A high entropy lithium alloy negative electrode and preparation method thereof

Abstract

The present invention belongs to the field of lithium battery technology and discloses a high-entropy lithium alloy negative electrode, a solid-state battery, and a preparation method thereof. Metallic lithium and multiple other metals or non-metals are heated and melted at high temperature to obtain a multiphase high-entropy alloy liquid composed of a lithium alloy phase and a non-lithium alloy phase; the multiphase high-entropy alloy liquid is cooled to room temperature to obtain a micro-nano three-dimensional skeleton network structure of the multiphase high-entropy alloy; wherein the lithium atoms in the high-entropy lithium alloy negative electrode material account for 20-50% of the total atomic ratio, and the other metals and / or non-metals account for 1-50% of the total atomic ratio. The micro-nano-sized three-dimensional skeleton high-entropy alloy network structure of the present invention is conducive to increasing the true specific surface area of ​​the negative electrode, effectively reducing the local current density, and inhibiting the formation of lithium dendrites; the high-entropy alloy skeleton network contains inert alloy components, which is conducive to improving the stability of the three-dimensional skeleton and the constancy of the negative electrode volume, and improving the lithium affinity of the three-dimensional skeleton, thereby improving the cycle life of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a high-entropy lithium alloy negative electrode and a preparation method thereof. Background Art

[0002] At present, lithium-ion batteries have become one of the most popular mobile energy storage methods since their successful commercialization in the 1990s, promoting the rapid development and progress of consumer electronics, electric transportation, military products and medical equipment. However, with the continuous development of society, lithium-ion batteries based on graphite negative electrodes (372mAh / g) are increasingly unable to meet the growing market demand. Metallic lithium has an ultra-high theoretical specific capacity (3860mAh / g), the lowest electrochemical potential (-3.04V vs standard hydrogen electrode) and an ultra-low density (0.53g / cm 3 ), is the "holy grail" of negative electrode materials for next-generation lithium secondary batteries.

[0003] During use, uneven lithium deposition in lithium metal anodes leads to the formation of numerous lithium dendrites. These dendrites can pierce the separator, causing battery short circuits and potentially leading to safety issues such as fire and explosion. Furthermore, the deposition of lithium without a "host structure" and the generation of "dead lithium" also lead to volume expansion of the lithium metal anode, causing battery deformation and shortening cycle life. These factors have severely hampered the commercialization of lithium metal anodes, preventing their mass production and application to date.

[0004] To address the various issues associated with metallic lithium anodes, a growing number of researchers are recognizing alloying as a highly effective modification method. Lithium alloy anodes possess an inherent alloy skeleton structure. During battery cycling, this alloy skeleton not only reduces the current density of the electrochemical reaction, thereby inhibiting dendrite formation, but also minimizes volume changes during the continuous release and deposition of lithium, thereby stabilizing the battery structure. Furthermore, the lithium alloy skeleton provides additional lithiophilic sites, which facilitate the nucleation and conformal deposition of metallic lithium, thereby improving Coulombic efficiency. However, many alloy skeleton structures lack mechanical strength and stability, and are prone to pulverization and breakage during repeated battery cycling, leading to skeleton collapse. Furthermore, some alloy skeletons, such as lithium-copper alloys, have limited lithium nucleation induction, which can lead to preferential lithium deposition on the skeleton surface, resulting in alloy skeleton failure and poor overall battery performance. Therefore, improving the lithiophilicity and structural stability of the lithium alloy skeleton is essential for the commercial application of lithium anodes.

[0005] High-entropy alloys (HEAs) are a new concept that has emerged in recent years. Unlike traditional alloys, their atoms are randomly and disorderly distributed across the crystal lattice, resulting in a thermodynamically high-entropy effect and superior mechanical and other properties. Second-generation HEAs, in particular, are composed of four or more alloying elements, with non-equiatomic ratios and a multiphase structure that allows for the coexistence of solid solutions and intermetallic compound phases. The dispersion strengthening of precipitated phases further enhances the mechanical and other properties of HEAs. Currently, HEAs have not been used as negative electrode materials for lithium batteries.

[0006] Through the above analysis, the problems and defects of the existing technology are as follows:

[0007] (1) The uneven lithium deposition behavior on the conventional metal lithium negative electrode side leads to the generation of a large number of lithium dendrites, which may pierce the diaphragm, causing battery short circuit, battery fire and explosion and other safety issues.

[0008] (2) The skeleton structure of the existing lithium alloy negative electrode has insufficient mechanical strength and poor structural stability. During the repeated cycling of the battery, it is easy to pulverize and break, resulting in skeleton collapse.

[0009] (3) The existing lithium-copper alloy skeleton has limited induction nucleation effect on lithium, which easily leads to preferential deposition of lithium on the skeleton surface, thereby causing the alloy skeleton to fail and significantly shortening the battery cycle life.

[0010] (4) The commercialization process of metallic lithium anodes has been severely hindered and has not yet been mass-produced and applied; and there are currently no reports on the use of high-entropy lithium alloys as battery anode materials. Summary of the Invention

[0011] In response to the problems existing in the prior art, the present invention provides a high-entropy lithium alloy negative electrode, a solid-state battery and a preparation method thereof, and in particular relates to a high-entropy lithium alloy negative electrode, a solid-state battery and a preparation method thereof containing a three-dimensional skeleton network.

[0012] The present invention is achieved by providing a method for preparing a high-entropy lithium alloy negative electrode, which comprises: obtaining a high-entropy alloy liquid containing lithium and multiple metal / non-metal elements by high-temperature melting metallurgy; utilizing the phase separation effect during cooling of the high-entropy alloy liquid to obtain a multiphase high-entropy alloy negative electrode material containing a lithium alloy phase and a non-lithium alloy phase; wherein the lithium atoms in the high-entropy lithium alloy negative electrode material account for 20-50% of the total atomic ratio, and other metals and / or non-metals account for 1-50% of the total atomic ratio.

[0013] Furthermore, the method for preparing a high entropy lithium alloy negative electrode comprises the following steps:

[0014] Step 1: obtaining a molten alloy liquid of lithium and other metal or non-metal elements at high temperature;

[0015] Step 2: Cool the molten alloy liquid to room temperature to obtain a high entropy lithium alloy negative electrode material.

[0016] Furthermore, in step 1, metallic lithium and multiple other metals or non-metals are heated and melted at a temperature of 300 to 1000° C. to obtain a high entropy alloy liquid.

[0017] Furthermore, in step 1, the other metal or non-metal elements are any three or more of Na, K, Mg, Ca, Ba, Ni, Zn, Al, In, Sn, Sb, Pb, Ag, B, Si or C.

[0018] Furthermore, in step 2, the molten alloy liquid is cooled to room temperature within 5 to 1800 seconds.

[0019] Furthermore, in step 2, phase separation occurs during the cooling process, and solidification forms a multiphase structure including a lithium alloy phase and a non-lithium alloy phase.

[0020] Furthermore, the multiphase structure is a micro-nano three-dimensional skeleton network structure of a high entropy alloy composed of a lithium alloy phase and a non-lithium alloy phase.

[0021] Furthermore, the three-dimensional skeleton network is a mixture of any one or more of a lithium alloy skeleton and a non-lithium alloy skeleton.

[0022] Another object of the present invention is to provide a high-entropy lithium alloy negative electrode material containing a three-dimensional skeleton network prepared by implementing the high-entropy lithium alloy negative electrode preparation method.

[0023] Another object of the present invention is to provide an application of the high-entropy lithium alloy negative electrode material containing a three-dimensional skeleton network in the preparation of a lithium battery. The lithium battery includes a positive electrode, a negative electrode, and an electrolyte placed between the positive electrode and the negative electrode, and the negative electrode is a high-entropy lithium alloy material.

[0024] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0025] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving these problems, we closely combine the technical solutions to be protected by the present invention and the results and data during the research and development process, and conduct a detailed and in-depth analysis of how the technical solutions of the present invention solve the technical problems and some creative technical effects brought about by solving the problems. The specific description is as follows:

[0026] The present invention utilizes high-temperature melt metallurgy to produce a high-entropy lithium alloy containing lithium and various metal / non-metal elements. Phase separation during cooling is then utilized to form a multiphase high-entropy lithium alloy material containing a lithium alloy phase and a non-lithium alloy phase. This in-situ construction of a three-dimensional network framework using the lithium alloy and non-lithium alloy phases not only enhances the stability of the negative electrode structure but also improves the framework's lithiophilicity and lithium-ion transport properties. The synergistic effect of the multiple elements in the framework enhances the electrochemical performance of the high-entropy lithium alloy negative electrode material.

[0027] The high-entropy lithium alloy of the present invention is different from conventional lithium alloys and has unique advantages in terms of phase structure, microstructure, and performance. The high-entropy lithium alloy's inherent three-dimensional skeleton structure has excellent mechanical properties and is composed of at least four elements, which facilitates the selection of different elements to optimize both mechanical and electrochemical properties. These measures not only increase the stability of the skeleton structure but also enhance its lithium affinity and the skeleton's lithium ion transport capacity, greatly improving the electrochemical performance of lithium batteries. The key factors are the ratio of metallic lithium to other metals or non-metals used in the cooling process, as well as the cooling process of the liquid alloy. These two factors are interrelated and play a key role in the final three-dimensional skeleton morphology and the electrochemical performance of the high-entropy lithium alloy.

[0028] In order to balance the mechanical stability and lithium affinity of the alloy skeleton, the present invention introduces a variety of metals or non-metals to obtain a high-entropy lithium alloy, which improves the mechanical properties of the alloy skeleton structure and the control performance of metallic lithium deposition, achieving a "win-win" situation. In the high-entropy lithium alloy negative electrode containing a three-dimensional skeleton obtained by the present invention, the skeleton structure is composed of a multi-element alloy, wherein a part of the skeleton structure remains electrochemically inert and does not undergo electrochemical alloying or dealloying reactions with metallic lithium during the electrochemical cycle, maintaining the stability of the skeleton. The other part of the skeleton structure can undergo alloying or dealloying reactions with metallic lithium, increasing the lithium affinity of the overall skeleton, inducing metallic lithium nucleation, and inhibiting the formation of lithium dendrites. This part of the skeleton structure also has a strong lithium ion transport capacity, effectively promoting the "conformal" uniform deposition of lithium and the skeleton structure, and improving the cycle stability of the battery. The multifunctionality of the high-entropy alloy three-dimensional skeleton improves the cycle life and safety of metal lithium batteries.

[0029] The three-dimensional skeletons with different components provided by the present invention have different functionalities. The introduction of copper increases the overall stability of the skeleton, while the introduction of zinc increases the affinity of the skeleton for lithium, and the zinc-based lithium alloy also has a high lithium ion migration ability. It can be seen that the zinc-based lithium alloy constructs a solid-phase diffusion channel for lithium ions, which is conducive to promoting the rapid transport of lithium ions along the skeleton. The three-dimensional skeleton structure of the high-entropy lithium alloy composed of multiple phases not only helps to improve the mechanical strength of the negative electrode, but also the synergistic effect between the multiple components helps to improve the deposition and dissolution behavior of lithium, thereby enhancing the electrochemical performance of the high-entropy lithium alloy negative electrode.

[0030] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are described in detail as follows:

[0031] The micro-nano-sized three-dimensional skeleton high-entropy alloy network structure obtained by the present invention is conducive to increasing the real specific surface area of ​​the negative electrode, effectively reducing the local current density, and inhibiting the formation of lithium dendrites; the high-entropy alloy skeleton network contains inert alloy components, which is conducive to improving the stability of the three-dimensional skeleton and the constancy of the negative electrode volume, and helps to improve the cycle life of the battery; the high-entropy alloy skeleton network contains electrochemically active lithium alloy components, which is conducive to improving the lithium affinity of the three-dimensional skeleton, effectively inducing lithium nucleation and growth, and improving the diffusion capacity of lithium ions in the skeleton structure, promoting the uniform deposition of lithium, and has a promoting effect on inhibiting dendrites and achieving conformal and uniform deposition of lithium; the high-entropy alloy skeleton provides a buffer for the deposition of metallic lithium, reducing the volume change of the metallic lithium negative electrode.

[0032] The preparation method of the present invention is simple, and a high-entropy lithium alloy material with a three-dimensional skeleton network can be prepared by a simple high-temperature melting metallurgy method, which is convenient for large-scale mass production and application.

[0033] Third, as auxiliary evidence for the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0034] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are as follows: Metal lithium batteries are the only choice for high-energy-density rechargeable batteries, and metal lithium is the ideal negative electrode material for metal lithium batteries. High-entropy lithium alloy negative electrodes can overcome a series of drawbacks of traditional lithium alloy negative electrodes and significantly improve the negative electrode's cycle performance. After commercialization, this solution can generate hundreds of millions of yuan in output value annually and has high commercial application value.

[0035] (2) The technical solution of the present invention fills a technological gap in the industry at home and abroad: High-entropy lithium alloys are a new type of lithium alloy that has not yet been used as a negative electrode material for lithium batteries, and there are no related reports. Compared with conventional lithium alloys, high-entropy lithium alloys have outstanding characteristics in terms of phase structure, microstructure and composition, which are conducive to solving the problems faced by conventional lithium negative electrodes. It can be seen that high-entropy lithium alloy negative electrodes are a new type of lithium negative electrode.

[0036] (3) The technical solution of the present invention solves a technical problem that people have long been eager to solve but have never been able to solve successfully: the existing lithium alloy negative electrode is difficult to solve its mechanical stability and the metal lithium deposition and dissolution process is prone to produce lithium dendrites, low coulombic efficiency and other shortcomings, resulting in parameters such as battery cycle life being difficult to meet the needs of practical applications. The reason is that it is difficult for traditional lithium alloy skeletons to simultaneously meet the requirements of indicators such as mechanical strength and lithium affinity. The present invention adopts high entropy lithium alloy, with the help of its excellent mechanical properties, supplemented by the role of lithium affinity components, to improve its lithium affinity and other indicators. The synergistic effect of the various components of the high entropy lithium alloy is expected to overcome this technical problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 This is a flow chart of a method for preparing a high entropy lithium alloy negative electrode provided by an embodiment of the present invention;

[0039] Figure 2 is an optical photograph of a high-entropy lithium alloy provided by an embodiment of the present invention;

[0040] FIG3( a ) is a scanning electron microscope (SEM) photograph of a high entropy lithium alloy provided in an embodiment of the present invention;

[0041] FIG3( b ) is an energy spectrum scanning diagram of the Zn element distribution in the alloy skeleton provided by an embodiment of the present invention;

[0042] FIG3( c ) is an energy spectrum scanning diagram of the distribution of Cu elements in the alloy skeleton provided by an embodiment of the present invention.

[0043] FIG4( a ) is a graph showing the current flow rate of the embodiment of the present invention and the comparative example at 1 mA cm -2 Comparison of electrochemical cycling performance under different current densities;

[0044] FIG4( b ) is a graph showing the current state of the embodiment of the present invention and the comparative example at 3 mA cm -2 Comparison of electrochemical cycling performance under different current densities. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] In response to the problems existing in the prior art, the present invention provides a high-entropy lithium alloy negative electrode, a solid-state battery and a preparation method thereof. The present invention is described in detail below with reference to the accompanying drawings.

[0047] 1. Explanatory Examples In order to enable those skilled in the art to fully understand how to implement the present invention, this section provides an illustrative example that expands upon the technical solutions of the claims.

[0048] like Figure 1 As shown, the method for preparing a high entropy lithium alloy negative electrode provided by an embodiment of the present invention includes the following steps:

[0049] S101, obtaining a molten alloy liquid of lithium and other multiple metal or non-metal elements at a high temperature;

[0050] S102, cooling the molten alloy liquid to room temperature to obtain a high entropy lithium alloy negative electrode material.

[0051] In the cooling process provided by the embodiment of the present invention, factors such as the content ratio of metallic lithium and other metals or non-metals used, the melting temperature, and the cooling process of the liquid alloy are key and interrelated, and play a key role in the final three-dimensional skeleton morphology and electrochemical properties of the high-entropy lithium alloy.

[0052] In order to balance the mechanical stability and lithium affinity of the alloy skeleton, the present invention introduces a variety of metals or non-metals to obtain a high-entropy lithium alloy, which improves the mechanical properties of the alloy skeleton structure and the control performance of metallic lithium deposition, achieving a "win-win" situation. In the high-entropy lithium alloy negative electrode containing a three-dimensional skeleton obtained by the present invention, the skeleton structure is composed of a multi-element alloy, wherein a part of the skeleton structure remains electrochemically inert and does not undergo electrochemical alloying or dealloying reactions with metallic lithium during the electrochemical cycle, maintaining the stability of the skeleton. The other part of the skeleton structure can undergo alloying or dealloying reactions with metallic lithium, increasing the lithium affinity of the overall skeleton, inducing metallic lithium nucleation, and inhibiting the formation of lithium dendrites. This part of the skeleton structure also has a strong lithium ion transport capacity, effectively promoting the "conformal" uniform deposition of lithium and the skeleton structure, and improving the cycle stability of the battery. The multifunctionality of the high-entropy alloy three-dimensional skeleton improves the cycle life and safety of metal lithium batteries.

[0053] In step S101 provided in an embodiment of the present invention, metallic lithium and multiple other metals or non-metals are heated and melted at a temperature of 300 to 1000° C. to obtain a high entropy alloy liquid.

[0054] In step S101 provided in an embodiment of the present invention, the other metal or non-metal elements are any three or more of Na, K, Mg, Ca, Ba, Ni, Zn, Al, In, Sn, Sb, Pb, Ag, B, Si or C.

[0055] In step S102 provided by the embodiment of the present invention, the molten alloy liquid is cooled to room temperature within 5 to 1800 seconds.

[0056] In step 2 provided in an embodiment of the present invention, phase separation occurs during the cooling process, and solidification forms a multiphase structure comprising a lithium alloy phase and a non-lithium alloy phase, and the lithium alloy phase and the non-lithium alloy phase constitute a micro-nano three-dimensional skeleton network structure of the high entropy alloy.

[0057] The three-dimensional skeleton network provided in the embodiment of the present invention is a mixture of any one or more of a lithium alloy skeleton and a non-lithium alloy skeleton.

[0058] The high entropy lithium alloy negative electrode material for a secondary metal lithium battery provided in an embodiment of the present invention comprises a skeleton structure composed of a lithium alloy and a non-lithium alloy phase.

[0059] Example 1

[0060] A preferred embodiment of the present invention provides a method for preparing a high-entropy lithium-copper-tin-antimony-zinc alloy negative electrode material containing a three-dimensional skeleton network, and the specific steps are as follows:

[0061] Metal lithium, copper, tin, antimony and zinc are placed in a crucible at a molar ratio of 50:10:3:5:32. The mixture is heated to 540°C in an argon atmosphere to melt the metal mixture. The mixture is stirred evenly for 10 minutes to obtain a molten liquid alloy. Then, the mixture is cooled to room temperature within 10 seconds to obtain a high-entropy lithium copper tin antimony zinc alloy negative electrode material containing a three-dimensional skeleton network. The electrode sheet is cut into pieces with the following morphology: Figure 2 The optical photograph and microscopic morphology are shown in the SEM photograph of Figure 3, and the distribution of Zn and Cu elements on the surface was measured by energy spectrum scanning.

[0062] The alloy negative electrode was cut into 10 mm diameter discs and assembled into a Li-Li symmetrical cell using a CR 2032 button cell case in an ester electrolyte (1M LiPF6 (lithium hexafluorophosphate) dissolved in EC (ethylene carbonate) / DEC (diethyl carbonate), v / v = 1 / 1). A Celgard 2325 separator was used. Charge and discharge tests were conducted at a constant areal current density, with the charge and discharge capacities set to 1 mAh cm. -2 The cycle life test results are shown in Figure 4. At 1mA cm -2 At the current density of 3 mA cm, the cycle life of the symmetrical battery reaches 800 hours; at a higher current density of 3 mA cm -2 The symmetrical battery cycle life reaches 450 hours.

[0063] Example 2

[0064] A preferred embodiment of the present invention provides a method for preparing a high-entropy lithium-silicon-nickel-boron-silver-calcium alloy negative electrode material containing a three-dimensional skeleton network, and the specific steps are as follows:

[0065] Lithium, silicon, nickel, boron, silver, and calcium were placed in a crucible at a molar ratio of 45:5:15:15:4:16. The mixture was heated to 1000°C under an argon atmosphere to molten metals. The mixture was then stirred for 60 minutes to form a molten multi-element alloy. This was then cooled to room temperature within 1800 seconds to produce a high-entropy lithium alloy anode material containing a three-dimensional skeleton network.

[0066] Example 3

[0067] A preferred embodiment of the present invention provides a method for preparing a high-entropy lithium-sodium-potassium-barium-indium-aluminum alloy negative electrode material containing a three-dimensional skeleton network, and the specific steps are as follows:

[0068] Lithium, sodium, potassium, barium, indium, and aluminum were placed in a crucible at a molar ratio of 30:12:14:4:29:11. The mixture was heated to 300°C under an argon atmosphere to molten state. The mixture was then stirred uniformly for 30 minutes to form a molten multi-element alloy. This was then cooled to room temperature within 5 seconds to produce a high-entropy lithium alloy anode material containing a three-dimensional skeleton network.

[0069] 2. Application Examples: In order to demonstrate the creativity and technical value of the technical solution of the present invention, this section provides application examples of the claimed technical solution on specific products or related technologies.

[0070] An application embodiment of the present invention provides a high-entropy lithium alloy negative electrode material containing a three-dimensional skeleton network prepared by implementing a high-entropy lithium alloy negative electrode preparation method. The lithium atoms in the high-entropy lithium alloy negative electrode material account for 20 to 50% of the total atomic ratio, and other metals and / or non-metals account for 1 to 50% of the total atomic ratio.

[0071] The lithium atoms provided in the application embodiment of the present invention preferably account for 30 to 50% of the total atoms.

[0072] An application embodiment of the present invention provides an application of a high-entropy lithium alloy negative electrode material containing a three-dimensional skeleton network in the preparation of a solid-state battery. The solid-state battery is a lithium battery, which includes a positive electrode, a negative electrode, and an electrolyte placed between the positive electrode and the negative electrode. The negative electrode is a high-entropy lithium alloy material.

[0073] 3. Evidence of the effects of the embodiments: The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the existing technology. The following content describes them with reference to the data, charts, etc. of the experimental process.

[0074] Comparative Example 1

[0075] Lithium and copper were placed in a crucible at a molar ratio of 60:1. The mixture was heated to 540°C under an argon atmosphere to molten metal. The mixture was then stirred evenly for 10 minutes to form a molten alloy. The mixture was then cooled to room temperature within 10 seconds, yielding a lithium-copper alloy anode material with a three-dimensional skeleton network.

[0076] The lithium copper alloy negative electrode and the pure metal lithium foil negative electrode were cut into 10 mm diameter discs, and symmetrical cells were assembled according to the method of Example 1. The same electrochemical tests were carried out under the same conditions. The results are shown in Figure 4. Obviously, the symmetrical cell using the pure metal lithium foil negative electrode has the worst cycle performance. At a current density of 1 mA cm -2 At a higher current density of 3 mA cm, the cycle life is less than 200 hours. -2 The cycle life of the symmetrical battery is less than 70 hours. The performance of the lithium-copper alloy negative electrode obtained by melting metallic lithium and copper at high temperature is significantly improved. -2 The cycle life reaches 400 hours at a higher current density of 3 mA cm -2 Under these conditions, the symmetrical battery cycle life reached 300 hours. Clearly, the lithium-copper alloy skeleton significantly improves battery cycle life. Compared to the previous two, the battery based on the high-entropy lithium-copper-tin-antimony-zinc alloy exhibited the longest cycle life under both test conditions, indicating that the high-entropy alloy skeleton has a stronger ability to induce the deposition and dissolution behavior of metallic lithium, significantly improving the reduction and growth state of metallic lithium.

[0077] Figure 2 This is an optical photograph of the high-entropy lithium alloy anode material synthesized in Example 1 of the present invention. Its pale yellow color is distinct from the bright white color of pure metallic lithium, indicating alloying of the metallic lithium with other elements. The sample's surface is relatively flat, interspersed with granular material, presumably representing a highly crystalline alloy phase.

[0078] Figure 3(a) is a scanning electron micrograph of a sample from Example 1 of the present invention, while Figures 3(b) and 3(c) are energy spectrum scanning distribution diagrams of the Zn and Cu elements in the corresponding regions, respectively. The electron micrograph shows two skeleton structures with distinct morphologies, each with significantly different elemental contents. Zinc is evenly distributed throughout all skeleton structures, while copper is selectively distributed, appearing only in the larger, intermediate-sized skeleton structures. These three-dimensional skeletons with varying compositions exhibit distinct functionalities. The introduction of copper increases the overall stability of the skeleton, while the introduction of zinc increases its lithium affinity. Furthermore, the zinc-based lithium alloy exhibits a high lithium ion transport capacity. This indicates that the zinc-based lithium alloy further constructs solid-phase diffusion channels for lithium ions, which facilitates rapid transport of lithium ions along the skeleton. The three-dimensional skeleton structure of the high-entropy lithium alloy, composed of multiple coexisting phases, not only improves the mechanical strength of the negative electrode, but the synergistic interaction between the various components also helps improve lithium deposition and dissolution behavior, enhancing the electrochemical performance of the high-entropy lithium alloy negative electrode. From the subsequent electrochemical test results, it can be seen that compared with the two examples in Comparative Example 1, namely the pure lithium foil negative electrode and the lithium-copper alloy negative electrode, the high entropy lithium alloy negative electrode in the embodiment of the present invention has a longer cycle life.

[0079] Figure 4(a) to Figure 4(b) This is a comparison of the electrochemical cycle performance test curves of three types of symmetrical batteries. The electrochemical cycle performance test uses a Li-Li battery system, in which the high-entropy lithium alloy electrode materials are all high-entropy lithium copper tin antimony zinc alloy materials containing a three-dimensional skeleton network synthesized in Example 1 above. As a control, pure metal lithium foil and the lithium copper alloy synthesized in Comparative Example 1 are also assembled into symmetrical batteries. A CR 2032 button battery shell is used, and an ester electrolyte (1M LiPF6 dissolved in EC / DEC, v / v=1 / 1) is used without electrolyte additives. The Celgard 2325 model diaphragm is tested under conditions of 1 or 3 mAcm -2 The current density is 1 mAh cm -2 Surface capacity.

[0080] As shown in Figure 4, due to the multifunctional synergistic effect of the high entropy alloy skeleton, the -2 The current density is 1 mAh cm -2 Under the conditions of surface capacity, the battery cycle stability of Example 1 is greatly improved, and it can be stably cycled for more than 800 hours and 450 hours, respectively. In comparison, the cycle life of the Li-Li symmetrical battery based on pure lithium negative electrode and the symmetrical battery based on conventional lithium-copper alloy negative electrode are both short. The Li-Li symmetrical battery based on pure lithium negative electrode can only cycle for less than 200 hours and 70 hours, respectively, while the symmetrical battery based on lithium-copper alloy negative electrode can only cycle for less than 400 hours and 300 hours, respectively. Obviously, the results of the comparative test show that the high-entropy lithium alloy negative electrode has better electrochemical performance than ordinary lithium-copper alloy and pure metal lithium negative electrode.

[0081] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a high entropy lithium alloy negative electrode, characterized in that: The method for preparing a high-entropy lithium alloy anode comprises: obtaining a high-entropy alloy liquid containing lithium and multiple metal / non-metal elements by high-temperature melt metallurgy; utilizing the phase separation effect of the high-entropy alloy liquid during the cooling process to obtain a multiphase high-entropy alloy anode material containing a lithium alloy phase and a non-lithium alloy phase; wherein the lithium atoms in the high-entropy lithium alloy anode material account for 20-50% of the total atomic ratio, and other metals and / or non-metals account for 1-50% of the total atomic ratio; The method for preparing a high entropy lithium alloy negative electrode comprises the following steps: Step 1: obtaining a molten alloy liquid of lithium and other metal or non-metal elements at high temperature; Step 2: Cooling the molten alloy liquid to room temperature to obtain a high entropy lithium alloy negative electrode material; In step 1, metallic lithium and other metals and / or non-metals are heated and melted at a temperature of 300 to 1000° C. to obtain a high entropy alloy liquid; In step 1, the other metal and / or non-metal elements are any three or more of Na, K, Mg, Ca, Ba, Ni, Zn, Al, In, Sn, Sb, Pb, Ag, B, Si, or C; In step 2, the molten alloy liquid is cooled to room temperature within 5 to 1800 seconds; The multiphase structure is a micro-nano three-dimensional skeleton network structure of a high entropy alloy composed of a lithium alloy phase and a non-lithium alloy phase.

2. The method for preparing a high entropy lithium alloy negative electrode according to claim 1, wherein: In step 2, phase separation occurs during the cooling process, and solidification forms a multiphase structure including a lithium alloy phase and a non-lithium alloy phase.

3. The method for preparing a high entropy lithium alloy negative electrode according to claim 2, wherein: The three-dimensional skeleton network is composed of any one or more mixed compositions of lithium alloy skeletons and non-lithium alloy skeletons.

4. A high entropy lithium alloy anode material containing a three-dimensional skeleton network prepared by implementing the high entropy lithium alloy anode preparation method as described in any one of claims 1 to 3.

5. A use of the high entropy lithium alloy negative electrode material containing a three-dimensional skeleton network as claimed in claim 4 in the preparation of a solid-state battery, characterized in that: Solid-state batteries are lithium batteries, which include a positive electrode, a negative electrode, and an electrolyte placed between the positive and negative electrodes. The negative electrode is a high-entropy lithium alloy material.

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