Solid-state battery and method of manufacturing the same, and electric device

Abstract

The present application relates to the technical field of solid-state batteries, and discloses a solid-state battery, a preparation method thereof and an electric device. The disclosed solid-state battery comprises at least two stacked electric units, each of which comprises a positive electrode sheet, an electrolyte layer and a negative electrode sheet stacked in sequence along the same direction of the thickness of the solid-state battery, the size of the negative electrode sheet is larger than that of the positive electrode sheet, and the positive electrode sheet is single-sided coated; and an insulating layer is arranged between two adjacent electric units. Compared with a conventional solid-state battery, the disclosed solid-state battery is equivalent to replacing a double-sided coated positive electrode sheet with two single-sided coated positive electrode sheets and adjusting the stacking order, so that the bending degree of the edge of the negative electrode sheet during the forming process of the solid-state battery can be reduced, and the edge cracking of the negative electrode sheet can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to solid-state batteries, their preparation methods, and electrical devices. Background Technology

[0002] Research has found that solid-state batteries require high pressure to be pressed into shape during the manufacturing process. At this time, the negative electrode sheet bends beyond the edge of the positive electrode sheet, which can easily cause cracks at the edge of the negative electrode sheet, thus easily leading to short circuits and safety risks.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a solid-state battery, a method for preparing the same, and an electrical device thereof, with the aim of improving the problem of easy cracking of the negative electrode edge during the battery pressing process.

[0005] This invention is implemented as follows: In a first aspect, the present invention provides a solid-state battery comprising at least two stacked electrical cells. Along the same direction of the thickness of the solid-state battery, each electrical cell includes a positive electrode, an electrolyte layer, and a negative electrode stacked sequentially. The size of the negative electrode is larger than that of the positive electrode, and the positive electrode is coated on one side. An insulating layer is disposed between two adjacent electrical cells.

[0006] In an optional embodiment, the insulating layer is a flexible insulating pad.

[0007] In optional embodiments, the flexible insulating pad is made of silicone rubber, EPDM rubber, polyurethane elastomer, polyimide, polycarbonate, nylon 11 / 12, butyl rubber, chloroprene rubber, polytetrafluoroethylene, thermoplastic elastomer, ethylene-vinyl acetate copolymer, thermoplastic polyolefin, cross-linked polyethylene, polyetheretherketone or polyester film, or a composite material of any two of the foregoing materials. And / or, the thickness of the flexible insulating pad is 2~5μm.

[0008] In an optional embodiment, each positive electrode includes a positive current collector and a positive active layer disposed on one side of the positive current collector, the positive active layer being disposed close to the electrolyte layer; Each negative electrode includes a negative current collector and a negative active layer disposed on one side of the negative current collector, with the negative active layer disposed close to the electrolyte layer.

[0009] In an optional implementation, the thickness of the positive electrode sheet is 120~250μm.

[0010] In an optional embodiment, the thickness of the positive current collector is 6~15μm, and the thickness of the positive active layer is 114~235μm.

[0011] In an optional embodiment, the thickness of the negative electrode current collector is 3~8μm, and the thickness of the negative electrode active layer is 20~80μm.

[0012] In an optional embodiment, the thicknesses of the positive electrode, electrolyte layer, negative electrode and insulating layer are 120~250μm, 20~60μm, 23~88μm and 2~5μm, respectively.

[0013] In an optional embodiment, when the solid-state battery includes two stacked electrical cells, the sum of the thicknesses of the two stacked electrical cells and the insulating layer is 328~801 μm.

[0014] In a second aspect, embodiments of the present invention provide a method for preparing the above-mentioned solid-state battery, comprising: stacking n sets of structures for forming electrical cells and n-1 insulating layers, where n≥2; The structure used to form the electrical unit includes a positive electrode, an electrolyte layer, and a negative electrode. After stacking, the tabs are soldered and packaged.

[0015] In an optional implementation, when n=2, the stacking method includes: An electrolyte layer is transferred to the surface of the negative electrode active layer of a negative electrode to obtain a composite structure. Two composite structures are obtained by following this method. A positive electrode, a composite structure, an insulating layer, another positive electrode, and a composite structure are stacked sequentially, followed by tab welding and encapsulation.

[0016] Thirdly, the present invention provides an electrical device comprising a solid-state battery as described in any of the foregoing embodiments.

[0017] The present invention has the following beneficial effects: The solid-state battery provided in this invention, compared to traditional solid-state batteries, is equivalent to replacing one double-sided coated positive electrode sheet with two single-sided coated positive electrode sheets, and adjusting the stacking order so that the spacing between the two negative electrode sheets changes from the original double-sided coated positive electrode sheet to the current single-sided coated positive electrode sheet, thus reducing the spacing. This reduces the bending degree of the negative electrode sheet edges during high-pressure battery molding, effectively improving the edge cracking of the negative electrode sheet. Using an insulating layer to separate the positive and negative electrode sheets ensures battery safety. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a solid-state battery comprising two electrical cells, provided in an embodiment of the present invention. Figure 2 A schematic diagram of the structure of a solid-state battery comprising three electrical cells provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an existing conventional solid-state battery. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0022] In the description of this invention, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0023] To address the safety risk posed by cracks at the edge of the negative electrode during the current packaging process, which can easily lead to short circuits, the inventors conducted research and analysis: In solid-state battery design, the negative electrode sheet is larger in both length and width than the positive electrode sheet. Conventional solid-state battery structures typically sandwich the positive electrode sheet and electrolyte layer between two negative electrode sheets, resulting in a large gap between the two negative electrode sheets at the cell edge. Due to this large gap, the encapsulation process causes significant bending at the edges of the two negative electrode sheets, making them highly susceptible to cracking. Based on this, the present invention is proposed.

[0024] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0025] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a solid-state battery, including at least two stacked electrical cells. Along the same direction of the thickness of the solid-state battery, each electrical cell includes a positive electrode, an electrolyte layer and a negative electrode stacked sequentially. The size of the negative electrode is larger than the size of the positive electrode (when laid flat, the width and length of the negative electrode are both larger than the width and length of the positive electrode, respectively). The positive electrode is coated on one side. An insulating layer is disposed between two adjacent electrical cells.

[0026] The solid-state battery provided in this embodiment of the invention, compared to traditional solid-state batteries (such as...), Figure 3As shown, this is equivalent to replacing one double-sided coated positive electrode sheet (i.e., a positive electrode sheet with an active layer on both sides) with two single-sided coated positive electrode sheets (i.e., a positive electrode sheet with an active layer on only one side), and adjusting the stacking order so that the spacing between the two negative electrode sheets changes from the original double-sided coated positive electrode sheet to the current single-sided coated positive electrode sheet, thus reducing the spacing. This reduces the bending degree of the negative electrode sheet edges during high-pressure battery forming, effectively improving the edge cracking of the negative electrode sheet. Using an insulating layer to separate the positive and negative electrode sheets ensures battery safety.

[0027] It should be noted that in this invention, the number of stacked electrical units is two or more (e.g., 3, 4, 5, 6, 7, 8, etc.). In practical applications, the appropriate number of stacked units can be selected according to the usage requirements.

[0028] Taking two stacked electrical units as an example, although the solid-state battery provided by this invention adds a positive current collector and an insulating layer compared to the traditional solid-state battery structure, the thickness of these two can usually be set to be very small, and has little impact on the overall thickness of the solid-state battery.

[0029] In an optional embodiment of the present invention, the size of the electrolyte layer is also larger than the size of the positive electrode (the width and length of the electrolyte layer in the flat state are both larger than the width and length of the positive electrode, respectively), and the size of the electrolyte layer is close to that of the negative electrode, so as to ensure that even if the edge of the negative electrode is deformed under high pressure during the encapsulation process, it can avoid direct contact with the positive electrode under the isolation effect of the edge of the electrolyte layer.

[0030] Preferably, the insulating layer is a flexible insulating pad. The flexible insulating pad has a certain degree of elasticity, which can buffer the volume expansion of the battery to a certain extent and further improve the safety of the battery.

[0031] In optional embodiments of the present invention, the flexible insulating mat is made of materials including, but not limited to: silicone rubber (VMQ), ethylene propylene diene monomer (EPDM), polyurethane elastomer (PU / TPU), polyimide (PI), polycarbonate (PC), nylon 11 / 12 (PA11 / PA12), butyl rubber (IIR), chloroprene rubber (CR), polytetrafluoroethylene (PTFE), thermoplastic elastomer (TPE), ethylene-vinyl acetate copolymer (EVA), thermoplastic polyolefin (TPO), cross-linked polyethylene (XLPE), polyetheretherketone (PEEK), or polyester film (PET), or composite materials of any two of the foregoing materials. These materials give the flexible insulating mat suitable elasticity and excellent insulation properties.

[0032] In an optional embodiment of the present invention, the thickness of the flexible insulating pad is 2~5μm (e.g., 2μm, 3μm, 4μm, or 5μm, or any value within the range of any two of the aforementioned values). Within this range, the flexible insulating pad exhibits good flexibility and mechanical strength. If the thickness is too high, it will increase the thickness of the battery, resulting in an excessively large battery volume; if the thickness is too low, the insulating pad will have low mechanical strength and may crack, failing to provide insulation.

[0033] In an optional embodiment of the present invention, the thickness of the positive electrode sheet is 120~250μm (e.g., 120μm, 130μm, 140μm, 150μm, 180μm, 200μm, or 250μm, or any value within the range of any two of the aforementioned values). The space within this thickness range is the bending space at the edge of the negative electrode sheet. This thickness is significantly smaller than the thickness of existing double-sided coated positive electrode sheets, which can better improve the edge cracking of the negative electrode sheet.

[0034] In an optional embodiment of the present invention, the thickness of the positive electrode current collector is 6~15μm (e.g., 6μm, 8μm, 10μm or 15μm, or any value within the range of any two of the aforementioned values), and the thickness of the positive electrode active layer is 114~235μm (e.g., 114μm, 120μm, 150μm, 180μm, 200μm, 210μm or 235μm). This thickness of positive electrode current collector provides suitable mechanical properties, and this thickness of positive electrode active layer ensures good electrochemical performance of the solid-state battery.

[0035] In solid-state battery systems, selecting a suitable positive electrode current collector can stably support the positive electrode active layer and construct an efficient and continuous electron transport channel, strengthening the interfacial bonding between the current collector and the positive electrode active layer and solid electrolyte. This effectively suppresses interfacial peeling and contact failure caused by electrode deformation during charge-discharge cycles. Simultaneously, it can withstand the high-potential environment of the positive electrode, avoiding corrosion, dissolution, and interfacial side reactions of the current collector, continuously reducing interfacial contact impedance, ensuring the overall structural integrity and conductivity stability of the electrode, thereby improving the rate performance, cycle life, and safety of the solid-state battery. It can also be matched with the fabrication and packaging processes of solid-state batteries, further ensuring the overall performance and long-term reliability of the cell. Therefore, in optional embodiments of this invention, the positive electrode current collector is aluminum foil, aluminum-based composite current collector, titanium foil, or stainless steel foil.

[0036] In the positive electrode active layer of solid-state batteries, the rational control of the proportion of each component can enable the positive electrode active material, conductive agent, binder and other functional additives to play a synergistic role. This not only ensures the proportion of active material to improve the energy density of the battery, but also builds a continuous and stable conductive network, effectively reducing the overall impedance of the electrode. At the same time, it can optimize the internal pore structure and interface contact state of the active layer, enhance the bonding strength between the components, alleviate the structural deformation and interface separation problems during charging and discharging, reduce the occurrence of solid-state interface side reactions, and thus significantly improve the rate performance, cycle stability and interface compatibility of solid-state batteries, taking into account both electrode processing feasibility and long-term service reliability of the cell. Therefore, in an optional embodiment of the present invention, the positive electrode active layer comprises, by weight, 60 to 90 parts (e.g., 60, 65, 70, 80, or 90 parts, or any value within the range of any two of the aforementioned values) of positive electrode active material, 5 to 35 parts (e.g., 5, 10, 15, 20, 25, 30, and 35 parts, or any value within the range of any two of the aforementioned values) of solid electrolyte, 1 to 5 parts (e.g., 1, 2, 3, 4, or 5 parts, or any value within the range of any two of the aforementioned values) of conductive agent, and 1 to 3 parts (e.g., 1, 2, or 3 parts, or any value within the range of any two of the aforementioned values) of binder.

[0037] The selection of suitable cathode active materials in solid-state batteries not only determines the theoretical energy density and voltage plateau of the battery, but also ensures efficient lithium-ion intercalation and deintercalation based on their crystal structure, ion conduction characteristics, and interfacial compatibility, and is compatible with the ion transport system of solid-state electrolytes. These materials must withstand structural deformation and high-potential environments during charge and discharge, suppress lattice collapse, particle pulverization, and interfacial side reactions, maintain a stable solid-solid contact interface between the cathode and the solid-state electrolyte, reduce interfacial impedance, and simultaneously ensure electrochemical reversibility and thermal stability, ultimately effectively improving the rate performance, cycle life, safety performance, and overall service performance of solid-state batteries. Therefore, in optional embodiments of this invention, the cathode active materials include, but are not limited to, one or more of NCM (high-nickel ternary materials), LFP (lithium iron phosphate), LCO (lithium cobalt oxide), lithium-rich manganese-based materials, and LNMO (lithium nickel manganese oxide).

[0038] In solid-state battery systems, selecting a suitable solid electrolyte is crucial for ensuring the normal operation of the cell. This electrolyte must possess excellent lithium-ion conductivity to enable efficient ion migration between the positive and negative electrodes, while also exhibiting good electronic insulation to prevent self-discharge and short-circuit risks within the cell. Furthermore, the material must form a stable and compatible solid-solid interface with the positive and negative electrode active materials, effectively suppressing interfacial side reactions, element interdiffusion, and continuous increase in interfacial impedance. It must also withstand stress changes within the battery's operating voltage range and during cycling, maintaining the integrity of the interfacial contact. In addition, it must possess excellent chemical stability, thermal stability, and mechanical properties to resist lithium dendrite penetration, improving battery safety and ultimately comprehensively improving the rate performance, cycle life, operating temperature range, and long-term service reliability of solid-state batteries. Therefore, in optional embodiments of this invention, the solid electrolyte in the positive electrode active layer includes, but is not limited to, Li3PS4 and Li7P3S. 11 Li 10 GeP2S 12 (LGPS), Li6PS5Cl (LPSC), Li7La3Zr2O 12 One or more of the following: (LLZO / LLZTO), Li1.3Al0.3Ti1.7(PO4)3 (LATP), Li3YCl6, Li3YBr6 and PEO (polyethylene oxide) based composite electrolyte.

[0039] In optional embodiments of the present invention, the conductive agent includes, but is not limited to, at least one of Super P, C65, Ketjen Black, acetylene black, graphite powder, CNTs (carbon nanotubes), VGCF (vapor-grown carbon fibers), CNFs (carbon nanofibers), graphene, and reduced graphene oxide (rGO).

[0040] Each of the above conductive agents has its own advantages, and multiple combinations can usually be selected. For example, a three-dimensional composite conductive network of zero-dimensional carbon black (dots) + one-dimensional carbon nanotubes (lines) + two-dimensional graphene (surfaces) can be selected to take advantage of each other's strengths and compensate for their weaknesses: carbon black fills the microscopic gaps, carbon nanotubes provide the long-range framework, and graphene provides lateral conductivity. It is difficult for a single conductive agent to simultaneously take into account compaction, rate capability, processing, and cost.

[0041] In optional embodiments of the present invention, the adhesive includes, but is not limited to, one or more of PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), SBR (styrene-butadiene rubber), HNBR (hydrogenated nitrile butadiene rubber), NBR (nitrile butadiene rubber), PI (polyimide), PEEK, CMC (carboxymethyl cellulose), PAA (polyacrylic acid), SEPS (styrene-ethylene-propylene-styrene block copolymer), and ethyl cellulose.

[0042] In the positive electrode active layer system of a battery, the selection of a suitable binder can effectively and uniformly bond the positive electrode active material, conductive agent and other components into one, stabilize the overall electrode structure, improve the interfacial bonding force between the active layer and the current collector, suppress particle shedding, interlayer peeling and electrode cracking caused by volume expansion and contraction during repeated charging and discharging, and ensure the integrity of the electrode structure. It can also optimize the continuity of the conductive network inside the electrode, reduce the interfacial contact impedance, and improve the electrode processing and forming performance, cycle stability and rate performance, ultimately achieving a comprehensive improvement in the battery electrochemical performance and long-term reliability.

[0043] In an optional embodiment of the present invention, each positive electrode includes a positive current collector and a positive active layer disposed on one side of the positive current collector, the positive active layer being disposed close to the electrolyte layer; each negative electrode includes a negative current collector and a negative active layer disposed on one side of the negative current collector, the negative active layer being disposed close to the electrolyte layer.

[0044] In an optional embodiment of the present invention, the thickness of the negative electrode current collector is 3~8 μm (e.g., 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm, or any value within the range of any two of the aforementioned values), and the thickness of the negative electrode active layer is 20~80 μm (e.g., 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm, or any value within the range of any two of the aforementioned values). A negative electrode current collector of this thickness has suitable mechanical properties, and a negative electrode active layer of this thickness ensures that the solid-state battery has good electrochemical performance.

[0045] In solid-state battery systems, selecting a suitable negative electrode current collector can effectively support the negative electrode active material and construct a stable conductive path, enhancing the interfacial bonding between the current collector and the negative electrode layer and solid electrolyte. This alleviates the interfacial desorption and contact failure problems caused by the volume deformation of the negative electrode material during battery cycling. Simultaneously, it can suppress lithium metal deposition, side reaction growth, and the continuous increase in interfacial impedance, ensuring the continuity and stability of electron conduction, improving battery cycle life, rate characteristics, and safety performance. Furthermore, it can adapt to the manufacturing process requirements of solid-state batteries, enhancing the overall structural stability of the electrode and the overall service reliability of the cell. Therefore, in optional embodiments of this invention, the negative electrode current collector can be selected from copper foil, copper-based composite current collector, titanium foil, stainless steel foil, or nickel foil.

[0046] In the active layer of the anode of a solid-state battery, scientifically optimizing the proportions of each component can enable the active material, conductive agent, and binder to form a synergistic system. While ensuring the proportion of active material to maximize lithium storage capacity, it can also construct a continuous conductive network and reduce the overall impedance of the electrode. A reasonable ratio can also regulate the pore structure and mechanical properties of the active layer, buffer the huge volume expansion and contraction of the anode material during charging and discharging, avoid particle pulverization, layer cracking, and solid-solid interface separation, reduce interfacial side reactions and impedance degradation, ensure the long-term stability of the contact state between the anode and the solid electrolyte, and improve the processing performance of electrode coating and molding. Ultimately, it can effectively improve the lithium storage capacity, rate performance, cycle stability, and overall reliability of the solid-state battery. In an optional embodiment of the present invention, by weight, it includes 70 to 85 parts (e.g., 70, 75, 80, or 85 parts, or any value within the range of any two of the aforementioned values) of negative electrode active material, 10 to 25 parts (e.g., 10, 15, 20, or 25 parts, or any value within the range of any two of the aforementioned values) of solid electrolyte, 2 to 5 parts (e.g., 2, 3, 4, or 5 parts, or any value within the range of any two of the aforementioned values) of conductive agent, and 2 to 5 parts (e.g., 2, 3, 4, or 5 parts, or any value within the range of any two of the aforementioned values) of binder.

[0047] In optional embodiments of the present invention, the negative electrode active material includes, but is not limited to, one or more of the following: artificial graphite, natural graphite, hard carbon, soft carbon, nano-silicon, silicon-carbon composite material, silicon-based alloy, metallic lithium, lithium-indium alloy, and lithium-tin alloy.

[0048] In optional embodiments of the present invention, the solid electrolyte in the negative electrode active layer includes, but is not limited to, Li3PS4 and Li7P3S. 11 Li 10 GeP2S 12 (LGPS), Li6PS5Cl (LPSC), Li7La3Zr2O 12 One or more of the following: (LLZO / LLZTO), Li1.3Al0.3Ti1.7(PO4)3 (LATP), Li3YCl6, Li3YBr6, and PEO-based polymer solid electrolytes.

[0049] In optional embodiments of the present invention, the conductive agent includes, but is not limited to, one or more of conductive carbon black (Super P, C65, Ketjen black, acetylene black), carbon nanotubes (CNTs), vapor-grown carbon fibers (VGCF), graphene, reduced graphene oxide (rGO), artificial graphite, nano-metal powders, metal fibers, and titanium nitride (TiN).

[0050] In optional embodiments of the present invention, the adhesive includes, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyimide (PI), polyetheretherketone (PEEK), hydrogenated nitrile butadiene rubber (HNBR), nitrile butadiene rubber (NBR), ethyl cellulose, sodium alginate, and polyurethane (PU).

[0051] In an optional embodiment of the present invention, the electrolyte layer comprises, by weight, 90 to 99 parts (e.g., 90, 92, 94, 96, 98, or 99 parts, or any value within the range of any two of the aforementioned values) of solid electrolyte and 1 to 10 parts (e.g., 1, 3, 5, 8, or 10 parts, or any value within the range of any two of the aforementioned values) of binder.

[0052] In optional embodiments of the present invention, the solid electrolyte in the electrolyte layer includes, but is not limited to, Li3PS4 and Li7P3S. 11 Li 10 GeP2S 12 (LGPS), Li6PS5Cl (LPSC), Li7La3Zr2O 12 One or more of the following: (LLZO / LLZTO), Li1.3Al0.3Ti1.7(PO4)3 (LATP), Li3YCl6, Li3YBr6, and polyethylene oxide (PEO) based polymer electrolytes.

[0053] In optional embodiments of the present invention, the binder in the electrolyte layer includes, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyimide (PI), polyetheretherketone (PEEK), styrene-butadiene rubber (SBR), nitrile rubber (NBR), carboxymethyl cellulose (CMC), and polyacrylic acid (PAA).

[0054] The thicknesses of the positive electrode, electrolyte layer, negative electrode, and insulating layer are, respectively, 120~250μm (e.g., 120μm, 130μm, 140μm, 150μm, 180μm, 200μm, or 250μm, or any value within the range of any two of the aforementioned values), 20~60μm (e.g., 20μm, 30μm, 40μm, 50μm, or 60μm, or any value within the range of any two of the aforementioned values), 23~88μm (e.g., 23μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, or 88μm), and 2~5μm (e.g., 2μm, 3μm, 4μm, or 5μm, or any value within the range of any two of the aforementioned values).

[0055] The thickness of the positive electrode is chosen to maximize the capacity of the positive electrode active material. Too thin a thickness leads to lower battery energy density, while too thick a thickness results in greater polarization and lower discharge capacity. The thickness of the negative electrode is adjusted based on the thickness of the positive electrode. Within this range, the electrolyte membrane effectively separates the positive and negative electrodes without affecting battery capacity. Too thin a membrane may cause a short circuit, while too thick a membrane leads to lower battery capacity. The flexible insulating pad exhibits good flexibility and mechanical strength within this range. Excessive thickness increases battery size, while insufficient thickness results in lower mechanical strength and potential breakage, failing to provide insulation. Therefore, within the aforementioned thickness range, superior electrochemical performance of the solid-state battery can be ensured.

[0056] In an optional embodiment of the present invention, when the solid-state battery comprises two stacked electrical cells, the sum of the thicknesses of the two stacked electrical cells and the insulating layer is 328~801 μm (e.g., 328 μm, 400 μm, 500 μm, 600 μm, 700 μm, or 801 μm, or any value within the range of any two of the aforementioned values). This thickness range meets the requirements of battery design principles and can ensure the electrochemical performance of the battery.

[0057] The method for preparing a solid-state battery provided in this embodiment of the invention includes: n sets of structures used to form the electrical unit and n-1 insulating layers are stacked, where n≥2; The structure for forming the electrical unit includes a positive electrode, an electrolyte layer, and a negative electrode. After stacking, the tabs are soldered and packaged.

[0058] The preparation method provided in this embodiment of the invention can produce the solid-state battery provided in this embodiment of the invention.

[0059] Specifically, the preparation method is as follows: S1. Preparation of positive electrode sheet The positive electrode active material, solid electrolyte, conductive agent, and binder are added to a suitable solvent in a certain mass ratio, and then the components are uniformly dispersed using a high-speed disperser to form a stable positive electrode slurry. After obtaining a uniform positive electrode slurry, a grooved die coater is used to evenly coat the slurry onto one side of the positive electrode current collector, forming a thin layer. After coating, the slurry is dried in an oven and then pressed into tablets.

[0060] In optional embodiments of the present invention, the solvent in this step includes, but is not limited to, one or more of toluene, xylene, n-hexane, cyclohexane, ethyl acetate, butyl acetate, tetrahydrofuran, cyclohexanone, dichloromethane, and isopropanol.

[0061] In an optional embodiment of the present invention, the solid content of the positive electrode slurry is 60-70% (e.g., 60%, 63%, 65%, 68%, or 70%, or any value within the range of any two of the aforementioned values). At this solid content, the slurry has good fluidity and coating stability, uniform coating thickness, and fewer defects such as streaks, pinholes, and missed coatings; it also ensures uniform distribution of each component in the positive electrode active layer, ensuring better electrochemical performance of the solid-state battery.

[0062] In an optional embodiment of the present invention, the drying method is as follows: first, pre-dry at 70~90℃ (e.g., 70℃, 75℃, 80℃, 85℃ or 90℃, or any value within the range of any two of the aforementioned values) for 1~3 hours (e.g., 1 hour, 2 hours or 3 hours, or any value within the range of any two of the aforementioned values); then transfer to a vacuum environment at 100~140℃ (e.g., 100℃, 110℃, 120℃ or 140℃, or any value within the range of any two of the aforementioned values) for 6~10 hours (e.g., 1 hour, 2 hours or 3 hours, or any value within the range of any two of the aforementioned values).

[0063] The advantages of this low-temperature pre-drying followed by high-temperature vacuum drying are as follows: Low-temperature pre-drying removes most of the surface solvent, avoiding the formation of a skin on the electrode surface and residual solvent encapsulation caused by direct high-temperature drying. Subsequent high-temperature vacuum drying thoroughly removes deep-seated solvents and trace amounts of moisture, ensuring the stability of the solid electrolyte and reducing the internal resistance of the cell. Step-by-step drying slows down slurry shrinkage, reduces electrode warping, cracking, and material loss, and improves electrode flatness and structural integrity. The overall process balances drying efficiency and electrode quality, resulting in better batch consistency.

[0064] In an optional embodiment of the present invention, the tableting pressure is 230~270 MPa (e.g., 230 MPa, 250 MPa or 270 MPa, or any value within the range of any two of the aforementioned values).

[0065] S2, Preparation of electrolyte layer Solid electrolyte and binder are placed in a solvent and stirred until homogeneous to obtain electrolyte slurry.

[0066] The electrolyte slurry is coated onto the release film and dried to obtain the electrolyte layer.

[0067] In an optional embodiment of the present invention, the solid content of the electrolyte slurry is 45-60% (45%, 50%, 55% or 60%, or any value within the range of any two of the aforementioned values). At this solid content, the slurry has good fluidity and coating stability, uniform coating thickness, and fewer defects such as streaks, pinholes, and missed coatings; it can also ensure uniform distribution of electrode components and improve the electrochemical consistency of the cell.

[0068] In optional embodiments of the present invention, the solvent in this step includes, but is not limited to, one or more of toluene, xylene, cyclohexane, butyl acetate, tetrahydrofuran, cyclohexanone, isopropanol, and dichloromethane.

[0069] S3. Preparation of negative electrode sheet The negative electrode active material, solid electrolyte, conductive agent, and binder are added to a suitable solvent in a certain mass ratio, and then the components are evenly dispersed using a high-speed disperser to form a stable negative electrode slurry. After obtaining a uniform negative electrode slurry, a grooved die coater is used to evenly coat the negative electrode slurry onto one side of the negative electrode current collector, forming a thin layer. After coating, the slurry is dried in an oven and then pressed into tablets.

[0070] In optional embodiments of the present invention, the solvent in this step includes, but is not limited to, one or more of toluene, p-xylene, anisole, n-hexane, n-heptane, n-dodecane, cyclohexane, butyl butyrate, isobutyl isobutyrate, dibutyl ether, cyclopentyl methyl ether, and tetrahydrofuran.

[0071] In an optional embodiment of the present invention, the solid content of the negative electrode slurry is 50-60% (e.g., 50%, 55%, or 60%, or any value within the range of any two of the aforementioned values). At this solid content, the slurry has good fluidity and coating stability, uniform coating thickness, and fewer defects such as streaks, pinholes, and missed coatings; it also ensures uniform distribution of each component in the negative electrode active layer, thus ensuring better electrochemical performance of the solid-state battery.

[0072] In an optional embodiment of the present invention, the drying method is as follows: first, pre-dry at 70~90℃ (e.g., 70℃, 80℃, 90℃, or any value within the range of any two of the aforementioned values) for 1~3 hours (e.g., 1 hour, 2 hours, or 3 hours, or any value within the range of any two of the aforementioned values); then transfer to a vacuum environment and dry at 100~140℃ (e.g., 100℃, 120℃, or 140℃, or any value within the range of any two of the aforementioned values) for 6~10 hours (6 hours, 8 hours, or 10 hours, or any value within the range of any two of the aforementioned values).

[0073] In an optional embodiment of the present invention, the tableting pressure is 230~270 MPa (e.g., 230 MPa, 250 MPa or 270 MPa, or any value within the range of any two of the aforementioned values).

[0074] S4, assembled as a battery Taking n=2 as an example, the stacking methods include: Prepare two electrolyte layers (first electrolyte layer and second electrolyte layer), two negative electrode plates (first negative electrode plate and second negative electrode plate), an insulating layer, and two positive electrode plates (first positive electrode plate and second positive electrode plate).

[0075] The first electrolyte layer is transferred onto the surface of the negative electrode active layer of the first negative electrode to obtain a first composite structure; the second electrolyte layer is transferred onto the surface of the negative electrode active layer of the second negative electrode to obtain a second composite structure. The first positive electrode, the first composite structure, the insulating layer, the second positive electrode, and the second composite structure are stacked sequentially to ensure that the active layer of each positive electrode faces the electrolyte layer and the active layer of each negative electrode faces the electrolyte layer. When n>2, the stacking pattern follows a cycle of one positive electrode, one composite structure, one insulating pad, then another positive electrode, one composite structure, one insulating pad, and so on.

[0076] After stacking, electrode tabs are soldered and encapsulated; Finally, the packaged battery is fixed with a stainless steel plate and placed in an isostatic press for isostatic pressing to obtain a solid-state battery.

[0077] In an optional embodiment of the present invention, the electrode welding process requires control of welding head pressure, amplitude, welding time and power parameters to avoid false welding or over-welding that burns the copper and aluminum foil. There should be no wrinkles or burrs at the electrode contact point. After welding, the peel strength and conductivity should be checked. At the same time, proper insulation protection of the electrode sheet should be provided to prevent welding debris from falling and causing internal short circuits in the battery cell or damage to the edge electrode sheet and lithium deposition.

[0078] In optional embodiments of the present invention, the encapsulation material includes, but is not limited to, aluminum-plastic film, stainless steel shell, aluminum alloy shell, nickel-plated steel shell, ceramic encapsulation material, epoxy resin, polyimide film, or fluoroplastic film. Aluminum-plastic film is preferred.

[0079] In an optional embodiment of the present invention, the isostatic pressing pressure is 280~320MPa (e.g., 280 MPa, 300 MPa, or 320 MPa, or any value within the range of any two of the aforementioned values), and the time is 25~35min (e.g., 25 min, 30 min, or 35 min, or any value within the range of any two of the aforementioned values). Isostatic pressing can improve the interfacial contact tightness of each layer and reduce interfacial impedance; optimize the internal pore structure of the electrode and electrolyte layers and shorten the ion transport path; improve the density and overall mechanical strength of the electrode and electrolyte membrane, and suppress structural cracking and interlayer delamination during cycling; uniform pressure distribution, improve the internal consistency of the cell, and stabilize electrochemical performance.

[0080] This invention also provides an electrical device including a solid-state battery. The solid-state battery or a battery pack including the solid-state battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include mobile devices (typically mobile phones, laptops, etc.), electric vehicles (typically pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, or energy storage systems.

[0081] For ease of assembly and testing, the following embodiments are all shown with solid-state batteries comprising two cells.

[0082] Example 1 This embodiment provides a solid-state battery with the following structure: Figure 1 As shown, it includes two positive electrode plates (first positive electrode plate and second positive electrode plate), two negative electrode plates (first negative electrode plate and second negative electrode plate), two electrolyte layers (first electrolyte layer and second electrolyte layer), and one insulating layer. The thicknesses of the first positive electrode plate, first electrolyte layer, first negative electrode plate, insulating layer, second positive electrode plate, second electrolyte layer, and second negative electrode plate are 180 μm, 30 μm, 50 μm, 4 μm, 180 μm, 30 μm, and 50 μm, respectively. The sum of the thicknesses of all these layers is 524 μm.

[0083] The positive electrode current collector of the positive electrode is made of aluminum foil with a thickness of 12 μm, and the positive electrode active layer has a thickness of 168 μm. The negative electrode current collector of the negative electrode is made of copper foil with a thickness of 6 μm, and the negative electrode active layer has a thickness of 44 μm. The insulating layer is made of silicone rubber.

[0084] The positive electrode is 70mm long and 100mm wide. The negative electrode, electrolyte layer and insulating layer are the same length and width, 72mm long and 106mm wide.

[0085] The specific method for preparing a solid-state battery provided in this embodiment is as follows: S1. Preparation of positive electrode sheet NCM811 cathode material, LPSC electrolyte powder, VGCF, and SEPS were added to a suitable butyl butyrate solvent in a mass fraction ratio of 75:20:3:2. The components were then uniformly dispersed using a high-speed disperser to form a cathode slurry with a solid content of 70%. After obtaining the cathode slurry, a grooved die coater was used to uniformly coat the slurry onto one side of the cathode current collector, forming a thin layer. After coating, the slurry was pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet was then pressed into a sheet under a pressure of 250 MPa.

[0086] S2, Preparation of electrolyte layer 9.9 kg of LPSC electrolyte powder and 0.1 kg of NBR were placed in xylene and stirred to obtain an electrolyte slurry with a solid content of 50%. The electrolyte slurry was coated on a release film and dried to obtain an electrolyte layer.

[0087] S3. Preparation of negative electrode sheet Silicon carbon material, LPSC electrolyte powder, VGCF, and PAA were added to xylene solvent in a mass fraction ratio of 65:30:3:2. The components were then uniformly dispersed using a high-speed disperser to form a stable negative electrode slurry with a solid content of 55%. The negative electrode slurry was uniformly coated onto a single surface of the negative electrode current collector with a thickness of 6 μm using a grooved die coating machine to form a thin layer. After coating, the electrode was pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet was then roll-formed under a pressure of 250 MPa.

[0088] S4, assembled as a battery Take the two electrolyte layers (first electrolyte layer and second electrolyte layer) prepared in step S2, the two negative electrode plates (first negative electrode plate and second negative electrode plate) prepared in step S3, the insulating layer, and the two positive electrode plates (first positive electrode plate and second positive electrode plate) prepared in step S1.

[0089] The first electrolyte layer is transferred onto the surface of the negative electrode active layer of the first negative electrode to obtain a first composite structure; the second electrolyte layer is transferred onto the surface of the negative electrode active layer of the second negative electrode to obtain a second composite structure. The first positive electrode, the first composite structure, the insulating layer, the second positive electrode, and the second composite structure are stacked sequentially to ensure that the active layer of each positive electrode faces the electrolyte layer and the active layer of each negative electrode faces the electrolyte layer. Then, the tabs are soldered and the aluminum-plastic film is encapsulated. Finally, the encapsulated battery is fixed with a stainless steel plate and placed in an isostatic press for isostatic pressing at 300 MPa for 30 minutes to obtain a solid-state battery.

[0090] Example 2 This embodiment provides a solid-state battery with the following structure: Figure 1 As shown, it includes two positive electrode plates (first positive electrode plate and second positive electrode plate), two negative electrode plates (first negative electrode plate and second negative electrode plate), two electrolyte layers (first electrolyte layer and second electrolyte layer), and one insulating layer. The thicknesses of the first positive electrode plate, first electrolyte layer, first negative electrode plate, insulating layer, second positive electrode plate, second electrolyte layer, and second negative electrode plate are 120 μm, 20 μm, 23 μm, 2 μm, 120 μm, 20 μm, and 23 μm, respectively. The sum of the thicknesses of all these layers is 328 μm.

[0091] The positive electrode current collector of the positive electrode is made of aluminum foil with a thickness of 12 μm, and the positive electrode active layer has a thickness of 108 μm. The negative electrode current collector of the negative electrode is made of copper foil with a thickness of 4 μm, and the negative electrode active layer has a thickness of 19 μm. The insulating layer is made of polyurethane elastomer.

[0092] The positive electrode is 70mm long and 100mm wide. The negative electrode, electrolyte layer and insulating layer are the same length and width, 74mm long and 106mm wide.

[0093] The specific method for preparing a solid-state battery provided in this embodiment is as follows: S1. Preparation of positive electrode sheet NCM811 cathode material, LPSC electrolyte powder, VGCF, and SEPS were added to a suitable butyl butyrate solvent in a mass fraction ratio of 75:20:3:2. The components were then uniformly dispersed using a high-speed disperser to form a cathode slurry with a solid content of 60%. After obtaining the cathode slurry, a grooved die coater was used to uniformly coat the slurry onto one side of the cathode current collector, forming a thin layer. After coating, the slurry was pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet was then pressed into a sheet under a pressure of 250 MPa.

[0094] S2, Preparation of electrolyte layer 9.9 kg of LPSC electrolyte powder and 0.1 kg of NBR were placed in xylene and stirred to obtain an electrolyte slurry with a solid content of 45%. The electrolyte slurry was coated on a release film and dried to obtain an electrolyte layer.

[0095] S3. Preparation of negative electrode sheet Silicon carbon material, LPSC electrolyte powder, VGCF, and PAA were added to xylene solvent in a mass fraction ratio of 65:30:3:2. The components were then uniformly dispersed using a high-speed disperser to form a stable negative electrode slurry with a solid content of 50%. The negative electrode slurry was uniformly coated onto a single surface of the negative electrode current collector with a thickness of 6 μm using a grooved die coating machine to form a thin layer. After coating, the electrode was pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet was then roll-formed under a pressure of 250 MPa.

[0096] S4, assembled as a battery Take the two electrolyte layers (first electrolyte layer and second electrolyte layer) prepared in step S2, the two negative electrode plates (first negative electrode plate and second negative electrode plate) prepared in step S3, the insulating layer, and the two positive electrode plates (first positive electrode plate and second positive electrode plate) prepared in step S1.

[0097] The first electrolyte layer is transferred onto the surface of the negative electrode active layer of the first negative electrode to obtain a first composite structure; the second electrolyte layer is transferred onto the surface of the negative electrode active layer of the second negative electrode to obtain a second composite structure. The first positive electrode, the first composite structure, the insulating layer, the second positive electrode, and the second composite structure are stacked sequentially to ensure that the active layer of each positive electrode faces the electrolyte layer and the active layer of each negative electrode faces the electrolyte layer. Then, the tabs are soldered and the aluminum-plastic film is encapsulated. Finally, the encapsulated battery is fixed with a stainless steel plate and placed in an isostatic press for isostatic pressing at 300 MPa for 30 minutes to obtain a solid-state battery.

[0098] Example 3 This embodiment provides a solid-state battery with the following structure: Figure 1 As shown, it includes two positive electrode plates (first positive electrode plate and second positive electrode plate), two negative electrode plates (first negative electrode plate and second negative electrode plate), two electrolyte layers (first electrolyte layer and second electrolyte layer), and one insulating layer. The thicknesses of the first positive electrode plate, first electrolyte layer, first negative electrode plate, insulating layer, second positive electrode plate, second electrolyte layer, and second negative electrode plate are 250 μm, 60 μm, 88 μm, 5 μm, 250 μm, 60 μm, and 88 μm, respectively. The sum of the thicknesses of all these layers is 801 μm.

[0099] The positive electrode current collector of the positive electrode is made of aluminum foil with a thickness of 12 μm, and the positive electrode active layer has a thickness of 235 μm. The negative electrode current collector of the negative electrode is made of copper foil with a thickness of 8 μm, and the negative electrode active layer has a thickness of 80 μm. The insulating layer is made of butyl rubber.

[0100] The positive electrode is 70mm long and 100mm wide. The negative electrode, electrolyte layer and insulating layer are the same length and width, 74mm long and 106mm wide.

[0101] The specific method for preparing a solid-state battery provided in this embodiment is as follows: S1. Preparation of positive electrode sheet NCM811 cathode material, LPSC electrolyte powder, VGCF, and SEPS were added to a suitable butyl butyrate solvent in a mass fraction ratio of 75:20:3:2. The components were then uniformly dispersed using a high-speed disperser to form a cathode slurry with a solid content of 65%. After obtaining the cathode slurry, a grooved die coater was used to uniformly coat the slurry onto one side of the cathode current collector, forming a thin layer. After coating, the slurry was pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet was then pressed into a sheet under a pressure of 250 MPa.

[0102] S2, Preparation of electrolyte layer 9.9 kg of LPSC electrolyte powder and 0.1 kg of NBR were placed in xylene and stirred to obtain an electrolyte slurry with a solid content of 60%. The electrolyte slurry was coated on a release film and dried to obtain an electrolyte layer.

[0103] S3. Preparation of negative electrode sheet Silicon carbon material, LPSC electrolyte powder, VGCF, and PAA were added to xylene solvent in a mass fraction ratio of 65:30:3:2. The components were then uniformly dispersed using a high-speed disperser to form a stable negative electrode slurry with a solid content of 60%. The negative electrode slurry was uniformly coated onto a single surface of the negative electrode current collector with a thickness of 6 μm using a grooved die coating machine to form a thin layer. After coating, the electrode was pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet was then roll-formed under a pressure of 250 MPa.

[0104] S4, assembled as a battery Take the two electrolyte layers (first electrolyte layer and second electrolyte layer) prepared in step S2, the two negative electrode plates (first negative electrode plate and second negative electrode plate) prepared in step S3, the insulating layer, and the two positive electrode plates (first positive electrode plate and second positive electrode plate) prepared in step S1.

[0105] The first electrolyte layer is transferred onto the surface of the negative electrode active layer of the first negative electrode to obtain a first composite structure; the second electrolyte layer is transferred onto the surface of the negative electrode active layer of the second negative electrode to obtain a second composite structure. The first positive electrode, the first composite structure, the insulating layer, the second positive electrode, and the second composite structure are stacked sequentially to ensure that the active layer of each positive electrode faces the electrolyte layer and the active layer of each negative electrode faces the electrolyte layer. Then, the tabs are soldered and the aluminum-plastic film is encapsulated. Finally, the encapsulated battery is fixed with a stainless steel plate and placed in an isostatic press for isostatic pressing at 300 MPa for 30 minutes to obtain a solid-state battery.

[0106] Example 4 This embodiment is basically the same as embodiment 1, except that the insulating layer is made of a non-elastic material, namely aluminum oxide. Example 5 This embodiment is basically the same as Embodiment 1, except that the thickness of the insulating layer is 10μm.

[0107] Comparative Example This comparative example provides a conventional solid-state battery with the following structure: Figure 2 As shown.

[0108] Its structure includes a first negative electrode, a first electrolyte layer, a double-coated positive electrode, a second electrolyte layer, and a second negative electrode arranged in sequence, with thicknesses of 50μm, 30μm, 348μm, 30μm, and 50μm, respectively.

[0109] In this example, the positive current collector of the double-coated positive electrode is aluminum foil with a thickness of 12 μm, and the thickness of the positive active layer on both sides is 184 μm. The negative electrode is the same as in Example 1.

[0110] The length and width of the positive electrode are the same as in Example 1, and the length and width of the negative electrode and electrolyte layer are also the same as in Example 1.

[0111] The specific method for preparing the solid-state battery in this comparative example is as follows: S1. Preparation of the positive electrode sheet: NCM811 positive electrode material, LPSC electrolyte powder, VGCF, and SEPS are added to a suitable butyl butyrate solvent in a mass fraction ratio of 75:20:3:2. The components are then uniformly dispersed using a high-speed disperser to form a positive electrode slurry with a solid content of 70%. After obtaining the positive electrode slurry, a grooved die coating machine is used to uniformly coat the slurry onto both sides of the positive electrode current collector, forming a thin layer. After coating, the electrode is pre-dried in an 80℃ oven for 2 hours, and then transferred to a 120℃ vacuum drying oven for 8 hours. The dried electrode sheet is then pressed into a sheet under a pressure of 250 MPa. S2. Preparation of electrolyte layer: The preparation method is the same as in Example 1, and the thickness of the electrolyte layer is also the same as in Example 1. S3. Preparation of negative electrode sheet: The method for preparing negative electrode sheet is the same as in Example 1, and the thickness of the obtained negative electrode sheet is also the same as in Example 1. S4. Assemble into a battery: Take the two electrolyte layers (first electrolyte layer and second electrolyte layer) obtained in step S2, the two negative electrode plates (first negative electrode plate and second negative electrode plate) obtained in step S3, the insulating layer, and the one positive electrode plate obtained in step S1.

[0112] The first electrolyte layer is transferred onto the surface of the negative electrode active layer of the first negative electrode to obtain a first composite structure; the second electrolyte layer is transferred onto the surface of the negative electrode active layer of the second negative electrode to obtain a second composite structure. The first composite structure, the insulating layer, the first positive electrode sheet, and the second composite structure are stacked sequentially to ensure that the active layer of each positive electrode sheet faces the electrolyte layer, and the active layer of each negative electrode sheet faces the electrolyte layer.

[0113] Experimental Example 1 The yield rate, process short-circuit rate, and battery energy density of the solid-state batteries in each embodiment and comparative example were tested in the following manner: Battery yield test: The voltage resistance of the battery cell after compression molding is evaluated using a voltage resistance meter to determine whether a short circuit has occurred in the battery cell manufacturing process. If a short circuit occurs, the cell is unqualified; if no short circuit occurs, the cell is qualified. The ratio of qualified cells to the total number of cells tested is the yield rate. The number of cells tested is 100 per group.

[0114] Short circuit rate during battery testing: First, the prepared and assembled solid-state battery cells need to be connected to the Xinwei Battery Testing System. Next, a constant current density of 0.5C is used to perform charge-discharge cycle tests on the solid-state batteries. "C" represents the battery's rated capacity, and the C-rate defines the charge-discharge rate; 0.5C means that a full charge or discharge can be completed within 2 hours. The number of batteries that short-circuited during 500 charge-discharge cycles is counted. The short-circuit rate during the battery test is the ratio of the number of batteries with short circuits to the total number of batteries tested. The average of the short-circuit rates measured from 10 batteries is taken as the final test result.

[0115] Record the test results in Table 1.

[0116] Table 1. Test results of solid-state batteries provided in each embodiment and comparative example.

[0117] As shown in Table 1, the solid-state batteries prepared according to the various embodiments of the present invention have a significantly higher yield and a significantly lower short-circuit rate during battery testing compared to conventional solid-state batteries (comparative examples). This indicates that the solid-state battery structure provided by the present invention, by replacing one double-sided coated positive electrode sheet with two single-sided coated positive electrode sheets and reconfiguring the stacking structure to reduce the spacing between the two negative electrode sheets, can effectively improve the edge cracking of the negative electrode sheets during high-pressure packaging, thereby increasing the battery yield.

[0118] Experimental Example 2 The energy density of each embodiment was measured.

[0119] Methods for testing cycle number and energy density: Before the test begins, the prepared and assembled solid-state battery cells must first be connected to the Xinwei Battery Testing System.

[0120] Next, the solid-state battery was subjected to charge-discharge cycle testing using a constant current density of 0.5C. "C" represents the battery's rated capacity, and the C-rate defines the charge-discharge rate. 0.5C means that a full charge or discharge can be completed within 2 hours. By setting a fixed current density for charge-discharge testing, consistency of test conditions can be ensured for each test, thus obtaining reliable cycle performance data. During the test, the system automatically records the battery's discharge energy. The discharge energy continuously decreases with each cycle; the number of charge-discharge cycles corresponding to a 20% decrease in energy density is recorded, which represents the battery's cycle life. Energy density = Discharge energy / Battery mass.

[0121] Record the test results in Table 2.

[0122] Table 2 Energy Density of Some Examples

[0123] As can be seen from Table 2, the solid-state batteries provided by the various embodiments of the present invention have high energy density. Comparing Embodiment 4 with Embodiment 1, Embodiment 4 has poor cycle performance, indicating that the use of an inelastic insulating layer in Embodiment 4 cannot alleviate the expansion of the battery during the cycle process and cannot improve the cycle performance. Comparing Embodiment 5 with Embodiment 1, Embodiment 5 has a larger battery mass due to the excessive thickness of the elastic insulating layer, which leads to a decrease in energy density. Therefore, the thickness of the elastic insulating layer is best when it is within the preferred range of the present invention.

[0124] In summary, the solid-state battery provided by this invention, compared to traditional solid-state batteries, replaces one double-sided coated positive electrode sheet with two single-sided coated positive electrode sheets, and adjusts the stacking order, so that the spacing between the two negative electrode sheets changes from the original double-sided coated positive electrode sheet to the current single-sided coated positive electrode sheet, thus reducing the spacing. This reduces the bending degree of the negative electrode sheet edges during high-pressure battery molding, effectively improving the edge cracking of the negative electrode sheet. Using an insulating layer to separate the positive and negative electrode sheets ensures battery safety.

[0125] In a preferred embodiment of the present invention, the insulating layer is selected as an elastic insulating pad, which can buffer the volume expansion of the battery to a certain extent and further improve the safety of the battery.

[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A solid-state battery, characterized in that, The solid-state battery comprises at least two stacked electrical cells along the same direction of its thickness. Each electrical cell includes a positive electrode, an electrolyte layer, and a negative electrode stacked sequentially. The size of the negative electrode is larger than that of the positive electrode, and the positive electrode is coated on one side. An insulating layer is disposed between two adjacent electrical cells.

2. The solid-state battery according to claim 1, characterized in that, The insulating layer is a flexible insulating pad.

3. The solid-state battery according to claim 2, characterized in that, The flexible insulating pad is made of silicone rubber, EPDM rubber, polyurethane elastomer, polyimide, polycarbonate, nylon 11 / 12, butyl rubber, chloroprene rubber, polytetrafluoroethylene, thermoplastic elastomer, ethylene-vinyl acetate copolymer, thermoplastic polyolefin, cross-linked polyethylene, polyetheretherketone or polyester film, or a composite material of any two of the aforementioned materials. And / or, the thickness of the flexible insulating pad is 2~5μm.

4. The solid-state battery according to claim 1, characterized in that, Each of the positive electrode plates includes a positive electrode current collector and a positive electrode active layer disposed on one side of the positive electrode current collector, the positive electrode active layer being disposed close to the electrolyte layer; Each of the negative electrode sheets includes a negative electrode current collector and a negative electrode active layer disposed on one side of the negative electrode current collector, the negative electrode active layer being disposed close to the electrolyte layer.

5. The solid-state battery according to claim 4, characterized in that, The thickness of the positive electrode sheet is 120~250μm; Optionally, the thickness of the positive current collector is 6~15μm, and the thickness of the positive active layer is 114~235μm.

6. The solid-state battery according to claim 4, characterized in that, The thickness of the negative electrode current collector is 3~8μm, and the thickness of the negative electrode active layer is 20~80μm.

7. The solid-state battery according to claim 1, characterized in that, The thicknesses of the positive electrode, the electrolyte layer, the negative electrode, and the insulating layer are 120~250μm, 20~60μm, 23~88μm, and 2~5μm, respectively. Optionally, when the solid-state battery includes two stacked electrical cells, the sum of the thicknesses of the two stacked electrical cells and the insulating layer is 328~801μm.

8. A method for preparing a solid-state battery as described in any one of claims 1 to 7, characterized in that, include: n sets of structures used to form the electrical unit and n-1 insulating layers are stacked, where n≥2; The structure for forming the electrical unit includes a positive electrode, an electrolyte layer, and a negative electrode. After stacking, the tabs are soldered and packaged.

9. The preparation method according to claim 8, characterized in that, When n=2, the stacking methods include: One of the electrolyte layers is transferred to the surface of the negative electrode active layer of the negative electrode sheet to obtain a composite structure. Two composite structures are obtained by following this arrangement. The positive electrode, the composite structure, the insulating layer, the positive electrode, and the composite structure are stacked sequentially, followed by tab welding and encapsulation.

10. An electrical appliance, characterized in that, Including the solid-state battery as described in any one of claims 1 to 7.

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