An ultrathin lithium metal / alloy anode, its preparation method, and its application in solid-state batteries

Abstract

An ultrathin lithium metal / alloy anode, its preparation method, and its application in solid-state batteries belong to the field of lithium-ion battery technology. The ultrathin lithium metal / alloy anode is prepared through a cryogenic pretreatment combined with cyclic rolling. This process can refine the grain size of the anode material to the micrometer or even submicrometer level. Grain boundaries, acting as physical barriers, hinder dislocation movement, significantly increasing the strain rate of the material under high stress, thereby improving the material's resistance to plastic deformation and effectively reducing the stacking pressure requirements of solid-state batteries. Simultaneously, the prepared lithium metal solid-state battery possesses the advantage of high energy density and maximizes battery cycle life by suppressing porosity accumulation during electrode-electrolyte cycling. This invention provides an effective solution for the development of low-cost, high-energy-density, high-safety, and long-cycle-performance lithium metal solid-state battery technology.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, and relates to an ultrathin lithium metal / alloy anode and its preparation method, specifically to a lithium metal anode material obtained based on cryogenic rolling technology, its preparation method, and its application in solid-state batteries. Background Technology

[0002] Driven by the global goal of carbon neutrality, the rapid development of the low-altitude economy, including electric vehicles, drones, and electric vertical takeoff and landing (eVTOL) aircraft, has created an urgent demand for high-energy-density lithium-ion batteries (LIBs). However, current commercially available lithium-ion batteries using liquid electrolytes are limited by inherent structural defects, making it difficult to meet the performance targets of next-generation batteries exceeding 350 Wh / kg. Solid-state batteries have become a research focus due to their intrinsic safety characteristics, such as non-flammability and leak-free operation. In particular, systems paired with lithium metal anodes (theoretical specific capacity of 3860 mAh / g, minimum redox potential of -3.04 V) are considered a cutting-edge technological path for next-generation high-energy-density and high-safety rechargeable batteries.

[0003] The practical application of solid-state lithium metal batteries faces multiple technical challenges, with the core difficulty lying in the controllable preparation of lithium metal anodes. The inherent high viscosity and poor processability of lithium metal make it difficult to precisely control the thickness using traditional mechanical pressing techniques. Currently, lithium metal anodes used in laboratory and industrial settings are generally tens to hundreds of micrometers thick. While excessive lithium reserves (N / P ratio > 10) can alleviate cycle stability issues, they create a contradiction of "high lithium consumption - low energy efficiency," not only wasting precious metal resources but also significantly reducing battery energy density. The key to overcoming the energy density bottleneck lies in using ultra-thin lithium metal-based anodes with a thickness of <50 μm, thereby increasing energy density by reducing the N / P ratio. Furthermore, the high reactivity of lithium metal poses a risk of combustion or even explosion in lithium-rich systems during battery failure, constituting a significant safety hazard.

[0004] Interface stability control is another core challenge in the development of solid-state batteries. At the interface between the lithium metal anode and the solid electrolyte, in addition to the dynamic evolution of the solid electrolyte interface (SEI) and the mixed conductive interface, the formation and accumulation of interfacial porosity within the lithium metal electrode significantly increases interfacial impedance, leading to deterioration in battery rate performance and cycle stability. Therefore, developing ultrathin lithium metal anode fabrication technology that combines scalable fabrication feasibility with excellent interfacial compatibility is of significant scientific and industrial value for balancing battery energy density, cycle life, and safety, and promoting the engineering application of high-energy-density solid-state batteries. Summary of the Invention

[0005] This invention addresses the challenges of ultrathin lithium metal anode material preparation and the tendency for interfacial delamination with solid electrolytes during the stripping process in existing technologies. It proposes an ultrathin lithium metal / alloy anode, its preparation method, and its application in solid-state batteries.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing an ultrathin lithium metal / alloy anode material, which achieves ultrathinness and performance optimization of the anode material through a synergistic process of cryogenic pretreatment and multi-pass cyclic rolling, includes the following steps:

[0008] Step 1: Preparation and Application of Low-Temperature Lubricating Oil: In an environment with a dew point below -40℃, weigh the base lubricant and additives according to a predetermined mass ratio, and mix them evenly using a magnetic stirrer at a speed of 300~400 rpm to obtain the low-temperature lubricating oil; 5~30 minutes before the start of the rolling process, evenly apply the low-temperature lubricating oil to the working surface of the roller, with the coating amount controlled at 0.5~1.0 g / m. 2 This is to prevent interfacial adhesion failure between the lithium metal foil and the roller during the initial rolling process;

[0009] Step 2: Initial rolling and leveling treatment: In an environment with a dew point below -40°C, the raw material is subjected to the first surface leveling rolling using a two-roll reversible rolling mill;

[0010] Step 3: Cryogenic Treatment: The lithium metal or lithium alloy material obtained in Step 2 is rapidly transferred to a cryogenic chamber for cooling. The cooling temperature range is -196℃ to -80℃, and the cooling time in the cryogenic chamber is 1 to 3 minutes to ensure that the internal temperature of the material reaches the required low temperature uniformly. The purpose of Step 3 is to significantly suppress dislocation movement and recrystallization behavior during subsequent rolling processes through cryogenic treatment, thereby optimizing the plastic deformation process of the material. The cryogenic environment helps to obtain a finer and more uniform grain structure, which is beneficial to improving the mechanical and electrochemical properties of the material.

[0011] Step 4: Multi-pass cryogenic rolling cycle: Roll the material after cryogenic treatment in Step 3. The deformation of each rolling pass is controlled at 6%~30%, and the rolling speed is 0.1~10mm / s to ensure uniform deformation. After each rolling pass, repeat the cryogenic treatment in Step 3 to gradually reduce the material thickness through cyclic rolling.

[0012] Further, in step one, the base lubricant comprises component A and component B, with a mass ratio of component A to component B of 98:2 to 1:1; component A is an anhydrous ester (palmitate, isopropyl benzoate, or dodecyl / tetradecyl oleate) or anhydrous ether (triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol butyl ether); component B is an alkane (n-hexane, isododecane) or anhydrous oil (cyclobutyric acid, cyclohexyl siloxane, dimethyl silicone oil, decamethylcyclopentasiloxane, diethyl silicone oil); the additive is one or more of heptafluorobutyric acid, perfluorooctanoic acid, and trifluoromethyltrimethoxysilane, with a mass ratio of base lubricant to additive of 100:0.05 to 0.4.

[0013] Furthermore, in step two, the raw material is lithium metal foil / block / circle or lithium alloy material with a purity >99%; the thickness of the raw material is 70~450μm, and the deformation amount of the first rolling is controlled at 5%~15% (the deformation amount is defined as (initial thickness - thickness after rolling) / initial thickness × 100%), to ensure that the material is initially formed without wrinkles or excessive deformation.

[0014] Furthermore, the lithium alloy is a combination of lithium with one or more of tin, zinc, magnesium, aluminum, and indium, with an atomic ratio of 5 to 150:1.

[0015] Furthermore, in step three, liquid nitrogen is used as the cooling medium in the cryogenic chamber.

[0016] Furthermore, in step four, the final thickness of the ultrathin lithium metal / alloy anode is 5~30 μm. The thickness is achieved through rolling cycles and freezing. Thin lithium anodes tend to stick to the rolls during simple rolling, but freezing hardens the material, improving its mechanical properties and thus the processing.

[0017] An ultrathin lithium metal / alloy anode prepared by the above-described method. The ultrathin lithium metal / alloy anode material prepared by the above method has a uniform and fine microcrystalline structure (the grain size can be refined to the micrometer or even submicrometer level). This structure can shorten the lithium-ion diffusion path, adjust the deposition uniformity, and significantly improve the yield strength and resistance to plastic deformation of the material, effectively adapting to volume changes during battery cycling.

[0018] An application of the ultrathin lithium metal / alloy anode prepared by the above method in solid-state batteries: The application is as follows: The uniform, high yield strength, dendrite-free ultrathin lithium metal / alloy anode prepared above is applied to solid-state batteries. Under low stacking pressure conditions, good electrode-electrolyte interface contact is maintained, significantly improving the high-rate cycle performance of the battery. The ultrathin characteristics and excellent mechanical properties of the material make it have broad application prospects in high-energy-density solid-state batteries, which can meet the high-performance battery requirements of portable electronic devices, electric vehicles and large-scale energy storage systems.

[0019] Furthermore, the electrolyte of the solid-state battery is a solid-state electrolyte. It can include common organic polymer solid-state electrolytes (PEO, PVDF, PVC) and inorganic solid-state electrolytes (LLZO, LLZTO, LATP, LAGP, Li). 10 GeP2S 12 At least one of (Li3YCl6, Li3YBr6).

[0020] Furthermore, the cathode material of the solid-state battery is lithium cobalt oxide, lithium-rich manganese-based oxide, or lithium nickel cobalt manganese oxide (such as LiNi). 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.83 Co 0.05 Mn 0.12 O2, LiNi 0.9 Co 0.05 Mn 0.05 One of the types of O2.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The ultrathin lithium metal / alloy anode material prepared by the present invention through cryogenic rolling technology has a smaller grain size (which can be refined to the micrometer or even submicrometer level), which significantly improves the yield strength and hardness of the material. Compared with lithium metal materials prepared by traditional methods, it has higher strength and better toughness.

[0023] (2) Due to the material's higher viscoplasticity and deformability, it can maintain good electrode-electrolyte interface contact under low stacking pressure. During battery operation, it suppresses interface delamination and lithium dendrite growth, thereby significantly improving the battery's high-rate cycling performance under low stacking pressure.

[0024] (3) The method proposed in this invention is applicable to the preparation of sodium, zinc and other alkali metals and other alloys. Attached Figure Description

[0025] Figure 1 Here is a SEM image of the lithium metal prepared in Example 1;

[0026] Figure 2 The image shows the XRD pattern of lithium metal prepared in Example 1.

[0027] Figure 3 An optical image of the ultrathin lithium metal foil prepared in Example 1;

[0028] Figure 4 The symmetrical cells of Example 1 and Comparative Example 1 were used at 3 mAh cm⁻¹ -2 Cyclic performance graph under the given conditions;

[0029] Figure 5 The symmetrical cells of Example 1 and Comparative Example 1 were used at 3 mAh cm⁻¹ -2 Impedance plot after 50 cycles under the given conditions;

[0030] Figure 6 The graph shows the cycle performance of the Li||NCM83 batteries in Example 1 and Comparative Example 1. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0032] This invention employs cryogenic rolling technology, leveraging the significant impact of the cryogenic environment on material processing to optimize and enhance material performance. Specifically, by rolling lithium metal or its alloys at extremely low temperatures, dislocation movement and recrystallization during plastic deformation are effectively suppressed, resulting in significant grain refinement. This grain-refined material exhibits not only higher strength but also superior toughness. Precise control of rolling process parameters allows for the controllable preparation of lithium metal / alloy anode materials with varying thicknesses. The ultrathin lithium metal / alloy anode material prepared by this invention, with its excellent resistance to plastic deformation, is particularly suitable for solid-state battery applications. In practical applications, this material can support high-rate cycling of batteries under low stacking pressure conditions, significantly enhancing overall battery performance and extending cycle life. Furthermore, the application of this material is expected to be a key factor in promoting the further development of solid-state battery technology and accelerating its commercialization.

[0033] The ultrathin lithium metal / alloy anode of this invention is prepared through a cryogenic rolling process combining cryogenic pretreatment and cyclic rolling. This process can refine the grain size of the anode material to the micrometer or even submicrometer level. Grain boundaries, acting as physical barriers, hinder dislocation movement, significantly increasing the strain rate of the material under high stress, thereby improving the material's resistance to plastic deformation and effectively reducing the stacking pressure requirements of solid-state batteries. Simultaneously, the prepared lithium metal solid-state battery possesses the advantage of high energy density and maximizes battery cycle life by suppressing porosity accumulation during electrode-electrolyte cycling. This invention provides an effective solution for the development of low-cost, high-energy-density, high-safety, and long-cycle-performance lithium metal solid-state battery technology.

[0034] Example 1

[0035] Step 1: Preparation and application of low-temperature lubricating oil: In an environment with a dew point below -40°C, triethylene glycol dimethyl ether and diethyl silicone oil are weighed at a mass ratio of 95:5, and perfluorooctanoic acid (PFOA) at a mass fraction of 0.2% is added to the mixture as a surfactant. The mixture is then stirred evenly at 300 rpm using a magnetic stirrer to obtain the low-temperature lubricating oil. Five minutes before the start of the rolling process, the low-temperature lubricating oil is evenly applied to the working surface of the roller using a spray coating device, with the coating amount controlled at 0.5~1.0 g / m². 2 This is to prevent plastic adhesion between the lithium metal foil and the roller during the initial rolling process.

[0036] Step 2, Initial Rolling and Leveling Treatment: In an environment with a dew point below -40℃, a two-roll reversible rolling mill is used to perform surface leveling on pure lithium metal foil with an initial thickness of 80 μm and a purity of 99wt.%. Through a single rolling operation, the thickness of the lithium metal foil is reduced to 70 μm, with the thickness tolerance controlled within ±1 μm. During the rolling process, the linear pressure is set to 20 N / mm and the roller speed is 10 rpm to ensure that there are no obvious wrinkles on the foil surface and the thickness uniformity deviation is ≤1.5%.

[0037] Step 3: Cryogenic Treatment with Liquid Nitrogen: The lithium metal foil obtained in Step 2 is rapidly transferred to a liquid nitrogen cryogenic chamber and held at -196℃ for 1 minute to obtain a cryogenically pretreated lithium metal foil. The rolling stress is eliminated by utilizing the lithium metal lattice contraction effect at low temperatures, resulting in the cryogenically pretreated lithium metal foil.

[0038] Step 4: Cryogenic Rolling and Cyclic Treatment: The cryogenically pretreated lithium metal foil is rolled. The deformation amount is controlled at 20% for the first 5 rolling passes and 10% for the last 4 passes (deformation amount is defined as (initial thickness - rolled thickness) / initial thickness × 100%). The roll feed speed is set to 5 mm / s. After each rolling pass, the foil is immediately placed in a -196℃ liquid nitrogen cryogenic chamber for 1 minute to suppress work hardening and restore material ductility. The final product is a lithium metal foil with a thickness of approximately 15 μm, and its thickness uniformity is controlled within ±0.5 μm. The SEM image of the ultrathin lithium metal foil prepared in this example is shown below. Figure 1 As shown, the lithium metal anode prepared by this method can form a dense deposition. XRD characterization shows that the cryogenic rolling method can also form an ordered texture (110) crystal plane, while the conventional rolling method produces a polycrystalline texture. The single-crystal texture is more conducive to improving the cycle stability of the battery. Optical photographs of the thin lithium metal foil are shown below. Figure 3 As shown, the cryogenic rolling method effectively alleviates the problem of lithium metal sticking to the rolls during the thinning process, and the rolled product has a distinct metallic luster.

[0039] Step 5: Fabrication of the lithium metal solid-state battery: The lithium metal anode material was cut into 14 mm diameter sheets. Nickel-cobalt-manganese cathode material was used as the positive electrode, and LLTZO (Lithium-ion-metal oxide) inorganic solid electrolyte was used as the electrolyte. A mold-type battery structure was used, and the battery assembly was completed under a stacking pressure of 2.8 MPa, followed by testing. The assembly of the lithium symmetric battery involves both electrodes being lithium metal anodes. The cycle performance and post-cycle impedance of the tested lithium metal symmetric battery are shown below. Figure 4 , 5 As shown, the lithium metal prepared in Example 1 was in a 3 mAh cm⁻¹ solution. -2 The Li||NCM83 battery can still cycle for 250 hours at its surface capacity, exhibiting high stability. In contrast, Comparative Example 1 showed significant polarization and battery failure in less than 50 hours, with a significantly higher impedance after cycling compared to the negative electrode obtained in Example 1. The Li||NCM83 battery's cycle performance is as follows: Figure 6 As shown, lithium metal that has undergone cryogenic rolling can ensure relatively stable cycle performance, while in the early cycle process (less than 50 cycles) of Comparative Example 1, the interface fails rapidly due to the accumulation and evolution of interfacial porosity, and the performance drops sharply.

[0040] The lithium metal battery assembled with the ultrathin lithium metal / alloy anode provided by this invention not only achieves high energy density, but also effectively alleviates the formation of pores at the lithium metal electrode-electrolyte interface by controlling the microstructure of the anode material to enhance its plastic deformation capability. This significantly reduces the stacking pressure required for solid-state lithium metal batteries, thereby improving the battery's electrochemical performance and extending its lifespan.

[0041] Example 2

[0042] The difference between this embodiment and Embodiment 1 is that the cryogenic rolling temperature is adjusted to -150℃.

[0043] Example 3

[0044] Steps one, two, and three are the same as in Example 1.

[0045] Step 4, Cryogenic Rolling and Cyclic Treatment: The cryogenically pretreated lithium metal foil is rolled, with the deformation per rolling pass controlled at 10% and the roll feed speed set at 5 mm / s. After each rolling pass, the foil is immediately placed in a -196℃ liquid nitrogen cryogenic chamber for 1 minute to suppress work hardening and restore the material's ductility. The above process is repeated 15 times to finally obtain a lithium metal foil with a thickness of 15 μm, and its thickness uniformity is controlled within ±0.5 μm.

[0046] Step five is the same as step five in Example 1.

[0047] Example 4

[0048] The difference between this embodiment and Embodiment 3 is that the cryogenic rolling temperature is adjusted to -100℃.

[0049] Example 5

[0050] The difference between this embodiment and Example 1 lies in the adjustment of the lubricating oil formulation in step one. Specifically, the original lubricating oil components are adjusted to a mixture of ethylene glycol butyl ether methyl silicone oil and decamethylcyclopentasiloxane (mass ratio of 2:1), and 0.3% by mass of trifluoromethyltrimethoxysilane is added to this mixture as an interfacial active agent. This adjusted formulation still achieves the same technical effect as Example 1. The lithium metal material obtained by rolling with the changed lubricating oil formulation was assembled into a lithium symmetric battery, and its interfacial impedance was tested to be 45 Ω. This indicates that the optimization of the lubricating oil formulation not only benefits the physical rolling process of the lithium metal anode but also effectively improves the solid-solid contact between the solid electrolyte and the lithium metal anode.

[0051] Example 6

[0052] Step 1: The preparation and application of the low-temperature lubricating oil are the same as in Example 1.

[0053] Step 2, Initial Rolling and Leveling: A two-roll reversible rolling mill is used to level the surface of the initial 80 μm thickness using a Li-2wt% Al alloy instead of pure lithium. Through a single rolling operation, the thickness of the lithium alloy foil is reduced to 70 μm, with the thickness tolerance controlled within ±1 μm. During the rolling process, the linear pressure is set to 20 N / mm and the roller speed is 10 rpm to ensure that there are no obvious wrinkles on the foil surface and the thickness uniformity deviation is ≤1.5%.

[0054] Step 3, cryogenic treatment with liquid nitrogen: The lithium alloy foil obtained in step 2 is quickly transferred to a cryogenic liquid nitrogen chamber and kept at -196℃ for 1 minute. The rolling stress is eliminated by utilizing the lattice contraction effect of lithium metal at low temperature, and a cryogenically pretreated lithium alloy is obtained.

[0055] Step 4: Cryogenic Rolling and Cyclic Treatment. The cryogenically pretreated lithium alloy foil is rolled, with the deformation per rolling pass controlled at 10% (deformation is defined as the relative thickness reduction rate). The roll feed speed is set to 5 mm / s. The edge condition of the foil is monitored in real time during rolling to avoid cracking defects. After each rolling pass, the foil is immediately placed in a -196℃ liquid nitrogen cryogenic chamber for 1 minute to suppress work hardening and restore the material's ductility. The above process is repeated 15 times to finally obtain a lithium alloy foil with a thickness of 15 μm, and its thickness uniformity is controlled within ±0.5 μm.

[0056] Step 5: Preparation of lithium alloy solid-state battery: The above lithium alloy anode material is cut into electrode sheets with a diameter of 14 mm. Nickel-cobalt-manganese cathode material is used as the cathode, and inorganic solid electrolyte LLZO is used as the electrolyte. The battery is assembled and tested under a stacking pressure of 2.8 MPa using a mold battery structure. The capacity retention rate is 81.1% after 188 cycles at room temperature.

[0057] Example 7

[0058] The difference between this embodiment and embodiment 6 is that the Li-2wt%Al material in step two is replaced with a Li-3wt%Mg alloy, which achieves the same effect.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that there is no cryogenic treatment step.

[0061] Comparative Example 2

[0062] Step 1: Apply low-temperature lubricating oil as in Example 1.

[0063] Step 2: Single-pass rolling and leveling. Roll the 80μm lithium foil to 70μm in one pass with a linear pressure of 20 N / mm.

[0064] Step 3: Multiple cryogenic treatments. No subsequent rolling is performed; only 15 cryogenic treatments at -196℃ (1 min each) are repeated. The material is left at room temperature for 1 min between each cryogenic rolling, and the final lithium foil thickness is still 70 μm.

[0065] Step 4: Non-circulating rolling process.

[0066] Step five is the same as step five in Example 1.

[0067] Table 1 Thickness variation of lithium metal during rolling process

[0068] (Taking lithium metal raw material with a thickness of 80 μm as an example, and taking the rolling process of Example 1 as an example)

[0069]

[0070] Finally, batteries for each embodiment and comparative example were assembled and their electrochemical performance was tested. Nickel-cobalt-manganese cathode material was used as the positive electrode, LLTZO as the electrolyte, and the corresponding lithium metal material as the negative electrode. The batteries were then installed in molds for testing. Their cycle performance data are shown in Table 2.

[0071] Table 2

[0072]

Claims

1. A method for preparing an ultrathin lithium metal / alloy anode, characterized in that: The method includes the following steps: Step 1: Preparation and Application of Low-Temperature Lubricating Oil: In an environment with a dew point below -40℃, weigh the base lubricant and additives according to a predetermined mass ratio, and mix them evenly using a magnetic stirrer at a speed of 300~400 rpm to obtain the low-temperature lubricating oil; 5~30 minutes before the start of the rolling process, evenly apply the low-temperature lubricating oil to the working surface of the roller, with the coating amount controlled at 0.5~1.0 g / m. 2 The base lubricant comprises component A and component B, with a mass ratio of component A to component B of 98:2 to 1:1; component A is an anhydrous ester or anhydrous ether, and component B is an alkane or anhydrous oil; the additive is one or more of heptafluorobutyric acid, perfluorooctanoic acid, and trifluoromethyltrimethoxysilane, with a mass ratio of base lubricant to additive of 100:0.05 to 0.

4. Step 2: Initial Rolling and Leveling Treatment: Under an environment with a dew point below -40℃, the raw material is subjected to initial surface leveling rolling using a two-roll reversible rolling mill; the raw material is lithium metal foil / block / circle or lithium alloy material with a purity >99%; the raw material thickness is 70~450μm, and the initial rolling deformation is controlled at 5%~15%; Step 3: Cryogenic treatment: The lithium metal or lithium alloy material obtained in Step 2 is quickly transferred to a cryogenic chamber for cooling. The cooling temperature range is -196℃ to -80℃, and the cooling time is 1 to 3 minutes. Step 4: Multi-pass cryogenic rolling cycle: Roll the material after cryogenic treatment in Step 3. The deformation of each rolling pass is controlled at 6%~30%, and the rolling speed is 0.1~10mm / s to ensure uniform deformation. After each rolling pass, repeat the cryogenic treatment in Step 3 to gradually reduce the material thickness through cyclic rolling.

2. The method for preparing an ultrathin lithium metal / alloy anode according to claim 1, characterized in that: The lithium alloy is a combination of lithium with one or more of tin, zinc, magnesium, aluminum, and indium, with an atomic ratio of 5 to 150:

1.

3. The method for preparing an ultrathin lithium metal / alloy anode according to claim 1, characterized in that: In step three, liquid nitrogen is used as the cooling medium in the cryogenic chamber.

4. The method for preparing an ultrathin lithium metal / alloy anode according to claim 1, characterized in that: In step four, the final thickness of the ultrathin lithium metal / alloy anode is 5~30 μm.

5. An ultrathin lithium metal / alloy anode prepared by the preparation method according to any one of claims 1 to 4.

6. The application of an ultrathin lithium metal / alloy anode prepared by the preparation method according to any one of claims 1 to 4 in a solid-state battery.

7. The application according to claim 6, characterized in that: The electrolyte in the solid-state battery is a solid electrolyte.

8. The application according to claim 6, characterized in that: The cathode material of the solid-state battery is one of lithium cobalt oxide, lithium-rich manganese-based oxide, or nickel-cobalt-manganese oxide.

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