A secondary gas-phase coated silicon monoxide anode material and its preparation method

Abstract

The present invention discloses a secondary gas-phase coated silicon monoxide anode material and a preparation method thereof, belonging to the technical field of lithium-ion battery electrode materials. A zinc metal framework is in-situ generated on the surface of graphene oxide nanosheets to obtain zinc metal framework / graphene nanosheets. Then, the zinc metal framework / graphene nanosheets are mixed into water-based epoxy resin to coat the lanthanum-doped magnesium secondary gas-phase coated silicon monoxide powder, and then carbonized to obtain carbon-coated lanthanum-doped magnesium silicon monoxide powder. The carbon-coated lanthanum-doped magnesium silicon monoxide powder, binder, conductive carbon black agent and deionized water are added to a mixing and defoaming machine, stirred and mixed, and dried to prepare the secondary gas-phase coated silicon monoxide anode material; it has higher electrical conductivity, first Coulomb efficiency, 100-cycle capacity retention rate and lower volume change percentage.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery electrode materials, and particularly relates to a secondary gas-phase coated silicon monoxide negative electrode material and a preparation method thereof. Background Art

[0002] With the rapid development of new energy vehicles, wearable devices, energy storage systems and other fields, lithium-ion batteries, as their core power sources, have increasingly higher requirements for energy density, cycle life and safety performance. As a key component of lithium-ion batteries, the performance of the negative electrode material directly affects the overall performance of the battery. At present, although commercial graphite negative electrode materials have been widely used, their theoretical specific capacity is limited and it is difficult to meet the requirements of high-energy density batteries. Therefore, the development of new high-performance negative electrode materials has become a research hotspot in the field of lithium-ion batteries. As a potential high-capacity negative electrode material, silicon monoxide has a high theoretical specific capacity and a moderate lithium intercalation potential, but there are still problems such as low initial Coulomb efficiency, low lithium deintercalation capacity and poor conductivity in its practical application.

[0003] The Chinese patent application with the publication number CN112086630A discloses a preparation method and a product of a silicon monoxide composite negative electrode material. The composite negative electrode material uses silicon and silicon dioxide as starting materials, generates silicon monoxide through a disproportionation reaction; after vaporizing the silicon monoxide, it is introduced into a chemical vapor deposition furnace containing a carbon material, and the primary product is obtained after chemical vapor deposition; finally, carbon coating is carried out to obtain the silicon monoxide composite negative electrode material. The lithium-ion battery assembled with this composite negative electrode material has a high capacity.

[0004] However, in lithium-ion battery products, the lithium ions in the silicon monoxide negative electrode material and the positive electrode material are prone to generate irreversible lithium oxide, resulting in a decrease in the initial Coulomb efficiency and capacity retention rate of the product. Summary of the Invention

[0005] In the present invention, lanthanum and magnesium are doped with silicon monoxide through a secondary gas-phase reaction, and a Zn metal framework is uniformly dispersed in water by being loaded on graphene oxide nanosheets and combined with water-based epoxy resin. Double carbon coating is achieved by spray drying, and after argon protection, a secondary gas-phase coated silicon monoxide negative electrode material is obtained.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a secondary gas-phase coated silicon monoxide negative electrode material, comprising the following steps:

[0008] Step 1: In-situ generate a zinc metal framework on the surface of graphene oxide nanosheets to obtain zinc metal framework / graphene nanosheets, and then mix the zinc metal framework / graphene nanosheets into waterborne epoxy resin and coat the lanthanum-doped magnesium secondary vapor-coated silicon oxide powder to obtain resin-coated lanthanum-doped magnesium silicon oxide powder;

[0009] Step 2: Place the resin-coated lanthanum-doped magnesium silicon oxide powder in a tube furnace, keep it at 600 - 800 °C for 30 - 60 min under argon protection, and then naturally cool it to room temperature to obtain carbon-coated lanthanum-doped magnesium silicon oxide powder;

[0010] Step 3: Add the carbon-coated lanthanum-doped magnesium silicon oxide powder, binder, conductive carbon black agent and deionized water into a mixing and degassing machine and stir for 15 - 30 min, dry the product to constant weight to prepare the secondary vapor-coated silicon oxide anode material.

[0011] Furthermore, the mass ratio of the carbon-coated lanthanum-doped magnesium silicon oxide powder, binder, conductive carbon black agent and deionized water is 8 - 10:1 - 3:1 - 3:15 - 17.

[0012] Furthermore, the zinc metal framework / graphene nanosheets are specifically prepared through the following steps:

[0013] Mix N,N-dimethylformamide and absolute ethanol to obtain a mixed solution, dissolve 2-aminoterephthalic acid and acetic acid in the mixed solution and add them into a reaction kettle, add zinc acetate and graphene oxide nanosheets and ultrasonically disperse for 10 - 20 min, keep it at 100 - 150 °C for 8 - 12 h, naturally cool it to room temperature, centrifuge to collect the precipitate, wash the precipitate with absolute ethanol, and dry it to obtain zinc metal framework / graphene nanosheets.

[0014] Furthermore, the mixed solution is obtained by mixing N,N-dimethylformamide and absolute ethanol according to a mass ratio of 9:1.

[0015] Furthermore, the dosage ratio of 2-aminoterephthalic acid, acetic acid, mixed solution, zinc acetate and graphene oxide nanosheets is 2 - 4 g:0.8 - 1.2 g:200 mL:0.8 - 1.2 g:1.5 - 2 g.

[0016] Furthermore, the resin-coated lanthanum-doped magnesium silicon oxide powder is specifically prepared through the following steps:

[0017] Add the zinc metal framework / graphene nanosheets, waterborne epoxy resin and water into a stirring kettle and stir and mix them, then add the lanthanum-doped magnesium secondary vapor-coated silicon oxide powder and ultrasonically disperse for 15 - 30 min, spray-dry the obtained mixed solution by a spray dryer, and then vacuum-dry the obtained powder at 90 - 110 °C for 4 - 6 h to obtain resin-coated lanthanum-doped magnesium silicon oxide powder with a particle size of 4.5 - 5 μm.

[0018] Furthermore, the dosage ratio of the zinc metal framework / graphene nanosheets, waterborne epoxy resin and water is 3 - 4 g : 60 - 80 g : 1000 - 1200 mL.

[0019] Furthermore, the lanthanum-doped magnesium secondary vapor-phase coated silicon monoxide powder is prepared by the following steps:

[0020] Mix the lanthanum powder, magnesium powder, silicon powder and silicon dioxide powder evenly and transfer them into a vacuum furnace. Keep them at a vacuum degree of 1 - 1.2 Pa and a temperature of 1000 - 1100 °C for 2 - 4 h, then raise the temperature to 1400 - 1500 °C and keep them for 20 - 24 h. Naturally cool the product to room temperature and grind it to obtain the lanthanum-doped magnesium secondary vapor-phase coated silicon monoxide powder with a particle size of 3 - 4 μm.

[0021] Furthermore, the mass ratio of the lanthanum powder, magnesium powder, silicon powder and silicon dioxide powder is 0.1 - 0.3 : 1 - 1.2 : 3 - 3.2 : 6 - 6.2.

[0022] Advantages of the present invention:

[0023] 1. During the preparation of the secondary vapor-phase coated silicon monoxide anode material of the present invention, firstly, the lanthanum-doped magnesium secondary vapor-phase coated silicon monoxide powder is obtained by using the method of secondary vapor-phase reaction. Then, the zinc metal framework / graphene nanosheets are mixed into the waterborne epoxy resin and used to coat the lanthanum-doped magnesium secondary vapor-phase coated silicon monoxide powder to obtain the resin-coated lanthanum-doped magnesium silicon monoxide powder, which has higher conductivity, first Coulomb efficiency, 100-cycle capacity retention rate and lower volume change percentage.

[0024] 2. In the lanthanum-doped magnesium secondary vapor-phase coated silicon monoxide powder of the present invention, the atomic radii of lanthanum and magnesium are relatively large. After doping, a rigid network structure can be formed to inhibit the volume expansion of the active phase of silicon monoxide. Moreover, the doped lanthanum and magnesium reduce a part of silicon monoxide, reduce the oxygen content in the material, reduce the content of the irreversible phase of lithium oxide generated by the reaction of the silicon monoxide anode material with lithium ions during the first charging, and reduce the irreversible capacity of the silicon monoxide anode material, thereby improving the Coulomb efficiency of the material.

[0025] 3. In the resin-coated lanthanum-doped magnesium silicon monoxide powder of the present invention, zinc metal frameworks / graphene nanosheets are dispersed. After the zinc metal frameworks are combined with graphene oxide nanosheets, the hydrophilicity of the graphene oxide nanosheets is utilized to improve their dispersibility in water-based epoxy resin and prevent material agglomeration. After the resin-coated lanthanum-doped magnesium silicon monoxide powder is carbonized, the zinc metal frameworks therein form zinc oxide particles with a stable porous structure. Dispersed in the carbon-coated shell, they can expand cracks, disperse stress, and zinc oxide may form a stable interface in the electrolyte, reduce side reactions, improve cycle stability, and thus increase the 100-cycle capacity retention rate of the silicon monoxide negative electrode material. Detailed Embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Embodiment 1: A preparation method of a secondary gas-phase coated silicon monoxide negative electrode material includes the following steps:

[0028] S1: Mix 0.1 kg of lanthanum powder, 1 kg of magnesium powder, 3 kg of silicon powder, and 6 kg of silicon dioxide powder evenly and transfer them into a vacuum furnace. Keep them at a vacuum degree of 1 Pa and a temperature of 1000 °C for 2 h, then raise the temperature to 1400 °C and keep it for 20 h to generate silicon monoxide vapor, magnesium vapor, and lanthanum vapor in the furnace. The uniformly mixed gaseous mixture is quickly condensed to form lanthanum-magnesium-silicon monoxide material. The product is naturally cooled to room temperature and ground to obtain lanthanum-doped magnesium secondary gas-phase coated silicon monoxide powder with a particle size of 3-4 μm.

[0029] As a strong reducing agent, magnesium preferentially reacts with silicon dioxide to form silicon monoxide under high-temperature vacuum conditions. The vapors of magnesium and lanthanum diffuse together in a vacuum to form a composite doping layer. The high diffusion rate of magnesium and the strong oxidation tendency of lanthanum are complementary, inhibiting the coarsening, agglomeration, and volume expansion of silicon grains and promoting uniform doping.

[0030] S2: Mix N,N-dimethylformamide and absolute ethanol according to a mass ratio of 9:1 to obtain a mixed solution. Dissolve 2 g of 2-aminoterephthalic acid and 0.8 g of acetic acid in 200 mL of the mixed solution and add them to a reaction kettle. Add 0.8 g of zinc acetate and 1.5 g of graphene oxide nanosheets and ultrasonically disperse for 10 min. Keep it at 100 °C for 8 h, naturally cool to room temperature, centrifuge to collect the precipitate, wash the precipitate with absolute ethanol 3 times, and dry it at 60 °C for 12 h to obtain zinc metal frameworks / graphene nanosheets.

[0031] S3: Add 3 g of zinc metal framework / graphene nanosheets, 60 g of waterborne epoxy resin, and 1000 mL of water into a stirring kettle, stir at a rotation speed of 1000 r / min for 30 min, then add 100 g of lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder and ultrasonically disperse for 15 min; for the obtained mixed solution, spray-dry it using a spray dryer, and vacuum-dry the obtained powder at 90 °C for 4 h to obtain resin-coated lanthanum-doped magnesium silicon monoxide powder with a particle size of 4.5 - 5 μm.

[0032] S4: Place 30 g of resin-coated lanthanum-doped magnesium silicon monoxide powder in a tube furnace, keep it at 600 °C for 30 min under argon protection, and naturally cool to room temperature to obtain carbon-coated lanthanum-doped magnesium silicon monoxide powder.

[0033] As a carbon precursor, the hydroxyl groups and ether bonds on the molecular chain of epoxy resin can bind to the surface of lanthanum-doped magnesium silicon monoxide through hydrogen bonds to form a uniformly coated composite slurry.

[0034] S5: Add carbon-coated lanthanum-doped magnesium silicon monoxide powder, binder, conductive carbon black agent, and deionized water into a mixing and degassing machine according to a mass ratio of 8:1:1:15, stir for 15 min, and dry the product at 50 °C to constant weight to prepare a secondary vapor-coated silicon monoxide anode material.

[0035] Example 2: A preparation method of a secondary vapor-coated silicon monoxide anode material, comprising the following steps:

[0036] S1: Mix 0.2 kg of lanthanum powder, 1.1 kg of magnesium powder, 3.1 kg of silicon powder, and 6.1 kg of silicon dioxide powder evenly and transfer them into a vacuum furnace. Keep it at a vacuum degree of 1.1 Pa and a temperature of 1050 °C for 3 h, then raise the temperature to 1450 °C and keep it for 22 h to generate silicon monoxide vapor, magnesium vapor, and lanthanum vapor in the furnace. The uniformly mixed gaseous mixture is quickly condensed to form lanthanum magnesium-silicon monoxide material. Naturally cool the product to room temperature and grind it to obtain lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder with a particle size of 3 - 4 μm.

[0037] S2: Mix N,N-dimethylformamide and absolute ethanol according to a mass ratio of 9:1 to obtain a mixed solution. Dissolve 3 g of 2-aminoterephthalic acid and 1 g of acetic acid in 200 mL of the mixed solution and add them into a reaction kettle. Add 1 g of zinc acetate and 1.8 g of graphene oxide nanosheets and ultrasonically disperse for 10 - 20 min. Keep it at 120 °C for 10 h, naturally cool to room temperature, centrifuge to collect the precipitate, wash the precipitate 4 times with absolute ethanol, and dry it at 70 °C for 18 h to obtain zinc metal framework / graphene nanosheets.

[0038] S3: Add 3.5 g of zinc metal framework / graphene nanosheets, 70 g of waterborne epoxy resin, and 1100 mL of water into a stirring kettle, stir at a rotation speed of 1100 r / min for 50 min, then add 110 g of lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder and ultrasonically disperse for 20 min; for the obtained mixed solution, spray-dry it using a spray dryer, and vacuum-dry the obtained powder at 100 °C for 5 h to obtain resin-coated lanthanum-doped magnesium silicon monoxide powder with a particle size of 4.5 - 5 μm.

[0039] S4: Place 40 g of resin-coated lanthanum-doped magnesium silicon monoxide powder in a tubular furnace, keep it warm for 50 min under argon protection and at 700 °C, and naturally cool it to room temperature to obtain carbon-coated lanthanum-doped magnesium silicon monoxide powder.

[0040] S5: Add carbon-coated lanthanum-doped magnesium silicon monoxide powder, binder, conductive carbon black agent, and deionized water into a mixing and degassing machine according to a mass ratio of 9:2:2:16, stir for 20 min, and dry the product at 55 °C until it reaches a constant weight to prepare a secondary vapor-coated silicon monoxide anode material.

[0041] Example 3: A preparation method of a secondary vapor-coated silicon monoxide anode material, comprising the following steps:

[0042] S1: Mix 0.3 kg of lanthanum powder, 1.2 kg of magnesium powder, 3.2 kg of silicon powder, and 6.2 kg of silicon dioxide powder evenly and transfer them into a vacuum furnace. Keep it warm at a vacuum degree of 1.2 Pa and a temperature of 1100 °C for 4 h, then raise the temperature to 1500 °C and keep it warm for 24 h to generate silicon monoxide vapor, magnesium vapor, and lanthanum vapor in the furnace. The uniformly mixed gaseous mixture undergoes rapid condensation to form lanthanum magnesium-silicon monoxide material. Naturally cool the product to room temperature and grind it to obtain lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder with a particle size of 3 - 4 μm.

[0043] S2: Mix N,N-dimethylformamide and absolute ethanol according to a mass ratio of 9:1 to obtain a mixed solution. Dissolve 4 g of 2-aminoterephthalic acid and 1.2 g of acetic acid in 200 mL of the mixed solution, add it into a reaction kettle, add 1.2 g of zinc acetate and 2 g of graphene oxide nanosheets, and ultrasonically disperse for 20 min. Keep it warm at 150 °C for 12 h, naturally cool it to room temperature, centrifuge to collect the precipitate, wash the precipitate 5 times with absolute ethanol, and dry it at 80 °C for 24 h to obtain zinc metal framework / graphene nanosheets.

[0044] S3: Add 4 g of zinc metal framework / graphene nanosheets, 80 g of waterborne epoxy resin, and 1200 mL of water into a stirring kettle, stir at a rotation speed of 1200 r / min for 60 min, then add 120 g of lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder and ultrasonically disperse for 30 min; for the obtained mixed solution, spray-dry it using a spray dryer, and vacuum-dry the obtained powder at 110 °C for 6 h to obtain resin-coated lanthanum-doped magnesium silicon monoxide powder with a particle size of 4.5 - 5 μm.

[0045] S4: Place 50 g of resin-coated lanthanum-doped magnesium silicon monoxide powder in a tube furnace, keep it at 800 °C for 60 min under argon protection, and naturally cool to room temperature to obtain carbon-coated lanthanum-doped magnesium silicon monoxide powder.

[0046] S5: Add carbon-coated lanthanum-doped magnesium silicon monoxide powder, binder, conductive carbon black agent, and deionized water into a mixing and degassing machine according to a mass ratio of 10:3:3:17, stir for 30 min, and dry the product at 60 °C to constant weight to prepare a secondary vapor-coated silicon monoxide anode material.

[0047] The binder used in Examples 1 - 3 is polyvinylidene fluoride.

[0048] Comparative Example 1: The difference from Example 1 is that no lanthanum powder is added in step S1, and the prepared magnesium-doped secondary vapor-coated silicon monoxide powder is used instead of the lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder, and the remaining steps remain unchanged to prepare a silicon monoxide anode material.

[0049] Comparative Example 2: The difference from Example 1 is that no lanthanum powder and magnesium powder are added in step S1, and the prepared secondary vapor-coated silicon monoxide powder is used instead of the lanthanum-doped magnesium secondary vapor-coated silicon monoxide powder, and the remaining steps remain unchanged to obtain a silicon monoxide anode material.

[0050] Comparative Example 3: The difference from Example 1 is that in step S3, conventional graphene oxide nanosheets are used to replace the zinc metal framework / graphene nanosheets prepared in step S2, and the remaining steps remain unchanged to prepare a silicon monoxide anode material.

[0051] The secondary vapor-coated silicon monoxide anode materials prepared in Examples 1 - 3 and Comparative Examples 1 - 3 are respectively mixed with acetylene black and polyvinylidene fluoride according to a mass ratio of 8:1:1, ground with N-methylpyrrolidone as a solvent until a uniform slurry is formed and coated on a copper foil, vacuum-dried at 90 °C for 24 h, and roll-pressed to obtain an electrode sheet; the obtained negative electrode sheet is cut into an electrode sheet with a diameter of 12 mm for battery assembly.

[0052] The assembly process was carried out in a glove box filled with argon, and the water and oxygen contents were both less than 0.01 ppm. The battery used a CR2032 button battery, with a lithium metal sheet as the counter electrode, a polypropylene film as the separator, and 1M lithium hexafluorophosphate as the electrolyte. The assembled button battery was tested for 0.5C charge-discharge cycle performance at 25°C within a voltage range of 0.01 - 1.5V, and the measured battery conductivity, initial Coulombic efficiency, percentage change in volume, and 100-cycle capacity retention rate were recorded. The results are shown in Table 1 as follows:

[0053] Table 1: Performance Test Results Table

[0054] Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Conductivity (S / cm) 32.1 32.8 33.4 31.3 32.2 32.0 Initial Coulombic efficiency (%) 89.3 89.9 91.2 86.5 85.4 89.5 Volume change percentage (%) 80 78 77 88 90 96 Capacity retention rate after 100 cycles (%) 82.7 83.3 84.2 76.8 75.3 72.8

[0055] As can be seen from Table 1, the performance of the secondary gas-phase coated silicon monoxide anode materials prepared in Examples 1 - 3 of the present invention is significantly better than that of the comparative examples, with higher conductivity, initial Coulombic efficiency, 100-cycle capacity retention rate, and lower percentage change in volume.

[0056] In Comparative Examples 1 and 2, the initial Coulombic efficiency and capacity retention rate decreased significantly, while the percentage change in volume increased. This is because the lanthanum-doped magnesium secondary gas-phase coated silicon monoxide powder has a better improvement effect on this aspect of performance compared to the single silicon monoxide material. It may be because the atomic radii of lanthanum and magnesium are relatively large, and a rigid network structure can be formed after doping to inhibit the volume expansion of the active phase of silicon monoxide. In addition, the doped lanthanum and magnesium reduce a part of the silicon monoxide, lowering the oxygen content in the material, reducing the content of the irreversible lithium oxide phase generated by the reaction of the silicon monoxide anode material with lithium ions during the first charge, and decreasing the irreversible capacity of the silicon monoxide anode material, thus improving the Coulombic efficiency of the material.

[0057] In Comparative Example 3, the percentage change in volume increased and the 100-cycle capacity retention rate decreased significantly. This may be because after the zinc metal framework / graphene nanoplate filler is carbonized, the zinc metal framework therein forms zinc oxide particles with a stable porous structure, which can expand cracks and disperse stress when dispersed in the carbon-coated shell. Without addition, it will lead to an increase in the percentage change in volume of the silicon monoxide anode material. And zinc oxide may form a stable interface in the electrolyte, reducing side reactions and improving cycle stability, thereby increasing the 100-cycle capacity retention rate of the silicon monoxide anode material.

[0058] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing a secondary gas-phase coated silicon oxide negative electrode material, characterized in that: The steps include: Step 1: in situ generating a zinc metal framework on the surface of graphene oxide nanosheets to obtain a zinc metal framework / graphene nanosheets, and then mixing the zinc metal framework / graphene nanosheets into a water-based epoxy resin and coating the lanthanum-doped magnesium secondary vapor-phase coated silicon oxide powder to obtain a resin-coated lanthanum-doped magnesium silicon oxide powder; Step 2: placing the resin-coated lanthanum-doped magnesium silicon oxide powder in a tube furnace, keeping the temperature at 600-800° C. for 30-60 minutes under argon protection, and naturally cooling to room temperature to obtain carbon-coated lanthanum-doped magnesium silicon oxide powder; Step 3: Add the carbon-coated lanthanum-doped magnesium silicon oxide powder, a binder, a conductive carbon black agent and deionized water into a mixing degassing machine and stir for 15-30 minutes, and dry the product to a constant weight to obtain a secondary gas-phase coated silicon oxide negative electrode material; The lanthanum-doped magnesium secondary vapor-phase coated silicon dioxide powder is prepared by the following steps: Lanthanum powder, magnesium powder, silicon powder and silicon dioxide powder are mixed evenly and transferred to a vacuum furnace, kept at a vacuum degree of 1-1.2 Pa and a temperature of 1000-1100°C for 2-4 hours, then heated to 1400-1500°C and kept for 20-24 hours, the product is naturally cooled to room temperature and ground to obtain lanthanum-doped magnesium secondary gas-coated silicon oxide powder with a particle size of 3-4 μm.

2. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 1, characterized in that: The mass ratio of the carbon-coated lanthanum-doped magnesium silicon oxide powder, the binder, the conductive carbon black agent and the deionized water in step three is 8-10:1-3:1-3:15-17.

3. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 1, characterized in that: The zinc metal framework / graphene nanosheet is specifically prepared by the following steps: N,N-dimethylformamide and anhydrous ethanol are mixed to obtain a mixed solution, 2-aminoterephthalic acid and acetic acid are dissolved in the mixed solution and added into a reaction kettle, zinc acetate and graphene oxide nanosheets are added and ultrasonically dispersed for 10-20 minutes, kept at 100-150° C. for 8-12 hours, naturally cooled to room temperature, centrifuged to collect precipitates, washed the precipitates with anhydrous ethanol, and dried to obtain zinc metal framework / graphene nanosheets.

4. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 3, characterized in that: The mixed liquid is obtained by mixing N,N-dimethylformamide and anhydrous ethanol in a mass ratio of 9:

1.

5. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 3, characterized in that: The usage ratio of the 2-aminoterephthalic acid, acetic acid, mixed solution, zinc acetate and graphene oxide nanosheets is 2-4g: 0.8-1.2g: 200mL: 0.8-1.2g: 1.5-2g.

6. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 1, characterized in that: The resin-coated lanthanum-doped magnesium silicon oxide powder is specifically prepared by the following steps: Zinc metal framework / graphene nanosheets, water-based epoxy resin and water are added into a stirring kettle and stirred and mixed, and then lanthanum-doped magnesium secondary vapor-coated silicon oxide powder is added and ultrasonically dispersed for 15-30 minutes, the obtained mixture is spray-dried by a spray dryer, and the obtained powder is vacuum-dried at 90-110° C. for 4-6 hours to obtain resin-coated lanthanum-doped magnesium silicon oxide powder with a particle size of 4.5-5 μm.

7. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 6, characterized in that: The usage ratio of the zinc metal framework / graphene nanosheets, water-based epoxy resin and water is 3-4 g: 60-80 g: 1000-1200 mL.

8. The method for preparing a secondary gas-phase coated silicon oxide negative electrode material according to claim 1, characterized in that: The mass ratio of the lanthanum powder, magnesium powder, silicon powder and silicon dioxide powder is 0.1-0.3:1-1.2:3-3.2:6-6.

2.

9. A secondary gas-phase coated silicon oxide negative electrode material, characterized in that: The material is prepared by the method for preparing a secondary gas-phase coated silicon monoxide negative electrode material as described in any one of claims 1 to 8.