positive electrode active material layer is replaced with an equal amount of sulfide electrolyte, as detailed in Table 1, and the rest are the same.

[0049] Example 16 Compared with Example 1, the difference is that the sulfide electrolyte of the negative electrode active material layer is replaced with a halide electrolyte in equal amounts, as detailed in Table 1, and the rest are the same.

[0050] Example 17 Compared with Example 1, the difference is that 2 parts by weight of polyvinylidene fluoride (PVDF) are added to the slurries of the first electrolyte layer and the second electrolyte layer, respectively, while the rest are the same.

[0051] Example 18 Compared with Example 1, the difference is that 2 parts by weight of polyvinylidene fluoride (PVDF) and 2 parts by weight of alumina nanoparticles are added to the slurries of the first electrolyte layer and the second electrolyte layer, respectively, while the rest are the same.

[0052] Examples 19-22 Compared with Example 1, the difference lies in changing the coating area of ​​the slurry of the first electrolyte layer, the slurry of the second electrolyte layer, the slurry of the positive electrode active material layer, and the slurry of the negative electrode active material layer, thereby changing M2, M4, M1, and M3 respectively, so that the values ​​of (M2-M1) / M2 and (M4-M3) / M4 are different, as detailed in Table 2, while the rest are the same.

[0053] Comparative Example 1 Compared with Example 1, this comparative example does not undergo in-situ polymerization, so there are no polymerizable monomers or initiators in the first and second electrolyte layers, but the rest are the same.

[0054] Comparative Example 2 Compared with Example 1, this comparative example does not add halide electrolyte to the second electrolyte precursor layer, and uses an equal amount of Li6PS5Cl to replace the missing Li3InCl6, so there is no halide electrolyte in the second electrolyte layer, and the rest are the same.

[0055] Comparative Example 3 Compared with Example 1, this comparative example does not add sulfide electrolyte to the first electrolyte precursor layer, and uses an equal amount of Li3InCl6 to replace the missing Li6PS5Cl, so there is no sulfide electrolyte in the first electrolyte layer, and the rest are the same.

[0056] Comparative Example 4 Compared with Example 1, the first electrolyte layer of this comparative example is mainly composed of sulfide electrolyte, and the second electrolyte layer is mainly composed of halide electrolyzer. The detailed amounts of the two electrolytes are shown in Table 1, and the rest are the same.

[0057] Performance testing: The all-solid-state batteries obtained in the examples and comparative examples have the same size, model, and corresponding test conditions; among them, the test batteries are tested at 25°C, a voltage test range of 2.8V-4.3V, and a 0.1C rate, for the first-cycle coulombic efficiency and the capacity retention rate after 50 cycles.

[0058] The test results are shown in Table 3.

[0059] Table 1 Table 2 Table 3 As shown in Comparative Examples 1-4 and Example 1, by setting a first electrolyte layer mainly composed of halides on the positive electrode side and a second electrolyte layer mainly composed of sulfides on the negative electrode layer, and obtaining the two electrolyte layers through an in-situ polymerization process, the initial efficiency and cycle capacity retention of the battery can be effectively improved, significantly extending the battery cycle life. This demonstrates a significant advantage in improving the long-term reliability of all-solid-state batteries. Specifically, the battery of this invention achieves an initial efficiency of 75%-87%, and a capacity retention rate of 70%-92% after 50 cycles.

[0060] As can be seen from Examples 1 and 5, the polyethylene glycol diacrylate monomer in Example 5 causes the electrolyte layer to have too high a degree of crosslinking, which is not conducive to lithium-ion transport and battery cycling. Therefore, its battery first efficiency and capacity retention rate are slightly worse than those of Example 1.

[0061] As can be seen from Examples 1-6, the system of the present invention can use at least one of acrylate compounds and styrene compounds as polymerizing monomers to achieve in-situ polymerization of two electrolyte layers. In the case of using polymerizing monomers composed of acrylate compounds and styrene compounds, the battery's first efficiency and cycle capacity retention are better.

[0062] As can be seen from Examples 1 and 15-16, when the positive electrode active material layer and the negative electrode active material layer are respectively a halide electrolyte and a sulfide electrolyte, the stability of the electrode is better, which is more conducive to improving the battery's first efficiency and cycle capacity retention.

[0063] As can be seen from Examples 17-18, the addition of PVDF and alumina nanoparticles mainly improves the film-forming properties of the slurry, enhances the mechanical bonding between layers, improves the structural stability and interface density after hot pressing, and helps to improve process stability, film integrity and long-term reliability.

[0064] As can be seen from Examples 1 and 19-21, the role of the M1–M4 ratio is mainly to ensure that the electrolyte layer forms a stable edge coating on the active material layer and maintains the stacking match. Its role is more inclined towards structural rationality and process tolerance control. Within the range of 1%≤(M2-M1) / M2≤10% and / or 1%≤(M4-M3) / M4≤10%, each example can maintain good interface contact, so the performance difference is small, and it is feasible and stable within this range.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A solid-state battery, characterized in that, It includes a positive current collector, a positive active material layer located on at least one side surface of the positive current collector, a first electrolyte layer, a second electrolyte layer, a negative current collector, and a negative active material layer located on at least one side surface of the negative current collector, wherein the first electrolyte layer is disposed on the positive active material layer and the second electrolyte layer is disposed on the negative active material layer; The first electrolyte layer is obtained by in-situ polymerization of the following raw material components in parts by weight: 70-90 parts of halide electrolyte, 1-6.4 parts of sulfide electrolyte, 10 parts of 4-fluorostyrene monomer, 0.5 parts of polyethylene glycol diacrylate monomer, 1-10 parts of lithium salt, 0-2 parts of initiator, 0-10 parts of polymer, and 0-10 parts of additives. The second electrolyte layer is obtained by in-situ polymerization of the following raw material components in parts by weight: 70-90 parts of sulfide electrolyte, 1-6.4 parts of halide electrolyte, 10 parts of 4-fluorostyrene monomer, 0.5 parts of polyethylene glycol diacrylate monomer, 1-10 parts of lithium salt, 0-2 parts of initiator, 0-10 parts of polymer, and 0-10 parts of additives. The polymers in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of the following: vinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, styrene-ethylene-butene-styrene copolymer, butadiene-styrene copolymer, polyvinylidene fluoride, polytetrafluoroethylene, cellulose, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyamide, polyimide, polyetherimide, polyethylene, polypropylene, polyethylene oxide, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-butadiene rubber, nitrile rubber, cis-butadiene rubber, butadiene rubber, sodium carboxymethyl cellulose, polyphenylene sulfide, and polyetheretherketone. The additives in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of ionic liquids, alumina nanoparticles, magnesium oxide nanoparticles, zirconium oxide nanoparticles, silicon oxide nanoparticles, titanium oxide nanoparticles, zinc oxide nanoparticles, lithium fluoride, magnesium fluoride, zinc fluoride, lithium chloride, lithium bromide, and lithium iodide.

2. The solid-state battery as described in claim 1, characterized in that, The sulfide electrolytes in the first electrolyte layer and the second electrolyte layer are each independently selected from Li2S-P2S5 and Li7P3S. 11 Li6PS5Cl, Li 5.5 PS5Cl 1.5 Li6PS5Br, Li6PS5I, Li 11 Si2PS 12 Li 10 Sn2PS 12 and Li 10 Ge2P2S 12 At least one of them.

3. The solid-state battery as described in claim 1, characterized in that, The halide electrolytes in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of Li3YCl6, Li2ZrCl6, Li3InCl6, Li2InCl5Br, Li3YBr3Cl3, Li3ScCl6, Li3HoCl6, Li3PBr6, Li3SbBr6 and LiCrBr4.

4. The solid-state battery as described in claim 1, characterized in that, The lithium salts in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium difluorooxalate borate, lithium dioxalate borate, lithium trifluoromethanesulfonate, lithium tetrachloroaluminate, lithium 4,5-dicyano-2-trifluoromethylimidazolium, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, and lithium nitrate.

5. The solid-state battery as described in claim 1, characterized in that, The initiators in the first electrolyte layer and the second electrolyte layer are each independently selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, potassium persulfate, ammonium persulfate, 2-hydroxy-2-methyl-1-phenylpropanone, methyl benzoylformate, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone.

6. The solid-state battery as described in claim 1, characterized in that, The following relationship must be satisfied: M3≥M1; and / or, M4≥M2; In the formula, M1 is the area of ​​the positive electrode active material layer, M2 is the area of ​​the first electrolyte layer, M3 is the area of ​​the negative electrode active material layer, and M4 is the area of ​​the second electrolyte layer.

7. The solid-state battery as described in claim 6, characterized in that, The following relationship must be satisfied: 1%≤(M2-M1) / M2×100%≤10%; And or, 1%≤(M4-M3) / M4×100%≤10%.

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. A slurry coated with a positive electrode active material layer on at least one side of the positive electrode current collector is dried and pressed to form a positive electrode active material layer on the positive electrode current collector. S2. The slurry for coating the first electrolyte layer onto the positive electrode active material layer is dried to form the first electrolyte layer precursor layer on the positive electrode active material layer, thus obtaining the positive electrode side component. S3. A slurry coated with a negative electrode active material layer on at least one side of the negative electrode current collector is dried and pressed to form a negative electrode active material layer on the negative electrode current collector. S4. The slurry that coats the negative electrode active material layer with the second electrolyte layer is dried to form the second electrolyte precursor layer on the negative electrode active material layer, thus obtaining the negative electrode side component. S5. Stack the positive electrode side component and the negative electrode side component to obtain a composite component; S6. Multiple composite components are alternately stacked and then cured to obtain a solid-state battery cell. The cell is then encapsulated to obtain a solid-state battery.

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