Ultrathin lithium metal / alloy negative electrode, preparation method thereof and application of ultrathin lithium metal / alloy negative electrode in solid-state battery

Abstract

The invention discloses an ultrathin lithium metal / alloy negative electrode and a preparation method and application thereof in a solid-state battery, and belongs to the technical field of lithium ion batteries. The ultrathin lithium metal / alloy negative electrode is prepared through a deep cooling rolling process combining deep cooling pretreatment with circulating rolling, the grain size of the negative electrode material can be refined to the micron order or even the submicron order through the process, the grain boundary serves as a physical barrier to hinder dislocation movement, the strain rate of the material under high stress is remarkably increased, and the service life of the material is prolonged. Therefore, the plastic deformation resistance of the material is improved, and the requirement of the solid-state battery on the stacking pressure is effectively reduced. Meanwhile, the prepared lithium metal solid-state battery has the advantage of high energy density, and the cycle life of the battery is prolonged to the maximum extent by inhibiting pore accumulation in the electrode-electrolyte cycle process. The invention provides an effective solution for the technical development of the lithium metal solid-state battery with low cost, high energy density, high safety and long cycle performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and relates to an ultra-thin lithium metal / alloy negative electrode and a preparation method thereof, and specifically to a lithium metal negative electrode material obtained based on deep cold rolling technology, a preparation method thereof, and its application in solid-state batteries. Background Art

[0002] Driven by global carbon neutrality goals, the rapid development of low-altitude economic sectors such as electric vehicles, drones, and electric vertical take-off and landing vehicles has created an urgent need for high-energy-density lithium-ion batteries (LIBs). However, current commercial lithium-ion batteries using liquid electrolytes are limited by inherent structural defects and struggle to meet the performance targets of next-generation batteries exceeding 350 Wh / kg. Solid-state batteries have become a research focus due to their inherent safety features such as non-flammability and zero leakage. In particular, systems with lithium metal anodes (theoretical capacity of 3860 mAh / g and minimum redox potential of -3.04 V) are considered a cutting-edge technology path for the next generation of high-energy-density, high-safety rechargeable batteries.

[0003] The practical application of solid-state lithium metal batteries faces multiple technical challenges, with the core difficulty centered on the controllable preparation of lithium metal anodes. The inherent high viscosity and poor processability of lithium metal make it difficult to achieve precise thickness control using traditional mechanical pressing technology. Currently, the thickness of lithium metal anodes used in laboratories and industrial scenarios generally ranges from tens to hundreds of microns. Although excessive lithium reserves (N / P ratio > 10) can alleviate the problem of cycle stability, it creates a contradiction of "high lithium consumption-low energy efficiency", which not only wastes precious metal resources but also significantly reduces battery energy density. The key to breaking through the energy density bottleneck lies in the use of ultra-thin lithium metal-based anodes with a thickness of <50 μm, and increasing energy density by reducing the N / P ratio. In addition, the high reactivity of lithium metal makes lithium-rich systems subject to the risk of combustion or even explosion when the battery fails, posing a major safety hazard.

[0004] Controlling interface stability 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 pores within the lithium metal electrode significantly increases interfacial impedance, leading to deterioration in battery rate performance and cycling stability. Therefore, developing ultra-thin lithium metal anode preparation technology that combines scalable fabrication feasibility with excellent interface compatibility has important scientific significance 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] The present invention addresses the difficulties in the prior art of ultra-thin preparation of lithium metal negative electrode materials and the easy interfacial delamination with solid electrolytes during the stripping process, and proposes an ultra-thin lithium metal / alloy negative electrode, a preparation method thereof, and its application in solid-state batteries.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing an ultra-thin lithium metal / alloy negative electrode, which achieves ultra-thinness and performance optimization of the negative electrode material through a collaborative process of cryogenic pretreatment and multi-pass cyclic rolling, comprising the following steps:

[0008] Step 1: Preparation and application of low-temperature lubricant: In an environment with a dew point below -40°C, weigh the base lubricant and additive according to the predetermined mass ratio, mix them evenly at a speed of 300-400 rpm using a magnetic stirrer to prepare the low-temperature lubricant; within 5-30 minutes before starting the rolling process, evenly apply the low-temperature lubricant to the working surface of the roller, and control the coating amount to 0.5-1.0 g / m 2 To prevent the interface bonding failure between lithium metal foil and 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 double-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 at a temperature range of -196°C to -80°C. The material cools in the cryogenic chamber for 1 to 3 minutes to ensure that the internal temperature of the material reaches the desired low temperature uniformly. The purpose of Step 3 is to significantly inhibit the movement of dislocations and recrystallization during subsequent rolling, thereby optimizing the material's plastic deformation process. The cryogenic environment helps to obtain a finer and more uniform grain structure, which is beneficial for improving the material's mechanical and electrochemical properties.

[0011] Step 4: Multi-pass cryogenic rolling cycle: Roll the material after cryogenic treatment in step 3, control the deformation of a single rolling to 6%~30%, and the rolling speed to 0.1~10mm / s to ensure uniform deformation; after each rolling pass, repeat the cryogenic treatment in step 3, and gradually thin the material through cyclic rolling.

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

[0013] Furthermore, in step 2, the raw material is lithium metal foil / block / disc or lithium alloy material with a purity greater than 99%; the raw material thickness is 70~450μm, and the initial rolling deformation is controlled to be 5%~15% (the deformation is defined as (initial thickness-thickness after rolling) / initial thickness×100%), ensuring that the material is initially formed without wrinkles or excessive deformation.

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

[0015] Furthermore, in step three, the cryogenic box uses liquid nitrogen as a cooling medium.

[0016] Furthermore, in step 4, the final thickness of the ultra-thin lithium metal / alloy negative electrode is 5-30 μm. This thickness is achieved through the number of rolling passes and freezing. Thin lithium metal can stick to the rollers during simple rolling, but freezing hardens the material, improving its mechanical properties and thus the processing process.

[0017] An ultra-thin lithium metal / alloy anode material prepared using the aforementioned method has a uniform and fine microscopic grain structure (the grain size can be refined to the micron or even submicron level). This structure shortens the lithium ion diffusion path, regulates deposition uniformity, and significantly improves the material's yield strength and resistance to plastic deformation, effectively adapting to volume changes during battery cycling.

[0018] An application of an ultra-thin lithium metal / alloy negative electrode prepared by the above preparation method in a solid-state battery, wherein the uniform, high-yield-strength, dendrite-free ultra-thin lithium metal / alloy negative electrode prepared as above is applied to a solid-state battery, maintaining good electrode-electrolyte interface contact under low stacking pressure conditions, significantly improving the high-rate cycle performance of the battery, and the ultra-thin characteristics and excellent mechanical properties of the material give it broad application prospects in high-energy-density solid-state batteries, which can meet the high-performance battery requirements in fields such as portable electronic devices, electric vehicles, and large-scale energy storage systems.

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

[0020] Furthermore, the positive electrode material of the solid-state battery is lithium cobalt oxide, lithium-rich manganese-based, 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 O2).

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

[0022] (1) The ultra-thin lithium metal / alloy anode material prepared by the freeze-rolling technology has a smaller grain size (which can be refined to the micron or even submicron level), significantly improving 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 deformation capacity, it can maintain good electrode-electrolyte interface contact at low stacking pressure. During battery operation, it inhibits interface delamination and the growth of lithium dendrites, thereby significantly improving the high-rate cycling performance of the battery at low stacking pressure.

[0024] (3) The method proposed in the present invention is applicable to the preparation of other alkali metals such as sodium and zinc and other alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a SEM image of metallic lithium prepared in Example 1;

[0026] Figure 2 This is the XRD pattern of metallic lithium prepared in Example 1;

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

[0028] Figure 4 The symmetrical battery of Example 1 and Comparative Example 1 at 3 mAh cm -2 Cyclic performance diagram under conditions;

[0029] Figure 5 The symmetrical battery of Example 1 and Comparative Example 1 at 3 mAh cm -2 Impedance diagram after 50 cycles under the same conditions;

[0030] Figure 6 This is a cycle performance diagram of the Li||NCM83 battery of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0032] The present invention adopts cryogenic rolling technology and utilizes the significant influence of cryogenic environment on material processing to optimize and improve the performance of materials. Specifically, by rolling lithium metal or its alloys in an extremely low temperature environment, the dislocation movement and recrystallization behavior of the material during plastic deformation are effectively suppressed, thereby achieving significant grain refinement. The material after this grain refinement treatment not only exhibits higher strength, but also has better toughness. With the help of precise regulation of rolling process parameters, the thickness of lithium metal / alloy negative electrode materials can be controlled. The ultra-thin lithium metal / alloy negative electrode material prepared by the present invention is particularly suitable for the field of solid-state batteries due to its excellent ability to resist plastic deformation. In practical applications, the material can support high-rate cycling of batteries under low stacking pressure conditions, significantly enhance the overall performance of the battery, and extend its cycle life. In addition, the application of this material is expected to become a key factor in promoting the further development of solid-state battery technology and accelerating its commercialization process.

[0033] The ultra-thin lithium metal / alloy negative electrode of the present invention is prepared by a deep cold rolling process combining deep cold pretreatment with cyclic rolling. This process can refine the grain size of the negative electrode material to the micron level or even the submicron level. The grain boundaries act as physical barriers to hinder the movement of dislocations, significantly improving the strain rate of the material under high stress, thereby improving the material's ability to resist plastic deformation and effectively reducing the solid-state battery's demand for stacking pressure. At the same time, the prepared lithium metal solid-state battery has the advantages of high energy density and maximizes the battery cycle life by suppressing pore accumulation during the electrode-electrolyte cycle. The present invention provides an effective solution for the development of lithium metal solid-state battery technology with low cost, high energy density, high safety and long cycle performance.

[0034] Example 1

[0035] Step 1. Preparation and application of low-temperature lubricating oil: In an environment with a dew point below -40°C, weigh triethylene glycol dimethyl ether and diethyl silicone oil in a mass ratio of 95:5, and add 0.2% by mass of perfluorooctanoic acid as a surfactant to the mixture; mix them evenly at a speed of 300 rpm using a magnetic stirrer to prepare the low-temperature lubricating oil; within 5 minutes before starting the rolling process, use a spray coating device to evenly apply the low-temperature lubricating oil to the working surface of the roller, and the coating amount is controlled to be 0.5~1.0 g / m 2 , to prevent the plastic bonding 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°C, a double-roll reversible rolling mill is used to level the surface of 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, and the thickness tolerance is controlled at ±1 μm. During the rolling process, the line 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: Liquid nitrogen cryogenic treatment: The lithium metal foil obtained in Step 2 is quickly transferred to a liquid nitrogen cryogenic box and kept at -196°C for 1 minute to obtain cryogenically pretreated lithium metal foil. The rolling stress is eliminated by the shrinkage effect of the lithium metal lattice at low temperatures, resulting in cryogenically pretreated lithium metal foil.

[0038] Step 4, cryogenic rolling and cyclic treatment: The lithium metal foil after cryogenic pretreatment is rolled, and the deformation of the first 5 rollings is controlled to 20%, and the deformation of the last 4 rollings is controlled to 10% (the deformation is defined as (initial thickness - thickness after rolling) / initial thickness × 100%), and the rolling feed speed is set to 5 mm / s; after each rolling, the foil is immediately placed in a -196°C liquid nitrogen deep freezer for 1 minute to inhibit work hardening and restore the ductility of the material. Finally, a lithium metal foil with a thickness of about 15 μm is obtained, and its thickness uniformity is controlled within ±0.5 μm. The SEM of the ultra-thin lithium metal foil prepared in this embodiment is as follows Figure 1 As shown in the figure, the lithium metal negative electrode prepared by this method can form a dense deposition. XRD characterization shows that the deep cold rolling method can also form an ordered texture (110) crystal plane, while the conventional rolling method obtains a polycrystalline texture. The single crystal texture is more conducive to improving the cycle stability of the battery. The optical photo of the thin lithium metal foil is shown in the figure. Figure 3 As shown in the figure, the deep cold rolling method effectively alleviates the problem of lithium metal sticking to the roller during the thinning process, and has obvious metallic luster after rolling.

[0039] Step 5. Preparation of lithium metal solid-state battery: Cut the above lithium metal negative electrode material into 14 mm diameter pole pieces, use nickel cobalt manganese positive electrode material as the positive electrode, and use inorganic solid electrolyte LLTZO as the electrolyte; adopt mold battery structure, complete battery assembly and test under 2.8 MPa stacking pressure. The assembly of lithium symmetric battery means that both electrodes are lithium metal negative electrodes. The cycle performance and post-cycle impedance of the lithium metal symmetric battery obtained by testing are as follows: Figure 4 、 5 As shown in Figure 1, the lithium metal prepared in Example 1 has a capacity of 3 mAh cm -2 The negative electrode can still be cycled for 250 h at a surface capacity of 100 nm, showing high stability. However, in Comparative Example 1, obvious polarization occurs in less than 50 h, and the battery fails. The impedance after cycling is significantly higher than that of the negative electrode obtained in Example 1. Figure 6 As shown, the lithium metal after deep cold rolling can ensure relatively stable cycle performance, while in the comparative example 1, due to the accumulation and evolution of interface pores in the early cycle process (less than 50 times), the interface quickly fails and the performance drops sharply.

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

[0041] Example 2

[0042] The difference between this embodiment and embodiment 1 is that the deep cold rolling temperature is adjusted to -150°C.

[0043] Example 3

[0044] Step 1, step 2 and step 3 are the same as in Example 1.

[0045] Step 4: Deep cold rolling and cyclic treatment: The lithium metal foil after deep cold pretreatment is rolled, and the single rolling deformation is controlled to 10%. The rolling feed speed is set to 5 mm / s. After each rolling pass, the foil is immediately placed in a -196°C liquid nitrogen deep cold box for 1 minute to inhibit work hardening and restore the ductility of the material. 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 5 is the same as step 5 in Example 1.

[0047] Example 4

[0048] The difference between this embodiment and embodiment 3 is that the deep cold rolling temperature is adjusted to -100°C.

[0049] Example 5

[0050] This embodiment differs from Example 1 in that the lubricant formulation in step 1 is adjusted, specifically by replacing the original lubricant with a mixture of ethylene glycol butyl ether methyl silicone oil and decamethylcyclopentasiloxane (at a mass ratio of 2:1), and adding 0.3% by mass of trifluoromethyltrimethoxysilane to this mixture as an interfacial active agent. This adjusted formulation still achieves the same technical effects as Example 1. The lithium metal material obtained by rolling with the modified lubricant formulation was assembled into a lithium symmetric cell and tested, resulting in an interfacial impedance of 45 Ω. This demonstrates that the optimized lubricant formulation not only facilitates 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: Preparation and application of low-temperature lubricating oil are the same as in Example 1.

[0053] Step 2: Initial rolling and leveling treatment: A double-roll reversible rolling mill is used to level the surface of the foil with an initial thickness of 80 μm, using 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, and the thickness tolerance is controlled within ±1 μm. During the rolling process, the line 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: Liquid nitrogen cryogenic treatment: The lithium alloy foil obtained in step 2 is quickly transferred to a liquid nitrogen cryogenic box and kept at -196°C for 1 minute to eliminate the rolling stress by utilizing the lithium metal lattice contraction effect at low temperature, thereby obtaining a cryogenically pretreated lithium alloy.

[0055] Step 4: Deep Cold Rolling and Circulation. The cryogenically pretreated lithium alloy foil is rolled, with a single rolling deformation of 10% (deformation defined as the relative thickness reduction rate). The rolling feed speed is set at 5 mm / s. The foil edge condition is monitored in real time during rolling to avoid cracking defects. After each rolling pass, the foil is immediately placed in a -196°C liquid nitrogen cryogenic freezer for 1 minute to inhibit work hardening and restore material ductility. This process is repeated 15 times, ultimately producing a 15 μm thick lithium alloy foil with a thickness uniformity within ±0.5 μm.

[0056] Step 5. Preparation of lithium alloy solid-state battery: Cut the above lithium alloy negative electrode material into pole pieces with a diameter of 14 mm, use nickel-cobalt-manganese positive electrode material as the positive electrode, and use inorganic solid electrolyte LLZO as the electrolyte; adopt mold battery structure, complete battery assembly and test under 2.8 MPa stacking pressure, and cycle 188 times at room temperature with a capacity retention rate of 81.1%.

[0057] Example 7

[0058] The difference between this embodiment and embodiment 6 is that the Li-2wt%Al material in step 2 is changed to Li-3wt%Mg alloy, which can achieve the same effect.

[0059] Comparative Example 1

[0060] This comparative example differs from Example 1 in 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 rolling flatness: Roll the 80μm lithium foil to 70μm in one pass with a line pressure of 20 N / mm.

[0064] Step 3: Multiple cryogenic treatments. No subsequent rolling was performed, and only 15 cycles of -196°C cryogenic treatment (1 minute each) were repeated. The material was left at room temperature for 1 minute between each cryogenic rolling. The final thickness of the lithium foil remained at 70 μm.

[0065] Step 4: No cycle rolling step.

[0066] Step 5 is the same as step 5 in Example 1.

[0067] Table 1 Thickness change of lithium metal during rolling

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

[0069]

[0070] Finally, batteries were assembled for each example and comparative example and their electrochemical performance was tested. Using a nickel-cobalt-manganese cathode material as the positive electrode, LLTZO as the electrolyte, and the corresponding lithium metal material as the negative electrode, the batteries were then assembled and tested in a molded battery. The cycling performance data is shown in Table 2.

[0071] Table 2

[0072]

Claims

1. A method for preparing an ultrathin lithium metal / alloy negative electrode, characterized in that: The method comprises the following steps: Step 1: Preparation and application of low-temperature lubricant: In an environment with a dew point below -40°C, weigh the base lubricant and additive according to the predetermined mass ratio, mix them evenly at a speed of 300-400 rpm using a magnetic stirrer to prepare the low-temperature lubricant; within 5-30 minutes before starting the rolling process, evenly apply the low-temperature lubricant to the working surface of the roller, and control the coating amount to 0.5-1.0 g / m 2 ; 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 double-roll reversible rolling mill; Step 3: Cryogenic treatment: The lithium metal or lithium alloy material obtained in step 2 is quickly transferred to a cryogenic box for cooling at a temperature ranging from -196°C to -80°C for 1 to 3 minutes. Step 4: Multi-pass cryogenic rolling cycle: Roll the material after cryogenic treatment in step 3, control the deformation of a single rolling to 6%~30%, and the rolling speed to 0.1~10mm / s to ensure uniform deformation; after each rolling pass, repeat the cryogenic treatment in step 3, and gradually thin the material through cyclic rolling.

2. The method for preparing an ultra-thin lithium metal / alloy negative electrode according to claim 1, wherein: In step 1, the base lubricant includes component A and component B, and the mass ratio of component A to component B is 98:2~1:1; the component A is an anhydrous ester (palmitate, isopropyl benzoate or lauryl / tetradecyl oleate) or an anhydrous ether (triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol butyl ether), and the component B is an alkane (n-hexane, isododecane) or an anhydrous oil (cyclotetrasiloxane, cyclohexasiloxane, dimethyl silicone oil, decamethylcyclopentasiloxane, diethyl silicone oil); the additive is one or more of heptafluorobutyric acid, perfluorooctanoic acid, and trifluoromethyltrimethoxysilane, and the mass ratio of the base lubricant to the additive is 100:0.05~0.

4.

3. The method for preparing an ultra-thin lithium metal / alloy negative electrode according to claim 1, wherein: In step 2, the raw material is lithium metal foil / block / disc or lithium alloy material with a purity greater than 99%; the raw material thickness is 70-450 μm, and the initial rolling deformation is controlled to be 5%-15%.

4. The method for preparing an ultra-thin lithium metal / alloy negative electrode according to claim 3, wherein: The lithium alloy is a combination of lithium and one or more of tin, zinc, magnesium, aluminum, and indium, with an atomic ratio of 5 to 150:

1.

5. The method for preparing an ultra-thin lithium metal / alloy negative electrode according to claim 1, wherein: In step three, the cryogenic box uses liquid nitrogen as the cooling medium.

6. The method for preparing an ultra-thin lithium metal / alloy negative electrode according to claim 1, wherein: In step 4, the final thickness of the ultra-thin lithium metal / alloy negative electrode is 5-30 μm.

7. An ultra-thin lithium metal / alloy negative electrode prepared by the preparation method according to any one of claims 1 to 6.

8. Use of an ultrathin lithium metal / alloy negative electrode prepared by the preparation method according to any one of claims 1 to 6 in a solid-state battery.

9. The use according to claim 8, characterized in that: The electrolyte of the solid-state battery is a solid electrolyte.

10. The use according to claim 8, characterized in that: The positive electrode material of the solid-state battery is one of lithium cobalt oxide, lithium-rich manganese base, and lithium nickel cobalt manganese oxide.

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