Lithium ion solid-state battery and preparation method and application thereof

Abstract

This invention belongs to the field of lithium-ion solid-state battery manufacturing technology, and relates to a lithium-ion solid-state battery, its preparation method, and its application. The preparation method includes: coating an interface slurry on one side of a positive electrode substrate, and curing it by irradiation with ultraviolet light of a gradient distribution with strong intensity at the center and weak intensity at the edges to form an interface layer; composite a three-dimensional porous metal framework on one side of a negative electrode substrate, then depositing magnetic nanoparticles on the three-dimensional porous metal framework, and applying a static magnetic field during the deposition process to form a conductive network layer; assembling a positive electrode with the interface layer, a solid electrolyte layer, and a negative electrode with the conductive network layer, such that the interface layer and the conductive network layer are respectively adjacent to opposite sides of the solid electrolyte layer, to obtain a lithium-ion solid-state battery. The initial DCR of this lithium-ion solid-state battery can be reduced to below 2 mΩ, and the increase after 500 cycles is no more than 15%.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion solid-state battery manufacturing technology, and relates to a lithium-ion solid-state battery, its preparation method and application. Background Technology

[0002] With the increasing demands for battery energy density from new energy vehicles, solid-state batteries have become a focus of industry research and development due to their high safety and potential for energy density breakthroughs. Among them, the solid-state battery system using "NCM9-based cathode + silicon-based anode" is highly anticipated due to its theoretical energy density of nearly 400Wh / kg. However, this solid-state battery system faces two major interface challenges in practical applications: (1) Ion transport hindrance at the cathode side interface. This is because the NCM9-based cathode material and the oxide solid electrolyte are prone to side reactions at the interface, generating a Li2CO3 passivation layer. This passivation layer severely hinders lithium-ion transport, resulting in a lithium-ion transference number of less than 0.4, which significantly increases the interface impedance; (2) High electron tunneling impedance at the anode side interface. This is because the silicon-based anode material undergoes a volume expansion of about 300% during charging and discharging, causing it to peel off from the solid electrolyte interface, resulting in discontinuous electron tunneling paths and a sharp increase in electron transport impedance.

[0003] To address the above challenges, existing technologies have proposed various solutions, but all have significant drawbacks. For example, some existing technologies coat the cathode surface with inorganic nanoparticles such as LLZTO and improve interfacial contact through hot pressing. However, this method has the following problems: (1) LLZTO reacts with the NCM9 cathode during hot pressing to generate more Li2CO3, which increases the impedance. (2) The hot pressing process increases the crystallinity of the polymer electrolyte, which reduces the lithium-ion transference number to below 0.3, thus significantly increasing the overall DC internal resistance (DCR). Other existing technologies add dynamic crosslinking agents such as disulfide bonds to the electrolyte and repair interfacial cracks through thermal triggering. The disadvantages are: (1) Disulfide bonds are unstable under high voltage conditions and easily decompose to generate -SO3. - Byproducts, the accumulation of which not only damages the original ion conduction network, but also causes a sharp drop in repair efficiency with the increase of cycle number, resulting in continuous deterioration of DCR; (2) This technology only focuses on local "interfacial mechanical repair", but ignores the large-scale transport efficiency of electrons in the entire positive electrode. Since the good local adhesion cannot make up for the weakness of the overall conductive network of the electrode, the transfer of electrons between materials is blocked, causing serious electrochemical polarization. This polarization effect significantly increases the equivalent resistance of the battery, which directly leads to the increase of DCR. Summary of the Invention

[0004] To address the issues of high interface impedance and poor long-term cycle stability in existing solid-state batteries, this invention provides a lithium-ion solid-state battery, its preparation method, and its application. The initial DCR of this lithium-ion solid-state battery can be reduced to below 2mΩ, and its increase after 500 cycles is no more than 15%.

[0005] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing a lithium-ion solid-state battery, comprising the following steps: An interface slurry is coated on one side of the positive electrode substrate and cured by irradiation with ultraviolet light of gradient intensity distribution, which is strong in the center and weak at the edge, to form an interface layer; wherein, the interface slurry contains thiol monomer, solid electrolyte nanowires, lithium salt and photoinitiator. A three-dimensional porous metal framework is composited on one side of the negative electrode substrate, and then magnetic nanoparticles are deposited on the three-dimensional porous metal framework. A static magnetic field is applied during the deposition process to form a conductive network layer. A positive electrode with the interface layer, a solid electrolyte layer, and a negative electrode with the conductive network layer are assembled such that the interface layer and the conductive network layer are respectively adjacent to opposite sides of the solid electrolyte layer to obtain a lithium-ion solid-state battery.

[0006] In conjunction with the first aspect of the present invention, in some specific embodiments, the light intensity in the central region of the ultraviolet light is 50~150 mW / cm². 2 The light intensity in the edge region is 20~40mW / cm². 2 .

[0007] In conjunction with the first aspect of the present invention, in some specific embodiments, the interface slurry comprises, by mass percentage: Thiol monomers 40%~60%; Solid electrolyte nanowires: 4%~6%; Lithium salts 3%~5%; Photoinitiator 0.5%~1.5%; Polymer electrolyte, balance.

[0008] In conjunction with the first aspect of the present invention, in some specific embodiments, the thiol monomer is one or more of (3-mercaptopropyl)trimethoxysilane, 3-mercaptopropyl methacrylate, mercaptosilane, mercaptopropyl acrylate, and 2-mercaptobenzoxazole; and / or, the solid electrolyte nanowire is a nanowire with an aspect ratio greater than 20, and its material is one or more of tantalum-doped lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium phosphorus oxy nitrogen, and lithium germanium phosphorus sulfur; and / or, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

[0009] In conjunction with the first aspect of the present invention, in some specific embodiments, the porosity of the three-dimensional porous metal skeleton is 90% ± 1.2%, and its material is one or more combinations of copper, nickel, and silver.

[0010] In conjunction with the first aspect of the present invention, in some specific embodiments, magnetic nanoparticles are deposited on the three-dimensional porous metal framework, and a static magnetic field is applied during the deposition process, including: Magnetic nanoparticles are deposited on the three-dimensional porous metal framework by electrodeposition. The magnetic nanoparticles are made of one of the following materials: silver (Ag), nickel (Ni), iron(III) oxide (Fe3O4), or Fe3O4@Ag with a core-shell structure (where the Fe3O4 core particle size is 10~20nm and the Ag shell thickness is 2~5nm), and the particle size is less than 50nm. A static magnetic field with an intensity of 0.5T to 2.0T is applied during the deposition process for a duration of 10 to 60 seconds.

[0011] In conjunction with the first aspect of the present invention, in some specific embodiments, after depositing magnetic nanoparticles, the method further includes: A ceramic coating is prepared on the surface of the conductive network layer, and the thickness of the ceramic coating is 5±0.2μm.

[0012] In conjunction with the first aspect of the present invention, in some specific embodiments, the positive electrode substrate is a high-nickel positive electrode sheet, and the negative electrode substrate is a silicon-based negative electrode sheet.

[0013] In a second aspect, the present invention provides a lithium-ion solid-state battery, which is prepared by the method for preparing a lithium-ion solid-state battery described in the first aspect.

[0014] Thirdly, the present invention provides an electrical device comprising the lithium-ion solid-state battery described in the second aspect.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: The lithium-ion solid-state battery provided by this invention has an initial DCR as low as below 2mΩ and can increase by no more than 15% after 500 cycles. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the preparation of the interface layer for this invention.

[0018] Figure 2 This is a flowchart illustrating the fabrication process of the conductive network layer in this invention.

[0019] Figure 3 This is a flowchart illustrating the assembly of a lithium-ion solid-state battery according to the present invention.

[0020] Figure 4 This is a schematic diagram of the structure of the lithium-ion solid-state battery provided by the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] In this article, "NCM9 series" refers to high-nickel ternary materials with a nickel content of 90% or higher in lithium nickel cobalt manganese oxide (NCM) materials. The high nickel content of NCM9 series materials gives them higher energy density, enabling them to provide longer driving range, making them suitable for applications with high energy density requirements, such as electric vehicles.

[0023] The method for preparing a lithium-ion solid-state battery provided by the present invention includes the following steps: An interface slurry is coated on one side of the positive electrode substrate and cured by irradiation with ultraviolet light of gradient intensity distribution, which is strong in the center and weak at the edge, to form an interface layer; wherein, the interface slurry contains thiol monomer, solid electrolyte nanowires, lithium salt and photoinitiator. A three-dimensional porous metal framework is composited on one side of the negative electrode substrate, and then magnetic nanoparticles are deposited on the three-dimensional porous metal framework. A static magnetic field is applied during the deposition process to form a conductive network layer. A lithium-ion solid-state battery is obtained by assembling a positive electrode with the interface layer, a solid electrolyte layer, and a negative electrode with the conductive network layer.

[0024] The present invention demonstrates through a comparison of Example 1 and Comparative Example 3 that, compared with uniform ultraviolet irradiation curing, irradiation curing using ultraviolet light with a gradient distribution of light intensity that is strong in the center and weak at the edges reduces the initial DCR from 2.15 mΩ to 1.50 mΩ, and after 500 cycles, the DCR increase decreases from +23% to +13%.

[0025] The present invention demonstrates through comparison of Example 1 and Comparative Example 4 that, compared with magnetic nanoparticle deposition without a magnetic field, applying a static magnetic field during the deposition of magnetic nanoparticles reduces the initial DCR from 2.05 mΩ to 1.50 mΩ, and the DCR increase after 500 cycles decreases from +19% to +13%.

[0026] The above results indicate that irradiation curing with ultraviolet light of a gradient distribution with strong intensity at the center and weak intensity at the edges, as well as applying a static magnetic field during the deposition of magnetic nanoparticles, can reduce the initial DCR and inhibit the growth of DCR during the cycling process.

[0027] In some embodiments of the present invention, the light intensity in the central region of the ultraviolet light is 50~150 mW / cm. 2 The light intensity in the edge region is 20~40mW / cm². 2 Preferably, the light intensity in the central region of the ultraviolet light is 80~100 mW / cm². 2 The light intensity in the edge region is 25~35mW / cm². 2 The ratio of light intensity in the central region to that in the edge region is (1.7~5):1. Preferably, the ratio is (2~4):1. More preferably, the ratio is 3.33.

[0028] In some embodiments of the present invention, the interface slurry comprises, by mass percentage: 40% to 60% thiol monomer; 4% to 6% solid electrolyte nanowires; 3% to 5% lithium salt; 0.5% to 1.5% photoinitiator; polymer electrolyte, balance.

[0029] The mass percentage of thiol monomers ranges from 40% to 60%, which ensures crosslinking degree and flexibility. Preferably, the mass percentage of thiol monomers ranges from 45% to 50%.

[0030] The photoinitiator has a mass percentage range of 0.5% to 1.5%, which ensures initiation efficiency while avoiding excessive side reactions. Preferably, the mass percentage range of the photoinitiator is 0.8% to 1.2%.

[0031] The lithium salt has a mass percentage range of 3% to 5%, which ensures that the lithium ion transference number is ≥0.6 while the crystallinity is not too high. Preferably, the lithium salt has a mass percentage of 4%.

[0032] Solid electrolyte nanowires, with a mass percentage range of 4% to 6%, can guarantee an ionic conductivity ≥1×10⁻⁶ at room temperature. - 3 While exhibiting S / cm, it also possesses low interfacial brittleness; preferably, the solid electrolyte nanowires have a mass percentage of 5%. Preferably, the solid electrolyte nanowires have a diameter of 30~80nm and a length of 1~2μm.

[0033] The remainder is polymer electrolyte to ensure film formation continuity.

[0034] In some embodiments of the present invention, the thiol monomer is one or more selected from (3-mercaptopropyl)trimethoxysilane, 3-mercaptopropyl methacrylate, mercaptosilane, mercaptopropyl acrylate, and 2-mercaptobenzoxazole. Preferably, the thiol monomer is (3-mercaptopropyl)trimethoxysilane, 2-mercaptobenzoxazole, or mercaptopropyl acrylate. The thiol groups (-SH) contained in these thiol monomers form disulfide bonds in the presence of a photoinitiator and ultraviolet light. These disulfide bonds can be used to repair interfacial cracks.

[0035] In some embodiments of the present invention, the photoinitiator is one or a combination of at least two of Irgacure 819, Irgacure 184, Darocur 1173, and TPO-L (acylphosphooxide).

[0036] In some embodiments of the present invention, the solid electrolyte nanowire is a nanowire with an aspect ratio greater than 20, and its material is one or more of tantalum-doped lithium lanthanum zirconium oxide (LLZTO), lithium lanthanum titanium oxide (LLTO), lithium phosphorus oxy nitrogen (LiPON), and lithium germanium phosphorus sulfide (LGPS).

[0037] In some embodiments of the present invention, the lithium salt is one or more selected from lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF6), and lithium tetrafluoroborate (LiBF4). These lithium salts have high thermal stability and a wide electrochemical window.

[0038] In some embodiments of the present invention, the porosity of the three-dimensional porous metal framework is 90% ± 1.2%, and its material is one or more combinations of copper, nickel, and silver. This high porosity results in discontinuous electron transport, and magnetic nanoparticles are deposited on the surface or in the pores of the three-dimensional porous metal framework. The three-dimensional porous metal framework and the magnetic nanoparticles together constitute a conductive network, forming a conductive network layer.

[0039] In some embodiments of the present invention, the polymer electrolyte is one or more of polyethylene oxide (PEO), polypropylene oxide (PPO), and polyethylene oxide-propylene oxide copolymer. These polymer electrolytes are polymers containing ether oxygen bonds (-O-), which can provide lithium-ion transport channels.

[0040] In some embodiments of the present invention, magnetic nanoparticles are deposited on the three-dimensional porous metal framework, and a static magnetic field is applied during the deposition process, including: Magnetic nanoparticles are deposited on the three-dimensional porous metal framework by electrodeposition. The magnetic nanoparticles are made of one of silver, nickel, and iron oxide, and have a particle size of less than 50 nm. A static magnetic field with an intensity of 0.5T to 2.0T is applied during the deposition process for a duration of 10 to 60 seconds.

[0041] In some embodiments of the present invention, after depositing magnetic nanoparticles, the method further includes: A ceramic coating is prepared on the surface of the three-dimensional porous metal framework. Preferably, the ceramic coating is an Al2O3 coating. In some embodiments, the thickness of the ceramic coating is 5 ± 0.2 μm.

[0042] In some embodiments of the present invention, the positive electrode substrate is a high-nickel positive electrode sheet, and the negative electrode substrate is a silicon-based negative electrode sheet.

[0043] The present invention also provides a lithium-ion solid-state battery, which is prepared by the above-described method for preparing a lithium-ion solid-state battery.

[0044] The present invention also provides an electrical device comprising the above-described lithium-ion solid-state battery.

[0045] The technical solution of the present invention will be described in detail below through specific embodiments. Unless otherwise specified, the raw materials used in the present invention are all commercially available commodities.

[0046] Example 1: Fabrication of a lithium-ion solid-state battery I. Preparation of the positive electrode sheet (I) Preparation of NCM9 cathode substrate 1. Preparation of positive electrode slurry (1) According to the mass ratio NCM9 (nickel-cobalt-manganese ternary cathode material, LiNi) 0.9 Co 0.05 Mn 0.05 O2): Conductive carbon black (SuperP): Polyvinylidene fluoride (PVDF, model 6020) = 96.5:1.5:2.0. Accurately weigh each raw material and mix them to obtain a mixed raw material; wherein, the NCM9 particle size D50 is controlled to be 8~12 μm, and the specific surface area of ​​the conductive carbon black is ≥60 m². 2 / g.

[0047] (2) Transfer the above mixed raw materials to a dual planetary mixer, add N-methylpyrrolidone (NMP, purity ≥99.5%, water content ≤0.05%) as a solvent, set the stirring temperature ≤45℃ (controlled by a water bath), and the stirring parameters are 30 rpm revolution and 1200 rpm rotation, and continue stirring for 120 minutes to obtain the positive electrode slurry. The final solid content of the positive electrode slurry is 63%±0.5% to ensure the coating performance of the slurry.

[0048] 2. Coating and Drying (1) Coating operation: The above positive electrode slurry was coated onto the surface of the aluminum foil current collector (thickness 12 μm, purity ≥99.8%) using a transfer coating machine. The wet film thickness was controlled by adjusting the doctor blade gap to ensure that the density after drying was 21.5±0.3 mg / cm³. 2 The coating speed was set to 1.5 m / min, and the edge blank width was 2~3 mm.

[0049] (2) Segmented drying: The aluminum foil current collector coated with wet film is sent into a three-stage hot air oven to remove NMP solvent from the slurry, thus obtaining NCM9 cathode substrate. The parameters of the three-stage hot air oven are set as follows: the temperature of the first stage is 80℃±2℃, the temperature of the second stage is 100℃±2℃, the temperature of the third stage is 110℃±2℃, the drying time of each stage is 3 minutes, and the air velocity in the oven is 3m / s.

[0050] (ii) Interface layer composite 1. Preparation of solid electrolyte nanowires (1) Raw material ratio: The raw materials were accurately weighed according to the molar ratio of Li2S (purity 99.9%):GeS2 (purity 99.99%):P2S5 (purity 99.9%) = 7:2:1, and 5 mol% of lithium iodide (LiI, purity 99.9%) was added to improve the chemical stability of the nanowires. The particle size of each raw material was ≤5μm.

[0051] (2) Melt synthesis: After mixing the above raw materials, the mixture is loaded into a quartz tube and vacuumed to 10°C using a vacuum unit. -3 After Pa, the two ends of the quartz tube were sealed with an oxyhydrogen flame. The sealed quartz tube was placed in a muffle furnace and heated to 900°C at a heating rate of 5°C / min. The temperature was held for 10 hours to carry out the melting reaction. Then the quartz tube was quickly transferred to an ice-water bath for quenching to obtain the glass precursor.

[0052] (3) Hot pressing: The glass precursor is crushed and ground to a particle size ≤10 μm, filled into a graphite mold (inner diameter 20 mm), placed in a hot press furnace, and hot pressed for 2 hours at a temperature of 550℃ and a pressure of 50 MPa to obtain lithium germanium phosphorus sulfur (LGPS) bulk material.

[0053] (4) Fiber preparation: The LGPS bulk material is fixed in the feeding device of the ultra-high temperature fiber drawing machine, the drawing temperature is set to 600℃ and the traction speed is 10 m / min, and continuous solid electrolyte nanowires (diameter 30~80 nm, length 1~2 μm) are prepared by the drawing die (pore size 50 μm) of the ultra-high temperature fiber drawing machine, hereinafter referred to as LGPS nanowires.

[0054] 2. Preparation of interfacial slurry (1) Weigh the following components precisely by mass percentage: 50% (3-mercaptopropyl)trimethoxysilane (purity 98%), 5% of the above LGPS nanowires, 4% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, purity 99.9%), 0.8% photoinitiator Irgacure 819 (purity 98%), and 40.2% polyethylene oxide (PEO, molecular weight 1 million). The error of each component is ≤ ±0.1%.

[0055] (2) Solvent and mixing: NMP (purity ≥99.5%) was added to the above mixed raw materials as a solvent, and the solid content of the slurry was controlled to be 40%±1%; the material was transferred to a planetary ball mill, agate balls were selected (ball-to-material ratio 5:1), the speed was set to 300rpm±10rpm, and the ball milling was carried out for 4 hours±15 minutes. During this period, the machine was stopped and stirred once every 1 hour to ensure that the LGPS nanowires were uniformly dispersed and there was no agglomeration, and finally a uniform interface slurry was obtained.

[0056] 3. Coating and UV gradient curing (1) Microgravure coating: The interface slurry is coated on the surface of the NCM9 positive electrode substrate (non-current collector side) prepared above using a microgravure coating machine. The mesh count of the anilox roller is 300 lines, the wet film thickness is controlled to be 50±2 μm, and the coating speed is 0.8m / min to ensure that the coating is free from defects such as missed coating and bubbles.

[0057] (2) Pre-drying treatment: The NCM9 positive electrode substrate coated with wet film is sent into the pre-drying oven and preheated and dried at 80°C for 60 seconds.

[0058] (3) UV gradient curing: The pre-baked NCM9 cathode substrate was irradiated and cured using a roll-to-roll UV-LED curing system (wavelength 365nm) to obtain a cathode sheet with an interface layer. The roll-to-roll UV-LED curing system consists of two independent control units: a central region and an edge region. ① Central area: Light intensity set at 100 mW / cm² 2 Irradiation time: 30 seconds; ②Edge area (within 5 mm of the electrode edge): Set the UV light intensity to 30 mW / cm 2 Irradiation time: 30 seconds.

[0059] (4) Winding process: The cured positive electrode sheet is wound up by a winding machine. The winding tension is set to 10 N / m and the winding speed is 0.5 m / min. During the winding process, wrinkles on the positive electrode sheet are avoided.

[0060] Table 1 Interface Layer and Key Parameters

[0061] II. Preparation of negative electrode sheet and magnetic field-induced conductive network (I) Preparation of SiOx-C negative electrode substrate 1. Slurry preparation (1) Raw material weighing: Weigh each raw material precisely according to the mass ratio of SiOx-C (silicon-oxygen-carbon composite material, x=0.5-1.0): sodium carboxymethyl cellulose (CMC, molecular weight 250,000): styrene-butadiene rubber (SBR, solid content 40%) = 94:3:3. The particle size D50 of SiOx-C is controlled to be 2~5μm and the specific surface area is ≤30m². 2 / g.

[0062] (2) Solvent addition: Add deionized water (conductivity ≤10μS / cm) to the mixed raw materials as a solvent. During the stirring process, control the solid content of the slurry to 45% to ensure the flowability of the slurry.

[0063] (3) Mixing and stirring: Transfer the material to a planetary mixer, set the speed to 500 rpm, stir for 60 minutes, and after stirring, perform vacuum degassing (vacuum degree -0.09MPa) for 15 minutes.

[0064] 2. Coating and Drying (1) Coating operation: The negative electrode slurry was coated onto the surface of the copper foil current collector (thickness 8μm, purity ≥99.9%) using a transfer coating machine, and the density after drying was controlled to be 12.5±0.2mg / cm³. 2 The coating speed is 1.2m / min, and the edge blank width is 2~3mm.

[0065] (2) Air knife drying: The coated electrode sheet is sent into the air knife dryer, the drying temperature is set to 90℃, the air knife speed is 4m / s, and the drying time is 5 minutes.

[0066] (II) Magnetic field-induced conductive network composite 1. Three-dimensional porous copper skeleton composite (1) Pretreatment of the skeleton: A commercially available ordinary three-dimensional porous copper skeleton (porosity 90.5±1.2%, pore size 8~12μm, thickness 10.3μm) was selected. The surface oil was removed by ultrasonic cleaning with ethanol for 10 minutes, and then dried in a vacuum drying oven at 60℃ for 30 minutes. The mass of the skeleton was weighed by a balance of 0.01%, and its surface density was calculated to be 5mg / cm³. 2 ±0.3mg / cm 2 .

[0067] (2) Cold pressing composite: The three-dimensional porous copper skeleton is covered on the surface (non-current collector side) of the SiOx-C negative electrode substrate prepared above, and placed in a roller press. The cold pressing pressure is set to 5MPa and held at room temperature (25℃) for 10 seconds to obtain a negative electrode sheet with a copper skeleton.

[0068] 2. Silver nanoparticle electrodeposition (1) Preparation of electrolyte: Prepare 0.1±0.01M silver nitrate (AgNO3, purity 99.9%) electrolyte, with deionized water as the solvent, and add 0.01M nitric acid (HNO3, purity 68%) to adjust the pH value to 2 to prevent the hydrolysis of silver ions.

[0069] (2) Impregnation treatment: Immerse the negative electrode sheet with copper skeleton into the above silver nitrate electrolyte for 10 seconds to ensure that the silver nitrate electrolyte fully penetrates into the pores of the copper skeleton.

[0070] (3) Electrodeposition operation: Electrodeposition was performed using a three-electrode system, with a composite electrode as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The DC current density was set to 10 mA / cm². 2 The deposition time was 30 minutes, and the electrolyte temperature was controlled at 25℃ during the deposition process.

[0071] 3. Static magnetic field orientation treatment (1) Magnetic field device: A static magnetic field generating device is constructed using a permanent magnet array (neodymium iron boron magnet). The magnetic field strength on the surface of the electrode is measured to be 1.0T by a gaussmeter. The magnetic field direction is perpendicular to the surface of the negative electrode (i.e., along the thickness direction of the electrode).

[0072] (2) Directional operation: Place the electrode plate after electrodeposition in the above static magnetic field device and maintain the magnetic field for 30 seconds.

[0073] 4. Preparation of Al2O3 ceramic protective layer (1) Preparation of coating slurry: 30wt% of Al2O3 nanoparticles (purity 99.9%, particle size 20~50nm) and 2wt% of PVDF binder (molecular weight 6020) are dispersed in NMP solvent and ultrasonically dispersed for 30 minutes using an ultrasonic disperser (power 500W).

[0074] (2) Spraying operation: A pneumatic sprayer is used, the spraying pressure is set to 0.3MPa, the distance between the spray gun and the electrode surface is 10cm, and the spraying speed is 5cm / s. The above coating slurry is sprayed on the surface of the conductive network layer. The thickness of the coating after drying is 5±0.2μm (detected by a laser thickness gauge) by controlling the number of sprays.

[0075] (3) Hot pressing curing: The coated electrode sheet is fed into the roller press, and the hot pressing temperature is set to 120℃, the pressure to 10MPa, and the hot pressing speed to 0.5m / min, and finally the negative electrode sheet is obtained.

[0076] Table 2 Conductive network layer and key parameters

[0077]

[0078] Note: The conductive network layer refers to the three-dimensional porous copper framework layer after silver nanoparticle electrodeposition and static magnetic field orientation treatment.

[0079] III. Battery Assembly 1. Component preparation: Take the solid electrolyte layer (Li7La3Zr2O) 12 Ceramic sheet, 100μm thick, 10.5cm² in area. 2 ) and the positive electrode sheet (10 cm² area) prepared in this embodiment. 2 ) and negative electrode plate (area 10cm²) 2 Assembly was carried out in an argon glove box (water and oxygen content ≤0.1ppm).

[0080] 2. Stacking and Packaging: Stack the components in the following order: "positive electrode (interface layer facing solid electrolyte layer) → solid electrolyte layer → negative electrode (conductive network layer facing solid electrolyte layer)", ensuring that each component is aligned and the edge deviation is ≤0.5mm. The stacked battery cell is then placed into an aluminum-plastic film packaging shell (100μm thick) and heat-sealed using a heat sealing machine (model: HF-300) at a temperature of 180℃±5℃, a pressure of 0.5MPa, and a time of 3 seconds to obtain the bare battery cell.

[0081] 3. Pressure shaping: The packaged bare cell is placed in a flatbed press and a pressure of 5MPa is applied at room temperature for 10 minutes to ensure full contact between the interfaces and obtain the final lithium-ion solid-state battery.

[0082] Example 2: (Low thiol monomer TEM + high photoinitiator PI) The operation steps in this embodiment are basically the same as those in Embodiment 1, except that the ratio of the interface slurry and the UV gradient curing time are different: The interface slurry contained 45% (3-mercaptopropyl)trimethoxysilane by mass (lower than 50% in Example 1), 1.2 wt% (higher than 0.8% in Example 1) of photoinitiator Irgacure 819 by mass, and 25 s of UV curing time (less than 30 s in Example 1).

[0083] Example 3: (Combination of mercaptosilane + LLZTO nanowires + LiFSI) The operation steps in this embodiment are basically the same as those in Embodiment 1, except for the following parts which are different from those in Embodiment 1: 1. Interface slurry: (1) The thiol monomer consists of 30 wt% (3-mercaptopropyl)trimethoxysilane and 20 wt% mercaptopropyl acrylate, the mass percentages of which are calculated relative to the total weight of the interfacial slurry.

[0084] (2) The solid electrolyte nanowires are made of LLZTO nanowires. The preparation method of LLZTO nanowires is as follows: ① Preparation of spinning solution: The raw materials were accurately weighed according to the molar ratio of lanthanum nitrate hexahydrate: zirconium oxychloride: tantalum pentoxide = 3:1.75:0.25, mixed, and lithium nitrate was weighed at 2 wt% of the mixture. Lithium nitrate, lanthanum nitrate hexahydrate, zirconium oxychloride, and tantalum pentoxide were dissolved in a DMF / acetic acid mixture (volume ratio 4:1), and polyvinylpyrrolidone was added at a concentration of 10 wt%. The mixture was ball-milled at 300 rpm for 6 h to obtain a spinning solution with a viscosity of 1200 ± 50 cP at room temperature.

[0085] ② Electrospinning: A custom magnetic strip receiving plate (insulated magnetic strip spacing 5 mm) is used, the high voltage electric field voltage is 20 kV, and the receiving distance is 15 cm; a 0.5T static magnetic field (NdFeB permanent magnet) is applied to make the LLZTO precursor fibers oriented along the magnetic field direction.

[0086] ③ Sintering process: In an argon atmosphere, the temperature is first increased to 600℃ at 2℃ / min and held for 2 hours (to remove PVP), and then increased to 950℃ at 5℃ / min and held for 4 hours (to crystallize) to obtain LLZTO nanowires.

[0087] 2. Pre-drying treatment: The coated electrode sheet is placed in a pre-drying oven and preheated at 80°C for 60 seconds, after which the humidity is controlled to be less than 30% (RH).

[0088] Example 4: (Dithiol monomer + LiPON nanowires) The operation steps in this embodiment are basically the same as those in Embodiment 1, except for the following parts: I. Preparation of the positive electrode sheet (a) Preparation of NCM9 cathode substrate: Same as in Example 1.

[0089] (ii) Interface layer composite: 1. Preparation of solid electrolyte nanowires In this embodiment, the solid electrolyte nanowire is made of LiPON nanowire, and the preparation method of LiPON nanowire is as follows: ① Raw material preparation Precursor: Nanoscale Li3PO4 powder.

[0090] Template: Anodized aluminum oxide (AAO) template.

[0091] Nitrogen source: High-purity nitrogen (purity ≥ 99.99%).

[0092] ② Precursor nitriding treatment Nanoscale Li3PO4 powder was heat-treated at 500°C for 6 hours in a flowing high-purity nitrogen atmosphere to nitridate it into LiPON material.

[0093] ③ Template filling Nitrided LiPON powder was mixed with anhydrous ethanol to prepare a slurry with a solid content of 30%, which was then ultrasonically dispersed. The slurry was injected into the pores of the AAO template and kept under a vacuum of -0.1 MPa for 30 minutes to ensure that the slurry fully penetrated into the nanopores of the template.

[0094] ④ High-temperature sintering The filled AAO template was placed under an argon atmosphere and heated to 750°C at a heating rate of 3°C / min. It was then held at this temperature for 4 hours to densify the LiPON material.

[0095] ⑤ Template Removal and Post-processing The sintered composite was immersed in a 5M sodium hydroxide (NaOH) solution for 2 hours to completely dissolve the AAO template. The released LiPON nanowires were then removed and repeatedly washed with deionized water until neutral. Finally, the sample was vacuum dried to obtain the LiPON nanowires.

[0096] 2. Preparation of interfacial slurry 1) Raw material ratio: Weigh each component precisely according to the mass percentage, including 40wt% of 2-mercaptobenzoxazole, 10wt% of 3-mercaptopropyl methacrylate, 4% of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, purity 99.9%), 1.0wt% of photoinitiator TPO-L (purity 98%), and 40.2% of polyethylene oxide (PEO, molecular weight 1 million). The error of each component is ≤±0.1%.

[0097] 3. Coating and UV gradient curing: Same as in Example 1.

[0098] II. Preparation of negative electrode sheet and magnetic field-induced conductive network: Same as in Example 1.

[0099] III. Battery assembly: Same as in Example 1.

[0100] Comparative Example 1: Hot pressing of LLZTO packing The steps for this comparative example are basically the same as those for Example 1, and the specific preparation method is as follows: I. Preparation of Positive Electrode (a) Preparation of NCM9 cathode substrate: Same as in Example 1.

[0101] (ii) Interface layer composite 1. Preparation of interfacial slurry (1) Raw material ratio: Weigh each component precisely according to the mass percentage. Among them, 5% of commercially available ordinary LLZTO nanoparticles and 95% of polyethylene oxide (PEO, molecular weight 1 million) are used. The error of each component is ≤ ±0.1%.

[0102] 2. Coating and UV gradient curing: Same as in Example 1.

[0103] II. Preparation of Negative Electrode Sheets (a) Preparation of SiOx-C negative electrode substrate: Same as in Example 1.

[0104] (ii) Magnetic field-induced recombination of conductive networks: None.

[0105] III. Battery assembly: Same as in Example 1.

[0106] Comparative Example 2: Disulfide Bond Repair The steps for this comparative example are basically the same as those for Example 1, and the specific preparation method is as follows: I. Preparation of the positive electrode sheet (a) Preparation of NCM9 cathode substrate: Same as in Example 1.

[0107] (ii) Interface layer composite: None II. Preparation of negative electrode sheet and magnetic field-induced conductive network: Same as in Example 1.

[0108] III. Preparation of Solid Electrolyte Layer Polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were dissolved in acetonitrile at a molar ratio of EO:Li = 18:1. 1,2-ethylenedithiol (98% purity) was added to make its mass fraction 3wt%. After stirring evenly, a solid electrolyte membrane with a thickness of 100μm was prepared and then vacuum dried for later use.

[0109] IV. Circulatory Repair Process: After each charge-discharge cycle, the battery is placed in a 60°C constant temperature chamber for 1 hour to trigger disulfide bond repair. Then it is allowed to cool naturally to 25°C before the next cycle.

[0110] V. Battery assembly: Same as in Example 1.

[0111] Comparative Example 3: Uniform UV Curing The comparative example follows essentially the same steps as Example 1, except for the UV curing method of the interface layer (using uniform light intensity with no gradient distribution). The preparation method is as follows: I. Preparation of the positive electrode sheet (a) Preparation of NCM9 cathode substrate: Same as in Example 1.

[0112] (ii) Interface layer composite 1. Preparation of solid electrolyte nanowires: Same as in Example 1.

[0113] 2. Preparation of interface slurry: Same as in Example 1.

[0114] 3. Coating and UV curing: (1) Micro-recessed coating: Same as in Example 1.

[0115] (2) Pre-drying treatment: Same as in Example 1.

[0116] (3) Uniform UV curing: A roll-to-roll UV-LED curing system (wavelength 365nm) is used, without distinguishing between the center and edge areas, and the light intensity is set to a uniform 70mW / cm² across the entire area. 2 Irradiation time: 30 seconds.

[0117] (4) Winding process: Same as in Example 1.

[0118] II. Preparation of the negative electrode sheet. Same as in Example 1.

[0119] III. Battery Assembly. Same as in Example 1.

[0120] Comparative Example 4 (Deposition without magnetic field) This comparative example is basically the same as Example 1 in terms of steps, except that a static magnetic field is not applied during the fabrication of the negative electrode conductive network. The fabrication method is as follows: I. Preparation of the positive electrode sheet: Same as in Example 1.

[0121] II. Preparation of the negative electrode sheet (a) Preparation of SiOx-C negative electrode substrate: Same as in Example 1.

[0122] (ii) Non-magnetic field induced conductive network composite (difference from Example 1) 1. Three-dimensional porous copper skeleton composite: Same as in Example 1.

[0123] 2. Silver nanoparticle electrodeposition: Same as in Example 1.

[0124] 3. No static magnetic field treatment: No static magnetic field is applied after electrodeposition, and the subsequent Al2O3 coating preparation is carried out directly.

[0125] 4. Preparation of Al2O3 ceramic protective layer: Same as in Example 1.

[0126] III. Battery Assembly. Same as in Example 1.

[0127] Performance testing: The lithium-ion solid-state batteries assembled in each embodiment and comparative example were tested according to the following methods: (1) Initial DC internal resistance (DCR) test: The initial DCR of the cell is tested by using a DC internal resistance tester and discharging at 1C current for 10 seconds at 25℃.

[0128] (2) Cyclic performance test: The battery test system was used and the charge and discharge regime was set as follows: 0.5C constant current charging to 4.3V, constant voltage charging to current ≤0.05C; then 0.5C constant current discharging to 2.7V, cycle temperature 25℃, and the cell DCR increase was tested after 500 charge and discharge cycles.

[0129] Table 3 Performance Comparison of Various Lithium-ion Solid-State Batteries

[0130] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0131] It should be noted that in this invention, 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. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0132] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a lithium-ion solid-state battery, characterized in that, Includes the following steps: An interface slurry is coated on one side of the positive electrode substrate and cured by irradiation with ultraviolet light of gradient intensity distribution, which is strong in the center and weak at the edge, to form an interface layer; wherein, the interface slurry contains thiol monomer, solid electrolyte nanowires, lithium salt and photoinitiator. A three-dimensional porous metal framework is composited on one side of the negative electrode substrate, and then magnetic nanoparticles are deposited on the three-dimensional porous metal framework. A static magnetic field is applied during the deposition process to form a conductive network layer. A positive electrode with the interface layer, a solid electrolyte layer, and a negative electrode with the conductive network layer are assembled such that the interface layer and the conductive network layer are respectively adjacent to opposite sides of the solid electrolyte layer to obtain a lithium-ion solid-state battery.

2. The method for preparing a lithium-ion solid-state battery according to claim 1, characterized in that: The light intensity in the central region of the ultraviolet light is 50~150mW / cm². 2 The light intensity in the edge region is 20~40mW / cm². 2 .

3. The method for preparing a lithium-ion solid-state battery according to claim 1, characterized in that: The interface slurry, by mass percentage, comprises: Thiol monomers 40%~60%; Solid electrolyte nanowires: 4%~6%; Lithium salts 3%~5%; Photoinitiator 0.5%~1.5%; Polymer electrolyte, balance.

4. The method for preparing a lithium-ion solid-state battery according to claim 3, characterized in that: The thiol monomer is one or more selected from (3-mercaptopropyl)trimethoxysilane, 3-mercaptopropyl methacrylate, mercaptosilane, mercaptopropyl acrylate, and 2-mercaptobenzoxazole; and / or, The solid electrolyte nanowires are nanowires with an aspect ratio greater than 20, and their material is one or more of tantalum-doped lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium phosphorus oxy nitrogen, and lithium germanium phosphorus sulfur; and / or, The lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

5. The method for preparing a lithium-ion solid-state battery according to claim 1, characterized in that: The porosity of the three-dimensional porous metal skeleton is 90%±1.2%, and its material is one or more of copper, nickel, and silver.

6. The method for preparing a lithium-ion solid-state battery according to claim 1, characterized in that: Magnetic nanoparticles are deposited on the three-dimensional porous metal framework, and a static magnetic field is applied during the deposition process, including: Magnetic nanoparticles are deposited on the three-dimensional porous metal framework by electrodeposition. The magnetic nanoparticles are made of one of silver, nickel, iron tetroxide or Fe3O4@Ag and have a particle size of less than 50 nm. A static magnetic field with an intensity of 0.5T to 2.0T is applied during the deposition process for a duration of 10 to 60 seconds.

7. The method for preparing a lithium-ion solid-state battery according to claim 1, characterized in that, After depositing magnetic nanoparticles, the process also includes: A ceramic coating is prepared on the surface of the conductive network layer, and the thickness of the ceramic coating is 5±0.2μm.

8. The method for preparing a lithium-ion solid-state battery according to claim 1, characterized in that: The positive electrode substrate is a high-nickel positive electrode sheet, and the negative electrode substrate is a silicon-based negative electrode sheet.

9. A lithium-ion solid-state battery, characterized in that: It is prepared by the method of any one of claims 1 to 8 for preparing a lithium-ion solid-state battery.

10. An electrical appliance, characterized in that, Including the lithium-ion solid-state battery as described in claim 9.

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