Self-repairing fast ionic conductor lithium metal anode and preparation method thereof

Abstract

The application discloses a self-repairing fast-ion conductor lithium metal negative electrode and a preparation method thereof, and relates to the technical field of lithium ion batteries. The self-repairing fast-ion conductor lithium metal negative electrode comprises a lithium metal layer and a man-made SEI film covering the upper surface of the lithium metal layer; the man-made SEI film is a mixture of a carbon skeleton and a loaded active component, the active component comprises nanoeutectic alloy particles and cuprous nitride; and the mass ratio of the nanoeutectic alloy particles and the cuprous nitride is 1:(1-3). The product can effectively solve the expansion and pulverization problems of the negative electrode active material by constructing a composite man-made SEI film on the lithium metal, and can significantly improve the safety, stability and electrochemical stability of the negative electrode in application.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a self-healing fast-ion conductor lithium metal anode and its preparation method. Background Technology

[0002] Lithium metal, when used as an anode, theoretically boasts a high specific capacity (3860 mAh / g) and low electrochemical potential, making it an ideal electrode material for lithium-ion batteries. However, lithium metal anodes present safety and stability issues in practical applications, primarily due to the significant volume effect they exhibit. When storing large amounts of lithium, the volume can expand several times its original size, drastically causing electrode pulverization and ultimately resulting in poor cycle performance. Furthermore, lithium metal anodes are accompanied by several prominent safety problems, including lithium dendrite growth and the peeling-growth-thickening of the passivation layer.

[0003] Currently, existing research suggests that the introduction of artificial SEI films can overcome the aforementioned difficulties. For example, LiF artificial SEI films possess excellent ionic conductivity and electrochemical stability, significantly contributing to the cycle life and safety of lithium batteries. Furthermore, the development and application of new electrolyte salts or electrolyte solutions also help address the problems associated with lithium metal anodes. While these methods can improve the cycle life of lithium batteries, the use of these materials can somewhat affect the specific capacity of the anode and even the overall charge / discharge capacity of the battery. Summary of the Invention

[0004] Based on the deficiencies of existing technologies, the purpose of this invention is to provide a self-healing fast ion conductor lithium metal anode. This product, by constructing a composite artificial SEI film on lithium metal, can not only effectively solve the problem of expansion and pulverization of the anode active material, but also significantly improve the safety, stability and electrochemical stability of the anode in application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A self-healing fast ion conductor lithium metal anode includes a lithium metal layer and an artificial SEI film covering the upper surface of the lithium metal layer; the artificial SEI film is a mixture of a carbon skeleton and its supported active components, the active components including nano-eutectic alloy particles and cuprous nitride;

[0007] The mass ratio of the nano-eutectic alloy particles to copper nitride is 1:(1-3).

[0008] In the self-healing fast-ion conductor lithium metal anode of this invention, the artificial SEI film contains two key active components: nano-eutectic alloy particles and cuprous nitride. Cuprous nitride reacts with lithium ions during the first charge of the anode to form lithium nitride. Lithium nitride, as a highly active fast-ion conductor, acts as a solid electrolyte during battery charging and discharging, thus increasing the overall energy density of the battery. On the other hand, the nano-eutectic alloy particles possess good specific capacity, conductivity, and self-healing properties. When applied to the artificial SEI film, they do not significantly reduce the anode capacity and also avoid damage caused by prolonged charging and discharging of the electrode. The combination of two active components, supported by a highly stable carbon framework, allows the nano-eutectic alloy particles and fast ion conductors to work synergistically during the charging and discharging of the lithium metal anode. This results in improved volume recovery and conductivity of the artificial SEI film, effectively solving problems such as excessively high reactivity of lithium metal, large volume expansion, and uneven deposition during operation in existing lithium metal anodes. It also suppresses capacity loss and safety issues caused by lithium dendrite formation during charging and discharging, demonstrating broad application prospects in the field of lithium-ion energy storage batteries. However, the ratio of the nano-eutectic alloy particles to cuprous nitride needs to be appropriate; an improper ratio will prevent the simultaneous achievement of these multiple properties and may even have negative effects.

[0009] Preferably, the nano-eutectic alloy particles are gallium and tin alloy particles, and the mass ratio of gallium to tin in the alloy particles is (9:1) to (4:6).

[0010] Preferably, the particle size of the nano-eutectic alloy particles is 100–200 nm.

[0011] Preferably, the thickness ratio of the lithium metal layer to the artificial SEI film is 1:(0.08~0.4).

[0012] Another object of the present invention is to provide a method for preparing the self-healing fast ion conductor lithium metal anode, comprising the following steps:

[0013] (1) Preparation of dispersed nano-eutectic alloy particles;

[0014] (2) The dispersed nano-eutectic alloy particles and cuprous nitride are evenly dispersed in a dispersion solvent, and then carbon nanotubes are added and the resulting mixture is subjected to ultrasonic dispersion treatment once to obtain suspension A; graphene oxide gel is added to suspension A and subjected to ultrasonic dispersion treatment a second time to obtain gel B; gel B is placed in a protective atmosphere for heating and heat preservation treatment, then crushed, ground and dried to obtain precursor powder C; the mass ratio of carbon nanotubes to graphene oxide gel is (0.5~1):(0.5~1.5);

[0015] (3) The precursor powder C is prepared into a slurry with adhesive and solvent and coated on the lithium metal layer. After drying, the self-healing fast ion conductor lithium metal anode is obtained.

[0016] The preparation method of the self-healing fast ion conductor lithium metal anode described in this invention has simple operation steps and low equipment requirements, and can be mass-produced in both laboratories and factories. Since the main carbon source of the carbon skeleton in the artificial SEI film of the product is a mixture of carbon nanotubes and graphene oxide gel, where graphene oxide gel provides the main mechanical support structure and carbon nanotubes serve as a dispersion and connection structure and provide a larger loading area, the ratio of the two has a significant impact on the overall structural stability of the product. If the addition ratio of the two carbon sources is inappropriate during heating and heat preservation treatment and subsequent product application, it may lead to poor structural stability of the product and even a decrease in electrochemical stability during application. After experimental screening, the application effect is best when the addition ratio range of the two sources described above is optimal.

[0017] Preferably, the mass ratio of the nano-eutectic alloy particles, cuprous nitride, carbon nanotubes, and graphene oxide gel is 1:(1-3):(0.5-1):(0.5-1.5).

[0018] Carbon nanotubes and graphene oxide gels serve as carbon frameworks to support nano-eutectic alloy particles and cuprous nitride particles. Therefore, the ratio between the loading material and the carbon source of the carbon framework also has a certain impact on the overall product. It has been verified that the product prepared with the above ratio has the best effect.

[0019] Preferably, in step (2), the dispersing solvent is anhydrous ethanol, the time for the first ultrasonic dispersion treatment is 8-12 min, and the time for the second ultrasonic dispersion treatment is 18-22 min.

[0020] Preferably, the specific steps of the heating and heat preservation treatment in step (2) are as follows: heat the gel liquid B to 150-200°C and keep it at that temperature for 1-3 hours, and then transfer it to an environment of 780-820°C and keep it at that temperature for 2-6 hours.

[0021] Preferably, in step (3), the adhesive is styrene-butadiene rubber with a concentration of 35-45 wt%, and the solvent is tetrahydrofuran.

[0022] Preferably, the method for preparing the dispersed nano-eutectic alloy particles includes the following steps:

[0023] The nano-eutectic alloy particles are added to a solvent containing a dispersant and mixed and ultrasonically dispersed for 10–30 min. After standing for 2.5–3.5 h, they are centrifuged, filtered, and dried to obtain the dispersed nano-eutectic alloy particles.

[0024] More preferably, the solvent is anhydrous ethanol, the dispersant is dodecyl mercaptan, and the mass ratio of the nano-eutectic alloy particles and the dispersant to the volume of the solvent is (0.35-0.4) g: 0.5 g: (5-20) mL.

[0025] Preferably, the method for preparing the cuprous nitride includes the following steps:

[0026] Cuprous oxide and urea are mixed evenly at a molar ratio of 1:(2-4), heated to 150-210℃ under a protective atmosphere and held for 6-18 hours, then cooled to room temperature, and then heated to 80-120℃ under a protective atmosphere and held for 0.5-1 hours, and then cooled to obtain cuprous nitride.

[0027] Another object of the present invention is to provide the application of the self-healing fast ion conductor lithium metal anode in the preparation of high-performance lithium-ion energy storage batteries.

[0028] The artificial SEI film contained in the self-healing fast ion conductor lithium metal anode of the present invention is actually a self-healing fast ion conductor composite material supported by a carbon skeleton. This material effectively reduces the reactivity of the lithium metal anode during battery operation, reduces the formation of lithium dendrites, and inhibits the degree of lithium metal expansion and pulverization. When this self-healing fast ion conductor lithium metal anode is used to prepare lithium-ion energy storage batteries, it not only has high safety and stability, but also ensures that the electrochemical activity of the lithium metal anode is fully utilized, providing high capacity and having high commercial value.

[0029] The beneficial effects of this invention are that it provides a self-healing fast-ion conductor lithium metal anode. This product, by constructing a composite artificial SEI film on lithium metal, not only effectively solves the problem of expansion and pulverization of the anode active material, but also significantly improves the safety, stability, and electrochemical stability of the anode during application. This invention also provides a method for preparing the product and its application in the preparation of high-performance lithium-ion energy storage batteries. Attached Figure Description

[0030] Figure 1 The image shows (a) of the self-healing fast ion conductor lithium metal anode prepared in Example 1 of the present invention; (b) and (c) of the cross-sectional scanning electron microscope (SEM) image of the artificial SEI film in the self-healing fast ion conductor lithium metal anode.

[0031] Figure 2 The image shows the EDS elemental analysis results of the nano-eutectic alloy particles in the self-healing fast ion conductor lithium metal anode prepared in Example 1 of this invention.

[0032] Figure 3 The graph shows the 1C rate charge-discharge cycle test results of the lithium metal anodes prepared in Example 1 and Comparative Example 1 of the present invention.

[0033] Figure 4 The images shown are: (a) a scanning electron microscope image of the lithium metal foil in the self-healing fast ion conductor lithium metal anode prepared in Example 1 of the present invention before testing; and (b) a scanning electron microscope image of the lithium metal foil in the lithium metal anode obtained in Example 1 and Comparative Example 1 (c) after cyclic testing. Detailed Implementation

[0034] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments / comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents, raw materials, and instruments designed in the embodiments and comparative examples of this invention are all commonly used reagents, raw materials, and instruments.

[0035] Example 1

[0036] An embodiment of the self-healing fast-ion conductor lithium metal anode and its preparation method according to the present invention includes the following steps:

[0037] (1) Preparation of dispersed nano-eutectic alloy particles: Under an argon protective atmosphere in a glove box, gallium and tin were melted in a crucible at a mass ratio of 80:20 at 200°C. After stirring and mixing for 1 hour, the mixture was cooled to room temperature to obtain gallium and tin alloy particles. 0.36 g of alloy particles were weighed, 5 mL of anhydrous ethanol solution was added, and 0.5 g of dodecanethiol was added and mixed evenly. The mixture was then ultrasonically dispersed for 10 min, allowed to stand for 3 hours, centrifuged and filtered, and dried at 50°C to obtain dispersed nano-eutectic alloy particles with a particle size of 100–200 μm.

[0038] (2) Preparation of cuprous nitride: In a glove box, cuprous oxide and urea were mixed evenly at a molar ratio of 1:2 and poured into a hydrothermal reactor. The hydrothermal reactor was then transferred to a muffle furnace and heated to 150°C under an argon protective atmosphere. The mixture was kept at this temperature for 18 hours. After cooling to room temperature, the product was dried and placed in a crucible. The mixture was then heated to 120°C in a glove box and kept at this temperature for 0.5 hours. After cooling, cuprous nitride was obtained.

[0039] (3) Preparation of precursor powder: 10 mg of dispersed nano-eutectic alloy particles and 30 mg of cuprous nitride were mixed and added to 5 mL of anhydrous ethanol. 10 mg of carbon nanotubes were added and ultrasonically dispersed for 10 min to obtain suspension A. 5 mg of graphene oxide gel was added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B was placed in a hydrothermal reactor and heated to 150 °C under argon atmosphere for 1 h. The obtained product was then placed in a tube furnace and heated to 800 °C under argon atmosphere for 2 h. The obtained product was crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0040] (4) Preparation of self-healing fast ion conductor lithium metal anode: The precursor powder C is placed in a beaker containing 50 mg of styrene-butadiene rubber with a concentration of 40 wt%, and 50 mL of tetrahydrofuran is added dropwise. The mixture is stirred for 3 h. In a glove box filled with argon, the slurry is uniformly coated on lithium metal foil with a scraper and dried to obtain the self-healing fast ion conductor lithium metal anode. The thickness of the lithium metal foil is 0.6 mm, and the thickness of the artificial SEI film is about 100 μm.

[0041] Example 2

[0042] An embodiment of the self-healing fast-ion conductor lithium metal anode and its preparation method according to the present invention includes the following steps:

[0043] (1) Preparation of dispersed nano-eutectic alloy particles: Under an argon protective atmosphere in a glove box, gallium and tin were melted in a crucible at a mass ratio of 90:10 at 300°C. After stirring and mixing for 2 hours, the mixture was cooled to room temperature to obtain gallium and tin alloy particles. 0.36 g of alloy particles were weighed, 5 mL of anhydrous ethanol solution was added, and 0.5 g of dodecanethiol was added and mixed evenly. The mixture was then ultrasonically dispersed for 10 min, allowed to stand for 3 hours, centrifuged and filtered, and dried at 50°C to obtain dispersed nano-eutectic alloy particles with a particle size of 100–200 nm.

[0044] (2) Preparation of cuprous nitride: In a glove box, cuprous oxide and urea were mixed evenly at a molar ratio of 1:4 and poured into a hydrothermal reactor. The hydrothermal reactor was then transferred to a muffle furnace and heated to 200°C under an argon protective atmosphere. After holding at this temperature for 6 hours, the product was cooled to room temperature, dried, and placed in a crucible. The product was then heated to 120°C in a glove box and held for 1 hour. After cooling, cuprous nitride was obtained.

[0045] (3) Preparation of precursor powder: 10 mg of dispersed nano-eutectic alloy particles and 30 mg of cuprous nitride were mixed and added to 5 mL of anhydrous ethanol. 10 mg of carbon nanotubes were added and ultrasonically dispersed for 10 min to obtain suspension A. 5 mg of graphene oxide gel was added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B was placed in a hydrothermal reactor and heated to 200 °C under argon atmosphere for 1 h. The obtained product was then placed in a tube furnace and heated to 800 °C under argon atmosphere for 6 h. The obtained product was crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0046] (4) Preparation of self-healing fast ion conductor lithium metal anode: The precursor powder C is placed in a beaker containing 50 mg of styrene-butadiene rubber with a concentration of 40 wt%, and 50 mL of tetrahydrofuran is added dropwise. The mixture is stirred for 3 h. In a glove box filled with argon, the slurry is uniformly coated on lithium metal foil with a scraper and dried to obtain the self-healing fast ion conductor lithium metal anode. The thickness of the lithium metal foil is 0.6 mm, and the thickness of the artificial SEI film is about 100 μm.

[0047] Example 3

[0048] An embodiment of the self-healing fast-ion conductor lithium metal anode and its preparation method according to the present invention includes the following steps:

[0049] (1) Preparation of dispersed nano-eutectic alloy particles: Under an argon protective atmosphere in a glove box, gallium and tin were melted in a crucible at a mass ratio of 80:20 at 200°C. After stirring and mixing for 1 hour, the mixture was cooled to room temperature to obtain gallium and tin alloy particles. 0.36 g of alloy particles were weighed, 5 mL of anhydrous ethanol solution was added, and 0.5 g of dodecanethiol was added and mixed evenly. The mixture was then ultrasonically dispersed for 10 min, allowed to stand for 3 hours, centrifuged and filtered, and dried at 50°C to obtain dispersed nano-eutectic alloy particles with a particle size of 100–200 nm.

[0050] (2) Preparation of cuprous nitride: In a glove box, cuprous oxide and urea were mixed evenly at a molar ratio of 1:2 and poured into a hydrothermal reactor. The hydrothermal reactor was then transferred to a muffle furnace and heated to 150°C under an argon protective atmosphere. The mixture was kept at this temperature for 18 hours. After cooling to room temperature, the product was dried and placed in a crucible. The mixture was then heated to 120°C in a glove box and kept at this temperature for 0.5 hours. After cooling, cuprous nitride was obtained.

[0051] (3) Preparation of precursor powder: 10 mg of dispersed nano-eutectic alloy particles and 20 mg of cuprous nitride were mixed and added to 5 mL of anhydrous ethanol. 5 mg of carbon nanotubes were added and ultrasonically dispersed for 10 min to obtain suspension A. 10 mg of graphene oxide gel was added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B was placed in a hydrothermal reactor and heated to 150 °C under argon atmosphere for 1 h. The obtained product was then placed in a tube furnace and heated to 800 °C under argon atmosphere for 2 h. The obtained product was crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0052] (4) Preparation of self-healing fast ion conductor lithium metal anode: The precursor powder C is placed in a beaker containing 50 mg of styrene-butadiene rubber with a concentration of 40 wt%, and 50 mL of tetrahydrofuran is added dropwise. The mixture is stirred for 3 h. In a glove box filled with argon, the slurry is uniformly coated on lithium metal foil with a scraper and dried to obtain the self-healing fast ion conductor lithium metal anode. The thickness of the lithium metal foil is 0.6 mm, and the thickness of the artificial SEI film is about 100 μm.

[0053] Comparative Example 1

[0054] A lithium metal anode comprising only lithium metal foil.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is that step (3) is as follows: 40 mg of cuprous nitride is added to 5 mL of anhydrous ethanol, 10 mg of carbon nanotubes are added, and the mixture is ultrasonically dispersed for 10 min to obtain suspension A. Then, 5 mg of graphene oxide gel is added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B is placed in a hydrothermal reactor and heated to 150 °C under an argon atmosphere for 1 h. The obtained product is then placed in a tube furnace and heated to 800 °C under an argon atmosphere for 2 h. The obtained product is crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0057] Comparative Example 3

[0058] The only difference between this comparative example and Example 1 is that step (3) is as follows: 40 mg of dispersed nano-eutectic alloy particles are added to 5 mL of anhydrous ethanol, 10 mg of carbon nanotubes are added, and ultrasonic dispersion is performed for 10 min to obtain suspension A. Then, 5 mg of graphene oxide gel is added to suspension A and ultrasonic dispersion is performed for 20 min to obtain gel B. Gel B is placed in a hydrothermal reactor and heated to 150 °C under an argon atmosphere for 1 h. The obtained product is then placed in a tube furnace and heated to 800 °C under an argon atmosphere for 2 h. The obtained product is crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0059] Comparative Example 4

[0060] The only difference between this comparative example and Example 1 is that step (3) is as follows: 5 mg of dispersed nano-eutectic alloy particles and 15 mg of cuprous nitride are mixed and added to 5 mL of anhydrous ethanol. 10 mg of carbon nanotubes are added and ultrasonically dispersed for 10 min to obtain suspension A. 5 mg of graphene oxide gel is then added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B is placed in a hydrothermal reactor and heated to 150 °C under an argon atmosphere for 1 h. The obtained product is then placed in a tube furnace and heated to 800 °C under an argon atmosphere for 2 h. The obtained product is crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0061] Comparative Example 5

[0062] The only difference between this comparative example and Example 1 is that step (3) is as follows: 15 mg of dispersed nano-eutectic alloy particles and 45 mg of cuprous nitride are mixed and added to 10 mL of anhydrous ethanol. 10 mg of carbon nanotubes are added and ultrasonically dispersed for 10 min to obtain suspension A. 5 mg of graphene oxide gel is then added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B is placed in a hydrothermal reactor and heated to 150 °C under an argon atmosphere for 1 h. The obtained product is then placed in a tube furnace and heated to 800 °C under an argon atmosphere for 2 h. The obtained product is crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0063] Comparative Example 6

[0064] The only difference between this comparative example and Example 1 is that step (3) is as follows: 10 mg of dispersed nano-eutectic alloy particles and 30 mg of cuprous nitride are mixed and added to 5 mL of anhydrous ethanol. 5 mg of carbon nanotubes are added and ultrasonically dispersed for 10 min to obtain suspension A. 10 mg of graphene oxide gel is then added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B is placed in a hydrothermal reactor and heated to 150 °C under an argon atmosphere for 1 h. The obtained product is then placed in a tube furnace and heated to 800 °C under an argon atmosphere for 2 h. The obtained product is crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0065] Comparative Example 7

[0066] The only difference between this comparative example and Example 1 is that step (3) is as follows: 15 mg of dispersed nano-eutectic alloy particles and 5 mg of cuprous nitride are mixed and added to 5 mL of anhydrous ethanol. 10 mg of carbon nanotubes are added and ultrasonically dispersed for 10 min to obtain suspension A. 5 mg of graphene oxide gel is then added to suspension A and ultrasonically dispersed for 20 min to obtain gel B. Gel B is placed in a hydrothermal reactor and heated to 150 °C under an argon atmosphere for 1 h. The obtained product is then placed in a tube furnace and heated to 800 °C under an argon atmosphere for 2 h. The obtained product is crushed and ground into powder and dried in a vacuum drying oven at 40 °C for 2 h to obtain precursor powder C.

[0067] Example 1

[0068] To verify the performance of the self-healing fast-ion conductor lithium metal anode described in this invention, the lithium metal anodes obtained in Example 1 and Comparative Example 1 were used as negative electrodes, with Celgard 2400 as the separator, and an electrolyte composition of EC:DMC:DEC = 1:1:1 containing 1 mol / L LiPF6. The counter electrode was a commercially available ternary cathode material. A CR2032 button cell was assembled in an argon-filled glove box, and charge-discharge cycle tests were conducted at 3–4.3V and a 1C rate (standard capacity setting 190 mAh / g). Before the tests, the self-healing fast-ion conductor lithium metal anode prepared in Example 1 was observed. Figure 1 As shown, the artificial SEI film is uniformly coated on the lithium metal foil, and from... Figure 1 The cross-sectional and front-side scanning electron microscope (SEM) images of the artificial SEI films in (b) and (c) show that the film thickness is moderate, and the nano-eutectic alloy particles and cuprous nitride are uniformly loaded on the carbon framework surface; EDS elemental analysis of the nano-eutectic alloy particles on the films yields the following results: Figure 2 As shown, the alloy particles have high purity. After 50 charge-discharge cycles, the test results are as follows: Figure 3As shown, compared to the product of Comparative Example 1 without an artificial SEI film, the discharge specific capacity of the self-healing fast ion conductor lithium metal anode of this invention is not significantly reduced, but its stability is significantly improved. The cycled battery was disassembled, and the lithium metal foil on the lithium metal anodes prepared in Example 1 and Comparative Example 1 was observed using scanning electron microscopy. The results are as follows: Figure 4 As shown, where Figure 4 (a) is the lithium metal foil obtained in Example 1 that has not been cycled, while the morphology of the product in Comparative Example 1 is similar to that of the product in Example 1. After cycling, the morphology of the product in Example 1 is as follows. Figure 4 As shown in (b), the product of Comparative Example 1 is as follows: Figure 4 As shown in (c), it is obvious that after charge-discharge cycles, the lithium metal prepared in Comparative Example 1 began to show defects such as dendrites, dead lithium, and fluffy structures on its surface, and the surface was not smooth and even, and the overall structure was damaged. In contrast, the self-healing fast ion conductor lithium metal prepared in Example 1 still had a relatively smooth surface.

[0069] Subsequently, the products prepared in the remaining examples and comparative examples were subjected to the same charge-discharge cycle test, and the results are shown in Table 1.

[0070] Table 1

[0071]

[0072] As can be seen from Table 1, the products obtained in each embodiment have good specific capacity and cycle stability when applied to lithium-ion batteries. However, the products obtained in Comparative Examples 2 to 6 have poor performance due to improper selection of active components or improper addition ratio of raw materials during product preparation.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A self-healing fast-ion conductor lithium metal anode, characterized in that, It includes a lithium metal layer and an artificial SEI film covering the upper surface of the lithium metal layer; the artificial SEI film is a mixture of a carbon skeleton and its supported active components, the active components including nano-eutectic alloy particles and cuprous nitride; The mass ratio of the nano-eutectic alloy particles to copper nitride is 1:(1~3); The method for preparing the self-healing fast-ion conductor lithium metal anode includes the following steps: (1) Preparation of dispersed nano-eutectic alloy particles; (2) The dispersed nano-eutectic alloy particles and cuprous nitride are evenly dispersed in a dispersion solvent, and then carbon nanotubes are added and the resulting mixture is subjected to ultrasonic dispersion treatment once to obtain suspension A; graphene oxide gel is added to suspension A and subjected to ultrasonic dispersion treatment a second time to obtain gel B; gel B is placed in a protective atmosphere for heating and heat preservation treatment, then crushed, ground and dried to obtain precursor powder C; the mass ratio of carbon nanotubes to graphene oxide gel is (0.5~1):(0.5~1.5); (3) The precursor powder C is prepared into a slurry with adhesive and solvent and coated on the lithium metal layer. After drying, the self-healing fast ion conductor lithium metal anode is obtained. The mass ratio of the nano-eutectic alloy particles, cuprous nitride, carbon nanotubes, and graphene oxide gel is 1:(1~3):(0.5~1):(0.5~1.5).

2. The self-healing fast-ion conductor lithium metal anode as described in claim 1, characterized in that, The nano-eutectic alloy particles are gallium and tin alloy particles, and the mass ratio of gallium to tin in the alloy particles is (9:1) to (4:6).

3. The self-healing fast-ion conductor lithium metal anode as described in claim 1, characterized in that, The particle size of the nano-eutectic alloy particles is 100~200nm.

4. The self-healing fast ion conductor lithium metal anode as described in claim 1, characterized in that, The thickness ratio of the lithium metal layer to the artificial SEI film is 1:(0.08~0.4).

5. The self-healing fast ion conductor lithium metal anode as described in claim 1, characterized in that, Includes at least one of the following (a) to (c): (a) In step (2), the dispersing solvent is anhydrous ethanol, the time for the first ultrasonic dispersion treatment is 8~12 min, and the time for the second ultrasonic dispersion treatment is 18~22 min; (b) The specific steps of the heating and heat preservation treatment in step (2) are as follows: heat the gel liquid B to 150~200℃ and keep it at 1~3h, then transfer it to an environment of 780~820℃ and keep it at 2~6h; (c) In step (3), the adhesive is styrene-butadiene rubber with a concentration of 35~45wt%, and the solvent is tetrahydrofuran.

6. The self-healing fast-ion conductor lithium metal anode as described in claim 1, characterized in that, The method for preparing the dispersed nano-eutectic alloy particles includes the following steps: The nano-eutectic alloy particles are added to a solvent containing a dispersant and mixed and ultrasonically dispersed for 10-30 minutes. After standing for 2.5-3.5 hours, they are centrifuged, filtered, and dried to obtain the dispersed nano-eutectic alloy particles.

7. The self-healing fast-ion conductor lithium metal anode as described in claim 6, characterized in that, The solvent is anhydrous ethanol, the dispersant is dodecyl mercaptan, and the mass ratio of the nano-eutectic alloy particles and the dispersant to the volume of the solvent is (0.35~0.4) g: 0.5 g: (5~20) mL.

8. The self-healing fast ion conductor lithium metal anode as described in claim 1, characterized in that, The method for preparing the cuprous nitride includes the following steps: After mixing cuprous oxide and urea at a molar ratio of 1:(2~4), the mixture is heated to 150~210℃ under a protective atmosphere and held for 6~18 hours. After cooling to room temperature, it is then heated to 80~120℃ under a protective atmosphere and held for 0.5~1 hours. After cooling, cuprous nitride is obtained.

9. The application of the self-healing fast ion conductor lithium metal anode as described in any one of claims 1 to 8 in the preparation of high-performance lithium-ion energy storage batteries.

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