Lithium alloy negative electrode with multi-dimensional dynamic skeleton sites and preparation of lithium alloy negative electrode

Abstract

The invention discloses a lithium alloy negative electrode with a multi-dimensional dynamic skeleton site and a preparation method of the lithium alloy negative electrode. The lithium alloy negative electrode with a multi-dimensional dynamic skeleton site can be prepared in a large area through the processes of shear force stirring melting, high-temperature homogenization, quenching pouring, constant-pressure rolling and low-temperature annealing. The method is simple in process, obvious in effect and suitable for batch production. The prepared lithium alloy negative electrode with the multi-dimensional dynamic skeleton sites is internally provided with nanometer one-dimensional dynamic lithium alloy lithium-loving sites and a topological structure three-dimensional dynamic lithium alloy skeleton, and the sites and the skeleton are uniformly dispersed and hidden in the lithium alloy negative electrode in an initial state; the sites and the framework are dynamically self-assembled and formed in the process that the lithium potential of the negative electrode is gradually increased, and a topological structure with the nano sites uniformly loaded on the surface of the alloy framework is formed. The lithium alloy negative electrode is used for a high-specific-energy secondary metal lithium battery negative electrode with the energy density larger than or equal to 450 Wh / kg, and the cycle life of the battery can be effectively prolonged.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery anode material technology, and relates to a lithium alloy anode for lithium metal batteries and its preparation; in particular, it relates to a lithium alloy anode with multidimensional dynamic framework sites and its preparation. Background Technology

[0002] The current development of major emerging fields such as electric aviation, low-altitude economy, and defense equipment has created an urgent demand for ultra-high specific energy (energy density ≥ 500 Wh / kg) battery systems. However, existing lithium-ion batteries are limited by the theoretical capacity limit of graphite anodes (theoretical specific capacity of only 372 mAh / g), and their energy density is already close to the theoretical limit, which cannot meet the demand of high-tech industries for ultra-high energy density batteries. Lithium metal anodes, due to their ultra-high theoretical specific capacity (3860 mAh / g), lowest electrochemical potential (-3.04 V vs. SHE), and unique advantages of being compatible with high-capacity cathodes, are considered one of the ideal choices for achieving high specific energy rechargeable batteries with an energy density ≥ 450 Wh / kg. Therefore, developing lithium metal batteries and related technologies is the key to breaking through the technological bottleneck of lithium battery energy density.

[0003] When lithium metal is used directly as both the anode active material and the current collector, the proportion of inactive materials can be significantly reduced, making it possible to construct high-energy-density rechargeable batteries. However, the inherent low mechanical strength and high plasticity of lithium metal, as well as its susceptibility to dendrite growth and unstable solid electrolyte interphase (SEI) formation during cycling, severely limit its practical application. On the other hand, copper, currently the mainstream anode current collector material, differs significantly from lithium metal in mechanical properties. When lithium-copper composites are achieved through simple rolling, repeated volume expansion and contraction and stress accumulation during battery cycling can lead to interfacial bonding failure, active layer lifting, and even detachment. This not only accelerates SEI rupture and reconstruction but also causes continuous consumption of active lithium and coulombic efficiency decay. Therefore, in the industrialization of lithium metal anodes, it is urgent to develop key technologies that can significantly improve the lithium-copper interfacial bonding strength, solve the pulverization and dendrite problems caused by SEI instability, and ultimately effectively improve the cycling reversibility of lithium metal anodes to overcome their practical application bottlenecks. To overcome these limitations, current research mainly focuses on the structural design and surface modification of current collectors. While such strategies can increase the specific surface area and reduce the local current density to some extent, they do not fundamentally solve the problem of weak ion / electron transport synergy within the framework. Deposited lithium preferentially concentrates on the outer surface or tip of the conductive framework, easily leading to a prominent "tip growth" phenomenon. As cycling progresses, the thickness of the deposited lithium increases, and the guiding effect of the surface modification layer gradually weakens, making it difficult to achieve long-term control over uniform lithium deposition and severely limiting the long-term cycling stability of the lithium metal anode.

[0004] Chinese patent application CN 116936790 A discloses a lithium alloy anode material comprising metallic lithium and non-lithium elements, wherein the non-lithium elements include one or more of aluminum, titanium, iron, cobalt, nickel, copper, zinc, germanium, molybdenum, palladium, silver, cadmium, indium, tin, magnesium, platinum, gold, lead, lanthanum, cerium, boron, and phosphorus. It combines metallic lithium and non-lithium elements through a molten composite process, enriching the non-lithium elements at the grain boundaries of metallic lithium in the lithium alloy anode material. This effectively mitigates side reactions between the lithium alloy and the electrolyte, maintaining good wettability and stability of the lithium alloy anode, thereby improving the cycle life of lithium-ion batteries. Its core idea is to enrich the non-lithium elements at the grain boundaries of metallic lithium through molten composite processing, thereby mitigating side reactions with the electrolyte and improving wettability and stability. However, it has the following key shortcomings: 1. Lack of dynamic structure and self-assembly capability: It only achieves the enrichment of non-lithium elements at the grain boundaries through a simple melt-cooling process, without forming a structure with dynamic response capabilities. In other words, while it possesses dynamic element enrichment characteristics, it does not form a corresponding structure; that is, the structure is static. This prevents it from dynamically adjusting the electrode structure morphology according to changes in lithium content during charging and discharging, thus failing to effectively solve problems such as uneven lithium deposition, dendrite growth, interfacial stress accumulation, and electrode volume expansion. 2. Inability to achieve multi-dimensional synergistic regulation: It only involves the characteristic of element grain boundary enrichment, thus bringing potential interface optimization effects, but does not involve the synergistic effect of one-dimensional lithiophilic sites and three-dimensional topological framework. Therefore, it lacks a dynamic guidance mechanism for lithium nucleation and deposition processes, making it difficult to avoid potential problems such as uneven local current density and solid electrolyte membrane rupture during long cycles. 3. Limited structural stability and cycle life: Although it improves interfacial stability through non-lithium element enrichment, its structure may still fail during cycling due to volume changes and stress accumulation, resulting in limited improvement in cycle life (only 25-30 cycles in the example), which cannot meet the long-cycle requirements of high-energy-density (≥450Wh / kg) batteries.

[0005] Therefore, in order to develop a novel anode construction strategy that can achieve deep integration of the mechanical and electrochemical properties of lithium metal and current collector, thereby suppressing interfacial failure and improving deposition uniformity and structural stability, this invention successfully constructs a lithium alloy anode with multidimensional dynamic framework sites through a preparation process of "shear-force stirring melting - high-temperature homogenization - rapid cooling casting - constant pressure rolling - low-temperature annealing". This structure possesses uniform embedding characteristics of nano-one-dimensional dynamic lithiophilic sites and a topological three-dimensional framework in its initial state, and dynamically assembles and forms with potential changes during electrochemical cycling, forming a stable topological structure in which nanosites are firmly loaded on the surface of the alloy framework. This significantly enhances the interfacial bonding strength, deposition uniformity, and cycle reversibility, providing an effective solution for the long cycle life of high-energy-density lithium metal batteries. Summary of the Invention

[0006] This invention provides a lithium alloy anode with multidimensional dynamic framework sites for lithium metal battery anodes and its preparation method, aiming to provide a new reference for the design and selection of lithium metal battery anodes. Due to the formation of a multidimensional dynamic structure, this invention will possess better interface adaptability and stability, and the formed three-dimensional topological framework will have a higher specific surface area and lithium capacity, resulting in more functional characteristics in reducing electrode deformation and suppressing electrode expansion.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] This invention provides a lithium alloy anode; the lithium alloy anode is composed of lithium and at least two alloying elements, and the lithium alloy anode has nano-one-dimensional dynamic lithium alloy lithiophilic sites and a three-dimensional dynamic lithium alloy framework with a topological structure. The sites and framework are uniformly dispersed and hidden within the lithium alloy anode in the initial state (e.g., ...). Figure 1 During the gradual increase of the lithium potential at the negative electrode, the sites and framework dynamically self-assemble and form (e.g.) Figure 2 ), and form a topological structure with nanosites uniformly loaded on the surface of the alloy framework (such as Figure 3 ).

[0009] As one implementation, the one-dimensional dynamic lithium alloy lithiophilic sites have a morphology of 100-1000 nm one-dimensional spherical structures, composed of lithium and at least one alloying element (such as...). Figure 4 Among them, the site spontaneously disperses and hides in the negative electrode phase when the lithium content increases. As the lithium content decreases, the site spontaneously disperses and is exposed to form nanospheres. The nano-sizing of the lithiophilic site will increase the surface energy, which is beneficial to reducing the lithium nucleation barrier and promoting uniform nucleation. The dynamic exposure-dispersion mode of the site is beneficial to provide stronger lithiophilicity at low lithium content and improve the uniformity of lithium deposition at high lithium content.

[0010] As one implementation, the three-dimensional dynamic lithium alloy framework is characterized by a three-dimensional topological network structure with pores ranging from 5 nm to 500 μm, composed of lithium and at least one framework alloying element (such as...). Figure 5 The framework spontaneously disperses and hides within the negative electrode phase as the lithium content increases. As the lithium content decreases, the framework elements spontaneously enrich and expose, forming a three-dimensional topological network structure. This topological framework helps to homogenize the interfacial current and reduce the critical current density, promoting uniform lithium deposition on the negative electrode. Simultaneously, at low lithium content, the framework provides a carrier support for lithiophilic sites, enhancing the structural strength of the negative electrode and ensuring electrode connectivity. This prevents a sudden drop in battery capacity during charging and discharging. The dynamic exposure-dispersion mode of the framework helps to provide a more uniform interfacial current and higher electrode strength at low lithium content, ensuring electrode connectivity. Meanwhile, the spontaneous dispersion of framework alloying elements at high lithium content effectively improves the structural strength of the negative electrode.

[0011] As one embodiment, the lithium alloy anode is composed of lithium, a lithiophilic alloying element, and a framework alloying element. Preferred proportions, based on a total weight of 10 parts, are: lithium 9-9.8 parts, lithiophilic alloying element 0.1-0.5 parts, and framework alloying element 0.1-0.5 parts. The high lithium content of 9 parts or more helps ensure a high specific capacity of the alloy anode; the lithiophilic alloying element content of 0.1-0.5 parts helps ensure uniform nano-sizing and good dispersion of the sites after exposure; and the framework alloying element content of 0.1-0.5 parts helps control the pore size of the framework topology, facilitating the formation of a uniform, porous three-dimensional topology.

[0012] As one implementation scheme, the lithiophilic alloying element mainly includes at least one of Ag, In, Sn, Au, Zn, and Sb, with Ag being preferred. The framework alloying element mainly includes at least one of Mg, B, Al, and C, with Mg being preferred. Among them, Ag, In, Sn, Au, Zn, and Sb are good lithiophilic elements, which are beneficial for forming dynamic sites with high lithiophilicity; Mg, B, Al, and C are lightweight and low-density components, which are beneficial for constructing a lightweight and high-strength framework.

[0013] This invention also provides a method for preparing a lithium alloy anode, wherein the lithium alloy anode is prepared in an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and adopts a process of "shear-stirring melting - high-temperature homogenization - rapid cooling casting - constant pressure rolling - low-temperature annealing", including the following steps:

[0014] S1. Shear-force stirring and melting: After lithium metal is heated to 350-380℃ and transformed into a molten state, it is continuously stirred at a speed of 300-500 rpm; lithium-loving alloying elements are added, and after stirring for 20-50 minutes, framework alloying elements are added, and stirring is continued for 20-50 minutes before stopping to obtain lithium alloy melt;

[0015] S2. High-temperature homogenization: The temperature is lowered to 250-300℃ and left to stand for 8-12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0016] S3. Rapid cooling casting: Reheat to 350-380℃ (after ensuring that the lithium alloy melt has good fluidity) and rapidly cast the homogeneous lithium alloy melt onto the surface of the cooling plate to obtain a homogeneous lithium alloy ingot.

[0017] S4. Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. (Using a hydraulic device, the lithium alloy ingot is compressed to a thickness of ≤1mm, and then constant pressure rolling is performed under a pressure of 10-15MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0018] S5. Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 50-70℃ for 1-2 hours to obtain the lithium alloy anode.

[0019] In one embodiment of the present invention, the lithiophilic alloying element mainly includes at least one of Ag, In, Sn, Au, Zn, and Sb; the framework alloying element mainly includes at least one of Mg, B, Al, and C. Based on a total weight of 10 parts, lithium accounts for 9 to 9.8 parts, the lithiophilic alloying element accounts for 0.1 to 0.5 parts, and the framework alloying element accounts for 0.1 to 0.5 parts.

[0020] As one embodiment of the present invention, the prepared lithium alloy anode has nano-one-dimensional dynamic lithium alloy lithiophilic sites and a three-dimensional dynamic lithium alloy skeleton with topological structure. The sites and skeleton are uniformly dispersed and hidden in the lithium alloy anode in the initial state. During the process of the lithium potential of the anode gradually increasing, the sites and skeleton dynamically self-assemble and form a topological structure with nano-sites uniformly loaded on the surface of the alloy skeleton.

[0021] In this invention, adding a lithiophilic element first in step S1 helps to ensure the formation and uniform dispersion of lithiophilic sites, and adding a framework element later helps to construct a characteristic structure in which lithiophilic sites are uniformly loaded on the framework after the lithium content of the negative electrode is reduced. Shear force stirring helps to cut off the connection between lithium melts caused by surface tension, making the entire melt composition more uniform.

[0022] As one embodiment of the present invention, the stirring device used for continuous stirring consists of a stirring paddle and a small stirring motor. The stirring paddle has a multi-stage blade structure, consisting of 14-16 fan-shaped main blades with a radius of 8-12mm, which mainly provide lateral shear force. The main blades are spaced 10-15° apart. The outer edge of the main blades has a branch blade structure perpendicular to the main blades. The branch blades mainly provide longitudinal shear force. The width of the branch blades is the same as that of the main blades, and the upper and lower ends protrude 1-3mm from the main blades.

[0023] In this invention, the rapid cooling process in step S3 helps to prevent segregation of internal components of the melt due to slow cooling, and facilitates the rapid solidification of internally dispersed lithium-affinity sites and framework elements. Simultaneously, rapid cooling casting facilitates the separation of the melt from the inner wall of the container, which is beneficial for subsequent processing. As one embodiment of this invention, the cooling plate is made of nickel or stainless steel and has a cooling unit at its bottom. The cooling unit consists of S-shaped arranged cooling copper pipes, with water as the cooling medium. An external circulating cooling device is connected to the cooling unit, and the cooling temperature is 8-12℃.

[0024] In this invention, step S5 helps to eliminate the surface stress accumulation caused by continuous rolling in step S4, which is beneficial to the stability of the crystal plane of the negative electrode and stress diffusion.

[0025] In some embodiments, the method comprises the following specific steps:

[0026] S1. Shear-force stirring melting: Weigh an appropriate amount of lithium metal and transfer it to a nickel crucible. Place the nickel crucible on a heating platform at 350–380°C for melting. After the lithium is completely molten, use a special stirring device to continuously stir the lithium melt at a speed of 300–500 rpm. According to the proportions, separately weigh out the lithiophilic alloying element and the framework alloying element. While the lithium melt is continuously stirred, first add the lithiophilic element and stir for 30 minutes. Then add the framework alloying element and continue stirring for another 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0027] S2. High-temperature homogenization: The temperature is lowered to 250-300℃, and the lithium alloy melt is allowed to stand at this temperature for 8-12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0028] S3. Rapid Cooling Casting: After reheating to 350-380℃ to ensure good fluidity of the lithium alloy melt, the homogeneous lithium alloy melt is rapidly cast onto the surface of a specially designed cooling plate to obtain a homogeneous lithium alloy ingot.

[0029] S4. Constant pressure rolling: The cooled homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed at a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0030] S5. Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60°C for 1-2 hours to obtain the lithium alloy anode as described in claim 1.

[0031] The specially designed stirring device consists of a stirring paddle and a small stirring motor. The stirring paddle has a multi-stage blade structure, consisting of 15 fan-shaped main blades with a radius of 10mm, primarily providing lateral shear force. The main blades are spaced 12° apart. The outer edge of each main blade has a segmented blade structure perpendicular to the main blade, primarily providing longitudinal shear force. The segmented blades have the same width as the main blades and protrude 2mm from the main blades at both ends. The specially designed cooling plate is made of nickel or stainless steel and has a cooling unit at the bottom. This cooling unit consists of S-shaped arranged cooling copper pipes, using water as the cooling medium. The cooling unit is connected to an external circulating cooling device, and the cooling temperature is 10℃.

[0032] The use of the aforementioned lithium alloy anode, or the lithium alloy anode prepared by the aforementioned method, as a lithium metal battery anode, and as a pre-lithiation material for lithium-ion battery anodes, are all within the scope of protection of this invention. The lithium alloy anode of this invention is mainly used as a lithium metal battery anode and a pre-lithiation material for lithium-ion battery anodes, particularly as a high-energy-density secondary lithium metal battery anode with an energy density ≥450Wh / kg, effectively extending battery cycle life.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The lithium alloy anode with multidimensional dynamic framework sites provided by the present invention has excellent charge and discharge stability in high-energy-density lithium metal batteries, which can meet the requirements of long battery life and has broad industrial application prospects.

[0035] (2) The preparation process of this invention realizes the dynamic dispersion-exposure of lithiophilic sites and alloy skeleton in lithium metal anode, providing technical and process reference for lithium metal battery anode design. Attached Figure Description

[0036] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0037] Figure 1 This is a lithium alloy anode with multidimensional dynamic framework sites as described in Example 1; wherein, the left image is a SEM image of the electrode surface structure; the middle image is a Mg element distribution map of the electrode surface; and the right image is an Ag element distribution map of the electrode surface.

[0038] Figure 2 The images show the morphology and elemental distribution of the lithium alloy anode with multidimensional dynamic framework sites in Example 1 with low lithium content; the left image is a SEM image of the electrode surface structure; the middle image is a Mg elemental distribution map of the electrode surface; and the right image is an Ag elemental distribution map of the electrode surface.

[0039] Figure 3 The images show the morphology and elemental distribution of the lithium alloy anode with multidimensional dynamic framework sites in Example 1 with high lithium content; the upper left image is a SEM image of the electrode surface structure; the upper right image is a distribution map of O on the electrode surface; the lower left image is a distribution map of Mg on the electrode surface; and the lower right image is a distribution map of Ag on the electrode surface.

[0040] Figure 4 The images show the morphology and elemental distribution of the one-dimensional dynamic lithium alloy lithiophilic sites on the lithium alloy anode of Example 1; the left image is a SEM image of the electrode surface structure; the middle image is a Mg elemental distribution map of the electrode surface; and the right image is an Ag elemental distribution map of the electrode surface.

[0041] Figure 5 The images show the three-dimensional dynamic lithium alloy skeleton morphology and elemental distribution of the lithium alloy anode in Example 1; where the left image is a SEM image of the electrode surface structure; the middle image is a Mg elemental distribution map of the electrode surface; and the right image is an Ag elemental distribution map of the electrode surface.

[0042] Figure 6 Flowchart of the process for preparing lithium alloy anodes;

[0043] Figure 7 The lithium alloy anode of Example 1 is shown in the cycle performance diagram of a 500Wh / kg high-energy-density lithium metal battery.

[0044] Figure 8 The images show the morphology and elemental distribution of the lithium alloy anode with multidimensional dynamic framework sites in Comparative Example 2 at low lithium content; the left image is a SEM image of the electrode surface structure; the middle image is an Ag elemental distribution map of the electrode surface; and the right image is a C elemental distribution map of the electrode surface.

[0045] Figure 9 The morphology of the lithium alloy anode with multidimensional dynamic framework sites in Comparative Example 3 is shown. Detailed Implementation

[0046] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0047] The descriptions of low and high lithium content in the following embodiments refer to the dynamic lithium content of the processed negative electrode during battery application. Because the battery negative electrode loses lithium during cycling, the lithium content of the negative electrode in a real battery is dynamically changing. Based on this, the lithium content in a fully processed fresh negative electrode is set at 100%. When 90% of this lithium is stripped away, a low lithium content (10%) negative electrode is formed. When the low lithium content negative electrode undergoes lithium deposition again, its lithium content gradually increases, thus forming a high lithium content (90%) negative electrode. Therefore, in this field, the lithium content of the negative electrode can reach 100% (restoring the lithium content of a fresh lithium negative electrode), or even more than 100% (the negative electrode lithium is deposited directly without stripping).

[0048] Example 1

[0049] Ag was selected as the lithiophilic alloying element, and Mg was selected as the framework alloying element. The alloy was prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm. The process employed was "shear-stirring melting - high-temperature homogenization - rapid quenching casting - constant-pressure rolling - low-temperature annealing," as detailed in the flowchart. Figure 6 ):

[0050] (1) Shear-force stirring melting: Based on a total weight of 10 parts, weigh an appropriate amount of lithium metal blocks and alloy element powders according to the following proportions: lithium 9.4 parts, lithiophilic alloying element 0.1 parts, and framework alloying element 0.5 parts. Transfer the lithium metal blocks to a nickel crucible, and place the nickel crucible on a 350°C heating platform for heating and melting. After the lithium is completely converted to a molten state, use a special stirring device to continuously stir the lithium melt at a speed of 500 rpm. First, add the lithiophilic element and stir for 30 minutes. Then, add the framework alloying element and continue stirring for 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0051] (2) High-temperature homogenization: The temperature is lowered to 300℃, and the lithium alloy melt is allowed to stand at this temperature for 12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0052] (3) Rapid cooling casting: After reheating to 350°C and ensuring that the lithium alloy melt has good fluidity, the homogeneous lithium alloy melt is rapidly cast onto the surface of a special cooling plate to obtain a homogeneous lithium alloy ingot.

[0053] (4) Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed under a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0054] (5) Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60℃ for 1.5h to obtain the lithium alloy anode.

[0055] The lithium alloy anode prepared under these conditions has a smooth and bright surface, and the lithium-affinity alloying element Ag and the framework alloying element Mg are uniformly dispersed in the bulk phase of the alloy anode. Figure 1 At low lithium content (10%), this lithium alloy anode exposes one-dimensional spherical dynamic lithiophilic sites with sizes ranging from 200 to 800 nm. Figure 2 , Figure 4 ) and a three-dimensional topological mesh framework with pores of 20-50 μm ( Figure 5The lithiophilic sites are uniformly dispersed on the surface of the alloy framework. The one-dimensional dynamic lithium alloy lithiophilic sites and the three-dimensional topological network framework are composed of the lithiophilic alloying element Ag and the framework alloying element Mg, with Ag as the main component in the lithiophilic sites and Mg as the main component in the framework. At a high lithium content (90%), the lithiophilic alloy sites and alloy framework are redispersed uniformly in the lithium alloy anode. Figure 3 The lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared from 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) were used to assemble a 470Wh / kg lithium metal battery. The battery retained 70% of its capacity after 120 cycles. Figure 7 ).

[0056] Example 2

[0057] Ag was selected as the lithiophilic alloying element, and Mg was selected as the framework alloying element. The alloy was prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm. The process employed was "shear-stirring melting - high-temperature homogenization - rapid quenching casting - constant-pressure rolling - low-temperature annealing," as detailed in the flowchart. Figure 6 ):

[0058] (1) Shear-force stirring melting: Based on a total weight of 10 parts, weigh an appropriate amount of lithium metal blocks and alloy element powders according to the following proportions: lithium 9.8 parts, lithiophilic alloying element 0.1 parts, and framework alloying element 0.1 parts. Transfer the lithium metal blocks to a nickel crucible, and place the nickel crucible on a 300°C heating platform for heating and melting. After the lithium is completely converted to a molten state, use a special stirring device to continuously stir the lithium melt at a speed of 400 rpm. First, add the lithiophilic element and stir for 30 minutes. Then, add the framework alloying element and continue stirring for 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0059] (2) High-temperature homogenization: The temperature is lowered to 250℃, and the lithium alloy melt is left to stand at this temperature for 12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0060] (3) Rapid cooling casting: After reheating to 300°C and ensuring that the lithium alloy melt has good fluidity, the homogeneous lithium alloy melt is rapidly cast onto the surface of a special cooling plate to obtain a homogeneous lithium alloy ingot.

[0061] (4) Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed under a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0062] (5) Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60℃ for 1h to obtain the lithium alloy anode.

[0063] The lithium alloy anode prepared under these conditions has a smooth and bright surface. The lithiophilic alloying element Ag and the framework alloying element Mg are uniformly dispersed in the bulk phase of the anode. At low lithium content (10%), the lithium alloy anode exposes one-dimensional spherical dynamic lithiophilic sites with sizes ranging from 100-500 nm and a three-dimensional topological network framework with pore sizes of 100-200 μm. The lithiophilic sites are uniformly dispersed on the surface of the alloy framework. The one-dimensional dynamic lithium alloy lithiophilic sites and the three-dimensional topological network framework are composed of both the lithiophilic alloying element Ag and the framework alloying element Mg, with Ag being the dominant element in the lithiophilic sites and Mg being the dominant element in the framework. At high lithium content (90%), the lithiophilic alloying sites and the alloy framework are redispersed uniformly within the lithium alloy anode. The lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared by mixing 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) were used to assemble a 500Wh / kg lithium metal battery, which retained 70% of its capacity after 100 cycles.

[0064] Example 3

[0065] Ag was selected as the lithiophilic alloying element, and Mg was selected as the framework alloying element. The alloy was prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm. The process employed was "shear-stirring melting - high-temperature homogenization - rapid quenching casting - constant-pressure rolling - low-temperature annealing," as detailed in the flowchart. Figure 6 ):

[0066] (1) Shear-force stirring melting: Based on a total weight of 10 parts, weigh an appropriate amount of lithium metal blocks and alloy element powders, with lithium accounting for 9 parts, lithiophilic alloying elements accounting for 0.5 parts, and framework alloying elements accounting for 0.5 parts. Transfer the lithium metal blocks to a nickel crucible, and place the nickel crucible on a 380°C heating platform for heating and melting. After the lithium is completely converted to a molten state, use a special stirring device to continuously stir the lithium melt at a speed of 300 rpm. First, add the lithiophilic elements and stir for 30 minutes. Then, add the framework alloying elements and continue stirring for 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0067] (2) High-temperature homogenization: The temperature is lowered to 300℃, and the lithium alloy melt is allowed to stand at this temperature for 12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0068] (3) Rapid cooling casting: After reheating to 380°C and ensuring that the lithium alloy melt has good fluidity, the homogeneous lithium alloy melt is rapidly cast onto the surface of a special cooling plate to obtain a homogeneous lithium alloy ingot.

[0069] (4) Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed under a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0070] (5) Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60℃ for 2h to obtain the lithium alloy anode.

[0071] The lithium alloy anode prepared under these conditions has a smooth and bright surface. The lithiophilic alloying element Ag and the framework alloying element Mg are uniformly dispersed in the bulk phase of the anode. At low lithium content (20%), the lithium alloy anode exposes one-dimensional spherical dynamic lithiophilic sites with a size of 500-1000 nm and a three-dimensional topological network framework with pores of 20-50 μm. The lithiophilic sites are uniformly dispersed on the surface of the alloy framework. The one-dimensional dynamic lithium alloy lithiophilic sites and the three-dimensional topological network framework are composed of both the lithiophilic alloying element Ag and the framework alloying element Mg, with Ag being the dominant element in the lithiophilic sites and Mg being the dominant element in the framework. At high lithium content (80%), the lithiophilic alloying sites and the alloy framework are redispersed uniformly in the lithium alloy anode. The lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared by mixing 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) were used to assemble a 470Wh / kg lithium metal battery, which retained 70% of its capacity after 80 cycles.

[0072] Comparative Example 1

[0073] Metallic Sn was selected as the lithiophilic alloying element, and metallic Al was selected as the framework alloying element. The alloy was prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm, using a process of "shear-stirring melting - high-temperature homogenization - rapid quenching casting - constant-pressure rolling - low-temperature annealing," as detailed in the flowchart. Figure 6 ):

[0074] (1) Shear-force stirring melting: Based on a total weight of 10 parts, weigh an appropriate amount of lithium metal blocks and alloy element powders, with lithium accounting for 9 parts, lithiophilic alloying elements accounting for 0.5 parts, and framework alloying elements accounting for 0.5 parts. Transfer the lithium metal blocks to a nickel crucible, and place the nickel crucible on a 380°C heating platform for heating and melting. After the lithium is completely converted to a molten state, use a special stirring device to continuously stir the lithium melt at a speed of 300 rpm. First, add the lithiophilic elements and stir for 30 minutes. Then, add the framework alloying elements and continue stirring for 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0075] (2) High-temperature homogenization: The temperature is lowered to 300℃, and the lithium alloy melt is allowed to stand at this temperature for 12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0076] (3) Rapid cooling casting: After reheating to 380°C and ensuring that the lithium alloy melt has good fluidity, the homogeneous lithium alloy melt is rapidly cast onto the surface of a special cooling plate to obtain a homogeneous lithium alloy ingot.

[0077] (4) Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed under a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0078] (5) Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60℃ for 2h to obtain the lithium alloy anode.

[0079] In the lithium alloy anode prepared under these conditions, the lithiophilic alloying element Sn and the framework alloying element Al are dispersed as particles in the bulk phase of the alloy anode. At a low lithium content (20%), this lithium alloy anode exposes particulate Sn dynamic lithiophilic sites and an Al alloy framework. This lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared from 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) were used to assemble a 450Wh / kg lithium metal battery. The battery retained 70% of its capacity after 50 cycles.

[0080] Comparative Example 2

[0081] Metallic Ag was selected as the lithiophilic alloying element, and non-metallic C was selected as the framework alloying element. The alloy was prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm, using a process of "shear-stirring melting - high-temperature homogenization - rapid quenching casting - constant-pressure rolling - low-temperature annealing," as detailed in the flowchart. Figure 6 ):

[0082] (1) Shear-force stirring melting: Based on a total weight of 10 parts, weigh an appropriate amount of lithium metal blocks and alloy element powders according to the following proportions: lithium 9.4 parts, lithiophilic alloying element 0.1 parts, and framework alloying element 0.5 parts. Transfer the lithium metal blocks to a nickel crucible, and place the nickel crucible on a 350°C heating platform for heating and melting. After the lithium is completely converted to a molten state, use a special stirring device to continuously stir the lithium melt at a speed of 500 rpm. First, add the lithiophilic element and stir for 30 minutes. Then, add the framework alloying element and continue stirring for 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0083] (2) High-temperature homogenization: The temperature is lowered to 300℃, and the lithium alloy melt is allowed to stand at this temperature for 12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0084] (3) Rapid cooling casting: After reheating to 350°C and ensuring that the lithium alloy melt has good fluidity, the homogeneous lithium alloy melt is rapidly cast onto the surface of a special cooling plate to obtain a homogeneous lithium alloy ingot.

[0085] (4) Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed under a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0086] (5) Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60°C for 1.5h to obtain the lithium alloy anode as described in claim 1.

[0087] In the lithium alloy anode prepared under these conditions, the lithiophilic alloying element Ag is uniformly dispersed and the framework element C is dispersed as particles in the bulk phase of the alloy anode. At a low lithium content (5%), this lithium alloy anode exposes particulate Ag dynamic lithiophilic sites and a C framework. Figure 8The lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared from 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) were used to assemble a 500Wh / kg lithium metal battery. The battery retained 70% of its capacity after 30 cycles.

[0088] Comparative Example 3

[0089] Metallic indium (In) was selected as the lithiophilic alloying element, and non-metallic boron (B) was selected as the framework alloying element. The alloy was prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm, using a process of "shear-stirring melting - high-temperature homogenization - rapid quenching casting - constant-pressure rolling - low-temperature annealing," as detailed in the flowchart. Figure 6 ):

[0090] (1) Shear-force stirring melting: Based on a total weight of 10 parts, weigh an appropriate amount of lithium metal blocks and alloy element powders, with lithium accounting for 9 parts, lithiophilic alloying elements accounting for 0.5 parts, and framework alloying elements accounting for 0.5 parts. Transfer the lithium metal blocks to a nickel crucible, and place the nickel crucible on a 380°C heating platform for heating and melting. After the lithium is completely converted to a molten state, use a special stirring device to continuously stir the lithium melt at a speed of 300 rpm. First, add the lithiophilic elements and stir for 30 minutes. Then, add the framework alloying elements and continue stirring for 30 minutes before stopping the stirring to obtain a lithium alloy melt.

[0091] (2) High-temperature homogenization: The temperature is lowered to 300℃, and the lithium alloy melt is allowed to stand at this temperature for 12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt.

[0092] (3) Rapid cooling casting: After reheating to 380°C and ensuring that the lithium alloy melt has good fluidity, the homogeneous lithium alloy melt is rapidly cast onto the surface of a special cooling plate to obtain a homogeneous lithium alloy ingot.

[0093] (4) Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. The lithium alloy ingot is compressed to a thickness of ≤1mm using a hydraulic device, and then constant pressure rolling is performed under a pressure of 12MPa until the thickness of the lithium alloy strip is ≤50μm to complete the rolling and obtain the rolled lithium alloy anode.

[0094] (5) Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 60℃ for 2h to obtain the lithium alloy anode.

[0095] In the lithium alloy anode prepared under these conditions, the lithium-affinity alloying element In and the framework element B are uniformly dispersed in the bulk phase. At a low lithium content (10%), this lithium alloy anode exposes particulate In dynamic lithium-affinity sites and a fibrous B framework. Figure 9 The lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared by mixing 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) were used to assemble a 470Wh / kg lithium metal battery, which retained 70% of its capacity after 50 cycles.

[0096] Comparative Example 4

[0097] Ag metal was selected as the lithiophilic alloying element, and Mg metal was selected as the framework alloying element. The alloys were prepared in an argon atmosphere with a water content of <1 ppm and an oxygen content of <1 ppm. Based on a total weight of 10 parts, lithium was allocated as follows: 9 parts lithium, 0.5 parts lithiophilic alloying element, and 0.5 parts framework alloying element. Appropriate amounts of lithium metal blocks and alloying element powders were weighed and prepared. The lithium metal blocks, lithiophilic alloying element, and framework alloying element were transferred to a nickel crucible. The nickel crucible was then heated to a 380℃ heating stage for 30 minutes. The lithium alloy melt was rapidly cooled at a rate of 100℃ / s to obtain a homogeneous lithium alloy ingot. The cooled homogeneous lithium alloy ingot was sealed and transferred to a dry environment with a dew point <-30℃ for post-processing. The lithium alloy ingot was compressed to a thickness ≤1 mm using a hydraulic device, and then subjected to constant pressure rolling at 12 MPa until the lithium alloy strip thickness was ≤50 μm, thus completing the rolling process and obtaining the rolled lithium alloy anode.

[0098] The lithium alloy anode, LATP ceramic separator, NCM811 cathode, and delocalized electrolyte (prepared by mixing 0.8M LiPF6, 0.1M LiFSI, 0.1M LiDFOB, and FEC, DFEC, FEMC, FIEMC, and TTE in a volume ratio of 1:1:1:1:1) prepared under these conditions were used to assemble a 470Wh / kg lithium metal battery, which retained 70% of its capacity after 30 cycles. This comparative example uses a "melt-cool" process, and the order of material addition and dispersion process were not controlled during melting. This directly resulted in the inability to achieve the multi-level, multi-dimensional dynamic structure of the electrode. Furthermore, the lack of more advanced dispersion and cooling processes creates a potential risk of alloy element segregation and uneven distribution, thus weakening electrode performance. Consequently, the battery cycle performance in this comparative example is significantly lower than that of the other examples. Finally, this comparative example did not undergo electrode annealing, which will result in uneven stress release on the electrode surface, directly affecting the distribution of surface crystal planes and grain boundaries.

[0099] In summary, this invention enables the large-area fabrication of lithium alloy anodes with multidimensional dynamic framework sites through a process of "shear-force stirring melting - high-temperature homogenization - rapid cooling casting - constant-pressure rolling - low-temperature annealing". This method is simple, effective, and suitable for mass production. The prepared lithium alloy anode with multidimensional dynamic framework sites contains nano-one-dimensional dynamic lithium alloy lithiophilic sites and a three-dimensional dynamic lithium alloy framework with a topological structure. These sites and the framework are uniformly dispersed and hidden within the lithium alloy anode in the initial state. As the lithium potential of the anode gradually increases, the sites and the framework dynamically self-assemble, forming a topological structure with nano-sites uniformly loaded on the surface of the alloy framework. This lithium alloy anode, when used as a high-energy-density secondary lithium metal battery anode with an energy density ≥450Wh / kg, can effectively extend the battery's cycle life.

[0100] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A lithium alloy anode, said lithium alloy anode being composed of lithium and at least two alloying elements, characterized in that, The lithium alloy anode has nano-one-dimensional dynamic lithium alloy lithiophilic sites and a three-dimensional dynamic lithium alloy skeleton with topological structure. The sites and skeleton are uniformly dispersed and hidden in the lithium alloy anode in the initial state. As the lithium potential of the anode gradually increases, the sites and skeleton dynamically self-assemble and form a topological structure with nano-sites uniformly loaded on the surface of the alloy skeleton.

2. The lithium alloy negative electrode according to claim 1, characterized in that, The morphology of the one-dimensional dynamic lithium alloy lithiophilic sites is a one-dimensional spherical structure of 100-1000 nm, composed of lithium and at least one lithiophilic alloying element.

3. The lithium alloy anode according to claim 1, characterized in that, The morphology of the three-dimensional dynamic lithium alloy skeleton is a three-dimensional topological network structure with pores ranging from 5nm to 500μm, and it is composed of lithium and at least one skeleton alloying element.

4. The lithium alloy negative electrode according to claim 1, characterized in that, The lithium alloy anode is composed of lithium, a lithiophilic alloying element, and a framework alloying element. Based on a total weight of 10 parts, lithium accounts for 9 to 9.8 parts, the lithiophilic alloying element accounts for 0.1 to 0.5 parts, and the framework alloying element accounts for 0.1 to 0.5 parts.

5. The lithium alloy negative electrode according to claim 4, characterized in that, The lithium-loving alloying elements mainly include at least one of Ag, In, Sn, Au, Zn, and Sb; the framework alloying elements mainly include at least one of Mg, B, Al, and C.

6. A method for preparing a lithium alloy anode, characterized in that, The lithium alloy anode is prepared in an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, using a process of "shear-stirring melting - high-temperature homogenization - rapid cooling casting - constant pressure rolling - low-temperature annealing", including the following steps: S1. Shear-force stirring and melting: After lithium metal is heated to 350-380℃ and transformed into a molten state, it is continuously stirred at a speed of 300-500 rpm; lithium-loving alloying elements are added, and after stirring for 20-50 minutes, framework alloying elements are added, and stirring is continued for 20-50 minutes before stopping to obtain lithium alloy melt; S2. High-temperature homogenization: The temperature is lowered to 250-300℃ and left to stand for 8-12 hours to fully homogenize the melt composition and obtain a homogeneous lithium alloy melt. S3. Rapid cooling casting: Reheat to 350-380℃ and rapidly cast the homogeneous lithium alloy melt onto the surface of the cooling plate to obtain a homogeneous lithium alloy ingot. S4. Constant pressure rolling: After cooling, the homogeneous lithium alloy ingot is sealed and transferred to a dry environment with a dew point of <-30℃ for post-processing. After the lithium alloy ingot is compressed to a thickness of ≤1mm, it is rolled under constant pressure of 10-15MPa until the thickness of the lithium alloy strip is ≤50μm. Rolling is then completed to obtain the rolled lithium alloy anode. S5. Low-temperature annealing: The rolled lithium alloy anode is sealed and transferred to an argon atmosphere with a water content of <1ppm and an oxygen content of <1ppm, and annealed at 50-70℃ for 1-2 hours to obtain the lithium alloy anode.

7. The method for preparing the lithium alloy negative electrode according to claim 6, characterized in that, The continuous stirring device consists of a stirring paddle and a small stirring motor. The stirring paddle has a multi-stage blade structure, consisting of 14-16 fan-shaped main blades with a radius of 8-12mm, which mainly provide lateral shear force. The main blades are spaced 10-15° apart. The outer edge of the main blades has a branch blade structure perpendicular to the main blades. The branch blades mainly provide longitudinal shear force. The width of the branch blades is the same as that of the main blades, and the upper and lower ends protrude 1-3mm from the main blades.

8. The method for preparing a lithium alloy negative electrode according to claim 6, characterized in that, The cooling plate is made of nickel or stainless steel and has a cooling unit at the bottom. The cooling unit consists of S-shaped cooling copper pipes, and the cooling medium is water. The cooling unit is connected to an external circulating cooling device, and the cooling temperature is 8-12℃.

9. The use of a lithium alloy anode as described in any one of claims 1-5, or a lithium alloy anode prepared by the method described in any one of claims 6-8, as a lithium metal battery anode.

10. The use of a lithium alloy anode as described in any one of claims 1-5, or a lithium alloy anode prepared by the method described in any one of claims 6-8, as a pre-lithiation material for lithium-ion battery anodes.

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