A high-stability lithium metal negative electrode material and a warm isostatic pressing treatment method for improving stability thereof

Abstract

The application relates to the technical field of lithium batteries, and provides a high-stability lithium metal negative electrode material and a warm isostatic pressing treatment method for improving the stability of the lithium metal negative electrode material. The warm isostatic pressing treatment method comprises the following steps: S100, mixing and treating metal lithium powder and ceramic nano powder in an inert atmosphere to obtain a mixture; S200, sequentially performing cold pre-pressing treatment, pre-annealing treatment and pre-packaging treatment on the mixture to obtain a pre-packaged blank; and S300, performing warm isostatic pressing treatment on the pre-packaged blank to obtain the lithium metal negative electrode material. Plastic flow and surface and bulk diffusion of particles are caused by the warm isostatic pressing, pore closure and material densification are realized, ceramic nanoparticles are introduced as a mechanical reinforcing phase and an interface regulating phase, the nucleation and deposition behavior of lithium is regulated, the growth of lithium dendrites is inhibited, and the contact area between electrolyte and active lithium metal is reduced, so that the electrochemical cycle stability, coulombic efficiency and safety of the material are improved.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a highly stable lithium metal anode material and a temperature isostatic pressing method for improving its stability. Background Technology

[0002] With the increasing demand for higher energy density in portable electronic devices, new energy vehicles, and energy storage systems, lithium metal, as an anode material, is widely regarded as a key material for realizing next-generation high-energy-density batteries due to its high theoretical specific capacity and low standard potential. However, lithium metal exhibits drastic volume changes during cycling, high surface activity, and a tendency to undergo side reactions with the electrolyte, forming an uneven solid-electrolyte interface. These problems lead to low coulombic efficiency, rapid cycle decay, and serious safety hazards.

[0003] Existing preparation and processing methods are difficult to simultaneously eliminate internal pores in materials and achieve precise control of interface and nucleation behavior; in particular, conventional powder pressing, casting and rolling or simple addition of additives often cannot completely eliminate internal interconnected pores and microcracks, resulting in uneven current distribution and the formation of local current density peaks, which induce irregular nucleation and rapid growth of lithium dendrites, ultimately manifesting as short cycle life, low coulombic efficiency and poor safety.

[0004] Therefore, there is an urgent need for a lithium metal anode material that achieves high density and also has interface control function, as well as a warm isostatic pressing method to improve its stability. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the purpose of this application is to provide a highly stable lithium metal anode material and a warm isostatic pressing treatment method to improve its stability.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: plastic flow and surface and bulk diffusion of particles are induced by isostatic pressing to achieve pore closure and material densification; ceramic nanoparticles are introduced as mechanical reinforcing phase and interface regulating phase to regulate the nucleation and deposition behavior of lithium, inhibit lithium dendrite growth and reduce the contact area between the electrolyte and active lithium metal, thereby improving the electrochemical cycle stability, coulombic efficiency and safety of the material.

[0007] In a first aspect, embodiments of this application provide a warm isostatic pressing method for improving the stability of lithium metal anode materials, comprising the following steps: S100, mixing lithium metal powder and ceramic nanopowder in an inert atmosphere to obtain a mixture; S200, subjecting the mixture to cold pre-pressing, pre-annealing, and pre-encapsulation treatment in sequence to obtain a pre-encapsulated blank; S300, subjecting the pre-encapsulated blank to warm isostatic pressing to obtain a lithium metal anode material.

[0008] In an optional implementation, in step S300, the warm isostatic pressing treatment includes a first stage of warm isostatic pressing treatment and a second stage of warm isostatic pressing treatment; wherein, the temperature of the first stage of warm isostatic pressing treatment is 50-110℃, the pressure is 40-80MPa, and the holding time is 10-60min; the temperature of the second stage of warm isostatic pressing treatment is 120-160℃, the pressure is 50-100MPa, and the holding time is 10-120min.

[0009] In an optional embodiment, before step S100, the method further includes: S001, pre-drying the lithium metal powder and ceramic nanopowder in an inert atmosphere.

[0010] In one optional embodiment, the pre-drying temperature of the lithium metal powder is 40-80°C for 2-4 hours; the pre-drying temperature of the ceramic nanopowder is 50-120°C.

[0011] In an optional implementation, in step S100, the mixing process employs a low-speed drum mixer or a slow-speed rotary mixer; and / or the mixing time is 5-60 min.

[0012] In an optional embodiment, step S100 further includes adding an additive to the mixture, the additive including one or more of a conductivity promoter, a surface wetting agent, or a binder.

[0013] In an optional implementation, in step S200, the pressure of the cold pre-compression treatment is 50-150 MPa and the temperature is 20-60°C; the temperature of the pre-annealing treatment is 120-160°C, for 1-6 hours, and the cooling rate is 5-20°C / min.

[0014] In an optional implementation, after step S300, the method further includes: S400, unsealing the pre-encapsulated blank after warm isostatic pressing in an inert environment, and performing mechanical trimming and / or low-temperature annealing.

[0015] In one alternative implementation, low-temperature annealing is carried out at 40-80°C for 1-6 hours.

[0016] Secondly, embodiments of this application provide a highly stable lithium metal anode material, prepared by any of the above-mentioned processing methods.

[0017] The beneficial effects of this application include at least the following: (1) Through cold pre-pressing, pre-annealing and warm isostatic pressing, the plastic flow and atomic diffusion of lithium metal particles are effectively promoted, the pores are fully closed and the neck grows, and a high-density lithium metal anode material is obtained, thereby reducing electrolyte penetration, forming a stable solid electrolyte interface, and inhibiting the growth of lithium dendrites caused by uneven local current density. (2) Ceramic nanoparticles dispersed in the lithium matrix serve as a mechanical reinforcing phase, which improves the mechanical strength of the composite material and can physically suppress the puncture of lithium dendrites. On the other hand, as an interface regulating phase, they provide uniform heterogeneous nucleation sites, guide the uniform nucleation and deposition of lithium ions, and thus significantly improve the electrochemical cycling stability and coulombic efficiency of the material. (3) From powder pre-drying to pre-encapsulation, the entire process is carried out under an inert atmosphere, which effectively prevents the oxidation and side reactions of lithium metal, ensuring the safety of the process and the purity of the material. The final lithium metal anode material has high electronic conductivity, excellent interface stability and mechanical properties, thereby comprehensively improving the energy density, cycle life and safety of lithium batteries. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are only for explaining this application, but the implementation of this application is not limited thereto.

[0019] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods.

[0020] With the continuous improvement of the specific energy density of portable electronic devices, new energy vehicles, and energy storage systems, lithium metal is regarded as a key anode material for realizing the next generation of high energy density batteries due to its high specific capacity and low standard potential. However, it suffers from drastic volume changes, high surface activity, and easy side reactions with electrolytes during cycling, resulting in uneven SEI. This leads to low coulombic efficiency, rapid cycle decay, and serious safety hazards. Existing preparation methods such as powder pressing, casting, or simple addition of additives are difficult to simultaneously eliminate the interconnected pores inside the material and accurately control the interface and nucleation behavior. This can easily cause uneven current distribution, local current density peaks, and irregular nucleation, thereby promoting lithium dendrite growth. As a result, the cycle life and safety requirements cannot be met.

[0021] To address the aforementioned shortcomings in existing technologies, this embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing (WIP) method to improve its stability. WIP induces plastic flow and surface or bulk diffusion in the particles, achieving pore closure and material densification. Simultaneously, the introduced ceramic nanoparticles, acting as a mechanical reinforcing phase and interface control phase, regulate lithium nucleation and deposition behavior, effectively suppressing lithium dendrite growth and reducing the contact area between the electrolyte and active lithium metal. This significantly improves the material's electrochemical cycle stability, coulombic efficiency, and safety performance.

[0022] In a first aspect, embodiments of this application provide a method for improving the stability of lithium metal anode materials through a temperature isostatic pressing process, comprising the following steps: S100. Under an inert atmosphere, lithium metal powder and ceramic nanoparticles are mixed to obtain a mixture. S200. The mixture is subjected to cold pre-pressing, pre-annealing and pre-encapsulation treatment in sequence to obtain a pre-encapsulated blank. S300: The pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material.

[0023] Preferably, in step S100, lithium metal powder and ceramic nanoparticles are uniformly mixed for 5-60 minutes under an inert atmosphere using a low-speed roller or slow-speed rotary mixer to achieve uniform dispersion of ceramic particles in the lithium powder. Using a low-speed roller or slow-speed rotary mixer avoids excessive heat or powder agglomeration caused by high-speed stirring, while ensuring that the nano-ceramic powder uniformly coats or fills the surface of the lithium powder particles. Furthermore, the mixing process increases the filling density of the mixed powder, suppresses large-scale agglomeration and local voids, provides more uniformly distributed interfaces and mechanically blocking phases for subsequent densification, and facilitates the uniformity of subsequent electrochemical deposition by providing dispersed heterogeneous nucleation sites. This step alters the contact geometry and surface energy between particles through uniformly dispersed nano-ceramics, reducing local voids and interconnected pores, and increasing the interparticle contact area, thereby facilitating the formation of a continuous metallic phase and rapid pore closure during cold pre-pressing and warm isostatic pressing.

[0024] Furthermore, prior to step S100, the process includes: S001, pre-drying the lithium metal powder and ceramic nanopowder separately in an inert atmosphere. This pre-drying process removes adsorbed moisture and volatile impurities from the powder surface, reducing the content of free gases and chemically active oxygen- or water-containing species in the powder. Since lithium is an extremely reactive alkali metal, its reaction with water vapor produces lithium hydroxide and hydrogen gas, which not only consumes active lithium and reduces material purity but may also pose safety hazards and degrade the electrochemical performance of subsequent batteries due to hydrogen accumulation. Drying the ceramic nanopowder prevents moisture from forming an insulating layer on its surface, ensuring sufficient and uniform contact between it and the lithium powder. This step uses heat to promote the evaporation of adsorbed moisture and its escape into the inert atmosphere. Simultaneously, the higher temperature helps to volatilize organic residues, resulting in a cleaner, chemically inert contact surface on the particles, creating favorable conditions for subsequent densification and interface control. In addition, reducing the water content also reduces the possibility of lithium reacting with water to produce hydrogen gas or alkaline products, improving process safety and finished product purity.

[0025] Furthermore, the pre-drying temperature for lithium metal powder is 40-80℃, and the time is 2-4 hours; the pre-drying temperature for ceramic nanopowder is 50-120℃. The pre-drying temperature for lithium metal powder effectively removes adsorbed moisture and volatile organic residues from the powder surface and pores, reducing the risk of hydrogen generation or oxidation reactions caused by moisture in subsequent processes, provided that the temperature does not approach the melting point of lithium and does not excessively soften or cause redispersion or agglomeration of the lithium surface. The 2-4 hour time is based on the high surface activity of lithium powder and the need for sufficient dehumidification, while avoiding excessive heating that could lead to unfavorable changes in particle size and morphology. The pre-drying temperature for ceramic nanopowder is set at 50-120℃, which provides gentle protection for the surface chemistry and structure of the nanopowder. This is because ceramic surfaces often contain adsorbed water, crystal water, or residual organic dispersants; higher temperatures can remove these components to reduce the risk of gas escape and agglomeration, but this temperature is still far below the range that could cause phase transitions or crystal rearrangement.

[0026] Preferably, step S100 further includes adding an additive to the mixture, which includes one or more of a conductivity promoter, a surface wetting agent, or a trace binder. Introducing additives addresses the potential adverse effects of ceramic nanopowder on the electronic connectivity and powder formability of the material. Conductivity promoters, such as carbon nanotubes and graphene, construct an efficient electronic conductivity network within the composite, compensating for the overall decrease in conductivity caused by the presence of the insulating ceramic phase, thereby maintaining excellent electronic conduction channels, reducing electrode internal resistance, and improving rate performance. Surface wetting agents reduce the interfacial energy between lithium and ceramic, improving wettability, which facilitates uniform nucleation of lithium ions at the ceramic-metal interface, guiding uniform lithium deposition, and promoting the formation of a more stable solid electrolyte interface, effectively inhibiting dendrite growth. Trace binders play a role in the cold pre-pressing stage, enhancing the cohesive force between powder particles, increasing the strength of the biomass, reducing the generation and propagation of microcracks, preventing the biomass from cracking or loosening during subsequent processing, and ensuring smooth process operation. In summary, additives promote close contact between particles and neck growth in subsequent processes by providing conductive networks, forming flexible adhesive layers, or reducing contact angles, thereby synergistically optimizing material properties in terms of conductivity, interface stability, and processability.

[0027] Preferably, in step S200, the cold pre-compression process initially compacts the loose mixed powder, bringing the particles closer together through plastic deformation, reducing large-scale pores, and forming a green body with mechanical strength. The subsequent pre-annealing process, based on this, drives atomic diffusion through heat input, further amplifying the diffusion necks between particles and promoting their initial growth. Simultaneously, it effectively releases the residual stress introduced by the cold pre-compression. This process not only partially passivates the active surface of lithium and improves the uniformity of the green body, but also significantly reduces the risk of cracking due to thermal stress concentration during subsequent high-temperature and high-pressure processing. The final pre-encapsulation process establishes a reliable airtight barrier outside the green body, isolating oxygen, moisture, and external contaminants during isostatic pressing, preventing the lithium metal from oxidizing, volatilizing, or reacting adversely with the encapsulation under heating and pressurization conditions, thereby ensuring the chemical stability and safety of the material during processing. In summary, step S200, through the three pretreatment steps described above, cold pre-pressing and pre-annealing, significantly improves the densification and structural integrity of the billet through the continuous action of mechanical deformation and diffusion healing. This not only reduces the process driving force required for subsequent warm isostatic pressing to achieve complete densification, but also effectively avoids defects and crack propagation caused by local over-density or over-porosity. Pre-encapsulation provides a pure and controllable reaction environment for this process.

[0028] Furthermore, the pressure of the cold pre-compression treatment is 50-150 MPa, and the temperature is 20-60℃. 50 MPa is the minimum pressure limit to achieve the initial plastic deformation and macroscopic pore closure of the powder and obtain sufficient powder strength, which can ensure that it will not scatter during subsequent handling and packaging. Controlling the pressure to the upper limit of 150 MPa can avoid adverse consequences such as mold wear, local excessive cold welding / uniform plastic flow or the introduction of residual stress that is difficult to eliminate due to excessive static pressure. The selected temperature range can reduce the adhesion of powder during compression and the large agglomeration caused by plastic flow, and also facilitate safe operation and packaging.

[0029] Furthermore, the pre-annealing treatment is carried out at a temperature of 120-160℃ for 1-6 hours, with a cooling rate of 5-20℃ / min. This temperature, lower than the lithium melting point but sufficient to significantly improve atomic diffusion rate and particle neck growth, promotes diffusion bonding at contact points, releases internal stress introduced by cold pressing, and improves the uniformity of the green body. The 1-6 hour duration ensures sufficient diffusion and stress relaxation while avoiding excessively long treatment times that could lead to unnecessary grain growth or adverse reactions with encapsulation / additives. Finally, the 5-20℃ / min cooling rate reduces thermal shock or cracking caused by sudden temperature changes, helps alleviate stress, and contributes to obtaining a stable microstructure.

[0030] Preferably, in step S300, isostatic pressure and controlled heating processes are used to induce plastic flow, surface and bulk diffusion of the particles, thereby achieving pore closure, neck growth, and overall densification. The warm isostatic pressing process includes a first stage and a second stage. The first stage uses a lower temperature to compress and close large pores and avoid rapid local lithium flow that could lead to morphological loss of control. The second stage enhances diffusion drive, expands particle necks, and completes high-density micro-rearrangement at higher temperatures and pressures, thereby achieving low porosity and good internal contact. Under warm isostatic pressing, soft lithium metal undergoes extensive plastic flow and forms diffusion necks at contact points. As the temperature increases, the atomic diffusion rate rises, and surface diffusion and grain boundary diffusion promote pore elimination and restoration of intergranular connectivity. Nanoceramics, as a dispersed phase, play a role in mechanical reinforcement and dendrite inhibition in the dense body, changing the local stress field and providing heterogeneous nucleation sites, thus thermodynamically increasing the energy barrier for irregular dendrite growth.

[0031] Furthermore, following step S300, the process includes: S400, in an inert environment, unpacking the pre-encapsulated blank after warm isostatic pressing, and then mechanically trimming and / or low-temperature annealing. First, the outer encapsulation material is removed in an inert environment, followed by mechanical trimming of the blank surface. This removes any adhering encapsulation residues or surface oxide layers, resulting in a dimensionally accurate and smooth negative electrode sheet, ensuring close contact between the electrode and the current collector and effectively reducing interfacial impedance. The trimmed electrode is then heat-treated at a relatively low temperature. Without inducing large-scale lithium metal flow or grain coarsening, driving atomic micro-diffusion enables stress relaxation and microstructure rearrangement in lattice and interface microregions. This effectively eliminates residual stress within the material, promotes the closure and passivation of microcracks, and significantly reduces the risk of these micro-defects evolving into dendrite nucleation points or crack propagation sources during subsequent electrochemical cycles. This improves the overall compactness and interface stability of the material structure and creates favorable conditions for the formation of a more uniform and stable initial solid electrolyte interface film, thereby contributing to improved first-cycle coulombic efficiency and long-term cycle life.

[0032] Secondly, this application also provides a highly stable lithium metal anode material. The lithium metal anode material includes a lithium metal matrix and ceramic nanoparticles in the matrix. The ceramic nanoparticles include one or more of alumina, silicon dioxide, titanium dioxide, or zirconium oxide. The material is prepared by any of the above processing methods. This lithium metal anode material has both excellent electronic connectivity and uniform ion accessibility, and its mechanical strength and anti-penetration ability are significantly improved. This allows for uniform control of the lithium nucleation and deposition process, effectively inhibiting lithium dendrite growth and reducing the contact area between the electrolyte and active lithium, ultimately improving electrochemical cycle stability, coulombic efficiency, and battery safety.

[0033] This application has undergone multiple experiments, and some of the test results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0034] Example 1 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 60°C for 3 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 100°C. S100. In an inert atmosphere, pre-dried lithium metal powder and ceramic nanopowder are mixed for 30 minutes using a low-speed drum mixer, and carbon nanotubes are added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 100MPa and 40℃, pre-annealed at 140℃ with a cooling rate of 10℃ / min for 3h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product. The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The first stage of isostatic pressing treatment is performed at a temperature of 80℃ and a pressure of 60MPa for 30 minutes. The second stage of isostatic pressing is performed at a temperature of 140℃ and a pressure of 80MPa for 60 minutes.

[0035] Example 2 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 80°C for 2 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 120°C. S100. In an inert atmosphere, pre-dried lithium metal powder and ceramic nanopowder are mixed for 10 minutes using a slow-speed rotary mixer, and lithium iodide is added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 150MPa and 20℃, pre-annealed at 160℃ with a cooling rate of 20℃ / min for 2h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product. The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The temperature of the first stage of isostatic pressing is 110℃, the pressure is 80MPa, and the holding time is 10min. The second stage of isostatic pressing is performed at a temperature of 160℃ and a pressure of 100MPa for 10 minutes.

[0036] Example 3 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 40°C for 4 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 60°C. S100. In an inert atmosphere, pre-dried lithium metal powder and ceramic nanopowder are mixed for 60 minutes using a slow-speed rotary mixer, and polyacrylic acid is added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 50MPa and 60℃, pre-annealed at 120℃ with a cooling rate of 5℃ / min for 6h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product. The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The first stage of isostatic pressing treatment is performed at a temperature of 50℃ and a pressure of 40MPa for 60 minutes. The second stage of isostatic pressing is performed at a temperature of 120℃ and a pressure of 50MPa for 120 minutes.

[0037] Example 4 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 50°C for 3 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 70°C. S100. In an inert atmosphere, pre-dried lithium metal powder and ceramic nanopowder are mixed for 50 minutes using a slow-speed rotary mixer, and graphene is added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 80MPa and 50℃, pre-annealed at 130℃ with a cooling rate of 15℃ / min for 3h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product. The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The first stage of isostatic pressing treatment is performed at a temperature of 70℃ and a pressure of 50MPa for 50 minutes. The second stage of isostatic pressing is performed at a temperature of 130℃ and a pressure of 70MPa for 100 minutes.

[0038] Example 5 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 60°C for 3 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 100°C. S100. In an inert atmosphere, lithium metal powder and ceramic nanopowder are mixed using a low-speed drum mixer for 30 minutes, and carbon nanotubes are added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 100MPa and 40℃, pre-annealed at 140℃ with a cooling rate of 10℃ / min for 3h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The first stage of isostatic pressing treatment is performed at a temperature of 80℃ and a pressure of 60MPa for 30 minutes. The second stage of isostatic pressing is performed at a temperature of 140℃ and a pressure of 80MPa for 60 minutes.

[0039] Example 6 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S100. In an inert atmosphere, lithium metal powder and ceramic nanopowder are mixed using a low-speed drum mixer for 30 minutes, and carbon nanotubes are added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 100MPa and 40℃, pre-annealed at 140℃ with a cooling rate of 10℃ / min for 3h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product. The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The first stage of isostatic pressing treatment is performed at a temperature of 80℃ and a pressure of 60MPa for 30 minutes. The second stage of isostatic pressing is performed at a temperature of 140℃ and a pressure of 80MPa for 60 minutes.

[0040] Example 7 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 60°C for 3 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 100°C. S100. In an inert atmosphere, pre-dried lithium metal powder and ceramic nanopowder are mixed for 30 minutes using a low-speed drum mixer, and carbon nanotubes are added to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 100MPa and 40℃, pre-annealed at 140℃ with a cooling rate of 10℃ / min for 3h, and pre-encapsulated to obtain a pre-encapsulated blank. S300: The pre-packaged blank is subjected to warm isostatic pressing at 140℃ and 80MPa for 90 minutes to obtain lithium metal anode material. S400. In an inert environment, the pre-encapsulated blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product.

[0041] Example 8 This embodiment provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability, specifically including the following steps: S001. Pre-dry lithium metal powder at 60°C for 3 hours in an inert atmosphere, and pre-dry ceramic nanopowder at 100°C. S100. In an inert atmosphere, the pre-dried lithium metal powder and ceramic nanopowder are mixed using a low-speed drum mixer for 30 minutes to obtain a mixture. S200. The mixture is subjected to cold pre-pressing at 100MPa and 40℃, pre-annealed at 140℃ with a cooling rate of 10℃ / min for 3h, and pre-encapsulated to obtain a pre-encapsulated blank. S300, the pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material; S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed, and then mechanically trimmed and annealed at low temperature to obtain the finished product. The warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The first stage of isostatic pressing treatment is performed at a temperature of 80℃ and a pressure of 60MPa for 30 minutes. The second stage of isostatic pressing is performed at a temperature of 140℃ and a pressure of 80MPa for 60 minutes.

[0042] Comparative Example 1 This comparative example provides a highly stable lithium metal anode material and a warm isostatic pressing method to improve its stability. The lithium metal anode material and the processing method are the same as those in Example 1, except that: there is no pre-annealing process in step S200, that is, the blank obtained after cold pre-pressing is not pre-annealed and is directly pre-encapsulated.

[0043] Comparative Example 2 This comparative example provides a highly stable lithium metal anode material and a warm isostatic pressing treatment method to improve its stability. The lithium metal anode material and treatment method are the same as those in Example 1, except that in step S100, a high-speed ball mill is used for mixing, the mixing time is 30 min, and the rotation speed is 300 r / min.

[0044] Test method: The lithium metal anode materials prepared in Examples 1-8 and Comparative Examples 1-2 were subjected to the following tests, and the test results are shown in Table 1: Density test: The actual density of the material is measured using the Archimedes displacement method, and its ratio to the theoretical density is calculated; Electrochemical cycling performance testing: A half-cell was assembled using the prepared material as the negative electrode and a high-purity lithium sheet as the counter electrode. The electrochemical cycling performance was tested at 1 mA / cm². 2 Charge-discharge cycle tests were performed at current densities, and capacity retention was recorded. Coulomb efficiency test: In a half-cell, the ratio of discharge capacity to charge capacity in each cycle is measured, and the average coulomb efficiency is calculated. Electrochemical impedance spectroscopy: This method measures the resistance to charge transfer at interfaces. Mechanical property testing: The hardness and elastic modulus of the material are measured using a nanoindenter.

[0045] Table 1 As shown in Table 1, Examples 1-4 performed best in all test indicators, achieving high density, high coulombic efficiency, and long cycle life. At the same time, they exhibited low interfacial impedance, indicating the formation of a stable and highly conductive SEI film. The high nanohardness proved the effective mechanical reinforcement effect of the ceramic nanoparticles.

[0046] Examples 1 and 5 show that without mechanical finishing and low-temperature annealing, the density, coulombic efficiency, and cycle life slightly decreased, the interfacial impedance increased, and microcracks appeared. This indicates that post-treatment can effectively release stress and repair micro-defects. Examples 1 and 6 show that without pre-drying, all properties significantly decreased. The decrease in density and the sharp increase in interfacial impedance demonstrate that moisture can trigger side reactions, forming an unstable SEI film that damages the material's structure and electrochemical performance. Comparing Examples 1 and 7 shows that using single-stage isostatic pressing resulted in decreased density and performance, demonstrating that two-stage heating and pressurization is a crucial step for achieving densification. Comparing Examples 1 and 8 shows that without any additives, the coulombic efficiency and cycle life decreased, and the interfacial impedance increased. This indicates that additives help build a conductive network, improve interfacial ion transport, and thus enhance electrochemical performance. Comparative Example 1 shows that, due to the lack of a pre-annealing step to release the stress introduced by cold pre-compression, the material is more prone to defects in subsequent processing, resulting in low density, severe dendrites and cracks, and a significant deterioration of all performance indicators. Comparative Example 2 shows that high-speed ball milling leads to lithium powder oxidation, cold welding and ceramic particle agglomeration, which destroys the uniformity of the material. The result is the worst electrochemical performance and the highest interfacial impedance, which fully demonstrates the necessity of low-speed and gentle mixing for obtaining a uniform composite structure.

[0047] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for improving the stability of lithium metal anode materials through warm isostatic pressing, characterized in that, Includes the following steps: S100. Under an inert atmosphere, lithium metal powder and ceramic nanoparticles are mixed to obtain a mixture. S200. The mixture is subjected to cold pre-pressing, pre-annealing and pre-encapsulation treatment in sequence to obtain a pre-encapsulated blank. S300. The pre-packaged blank is subjected to warm isostatic pressing to obtain lithium metal anode material.

2. The processing method according to claim 1, characterized in that, In step S300, the warm isostatic pressing process includes a first stage of warm isostatic pressing and a second stage of warm isostatic pressing. The temperature of the first stage of isostatic pressing is 50-110℃, the pressure is 40-80MPa, and the holding time is 10-60min. The second stage of isostatic pressing is performed at a temperature of 120-160℃ and a pressure of 50-100MPa for 10-120 minutes.

3. The processing method according to claim 1, characterized in that, The steps preceding step S100 also include: S001. Pre-dry the lithium metal powder and ceramic nanopowder in an inert atmosphere.

4. The processing method according to claim 3, characterized in that, The pre-drying treatment of the lithium metal powder is performed at a temperature of 40-80℃ for 2-4 hours. The pre-drying temperature of the ceramic nanopowder is 50-120℃.

5. The processing method according to claim 1, characterized in that, In step S100, The mixing process employs a low-speed drum mixer or a slow-rotating mixer; and / or The mixing process takes 5-60 minutes.

6. The processing method according to claim 1, characterized in that, In step S100, an additive is added to the mixture, the additive including one or more of a conductivity promoter, a surface wetting agent, or a binder.

7. The processing method according to claim 1, characterized in that, In step S200, The pressure of the cold pre-compression treatment is 50-150MPa, and the temperature is 20-60℃; The pre-annealing treatment is performed at a temperature of 120-160℃ for 1-6 hours, with a cooling rate of 5-20℃ / min.

8. The processing method according to claim 1, characterized in that, Following step S300, the method further includes: S400. In an inert environment, the pre-packaged blank after warm isostatic pressing is unsealed and mechanically trimmed and / or annealed at low temperature.

9. The processing method according to claim 7, characterized in that, The low-temperature annealing is carried out at 40-80℃ for 1-6 hours.

10. A highly stable lithium metal anode material, characterized in that, The lithium metal anode material is prepared by the processing method described in any one of claims 1-9.

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