Hypoeutectic alloy negative electrode material, preparation method and application of hypoeutectic alloy negative electrode material in solid-state lithium battery

Abstract

The invention provides a hypoeutectic alloy negative electrode material, a preparation method and application of the hypoeutectic alloy negative electrode material in a solid-state lithium battery, and relates to the technical field of solid-state lithium batteries. The hypoeutectic alloy negative electrode material comprises tin and bismuth elements, wherein the mass ratio of the tin to the bismuth is (60-70): (30-40); wherein in the hypoeutectic alloy negative electrode material, tin and bismuth are respectively staggered with each other in a 100-500nm wire-rod-shaped structure, and meanwhile, a part of bismuth is distributed in a tin matrix in a solid solution form. The alloy negative electrode has ultrahigh lithium ion conductivity and lithium ion diffusion coefficient, can be used for preparing a solid-state lithium battery, can perform charge-discharge cycle under low N / P ratio and ultrahigh current density, does not have lithium dendrite growth, ensures that the solid-state battery shows high safety, high energy density, high rate performance and ultra-long cycle stability at the same time, and has a wide application prospect. And the defects in the prior art are overcome.

Description

Technical Field

[0001] This application relates to the field of solid-state lithium batteries, and in particular to a hypoeutectic alloy anode material, its preparation method, and its application in solid-state lithium batteries. Background Technology

[0002] With the rapid development of electric vehicles, large-scale energy storage grids, and 3C electronic products, existing battery technologies are increasingly unable to meet the energy storage market's requirements for battery safety, energy density, charging speed, and cycle stability. Currently, liquid lithium batteries with fast-charging capabilities do not offer satisfactory safety and energy density, while solid-state lithium batteries, which offer higher safety and energy density, suffer from problems such as long charging times, short cycle life at high-rate charge and discharge, and susceptibility to dendrite growth leading to short circuits. Therefore, developing solid-state lithium batteries that combine high safety, high energy density, high charging speed, and long cycle stability is considered one of the most promising technological routes for the future development of the energy storage field.

[0003] Among the anode material systems suitable for solid-state lithium batteries, lithium metal and silicon-based anode materials possess ultra-high specific capacity, enabling solid-state batteries to achieve high energy density levels. However, lithium metal has an extremely low critical current density (typically <1.0 mA / cm² at 25°C), which significantly limits its application in high-rate charge-discharge scenarios. Silicon-based materials also suffer from relatively poor ionic and electronic conductivity, exhibiting significant polarization at high current densities and posing risks such as dendrite growth leading to battery short circuits. While lithium titanate and LVO anode materials offer excellent rate performance, meeting the fast-charging requirements of solid-state batteries, their lower specific capacity and higher electrode potential make it difficult to meet the energy density demands of solid-state batteries.

[0004] Unlike liquid lithium-ion battery systems, in solid-state lithium batteries, the main factors affecting lithium dendrite growth are poor interfacial contact and slow, uneven diffusion of lithium ions at the interface. This leads to uneven current density distribution at the interface, resulting in significant polarization and overpotential, which in turn causes lithium dendrite formation. Therefore, to achieve solid-state lithium batteries with high safety, high energy density, high rate performance, and long cycle stability, the key lies in developing anode materials that simultaneously possess the following properties: low hardness, low Young's modulus, high specific capacity, moderate electrode potential (0.3–0.7V), and high ionic / electronic conductivity. Comprehensively balancing and optimizing these properties can provide crucial technical support for developing solid-state lithium batteries with high safety, high energy density, high charging rate, and long cycle stability. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of existing technologies by providing a hypoeutectic alloy anode material, its preparation method, and its application in solid-state lithium batteries. This application uses tin and bismuth metal elements to prepare an alloy material with a hypoeutectic structure. This alloy has both ultra-high lithium-ion conductivity and lithium-ion diffusion coefficient. When used to prepare solid-state lithium batteries, it can be charged and discharged at low N / P ratios and ultra-high current densities without lithium dendrite growth. This ensures that the solid-state battery exhibits high safety, high energy density, high rate performance, and ultra-long cycle stability, thus overcoming the shortcomings of existing technologies.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: According to one aspect of this application, a hypoeutectic alloy anode material comprises the following elemental composition by mass percentage: tin 57-70%, bismuth 27-40%, and dopant elements 0-3%; wherein, Tin and some bismuth are interwoven in a rod-like structure of 100-500 nm, while some bismuth is distributed in solid solution form inside the Sn crystal phase, wherein the mass ratio of bismuth present in solid solution atomic form is ≤5%; The doping element is selected from one or more of silver (Ag), copper (Cu), antimony (Sb), zinc (Zn), and aluminum (Al).

[0007] Preferably, the mass percentage of the dopant element is 1-3%, for example, it can be 1%, 1.5%, 2%, 2.5%, 3% or any range therebetween.

[0008] Preferably, the doping element is selected from Zn and Al in a mass ratio of 2.2:1.

[0009] Preferably, the doping elements are selected from Zn, Al and Sb in a mass ratio of 1.7:1:0.5.

[0010] Furthermore, adding doping elements to hypoeutectic alloy anode materials, especially adding a certain proportion of Ag, Al or Ag, Al and Sb, can promote the directional growth of the Sn phase, limit the coarsening of the Bi phase, form a uniform linear arrangement, increase structural uniformity, and improve cycle stability.

[0011] Furthermore, the melting point of the hypoeutectic alloy anode material is 143–185°C.

[0012] Furthermore, the lithium-ion conductivity of the hypoeutectic alloy anode material is 0.1–3.0 mS / cm, and the lithium-ion diffusion coefficient is 0.2–6.0 × 10⁻⁶. -12 m 2 / s.

[0013] Furthermore, the tensile strength of the hypoeutectic alloy anode material is 50–80 MPa.

[0014] According to another aspect of this application, a method for preparing a hypoeutectic alloy anode material is provided, comprising the following steps: S1. Mix metallic tin, bismuth and doping elements evenly, calcine at high temperature under inert gas protection, cool down to 300-330℃ after calcine, add refining agent to refine and remove slag, then ultrasonically treat for 10-20s to degas, and finally air cool to room temperature to obtain hypoeutectic alloy. S2. Heat the hypoeutectic alloy to 20-30°C above the eutectic point to melt it, hold it at that temperature for 1-2 hours, then cool it down to the eutectic point temperature. Then coat it onto a preheated metal foil or stainless steel and hold it at that temperature for 30-40 minutes. S3. After the heat preservation is completed and the material is cooled, the foil is peeled off and rolled to make the surface flat, thus obtaining the hypoeutectic alloy anode material.

[0015] Furthermore, in step S1, the high-temperature calcination temperature is 400-500℃, and the time is 1-2 hours.

[0016] Furthermore, in step S1, the frequency of the ultrasonic treatment is 20–30 kHz.

[0017] Further, in step S1, during the refining process, high-purity argon gas is used as a carrier to uniformly spray the refining agent into the melt for refining; the temperature during the refining process is 300-320℃, and the time is 10-20 min; the refining agent includes the following components by mass percentage: NaCl 35-42%, NaOH 46-56%, Na2CO3 5-10%, CaF2 2-4%.

[0018] Combined with ultrasonic treatment, impurities can be removed to the greatest extent and their influence can be avoided. It can also change the surface tension and interfacial energy of the melt, promote the directional growth of the tin-bismuth phase, form a regular linear arrangement, and inhibit the growth of coarse dendrites, thereby forming a uniform structure.

[0019] Furthermore, in step S2, the eutectic point temperature is 138–140 °C.

[0020] This application employs a method of first heating the hypoeutectic alloy to above the eutectic point and holding it at that temperature, then cooling it to the eutectic point temperature before coating. This method effectively degassing and homogenizing the composition, thereby ensuring coating uniformity, inhibiting coarse grain growth, mitigating the volume expansion of the alloy anode material during charge and discharge, reducing crack formation, and extending the cycle life and structural stability of the anode. Further, in step S2, the metal foil is any one of copper foil, nickel foil, titanium foil, platinum foil, tungsten foil, and ruthenium foil; the preheating temperature of the metal foil is 140-145°C.

[0021] Furthermore, in step S3, the cooling is performed by rapid cooling in nitrogen, or by a cooling rate of 500 k / s or higher.

[0022] According to another aspect of this application, the application of the hypoeutectic alloy anode material described above in solid-state lithium batteries is provided.

[0023] According to another aspect of this application, a solid-state lithium battery is provided, comprising a hypoeutectic alloy anode material, a solid electrolyte, and a cathode material.

[0024] Furthermore, the areal capacity ratio of the hypoeutectic alloy anode material to the cathode material is 1.02 to 2.5, for example, it can be any range from 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5.

[0025] Furthermore, the solid electrolyte is a conventional choice in the art and is not particularly limited, for example, it can be Li6PS5Cl, Li 5.5 PS 4.5 Cl 1.5 Li3PS4, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 0.33 La 0.56 TiO3, Li7La3Zr2O 12 Any one or more of Li3InCl6.

[0026] Furthermore, the cathode material is a conventional choice in the art and is not particularly limited; for example, it could be LiNi. x Co y Mn 1-x-y Any one or more of O2, LiCoO2, LiFePO4, LiMn2O4, TiS2, and S.

[0027] Compared with the prior art, this application has the following beneficial effects: 1. The alloy anode material provided in this application is made by doping tin and bismuth with a small amount of other elements. The tin and bismuth elements in this material are dispersed at the nanoscale, thereby significantly improving the lithium-ion transport rate inside the alloy. The uniformly dispersed bismuth elements, after lithiation, form a lithium-bismuth alloy with ultra-high ionic conductivity, thereby forming an interconnected fast lithium-ion transport network inside the alloy, and thus achieving ultra-fast diffusion of lithium ions throughout the entire anode system.

[0028] 2. The alloy anode provided in this application is suitable for high areal capacity solid-state lithium batteries. During charge-discharge cycles at low N / P ratios and high current densities, lithium dendrites will not grow on the anode surface. Based on this, solid-state lithium batteries, using high areal capacity cathode materials, can exhibit high energy density at high current densities while ensuring no dendrite growth and achieving stable cycling. Attached Figure Description

[0029] Figure 1 This is a scanning electron microscope image of the hypoeutectic alloy negative electrode obtained in Example 1 of this application. Detailed Implementation

[0030] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of this application, but do not limit this application in any way. The following content is merely an exemplary description of the scope of protection claimed in this application, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection claimed in this application.

[0031] The present application will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of this application are obtained through conventional commercial means.

[0032] Example 1 This embodiment provides a method for preparing a hypoeutectic alloy anode material, including the following steps: S1. Tin and bismuth metal powders are mixed in a mass ratio of 70:30 and placed in a tube furnace filled with argon. The mixture is heated and calcined at 400 °C for 2 hours. After calcination, the temperature is lowered to 300 °C, a refining agent is added and the mixture is refined for 10 minutes. Then, the mixture is ultrasonically treated at a frequency of 20 kHz for 20 seconds to degas. Finally, it is air-cooled to room temperature to obtain a hypoeutectic alloy. The refining agent comprises the following components by mass percentage: NaCl 35%, NaOH 56%, Na2CO 35%, CaF2 4%; S2. After heating the eutectic alloy to 158℃ to melt it, hold it at that temperature for 2 hours, then cool it to 138℃ and uniformly coat it onto the surface of copper foil (preheated to 140℃). After holding it at that temperature for 30 minutes, quickly transfer it to a liquid nitrogen tank for rapid cooling. Peel off the foil and use a roller press to roll the hypoeutectic alloy foil to 20μm at 100℃, thereby obtaining Sn. 0.70 Bi 0.30 Hypoeutectic alloy anode.

[0033] Scanning electron microscope image of the obtained hypoeutectic alloy anode is as follows: Figure 1 As shown, the light-colored area is the Bi crystal phase, and the dark-colored area is the Sn crystal phase (which will dissolve a small amount of Bi atoms). It can also be seen that the tin and bismuth grains are mostly rod-shaped, and the grain size (the smallest spacing between the rod-shaped grains) is mostly concentrated in the range of 100-500nm and shows a uniform and fine distribution.

[0034] Example 2 S1. Tin, bismuth and zinc metal powders are mixed in a mass ratio of 70:29:1 and placed in a tube furnace filled with argon. The mixture is heated and calcined at 500°C for 1 hour. After calcination, the temperature is lowered to 320°C, a refining agent is added and the mixture is refined for 20 minutes. Then, the mixture is ultrasonically treated at a frequency of 30kHz for 10 seconds to remove gas. Finally, it is air-cooled to room temperature to obtain a hypoeutectic alloy. The refining agent comprises the following components by mass percentage: NaCl 42%, NaOH 46%, Na2CO3 10%, CaF2 2%; S2. After heating the eutectic alloy to 170℃ to melt it, hold it at that temperature for 1 hour and then cool it down to 140℃. Then, coat it evenly on the surface of copper foil (preheat the copper foil to 145℃). After holding it at that temperature for 40 minutes, quickly transfer it to a liquid nitrogen tank to cool it rapidly. Peel off the foil and use a roller press to roll the hypoeutectic alloy foil to 20μm at a temperature of 100℃ to obtain the hypoeutectic alloy negative electrode.

[0035] Example 3 The difference from Example 2 is that in step S1, the metal powder is tin, bismuth and doping elements in a mass ratio of 70:28:2; the doping elements are zinc and aluminum in a mass ratio of 2.2:1.

[0036] Example 4 The difference from Example 2 is that in step S1, the metal powder is tin, bismuth and dopant in a mass ratio of 70:27:3, and the dopant is Zn, Al and Sb in a mass ratio of 1.7:1:0.5.

[0037] Example 5 The difference from Example 4 is that the mass ratio of tin, bismuth, and dopant is 57:40:3, and the dopant remains unchanged.

[0038] Comparative Example 1 The difference from Example 4 is that the rapid cooling in liquid nitrogen in step S2 is replaced by natural cooling in air.

[0039] Comparative Example 2 The difference from Example 4 is that in step S1, the metal powder is bismuth with a mass ratio of 97:3 and doping elements, and the doping elements remain unchanged.

[0040] Comparative Example 3 The difference from Example 4 is that in step S1, the metal powder is tin with a mass ratio of 97:3 and doping elements, and the doping elements remain unchanged.

[0041] Comparative Example 4 The difference from Example 4 is that in step S1, the metal powder is tin, bismuth and doping elements in a mass ratio of 75:22:3, and the doping elements remain unchanged.

[0042] Comparative Example 5 The difference from Example 4 is that in step S1, the metal powder is tin, bismuth and doping elements in a mass ratio of 54:43:3, and the doping elements remain unchanged.

[0043] Comparative Example 6 The difference from Example 4 is that in step S1, the metal powder is tin, bismuth and doping elements in a mass ratio of 65:30:5, and the doping elements remain unchanged.

[0044] Comparative Example 7 The difference from Example 4 is that the doping element in step S1 is replaced with indium.

[0045] Comparative Example 8 The difference from Example 4 is that in step S1, after calcination, a refining agent is directly added for refining and slag removal.

[0046] Comparative Example 9 The difference from Example 4 is that in step S1, the refining agent includes the following components by mass percentage: NaCl 42%, NaOH 46%, and Na2CO3 12%.

[0047] Comparative Example 10 The difference from Example 4 is that in step S1, the refining agent includes the following components by mass percentage: NaCl 42% and NaOH 58%.

[0048] Comparative Example 11 The difference from Example 4 is that in step S2, after heating and calcining at 500°C for 1 hour, the alloy is directly air-cooled to room temperature to obtain a hypoeutectic alloy.

[0049] Comparative Example 12 The difference from Example 4 is that in step S2, the hypoeutectic alloy is heated to the eutectic point of 140°C to melt and then kept at that temperature for 1 hour before coating.

[0050] Experimental Example 1 The tensile strength, areal capacity, and lithium-ion conductivity at 50% lithiation of the hypoeutectic alloys obtained in the above embodiments and comparative examples were tested. The test results are shown in Table 1 below. (Test method?) Table 1. Properties of hypoeutectic alloys

[0051] As shown in the table, in Example 1, tin and bismuth were used to prepare the alloy material without adding any dopant. The resulting alloy material exhibits high strength, high areal capacity, and high lithium-ion conductivity at 50% lithiation. Compared to Example 1, Examples 2-5 added dopant elements, which improved the tensile strength of the alloy while maintaining high areal capacity and lithium-ion conductivity. Therefore, the alloy anode material provided in this application has high strength, enables ultra-fast lithium-ion diffusion, and is suitable for high areal capacity solid-state lithium batteries.

[0052] Compared to the examples, in Comparative Example 1, natural cooling was used during alloy preparation, resulting in a decrease in the lithium-ion conductivity and lithium-ion diffusion coefficient of the obtained alloy material. In Comparative Example 2, the removal of metallic tin significantly reduced the strength of the obtained alloy material; in Comparative Example 3, the removal of metallic bismuth improved the strength of the obtained alloy material, but reduced the lithium-ion conductivity and lithium-ion diffusion coefficient, and decreased the rapid diffusion efficiency of lithium ions.

[0053] Application examples A method for preparing a solid-state lithium-ion battery includes the following steps: A 25 μm thick Li6PS5Cl solid electrolyte membrane with an areal capacity of 5.0 mAh / cm² was used. 2 LiNi 0.8 Co 0.1 Mn 0.1 The O2 positive electrode (alloy negative electrode surface capacity / positive electrode surface capacity = 1.24) was assembled into a multilayer solid-state lithium-ion pouch battery by stacking the hypoeutectic alloy negative electrode obtained in the above examples and comparative examples with Li6PS5Cl and ternary positive electrode, and left to stand for 5 hours.

[0054] Solid-state lithium-ion batteries #1-17 were prepared according to the above method. The solid-state lithium-ion batteries were tested at 4 mA / cm². 2 Energy density at current density, 24 mA / cm 2 The capacity retention rate after 500 continuous charge-discharge cycles at the current density is tested using the following method: All-solid-state lithium battery samples were tested on a LAND CT 2001C secondary battery performance testing device at 298±1K and an external stacking pressure of 50MPa. Each battery was first allowed to stand for 120 minutes. Then, a charge-discharge cycle test was performed at a 0.5C rate: charging at 0.5C to 4.00V and then discharging at 0.5C to 2.20V constituted one cycle. The discharge capacity of the first cycle was recorded, and this process was repeated twice to activate the battery. Next, the cycle was repeated 400 times, charging at 6C to 4.00V and then discharging at 6C to 2.20V. The discharge capacity of the 400th cycle was recorded, and the capacity retention rate was calculated based on the initial discharge capacity.

[0055] The results are shown in Table 2 below.

[0056] Table 2. Battery performance test results

[0057] As shown in the table, the battery No. 6 made using the alloy material of Comparative Example 1 has a low energy density, at 50 mA / cm². 2 After 74 consecutive charge-discharge cycles at the current density, the battery failed due to a short circuit. Disassembly of the cycled battery revealed a large number of lithium dendrites on the alloy negative electrode. The alloy material of Comparative Example 2 was difficult to foil-form, making it impossible to assemble a full cell for testing. Battery #12, prepared using the alloy material obtained in Comparative Example 3, although at 4 mA / cm²... 2 It has high energy density at current density, but at 24 mA / cm² 2 After four consecutive charge-discharge cycles at the current density, the battery failed due to a short circuit. Disassembly of the cycled battery revealed a large number of lithium dendrites on the alloy negative electrode. In contrast, batteries #1-#5 had high energy densities, at 24 mA / cm². 2 The battery exhibits high capacity retention and high average coulombic efficiency after 400 continuous charge-discharge cycles at current density. Disassembly after battery cycling revealed that no lithium dendrites were generated on the alloy anode. This means that no lithium dendrites grow on the anode surface during charge-discharge cycles at low N / P ratio and high current density, achieving stable cycling.

[0058] Furthermore, the above-described solid-state lithium-ion battery is prepared using only a specific solid electrolyte membrane, positive electrode, and positive and negative electrode areal capacities as examples. It is understood that other conventional choices in the art can achieve the same effect. Since there are many choices for electrolytes and positive electrode materials, they will not be elaborated here, and the areal capacity only needs to be between 1.02 and 2.5. The above embodiments do not constitute a limitation of this application.

[0059] In summary, this application uses tin and bismuth (or adds doped metals) to prepare alloy anode materials. During the preparation of the alloy materials, a rapid cooling method is used to obtain a hypoeutectic tin-bismuth alloy in which the tin and bismuth components exhibit an interlaced rod-like structure of 100-500 nm. At the same time, some bismuth is distributed in solid solution within the tin matrix. This special dispersion structure greatly enhances the diffusion rate of lithium ions in the alloy, giving the alloy both ultra-high lithium-ion conductivity and lithium-ion diffusion coefficient, as well as high tensile strength and excellent overall performance. The solid-state lithium battery composed of this alloy anode, solid electrolyte membrane, and high areal capacity cathode material can be charged and discharged at low N / P ratio and ultra-high current density without lithium dendrite growth, ensuring that the solid-state battery simultaneously exhibits high safety, high energy density, high rate performance, and ultra-long cycle stability.

[0060] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the protection scope of this application.

Claims

1. A hypoeutectic alloy negative electrode material, characterized by, comprising the following element components in mass percentage: tin 57-70%, bismuth 27-40%, doping element 0-3%; wherein, tin and part of bismuth are interlaced with each other in the form of 100-500 nm linear rod-like structure, and part of bismuth is distributed in the form of solid solution in the Sn crystal phase, wherein the mass ratio of bismuth existing in the form of solid solution is ≤5%; the doping element is selected from any one or more of Ag, Cu, Sb, Zn, and Al.

2. The hypoeutectic alloy negative electrode material of claim 1, wherein, the percentage of the doping element in the total mass is 1-3%.

3. The hypoeutectic alloy negative electrode material of claim 1, wherein, the doping element is selected from Zn and Al in a mass ratio of 2.2:

1.

4. The hypoeutectic alloy negative electrode material of claim 1, wherein, the doping element is selected from Zn, Al, and Sb in a mass ratio of 1.7:1:0.

5.

5. The hypoeutectic alloy negative material according to any one of claims 1-4, characterized in that, the hypoeutectic alloy negative electrode material has at least one of the following properties: melting point is 143-185℃; lithium ion conductivity is 0.1-3.0 mS / cm; The lithium ion diffusion coefficient is 0.2-6.0 x 10 –12 m 2 / s.

6. The method of producing a hypoeutectic alloy negative electrode material according to any one of claims 1 to 5, characterized by, comprising the following steps: S1, uniformly mixing metallic tin, bismuth, and a doping element, high-temperature calcination under inert gas protection, cooling to 300-330℃ after calcination, adding a refining agent for refining and slagging, then ultrasonic treatment for 10-20s to remove gas, and finally cooling to room temperature; S2, heating the hypoeutectic alloy to 20-30℃ above the eutectic point to melt it, then cooling to the eutectic point temperature after 1-2h of heat preservation, then coating on a copper foil or stainless steel, and heat preservation for 30-40min; S3, cooling after heat preservation, taking out the hypoeutectic alloy, rolling to make the surface flat, and obtaining the hypoeutectic alloy negative electrode material.

7. The production method according to claim 6, wherein In step S1, the frequency of ultrasonic treatment is 20-30kHz; In the refining process, high-purity argon is used as a carrier to uniformly spray the refining agent into the melt for refining; the temperature during the refining process is 300-320℃, and the time is 10-20min; the refining agent comprises the following components in mass percentage: NaCl 35-43%, NaOH 48-54%, Na2CO3 5-15%, and CaF2 2-4%.

8. The preparation method according to claim 6, characterized in that, In step S2, the eutectic point temperature is 138-140℃.

9. The hypoeutectic alloy negative electrode material of any one of claims 1-5 or the hypoeutectic alloy negative electrode material prepared by the preparation method of any one of claims 6-8 is applied in a solid-state lithium battery.

10. A solid-state lithium battery, characterized by, comprising the hypoeutectic alloy negative electrode material of any one of claims 1-5 or the hypoeutectic alloy negative electrode material prepared by the preparation method of any one of claims 6-8, a solid-state electrolyte, and a positive electrode material; the surface capacity ratio of the hypoeutectic alloy negative electrode material to the positive electrode material is 1.02-2.5.

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