A high-entropy lithium alloy material, a preparation method, a negative electrode material and a battery

Abstract

The present application relates to the technical field of battery, and particularly relates to a high-entropy lithium alloy material, a preparation method, a negative electrode material and a battery. The preparation method provided by the present application grinds metal raw materials of lithium, aluminum, magnesium, tin and zinc into mixed powder; provides a lithium compensation agent, heats the mixed powder to a melting temperature under a protective gas atmosphere, and then adds the lithium compensation agent to form a melt, cools the melt based on a rapid quenching process to obtain a porous composite structure thin strip; places the cooled porous composite structure thin strip in an oxygen-containing gas atmosphere, and the zinc atoms, magnesium atoms and aluminum atoms on the surface of the porous composite structure thin strip respectively react with oxygen and form a passivation layer on the surface of the porous composite structure thin strip; performs fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip to form a protective layer; and performs annealing treatment on the porous composite structure thin strip after the fluorination treatment to obtain a high-entropy lithium alloy material. The problem of insufficient volume expansion inhibition of the high-entropy lithium alloy structure as a negative electrode material is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a high-entropy lithium alloy material, a preparation method, a negative electrode material and a battery. BACKGROUND

[0002] Traditional alloy negative electrodes will produce huge volume expansion during lithium intercalation, resulting in electrode pulverization and capacity reduction. In recent years, high-entropy materials have shown potential in structural buffering and interface regulation due to their unique lattice distortion effect and slow diffusion characteristics. However, the selection of elements and the design of structures in high-entropy lithium alloy material systems still lack systematic guidance, making it difficult to balance electrical conductivity, structural stability and interface compatibility. Therefore, a preparation method of high-entropy lithium alloy material is sought to prepare a high-entropy lithium alloy material with controllable composition and coordinated structure, so as to effectively suppress the volume effect of the negative electrode material and comprehensively improve the electrochemical performance. SUMMARY

[0003] In order to solve the problem of insufficient volume expansion suppression of the existing high-entropy lithium alloy structure as a negative electrode material, the present application provides a high-entropy lithium alloy material, a preparation method, a negative electrode material and a battery.

[0004] To solve the above technical problems, the present application provides the following technical solution: a preparation method of a high-entropy lithium alloy material, the preparation method of the high-entropy lithium alloy material comprising: providing metal raw materials of lithium, aluminum, magnesium, tin and zinc, grinding the metal raw materials of lithium, aluminum, magnesium, tin and zinc into a mixed powder; providing a lithium compensation agent, heating the mixed powder to a melting temperature under a protective gas atmosphere, then adding the lithium compensation agent to form a molten body, cooling the molten body based on a rapid quenching process, forming a nanocrystalline region and an amorphous region during the cooling process of the molten body, and obtaining a porous composite structure thin strip after cooling; placing the cooled porous composite structure thin strip in an oxygen-containing gas atmosphere, and reacting zinc atoms, magnesium atoms and aluminum atoms on the pore surface of the porous composite structure thin strip with oxygen to form a passivation layer completely covering the porous composite structure thin strip; performing fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip to form a protective layer; annealing the porous composite structure thin strip after fluorination treatment, and tin atoms and lithium atoms in the porous composite structure thin strip form Li 22 Sn5, zinc atoms and lithium atoms form Li2Zn, and Li 22 Sn5 and Li2Zn form a buffer region between the nanocrystalline region and the amorphous region inside the porous composite structure thin strip, and the annealing treatment is completed to obtain a high-entropy lithium alloy material.

[0005] Preferably, the grinding of the metal raw materials of lithium, aluminum, magnesium, tin and zinc into a mixed powder comprises: providing the metal raw materials of lithium, aluminum, magnesium, tin and zinc, pretreating the metal raw materials into metal powders of lithium, aluminum, magnesium, tin and zinc, wherein the powder particle size of lithium metal ranges from 1 to 10 μm, the metal powder particle size of aluminum, magnesium, tin and zinc ranges from 10 to 50 nm, and the mass ratio of lithium, aluminum, magnesium, tin and zinc in the mixed powder is lithium: aluminum: magnesium: tin: zinc = (80-90%: 2-6%: 1-4%: 1-5%: 1-5%); providing a ball milling device, and preheating the ball milling device to 600-800°C at a heating rate of 5-10°C / min, and after heating, placing the metal powders of lithium, aluminum, magnesium, tin and zinc into the ball milling device and grinding at a stirring speed of 100-400 rpm and a ball-to-material ratio of (15:1-20:1) for 4-8 hours to obtain the mixed powder.

[0006] Preferably, the heating of the mixed powder to a melting temperature under a protective gas atmosphere and the addition of a lithium compensation agent to form a melt comprises: providing a lithium compensation agent, the lithium compensation agent being any one or more combinations of lithium nitride or lithium oxide; heating the mixed powder from room temperature to a melting temperature of 1200-1300°C under a protective gas atmosphere at a heating rate of 10-20°C / min; after heating to the melting temperature, adding the lithium compensation agent, and the lithium compensation agent and the molten mixed powder forming a melt.

[0007] Preferably, the cooling of the melt based on a rapid quenching process comprises: providing a rapid quenching device, the rapid quenching device being provided with a nozzle and a single roller spaced from the nozzle; controlling the linear speed of the roller surface of the single roller to be 30±5 m / s, and controlling the distance between the end of the nozzle and the roller surface of the single roller to be 300±50 μm; and spraying the melt out of the nozzle to the roller surface of the single roller for cooling under a protective gas atmosphere, wherein the pressure of the protective gas atmosphere is 0.6±0.1 bar, and the melt is cooled from 1200-1300°C to room temperature after contacting the roller surface of the single roller, and during the cooling process, zinc atoms and tin atoms in the melt gather on one side of the melt to form a zinc / tin zone, and after the cooling process, a porous composite structure thin strip is obtained.

[0008] Preferably, the zinc atoms, magnesium atoms and aluminum atoms react with oxygen and form a passivation layer on the surface of the porous composite structure thin strip, which comprises: zinc atoms reacting with oxygen to obtain zinc oxide, magnesium atoms reacting with oxygen to obtain magnesium oxide, and aluminum atoms reacting with oxygen to obtain aluminum oxide; and the zinc oxide, magnesium oxide and aluminum oxide forming a passivation layer on the surface of the porous composite structure thin strip.

[0009] Preferably, the fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip comprises: providing argon and tetrafluoromethane gas, mixing the argon and tetrafluoromethane gas into a mixed gas at a flow ratio of (1:1) to (3:1); placing the porous composite structure thin strip forming the passivation layer in a vacuum environment, introducing the mixed gas, and performing plasma treatment at a power of 150-250 W and a room temperature-60°C for 30-45 minutes to form a protective layer on the side of the passivation layer away from the porous composite structure thin strip.

[0010] Preferably, the porous composite structure thin strip after the fluorination treatment is first heated to 150-200°C at a rate of 1-5°C / min, first heat preserved for 30-60 minutes, and tin atoms and lithium atoms in the porous composite structure thin strip form Li 22 Sn5, zinc atoms and lithium atoms form Li 22 Sn5and Li2Zn form a buffer region in the region between the nanocrystalline region and the amorphous region in the porous composite structure thin strip; after the first heat preservation, second heating is performed to 300-400°C, second heat preservation is performed for 15-30 minutes, and after the second heat preservation is completed, cooling to room temperature at 0-5°C / min obtains a high-entropy lithium alloy material.

[0011] The present application provides another technical solution to solve the above technical problems: a high-entropy lithium alloy material prepared by the preparation method of the high-entropy lithium alloy material, the high-entropy lithium alloy material comprising a porous composite structure thin strip, a buffer region, a passivation layer, and a protective layer; the porous composite structure thin strip comprises a nanocrystalline region and an amorphous region, and the buffer region is arranged in the region between the nanocrystalline region and the amorphous region; the passivation layer is arranged on the outer surface of the porous composite structure thin strip and completely covers the porous composite structure thin strip, and the protective layer is arranged on the side of the passivation layer away from the porous composite structure thin strip.

[0012] The present application provides another technical solution to solve the above technical problems: a negative electrode material comprising a current collector and the high-entropy lithium alloy material.

[0013] The present application provides another technical solution to solve the above technical problems: a battery comprising a positive electrode material, an electrolyte, and the high-entropy lithium alloy material.

[0014] Compared with the prior art, the high-entropy lithium alloy material, the preparation method, the negative electrode material, and the battery provided by the present application have the following beneficial effects:

[0015] 1. A method for preparing a high-entropy lithium alloy material provided by an embodiment of the present invention, the method comprising: providing lithium, aluminum, magnesium, tin and zinc metal raw materials; grinding the lithium, aluminum, magnesium, tin and zinc metal raw materials into a mixed powder; providing a lithium compensator; heating the mixed powder to a melting temperature under a protective gas atmosphere and then adding the lithium compensator to form a melt; cooling the melt using a rapid quenching process; forming nanocrystalline and amorphous regions during the cooling process; obtaining a porous composite structure thin strip after cooling; placing the cooled porous composite structure thin strip in an oxygen-containing gas atmosphere; the zinc, magnesium and aluminum atoms on the pore surface of the porous composite structure thin strip reacting with oxygen to form a passivation layer that completely covers the porous composite structure thin strip; performing fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip to form a protective layer; annealing the fluorinated porous composite structure thin strip; and forming a Li+ layer by annealing the tin and lithium atoms inside the porous composite structure thin strip. 22 Sn5, zinc atoms and lithium atoms form Li2Zn, Li 22 Sn5 and Li2Zn form a buffer region between the nanocrystalline and amorphous regions within the porous composite thin strip, and annealing completes the process to obtain a high-entropy lithium alloy material. This embodiment demonstrates the preparation of a high-entropy lithium alloy material with a multi-level buffer structure, enabling it to exhibit high capacity and high interfacial stability when used as an anode material.

[0016] 2. The present invention defines the grinding of lithium, aluminum, magnesium, tin, and zinc metal raw materials into a mixed powder as follows: providing lithium, aluminum, magnesium, tin, and zinc metal raw materials, and pretreating the metal raw materials into lithium, aluminum, magnesium, tin, and zinc metal powders, wherein the particle size range of lithium metal powder is 1~10μm, and the particle size range of aluminum, magnesium, tin, and zinc metal powders is 10~50nm. The lithium metal powder has a larger particle size compared to the other metal powders. Lithium is an extremely reactive alkali metal; using micron-sized lithium powder can effectively reduce the specific surface area and the area in contact with air, thereby reducing the risk of oxidation and thermal runaway. Furthermore, if the lithium metal powder particle size is small, lithium particles are prone to agglomeration and are difficult to disperse uniformly. The mass ratio of lithium, aluminum, magnesium, tin, and zinc in the mixed powder is lithium:aluminum:magnesium:tin:zinc = (80~90% : 2~6% : 1~4% : 1~5% : 1~5%). A ball mill is provided, preheated to 600~800℃ at a heating rate of 5~10℃ / min. After heating, the lithium, aluminum, magnesium, tin, and zinc metal powders are placed in the ball mill and ground for 4~8 hours with a stirring speed of 100~400rpm and a ball-to-material ratio of (15:1~20:1) to obtain the mixed powder. Through the synergistic design of metal powder classification pretreatment and high-energy ball milling, the technical problems of poor compositional uniformity and lithium volatilization loss in traditional lithium alloy preparation are solved.

[0017] 3. The method of claim 1, wherein the lithium compensating agent is provided, the lithium compensating agent is any one or more combinations of lithium nitride or lithium oxide; the mixed powder is heated from room temperature to a melting temperature of 1200-1300 °C at a heating rate of 10-20 °C / min under a protective gas atmosphere; and the lithium compensating agent is added after the mixed powder is heated to the melting temperature, and the lithium compensating agent and the melted mixed powder form a melt. The embodiment dynamically regulates the lithium compensating agent, accurately controls the temperature, and cooperates with the protective atmosphere to avoid lithium loss and composition unevenness during high-temperature melting.

[0018] 4. The method of claim 1, wherein the melt is cooled based on a rapid quenching process, the rapid quenching device is provided, the rapid quenching device is provided with a nozzle and a single roller spaced from the nozzle; the linear speed of the roller surface of the single roller is controlled to be 30±5 m / s, the distance between the end of the nozzle and the roller surface of the single roller is controlled to be 300±50 μm, the melt is sprayed out to the roller surface of the single roller for cooling under a protective gas atmosphere, the pressure of the protective gas atmosphere is 0.6±0.1 bar, the melt is cooled from 1200-1300 °C to room temperature after contacting the roller surface of the single roller, and the zinc atoms and tin atoms in the melt gather to one side of the melt to form a zinc / tin zone during the cooling process, and a porous composite structure thin strip is obtained after the cooling process. The embodiment rapidly obtains amorphous / nanocrystalline phase of high-entropy lithium alloy material through the rapid quenching process.

[0019] 5. The method of claim 1, wherein the zinc atoms, magnesium atoms, and aluminum atoms respectively react with oxygen to form a passivation layer on the surface of the porous composite structure thin strip, the oxygen-containing gas atmosphere refers to an air environment, and the oxygen content is less than or equal to 21%; the zinc atoms react with oxygen to obtain zinc oxide, the magnesium atoms react with oxygen to obtain magnesium oxide, and the aluminum atoms react with oxygen to obtain aluminum oxide; and the zinc oxide, magnesium oxide, and aluminum oxide form a passivation layer on the surface of the porous composite structure thin strip. The embodiment constructs a stable in-situ passivation layer through micro-oxygen regulation and multi-element synergistic oxidation, and improves the stability and cycle life of the high-entropy lithium alloy in air.

[0020] 6. The method of claim 1, wherein the porous composite structure thin strip is subjected to fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip, argon and tetrafluoromethane gas are provided, the argon and tetrafluoromethane gas are mixed into a mixed gas at a flow ratio of (1:1) to (3:1), the porous composite structure thin strip with the passivation layer is placed in a vacuum environment and the mixed gas is introduced, and a protective layer is formed on the side of the passivation layer away from the porous composite structure thin strip by plasma treatment at a power of 150-250 W and a room temperature to 60 °C for 30-45 minutes. The protective layer is formed by optimizing the gas ratio and plasma parameters, which provides interface protection for the high-entropy lithium alloy material. The high-entropy lithium alloy is applied to a battery, which can improve the cycle life of the battery.

[0021] 7. The annealing process of the porous composite structure thin strip after fluorination treatment defined in the present application comprises: first heating the porous composite structure thin strip after fluorination treatment to 150-200℃ at a rate of 1-5℃ / min, first holding for 30-60 minutes, and tin atoms and lithium atoms in the porous composite structure thin strip forming Li 22 Sn5, zinc atoms and lithium atoms forming Li2Zn, Li 22 Sn5and Li2Zn form a buffer region between the nanocrystalline region and the amorphous region in the porous composite structure thin strip; after the first holding, second heating to 300-400℃, second holding for 15-30 minutes, and after the second holding, cooling to room temperature at a rate of 0-5℃ / min to obtain a high-entropy lithium alloy material. The annealing process controls the internal stress and the distribution of the buffer region, so that the high-entropy lithium alloy has high capacity and long cycle stability.

[0022] 8. The present application also provides a high-entropy lithium alloy material prepared by the preparation method of the high-entropy lithium alloy material described above, which comprises a porous composite structure thin strip, a buffer region, a passivation layer and a protective layer; the porous composite structure thin strip comprises a nanocrystalline region and an amorphous region, and the buffer region is arranged between the nanocrystalline region and the amorphous region; the passivation layer is arranged on the outer surface of the porous composite structure thin strip and completely covers the porous composite structure thin strip, and the protective layer is arranged on the side of the passivation layer away from the porous composite structure thin strip. The problems of structural failure and interface instability caused by repeated volume changes during the cycle process of the traditional lithium alloy negative electrode are solved.

[0023] 9. The present application also provides a negative electrode material comprising a current collector and the high-entropy lithium alloy material described above arranged in layers. The high-entropy lithium alloy material can maintain the integrity of its own structure during the cycle process, thereby obtaining a negative electrode material with good anti-expansion performance in combination with the current collector.

[0024] 10. The present application also provides a battery comprising a positive electrode material, an electrolyte and the high-entropy lithium alloy material described above. The negative electrode material of the present application has good anti-expansion performance during the entire cycle process, thereby providing the battery with stable capacity output and long cycle life. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 is a flowchart of a preparation method of a high-entropy lithium alloy material provided by the first embodiment of the present application.

[0027] Figure 2 is a schematic diagram of a porous composite structure thin strip structure provided by the first embodiment of the present application.

[0028] Figure 3 is Figure 2 is an enlarged view of region A.

[0029] Figure 4 is a schematic diagram of the porous composite structure thin strip structure completely covered by the passivation layer provided by the first embodiment of the present application.

[0030] Figure 5 is a schematic diagram of the high-entropy lithium alloy material after annealing provided by the first embodiment of the present application.

[0031] Figure 6 is Figure 5 is an enlarged view of region B.

[0032] Figure 7 is a schematic diagram of a high-entropy lithium alloy material provided by the second embodiment of the present application.

[0033] Figure 8 is Figure 7 is an enlarged view of region C. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0035] In the embodiments provided by the present application, it should be understood that “B corresponding to A” means that B is associated with A and B can be determined according to A. However, it should also be understood that the determination of B according to A does not mean that B is determined only according to A, but B can also be determined according to A and / or other information.

[0036] It should be understood that “one embodiment” or “an embodiment” mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, “in one embodiment” or “in an embodiment” appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also know that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present application.

[0037] In various embodiments of the present application, it should be understood that the size of the sequence number of the above-mentioned processes does not mean the inevitable sequence of execution order, and the execution order of the processes should be determined according to their functions and internal logic, and should not constitute any limitation on the implementation process defined by the present application.

[0038] In the flowcharts and block diagrams in the drawings of the present application, the methods and possible implemented architectures, functions and operations according to various embodiments of the present application are illustrated. In this regard, each block in the flowchart or block diagram can represent a part of a step. It should also be noted that in some alternative implementations, the functions denoted in the blocks can also occur in a different order from that denoted in the drawings. For example, two blocks denoted in succession can actually be executed substantially in parallel, and they can also be executed in reverse order, based on the functions involved.

[0039] The conventional alloy negative electrode will produce huge volume expansion during lithium intercalation, resulting in electrode pulverization and capacity reduction. In recent years, high-entropy materials have shown potential in structural buffering and interface regulation due to their unique lattice distortion effect and slow diffusion characteristics. However, in the high-entropy lithium alloy material system, the selection of elements and the design of structure still lack systematic guidance, and it is difficult to balance the conductivity, structural stability and interface compatibility. Therefore, a preparation method of high-entropy lithium alloy material is sought, and a high-entropy lithium alloy material with controllable composition and coordinated structure is prepared to effectively suppress the volume effect of the negative electrode material and comprehensively improve the electrochemical performance.

[0040] Please Figure 1 The first embodiment of the present application provides a preparation method of high-entropy lithium alloy material, which comprises the following steps:

[0041] S1, providing metal raw materials of lithium, aluminum, magnesium, tin and zinc, and grinding the metal raw materials of lithium, aluminum, magnesium, tin and zinc into a mixed powder;

[0042] S2, providing a lithium compensation agent, heating the mixed powder to a melting temperature under a protective gas atmosphere, and then adding the lithium compensation agent to form a molten body, cooling the molten body based on a rapid quenching process, forming a nanocrystalline region and an amorphous region during the cooling process of the molten body, and obtaining a porous composite structure thin strip after cooling;

[0043] S3, placing the cooled porous composite structure thin strip in an oxygen-containing gas atmosphere, and reacting zinc atoms, magnesium atoms and aluminum atoms on the pore surface of the porous composite structure thin strip with oxygen to form a passivation layer completely covering the porous composite structure thin strip;

[0044] S4, performing fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip to form a protective layer; and

[0045] S5, annealing the porous composite structure thin strip after fluorination treatment, tin atoms and lithium atoms in the porous composite structure thin strip form Li 22 Sn5, zinc atoms and lithium atoms form Li2Zn, Li 22 Sn5and Li2Zn form a buffer region between the nanocrystalline region and the amorphous region in the porous composite structure thin strip, and the annealing process is completed to obtain a high-entropy lithium alloy material.

[0046] It can be understood that in the embodiment, the synergistic design of multiple metal components and the multi-stage process control are used. Specifically, please combine Figure 2 and Figure 3 , in step S1, lithium, aluminum, magnesium, tin, and zinc are selected for grinding together to form a mixed powder. Through grinding, the five metals are uniformly dispersed at the atomic level. Among the selected metals, lithium is used in the negative electrode material as the main electrochemically active element; aluminum and magnesium can increase the strength of the alloy, reduce the density, and form a dense composite oxide passivation layer on the surface in situ after exposure to air; tin and zinc can form high-capacity intermetallic compounds with lithium, which are segregated at the grain boundaries, effectively inhibiting the growth of lithium dendrites and accommodating volume changes. The amorphous region has high uniformity and elastic limit, and can effectively dissipate and redistribute stress through uniform plastic deformation, thereby inhibiting the initiation and propagation of microcracks. Further, step S2 is carried out under a protective atmosphere and introduces a lithium compensation agent, followed by cooling using a rapid quenching process. The extremely high cooling rate during rapid quenching inhibits the long-range diffusion and ordered arrangement of atoms, allowing the molten body to form nanocrystalline regions and amorphous regions simultaneously during solidification. The nanocrystalline region serves as a strength support point, providing mechanical stability; the amorphous region has better toughness and can effectively dissipate stress. The two are interwoven to form a composite structure with both toughness and strength. At the same time, the rapid quenching process forms a porous structure inside the porous composite structure thin strip. These pores not only provide additional channels for lithium ion migration, but more importantly, provide a buffer space for the volume expansion of the negative electrode material, thereby alleviating the damage to the overall structure caused by volume changes at the root. In the embodiment, amorphous / nanocrystalline exists inside the porous composite structure thin strip, which can adapt to the stress changes of repeated lithiation / delithiation inside the porous composite structure thin strip.

[0047] Further, please combine Figure 3 and Figure 4, step S3 places the porous composite structure thin strip in an oxygen-containing gas atmosphere, and uses the high affinity of zinc, magnesium, aluminum and other metal elements for oxygen to make them react with oxygen on the pore surface and the outer surface of the material to form a dense metal oxide passivation layer. The passivation layer can effectively isolate the external air and moisture from the internal active lithium, significantly improving the air stability of the porous composite structure thin strip. Further, step S4 performs fluorination treatment to further build a protective layer rich in metal fluoride on the outside of the passivation layer. The fluoride layer has excellent chemical inertness and electrochemical stability, and can effectively inhibit the occurrence of side reactions and reduce the irreversible consumption of active lithium, especially in the lithium ion battery electrolyte environment. The protective layer and the passivation layer jointly ensure the interface integrity of the high-entropy lithium alloy material during long-term cycling from the dimensions of physical barrier and chemical stability.

[0048] Further, please combine Figure 5 and Figure 6 , step S5 annealing treatment makes the atoms inside the porous composite structure thin strip have sufficient migration ability under heat conditions, promoting the formation of Li 22 Sn5 alloy phase and Li2Zn alloy phase of zinc and lithium. The formed lithium alloy phase is not randomly distributed, but precipitates at the interface between the nanocrystalline region and the amorphous region, thereby forming a uniformly distributed buffer region in the porous composite structure thin strip. The buffer region can more effectively coordinate the uneven expansion and contraction between hard nanocrystals and soft amorphous phases during charging and discharging by its different volume change behavior during charging and discharging, and the local stress concentration is minimized. It should be understood that the present embodiment prepares a high-entropy lithium alloy material with a multi-level buffer structure. When used as a negative electrode material, it can have high capacity and high interface stability.

[0049] Specifically, in the above step S1, the metal raw materials of lithium, aluminum, magnesium, tin and zinc are ground into a mixed powder, which includes:

[0050] The metal raw materials of lithium, aluminum, magnesium, tin and zinc are provided, and the metal raw materials are pretreated into metal powders of lithium, aluminum, magnesium, tin and zinc, wherein the powder particle size of lithium metal is 1-10 μm, and the powder particle size of aluminum, magnesium, tin and zinc is 10-50 nm, and the mass ratio of lithium, aluminum, magnesium, tin and zinc in the mixed powder is lithium: aluminum: magnesium: tin: zinc = (80-90% : 2-6% : 1-4% : 1-5% : 1-5%) ;

[0051] The ball milling device is provided, and the ball milling device is heated to 600-800°C at a temperature increasing rate of 5-10°C / min in advance, and after heating, metal powders of lithium, aluminum, magnesium, tin, and zinc are placed in the ball milling device and are milled at a stirring speed of 100-400 rpm and a ball-to-material ratio of (15:1-20:1) for 4-8 hours to obtain a mixed powder.

[0052] The embodiment solves the technical problems of poor component uniformity and lithium volatilization loss in the preparation of a traditional lithium alloy by the synergistic design of metal powder grading pretreatment and a high-energy ball milling process. The powder particle size range of the metal and the selective particle size range of other metal powders reduce the oxidation risk of high-activity lithium powder, and the high dispersibility of the nano-powder promotes atomic-level mixing, and the mechanical energy input of the ball-to-material ratio of (15:1-20:1) and the rotation speed of 100-400 rpm effectively avoids the stratification phenomenon caused by the density difference. Alternatively, the powder particle size range of the lithium metal can be 1-5 μm, 4-10 μm, or 3-8 μm. The powder particle size range of aluminum, magnesium, tin, and zinc can be 15-35 μm, 20-40 μm, or 3-30 μm.

[0053] Specifically, the temperature of 600-800°C in the ball milling process reduces the atomic diffusion energy barrier, realizes low-temperature alloying, and inhibits lithium metal volatilization. The 4-8 hour ball milling period balances the powder cold welding and crushing rate, ensuring that the powder particle size deviation of the same metal in the mixed powder is small. Among them, 80-90% of lithium can guarantee the lithium storage capacity, 2-6% of aluminum and 1-4% of magnesium can form a passivation layer subsequently, and the passivation layer can provide the stability of the high-entropy lithium alloy material, and 1-5% of tin and zinc form a buffer region through grain boundary segregation, which can inhibit dendrites.

[0054] Further, in the above step S2, after heating the mixed powder to a melting temperature under a protective gas atmosphere, a lithium compensation agent is added to form a melt, including:

[0055] The lithium compensation agent is any one or a combination of lithium nitride or lithium oxide;

[0056] The mixed powder is heated from room temperature to a melting temperature of 1200-1300°C at a heating rate of 10-20°C / min under a protective gas atmosphere;

[0057] After being heated to the melting temperature, the lithium compensation agent is added, and the lithium compensation agent and the molten mixed powder form a melt.

[0058] It can be understood that the embodiment avoids the loss of lithium volatilization and uneven composition in the high-temperature melting process by adding lithium compensation agent and precise temperature control, makes up for and offsets the inevitable loss of lithium volatilization in the high-temperature smelting process. Lithium is easy to volatilize at high temperature above 1200℃. By selecting lithium nitride or lithium oxide as the compensation agent, metallic lithium is released at a melting temperature of 1200~1300℃, filling the lithium vacancy caused by volatilization. At the same time, the trace gas generated by decomposition forms a protective interface layer on the surface of the melt, inhibiting secondary oxidation. The linear heating rate of 10~20℃ / min ensures that the internal temperature gradient of the mixed powder changes little, avoiding local overheating that leads to preferential volatilization of lithium; the 1200~1300℃ melting interval balances the complete melting of high-melting-point metals and the control of lithium vapor pressure, reduces lithium volatilization through thermodynamic equilibrium, and ensures the uniformity of the melt composition. The protective gas atmosphere can be helium or argon, which effectively isolates air and moisture to avoid the formation of impurities such as Li2O and LiOH, ensuring the quality of subsequent rapid quenching and forming. It should be understood that the embodiment avoids the loss of lithium volatilization in the high-temperature melting process by adding lithium compensation agent and controlling temperature, and at the same time obtains a melt with high uniformity and in a high-energy state, which is convenient for subsequent rapid quenching to obtain uniform amorphous / nanocrystalline composite structure.

[0059] Further, please refer to Figure 2 and Figure 3 In the above step S2, cooling the melt based on the rapid quenching process includes:

[0060] A rapid quenching device is provided, and a nozzle and a single roller spaced from the nozzle are arranged in the rapid quenching device;

[0061] The linear speed of the roller surface of the single roller is controlled to be 30±5 m / s, the distance between the end of the nozzle and the roller surface of the single roller is controlled to be 300±50μm, the melt is sprayed out to the roller surface of the single roller for cooling under a protective gas atmosphere, the pressure of the protective gas atmosphere is 0.6±0.1 bar, the melt contacts the roller surface of the single roller, and then cools from 1200~1300℃ to room temperature, during the cooling process, zinc atoms and tin atoms in the melt gather on one side of the melt to form a zinc / tin zone, and after the cooling is completed, a porous composite structure thin strip is obtained.

[0062] It can be understood that the embodiment forms the amorphous / nanocrystalline phase in the high-entropy lithium alloy material by a rapid quenching process. The rapid quenching process realizes non-equilibrium solidification through ultrafast cooling, not by setting a fixed cooling rate, but by rapidly cooling the molten body with the process parameters of the rapid quenching equipment. The parameters of the rapid quenching process work together, which are reflected in the single roller linear speed, nozzle distance and protective gas pressure. The single roller linear speed and nozzle distance control ensure that the molten body is in full contact with the roller surface to form a uniform thin strip; the micro-positive pressure protective atmosphere ensures the stable flow of the molten body and avoids oxidation pollution. Ultrafast cooling prevents grain growth through kinetic inhibition effect, forms an amorphous / nanocrystalline composite structure, and provides a rich lithium diffusion channel. At the same time, the temperature gradient induces directional migration of zinc and tin atoms to enrich, forming a Li2Zn / Li 22 Sn5 buffer region, which forms a prerequisite for the subsequent annealing process. The porous structure formed in the rapid quenching process is realized by the cooperation of gas escape, volume shrinkage and thermal expansion difference, which can relieve the volume expansion of lithium deposition, so that the high-entropy lithium alloy material as a negative electrode material can increase the contact area and promote the infiltration of the electrode and the electrolyte, and improve the interface stability. The porous composite structure thin strip formed by rapid quenching also presents a porous structure, and the pores can also provide a buffer space for the expansion of the negative electrode material.

[0063] Further, please combine Figure 3 and Figure 4 In the above step S3, the zinc atoms, magnesium atoms and aluminum atoms respectively react with oxygen and form a passivation layer on the surface of the porous composite structure thin strip, including:

[0064] The zinc atoms react with oxygen to obtain zinc oxide, the magnesium atoms react with oxygen to obtain magnesium oxide, and the aluminum atoms react with oxygen to obtain aluminum oxide;

[0065] The zinc oxide, magnesium oxide and aluminum oxide form a passivation layer on the surface of the porous composite structure thin strip.

[0066] It can be understood that the surface oxide layer of the conventional lithium alloy is uneven. The embodiment builds a continuous and dense passivation layer on the surface of the porous composite structure thin strip through the oxygen-containing gas atmosphere regulation and multi-element synergistic oxidation mechanism. The passivation layer is composed of Al2O3, MgO and ZnO composite oxides, which has the advantages of strong interface bonding force and uniform thickness. The oxygen-containing gas atmosphere in the embodiment refers to an air environment, i.e. the oxygen content is less than or equal to 21%, which avoids the discontinuity of the passivation layer caused by low oxygen and prevents excessive oxidation and brittle layer formation caused by high oxygen. Zinc, magnesium and aluminum are preferentially oxidized based on chemical activity, and the generated composite oxides form a passivation layer covering the surface of the porous composite structure thin strip. The passivation layer can basically cover the surface of the porous composite structure thin strip, and acts as a stable solid-state electrolyte interface preset layer in the battery system, effectively blocking the direct contact of the electrolyte with the alloy matrix, thereby inhibiting the uncontrollable growth of side reactions and lithium dendrites, and significantly improving the air exposure resistance and electrochemical cycle life of the high-entropy lithium alloy material.

[0067] Further, please refer to Figure 4 and Figure 5 In the step S4, the fluorination treatment is performed on the side of the passivation layer away from the porous composite structure thin strip, including:

[0068] Argon and tetrafluoromethane gas are provided, and the argon and tetrafluoromethane gas are mixed into a mixed gas at a flow ratio of (1:1) to (3:1);

[0069] The porous composite structure thin strip forming the passivation layer is placed in a vacuum environment and the mixed gas is introduced, and a protective layer is formed on the side of the passivation layer away from the porous composite structure thin strip by plasma treatment at a power of 150-250 W and a room temperature-60°C for 30-45 minutes.

[0070] It can be understood that in the embodiment, the concentration of active fluorine species in the plasma is controlled by controlling the flow ratio of argon and tetrafluoromethane gas to be (1:1)~(3:1), the high argon ratio enhances the bombardment energy to promote molecular cracking, and the high tetrafluoromethane ratio increases the fluorine source supply, ensuring the uniformity and continuity of the protection layer. Specifically, the protection layer can be lithium fluoride. Activating gas molecules at a power of 150~250W can avoid damaging the passivation layer. In a temperature range from room temperature to 60°C, a lower temperature can effectively prevent the porous structure from being damaged due to thermal stress. A moderate time balance protects the growth of the protection layer and the crystallinity, and promotes the growth of high ionic conductivity columnar crystals. The protection layer can complement the function of the passivation layer, and the passivation layer provides a physical barrier, and the protection layer promotes lithium ion diffusion. Plasma treatment is a technology for modifying the surface of a material using high-energy plasma. Plasma, as the fourth state of matter, is composed of partially ionized gas, including electrons, ions, and neutral particles, and has high reactivity. Through physical collision or chemical reaction between plasma and the surface of the material, the chemical composition, microstructure, and interface performance of the surface can be changed to achieve functions such as surface cleaning, activation, etching, or coating deposition. In the embodiment, the protection layer is formed by plasma treatment, and the protection layer and the passivation layer work together: the passivation layer mainly provides physical barrier to prevent bulk phase oxidation; and the protection layer, as an artificial solid-state electrolyte interface, has high interface energy to guide uniform deposition of lithium ions, thereby effectively inhibiting the growth of lithium dendrites. At the same time, the hydrophobic property of the protection layer helps to reduce electrolyte side reactions and reduce interface impedance.

[0071] Further, please refer to Figure 5 and Figure 6 In the above step S5, the annealing treatment of the porous composite structure thin strip after fluorination treatment includes:

[0072] The porous composite structure thin strip after fluorination treatment is first heated to 150~200°C at a rate of 1~5°C / min, and the first holding time is 30~60 minutes. During the first heating process, tin atoms and lithium atoms in the porous composite structure thin strip form Li 22 Sn5, zinc atoms and lithium atoms form Li 22 2Zn, and Li 22 Sn5and Li2Zn form a buffer region between the nanocrystalline region and the amorphous region in the porous composite structure thin strip. After the first holding, the second heating is carried out to 300~400°C, and the second holding time is 15~30 minutes. After completing the second holding, cooling to room temperature at a rate of 0~5°C / min obtains a high-entropy lithium alloy material.

[0073] It can be understood that the annealing treatment controls the heating rate and holding time to guide the directional diffusion of tin and zinc atoms and react with lithium to form Li 22Sn5 / Li2Zn buffer region, forming a buffer region between the nanocrystalline region and the amorphous region. Specifically, the method of stepwise heating is used to heat at a rate of 3~5℃ / min to 200℃ and keep for 60 minutes, which releases internal stress mildly and avoids stress concentration leading to microcracks; continue to heat to 400℃ for 30 minutes, which promotes tin and zinc atoms to segregate to the grain boundaries and react in situ with lithium to generate uniformly distributed Li 22 Sn5 / Li2Zn buffer region. Wherein Li 22 The low volume expansion property of Sn5 and the high plasticity of Li2Zn synergistically alleviate the volume change, improve the interface bonding strength and inhibit the dendrite growth, and improve the cycle stability. Finally, slow cooling at 0~5℃ / min is used to avoid thermal shock, ensure that the buffer region precipitates in a thermodynamically stable structure, reduce the interface stress generated by the difference in thermal expansion coefficient, and protect the integrity of the porous composite structure thin strip. The annealing treatment of the embodiment regulates the internal stress and the distribution of the buffer region, so that the high-entropy lithium alloy has high capacity and long cycle stability.

[0074] Please refer to Figure 7 and Figure 8 , the second embodiment of the present application further provides a high-entropy lithium alloy material prepared by the preparation method of the high-entropy lithium alloy material, the high-entropy lithium alloy material comprising a porous composite structure thin strip, a buffer region, a passivation layer and a protective layer; the porous composite structure thin strip comprises a nanocrystalline region and an amorphous region inside, and a buffer region is arranged between the nanocrystalline region and the amorphous region; the passivation layer is arranged on the outer surface of the porous composite structure thin strip and completely covers the porous composite structure thin strip, and the protective layer is arranged on the side of the passivation layer away from the porous composite structure thin strip.

[0075] Specifically, the thickness of the porous composite structure thin strip is 50 nm~500 nm. The porous composite structure thin strip shortens the diffusion distance of lithium ions in the material, which is beneficial to realize fast charge and discharge and improve the rate performance. The protective layer is 10~15 nm, which is a stable artificial solid-state electrolyte interface, can effectively inhibit the side reaction of electrolyte and electrode material, and reduce the irreversible consumption of active lithium. The passivation layer is 8~12 nm, which forms a dense and continuous oxide layer, effectively isolates air and moisture, prevents corrosion and loss of internal active lithium, and significantly improves the stability of the material in air.

[0076] It can be understood that the high-entropy lithium alloy material provided in the embodiment solves the problems of structural failure and interface instability caused by repeated volume changes of the conventional lithium alloy negative electrode in the cycle process. Specifically, the porous composite structure thin strip constitutes the matrix of the high-entropy lithium alloy material. The inside of the matrix is formed by the interweaving of the nanocrystalline region and the amorphous region to form a composite structure. The nanocrystalline region serves as a strong skeleton to provide the necessary mechanical strength for the material, preventing the material from undergoing overall plastic deformation or collapse during the charging and discharging process; and the amorphous region has a higher atomic disorder degree and free volume, which can make the material itself have toughness and stress dissipation capacity. The high-entropy lithium alloy material can effectively absorb and disperse the internal stress generated by the lithium ion insertion / extraction, significantly inhibiting the initiation and expansion of microcracks. Further, the uniformly distributed pore structure in the high-entropy lithium alloy material provides a preset accommodation space for the volume expansion of the active material during the cycle process, thereby greatly reducing the damage to the overall structural integrity caused by the volume change.

[0077] Specifically, a buffer region composed of Li 22 Sn5and Li2Zn, etc. The region is generated during annealing and is closely combined with the nanocrystalline region and the amorphous region. When uneven expansion or contraction occurs in different phase regions due to charging and discharging, the buffer region can coordinate the deformation difference of the adjacent regions through its own elastic deformation, effectively passivating the stress concentration at the phase interface and avoiding debonding or cracking caused by poor interface bonding. The passivation layer is mainly composed of oxides of zinc, magnesium, aluminum and other metals. It completely covers the outer surface of the porous thin strip and the inner surface of the pores, forming the first physical and chemical barrier. The passivation layer can effectively prevent the intrusion of moisture and oxygen in the environment into the material interior, significantly improving the storage stability and processing feasibility of the material. At the same time, the oxide layer is firmly combined with the matrix, providing stable support for the external protective layer. The protective layer arranged outside the passivation layer is rich in metal fluoride components through fluorination treatment, which can greatly inhibit the occurrence of harmful side reactions between the electrode material and the electrolyte, reduce the loss of active lithium and the formation of irreversible phases. The passivation layer ensures physical protection, and the protective layer focuses on the stability of the electrochemical interface, ensuring that the high-entropy lithium alloy material can maintain a thin and stable solid-state electrolyte interface film in long-term electrochemical cycling, thereby guaranteeing high coulomb efficiency and long cycle life.

[0078] In order to verify the effects of the high-entropy lithium alloy material provided in the embodiment, the following experiments are now performed:

[0079] Experimental group:

[0080] Step 1: Lithium, aluminum, magnesium, tin and zinc metal powders with purity of 99.9% were ball-milled at 800℃ for 8h at a rotation speed of 400rpm and a ball-to-powder ratio of 20:1 to obtain a mixed powder.

[0081] Step 2: The mixed powder was heated to 1300℃ under a helium atmosphere to form a molten mixture, and the molten mixture was sprayed through a 0.8mm quartz nozzle slit under a pressure of 0.6bar, with the tip of the nozzle kept at a distance of 300μm from the surface of a high-speed rotating copper roller, and the linear speed of the roller surface was controlled at 30m / s. The molten mixture was cooled on the surface of the copper roller to obtain a porous composite structure thin strip, and a passivation layer was naturally formed on the surface of the porous composite structure thin strip.

[0082] Step 3: The porous composite structure thin strip with the passivation layer was placed in a chamber, and the chamber was evacuated to a vacuum degree of less than 1×10⁻³ Pa, then a mixed gas of argon and tetrafluoromethane was introduced, with the flow ratio of Ar to CF4 controlled at 1:1, and the working pressure of the chamber maintained at 20 Pa. Then a radio frequency power source was started, and the porous composite structure thin strip with the passivation layer was treated at a power of 250 W and a temperature of 60°C for 30 minutes, and the chamber was flushed with high-purity argon gas. Finally, a dense and uniform lithium fluoride protective layer was obtained on the surface of the porous composite structure thin strip with the passivation layer.

[0083] Step 4: The porous composite structure thin strip with the protective layer was placed in a vacuum-protected heat treatment furnace, and first heated to 200°C at a rate of 5°C / min and held for 60 minutes to eliminate internal stress; then continued to heat to 300°C at the same rate and held for 120 minutes, and finally heated to 400°C and held for 30 minutes. After completion, the furnace was cooled to room temperature to obtain a high-entropy lithium alloy material, which was used as a negative electrode material.

[0084] Comparative Group 1: Pure lithium metal foil as negative electrode material

[0085] Comparative Group 2: Binary lithium alloy Li 20 Sn5 as negative electrode material

[0086] Comparative Group 3: The same as the experimental group, except that the obtained ingot alloy was used as a negative electrode material without rapid quenching and annealing treatment

[0087] Comparative Group 4: The same as the experimental group, except that the sample without plasma fluorination treatment was used as a negative electrode material.

[0088] Volume expansion rate: The negative electrode materials of the experimental group and the comparative groups were respectively made into CR2032 button cells, lithium sheet was used as the counter electrode, and 1mol LiPF8 / EC:DMC (volume ratio 1:1) was used as the electrolyte. After 50 cycles at a rate of 0.1C, the change in particle size was observed by electron microscopy, and the volume expansion rate was calculated.

[0089] Li⁺ diffusion coefficient: The electrochemical workstation tests the negative electrode materials of the experimental group and the comparative group by EIS, and calculates the lithium ion chemical diffusion coefficient according to the Warburg impedance in the low frequency region. The Warburg impedance is an impedance form in electrochemistry to describe the diffusion control, and the Warburg impedance can describe the resistive component of electron transfer in the electrolyte solution under diffusion control.

[0090] Cycle performance: The negative electrode materials of the experimental group and the comparative group are made into half batteries, the first charge-discharge curve is tested at 0.1C rate, and the first coulombic efficiency is calculated; 0.5C rate is cycled for 200 cycles, and the capacity retention rate is recorded.

[0091] Experimental results:

[0092] Table 1, performance indication table

[0093]

[0094] From the results in Table 1, it can be seen that the high-entropy lithium alloy material prepared in the embodiment as the negative electrode material is significantly better than all the comparative examples in high initial efficiency, long cycle life, low volume expansion and excellent environmental stability.

[0095] The third embodiment of the present application provides a negative electrode material, which comprises a current collector and the above-mentioned high-entropy lithium alloy material arranged in a stacked manner. It can be understood that the high-entropy lithium alloy material is arranged in a stacked manner on the current collector in the form of a thin strip. The porous composite matrix, amorphous / nanocrystalline dual-phase structure and interface buffer region inside the high-entropy lithium alloy material jointly play a synergistic role. When the battery is charged and discharged, the active material will inevitably expand and shrink in volume. The porous structure inside the high-entropy lithium alloy material provides the primary accommodation space for the volume change, and the amorphous / nanocrystalline inside the high-entropy lithium alloy material converts the macroscopic volume deformation into microscopic stress absorption and dispersion through its own ductile deformation and strength support, greatly inhibiting the plastic deformation of the negative electrode material as a whole. The buffer region located at the amorphous / nanocrystalline grain boundary further passivates the internal stress concentration, preventing the initiation and propagation of microcracks from the inside of the material. The protective layer and the passivation layer jointly guarantee the interface integrity of the negative electrode material in long-term cycling from the two dimensions of physical barrier and chemical stability. The high-entropy lithium alloy material in the embodiment can maintain the integrity of its own structure during the cycle process, thereby obtaining a negative electrode material with good anti-expansion performance in combination with the current collector.

[0096] The fourth embodiment of the present application is a battery, which comprises a positive electrode material, an electrolyte and the above-mentioned negative electrode material. It can be understood that, during the charging and discharging process, lithium ions reciprocally embed and extract between the positive electrode and the negative electrode. When lithium ions embed the negative electrode material, the porous composite structure thin strips inside the negative electrode material first provide an initial expansion space, and the amorphous / nanocrystalline dual-phase composite matrix inside the negative electrode material effectively absorbs and disperses the lattice stress generated by the embedding of lithium ions through its own toughness deformation and strength support, thereby avoiding the pulverization of the active material particles. The buffer region located at the dual-phase interface further coordinates the deformation difference between different phases, and reduces the local stress concentration that may cause structural damage to the minimum. The protective layer and the passivation layer jointly guarantee the interface integrity of the negative electrode material in the battery during long-term cycling. The negative electrode material of the present embodiment can maintain the physical integrity of its structure during the entire cycling process, thereby providing stable capacity output and long cycle life for the battery.

[0097] The preparation method of the high-entropy lithium alloy material, the high-entropy lithium alloy material and the preparation method of the negative electrode material disclosed in the above embodiments of the present application are described in detail. The principles and implementation manners of the present application are described by applying specific examples. The above embodiment descriptions are only used to help understand the method of the present application and its core idea. Meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In summary, the content of the present specification should not be understood as a limitation of the present application. Any modification, equivalent replacement and improvement within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a high-entropy lithium alloy material, characterized in that: The preparation method of the high-entropy lithium alloy material includes: Provide metallic raw materials of lithium, aluminum, magnesium, tin and zinc, and grind the metallic raw materials of lithium, aluminum, magnesium, tin and zinc into mixed powder; A lithium compensator is provided. The mixed powder is heated to the melting temperature under a protective gas atmosphere and then the lithium compensator is added to form a melt. The melt is cooled based on a rapid quenching process. During the cooling process, nanocrystalline and amorphous regions are formed in the melt. After cooling, a porous composite structure thin strip is obtained. The cooled porous composite structure strip is placed in an oxygen-containing gas atmosphere. The zinc, magnesium and aluminum atoms on the pore surface of the porous composite structure strip react with oxygen to form a passivation layer that completely covers the porous composite structure strip. A protective layer is formed by fluorination on the side of the passivation layer away from the porous composite structure thin strip; and The porous composite structure thin strip after fluorination was annealed, and the tin and lithium atoms inside the porous composite structure thin strip formed Li 22 Sn5, zinc atoms and lithium atoms form Li2Zn, Li 22 Sn5 and Li2Zn form a buffer region between the nanocrystalline and amorphous regions inside the porous composite thin strip, and the high-entropy lithium alloy material is obtained after annealing.

2. The method for preparing the high-entropy lithium alloy material as described in claim 1, characterized in that: Grinding metallic raw materials such as lithium, aluminum, magnesium, tin, and zinc into a mixed powder includes: Provides lithium, aluminum, magnesium, tin and zinc metal raw materials, pre-processes the metal raw materials into lithium, aluminum, magnesium, tin and zinc metal powders, wherein the lithium metal powder particle size ranges from 1 to 10 μm, and the aluminum, magnesium, tin and zinc metal powder particle size ranges from 10 to 50 nm, and the mass ratio of lithium, aluminum, magnesium, tin and zinc in the mixed powder is lithium:aluminum:magnesium:tin:zinc = (80~90% : 2~6% : 1~4% : 1~5% : 1~5%). Provide ball milling equipment. Preheat the ball milling equipment to 600-800℃ at a heating rate of 5-10℃ / min. After heating, place the metal powders of lithium, aluminum, magnesium, tin and zinc into the ball milling equipment and grind them for 4-8 hours at a stirring speed of 100-400rpm and a ball-to-material ratio of (15:1-20:1) to obtain mixed powder.

3. The method for preparing the high-entropy lithium alloy material as described in claim 1, characterized in that: The process involves heating the mixed powder to its melting temperature under a protective gas atmosphere, followed by adding a lithium compensator to form a melt, including: Provide a lithium compensator, wherein the lithium compensator is any one or more combinations of lithium nitride or lithium oxide; The mixed powder was heated from room temperature to a melting temperature of 1200-1300°C at a heating rate of 10-20°C / min under a protective gas atmosphere; After heating to the melting temperature, lithium compensator is added, and the lithium compensator and the molten mixed powder form a melt.

4. The method for preparing the high-entropy lithium alloy material as described in claim 1, characterized in that: Cooling of melts based on rapid quenching processes includes: Provide rapid quenching equipment, which is equipped with nozzles and single rollers spaced apart from the nozzles; The linear velocity of the single roller surface is controlled at 30±5 m / s, and the distance between the nozzle tip and the roller surface is controlled at 300±50 μm. The melt is sprayed through the nozzle onto the roller surface of the single roller under a protective gas atmosphere for cooling. The pressure of the protective gas atmosphere is 0.6±0.1 bar. After the melt comes into contact with the roller surface of the single roller, it is cooled from 1200~1300℃ to room temperature. During the cooling process, zinc atoms and tin atoms in the melt aggregate to one side of the melt to form a zinc / tin region. After cooling, a porous composite structure thin strip is obtained.

5. The method for preparing the high-entropy lithium alloy material as described in claim 1, characterized in that: Zinc atoms, magnesium atoms, and aluminum atoms react with oxygen to form a passivation layer on the surface of the porous composite strip, including: Zinc atoms react with oxygen to produce zinc oxide, magnesium atoms react with oxygen to produce magnesium oxide, and aluminum atoms react with oxygen to produce aluminum oxide. Zinc oxide, magnesium oxide, and aluminum oxide form a passivation layer on the surface of the porous composite strip.

6. The method for preparing the high-entropy lithium alloy material as described in claim 1, characterized in that: Fluorination treatment on the side of the passivation layer away from the porous composite structure thin strip includes: Argon and tetrafluoromethane gas are provided, and the argon and tetrafluoromethane gas are mixed in a flow ratio of (1:1) to (3:1) to form a mixed gas; The porous composite structure thin strip with the passivation layer is placed in a vacuum environment and a mixed gas is introduced. Then, it is subjected to plasma treatment for 30 to 45 minutes at a power of 150 to 250 W and a room temperature to 60°C to form a protective layer on the side of the passivation layer away from the porous composite structure thin strip.

7. The method for preparing the high-entropy lithium alloy material as described in claim 1, characterized in that: Annealing the fluorinated porous composite strip includes: The fluorinated porous composite thin strip was first heated to 150-200℃ at a rate of 1-5℃ / min, and held at that temperature for 30-60 minutes. During the first heating process, tin and lithium atoms inside the porous composite thin strip formed Li 22 Sn5, zinc atoms and lithium atoms form Li2Zn, Li 22 Sn5 and Li2Zn form a buffer region between the nanocrystalline and amorphous regions inside the porous composite structure thin strip; after the first heat preservation, the temperature is raised to 300~400℃ for the second time and kept for 15~30 minutes. After the second heat preservation, the material is cooled to room temperature at 0~5℃ / min to obtain a high-entropy lithium alloy material.

8. A high-entropy lithium alloy material, prepared by the preparation method of any one of claims 1 to 7, characterized in that: The high-entropy lithium alloy material includes a porous composite structure strip, a buffer region, a passivation layer, and a protective layer; the porous composite structure strip includes a nanocrystalline region and an amorphous region, and the buffer region is disposed between the nanocrystalline region and the amorphous region; the passivation layer is disposed on the outer surface of the porous composite structure strip and completely covers the porous composite structure strip, and the protective layer is disposed on the side of the passivation layer away from the porous composite structure strip.

9. A negative electrode material, characterized in that: It includes stacked current collectors and the high-entropy lithium alloy material as described in claim 8.

10. A battery, characterized in that: The battery includes a positive electrode material, an electrolyte, and a negative electrode material as claimed in claim 9.

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