Preparation method of efficient lithium oxalate lithium supplement agent

Abstract

The invention discloses a preparation method of an efficient lithium oxalate lithium supplement agent, and relates to the field of preparation of lithium ion battery positive electrode lithium supplement agents, and the preparation method comprises the following steps: S1, adding CNTs into an organic solvent for ultrasonic cleaning, then cleaning the CNTs with pure water, and finally drying; s2, concentrated sulfuric acid and concentrated nitric acid are prepared into a mixed acid solution, CNTs are added, and ultrasonic reflux is carried out; then cleaning the CNTs until the washing water is neutral, and finally drying to obtain oxidized CNTs; s3, the oxidized CNTs and (NH4) 2MoS4 are dissolved in water, then the precursor solution is atomized into micron-sized liquid drops, the micron-sized liquid drops are cracked in an inert atmosphere, and a three-dimensional composite material MoSx-CNTs is prepared; and S4, dissolving the three-dimensional composite material MoSx-CNTs and lithium oxalate in an ethanol solution, and drying in an inert atmosphere in a high-pressure spray dryer to obtain the lithium oxalate-coated MoSx-CNTs composite material. According to the invention, low-voltage and efficient decomposition of lithium oxalate is realized by regulating and controlling metal nodes and pore structures of MOFs, and meanwhile, the damage of residues to the microstructure of the battery is avoided.

Description

TECHNICAL FIELD

[0001] The application relates to the preparation field of lithium ion battery positive electrode lithium supplement agents, in particular to a preparation method of a high-efficiency lithium oxalate lithium supplement agent. BACKGROUND

[0002] With the continuous rise of the energy density demand of lithium ion batteries, the positive electrode lithium supplement agent as a core material for compensating the irreversible lithium loss in the cycle process has become one of the key technologies for improving the initial efficiency and cycle life of the battery. Although the traditional lithium supplement agent (such as Li5FeO4, Li2NiO2, etc.) can effectively supplement lithium, the problems of poor stability and many residual alkaline by-products seriously restrict the development of high-energy-density battery systems. Lithium oxalate (Li2C2O4) is considered as a potential new generation of lithium supplement agent due to its high theoretical capacity of 525 mAh / g and the characteristic of generating only gas after decomposition.

[0003] Chinese patent CN118231661A discloses a lithium oxalate lithium supplement agent and a preparation method and application thereof. The lithium oxalate lithium supplement agent comprises a three-dimensional network structure and matrix particles filled in the three-dimensional network structure. The three-dimensional network structure is formed by assembling carbon nanotubes, and the matrix particles comprise lithium oxalate particles, conductive carbon particles and catalyst particles. By limiting the structure and components of the lithium oxalate lithium supplement agent, the lithium oxalate is combined with the carbon material and the catalyst to reduce the decomposition voltage. The lithium oxalate lithium supplement agent applied to the positive electrode material can maximize the lithium supplement effect of lithium oxalate.

[0004] However, the above-mentioned patent uses molybdenum oxide, molybdenum carbide, molybdenum nitride and other materials, although they are all catalysts for improving the performance of the lithium oxalate lithium supplement agent, but Mo in them is in a fixed valence state, and the above-mentioned patent uses high-speed mechanical dispersion treatment for mixing, which cannot well control the size and distribution of the particles, and thus is not conducive to improving the activity and stability of the lithium supplement agent SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art, and a preparation method of a high-efficiency lithium oxalate lithium supplement agent is provided. By adjusting the metal nodes and channel structures of MOFs, the low-pressure and high-efficiency decomposition of lithium oxalate is realized, and the damage of the residual to the microstructure of the battery is avoided, thereby providing a new solution for the development of high-initial-efficiency and long-life lithium ion batteries.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a preparation method of a high-efficiency lithium oxalate lithium supplement agent, comprising the following steps:

[0007] S1, CNTs are added to an organic solvent for ultrasonic cleaning for 1-2 hours; then the solution is transferred to a centrifuge for dealcoholization treatment, and the CNTs are cleaned with pure water; finally, the cleaned wet material is placed in a vacuum drying oven at 85°C for drying treatment;

[0008] S2, concentrated sulfuric acid and concentrated nitric acid are mixed to form a mixed acid solution, and the CNTs cleaned and dried in step S1 are added, and ultrasonic reflux is performed for 2-4 hours; then the solution is transferred to a centrifuge for deacidification treatment, and the CNTs are repeatedly cleaned with pure water until the washing water is neutral, and finally the cleaned CNTs are placed in a vacuum drying oven at 85°C for drying treatment to obtain oxidized CNTs;

[0009] S3, the oxidized CNTs in step S2 and (NH4)2MoS4 are dissolved in water, and the solid content is controlled at 15%-25%. The precursor solution is atomized into micron-sized droplets by ultrasonic waves, and pyrolysis is performed at a cavity temperature of 325-385°C in an inert atmosphere to prepare a three-dimensional composite material MoSx-CNTs;

[0010] S4, the three-dimensional composite material MoSx-CNTs in step S3 and lithium oxalate are dissolved in an ethanol solution, and the solid content is controlled at 20%-30%, and sanding is performed for 1-2 hours. The solid content of the material is adjusted to 10%-15% by adding pure water, and then dried in a high-pressure spray dryer under the protection of an inert atmosphere at an air outlet temperature of 100-110°C to obtain a lithium oxalate@MoSx-CNTs composite material.

[0011] As a further description of the above technical solutions:

[0012] The organic solvent in step S1 is ethanol, propylene glycol, or acetone.

[0013] As a further description of the above technical solutions:

[0014] The ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution in step S2 is 3-5:1; and the mass ratio of CNTs to mixed acid solution in step S2 is 1:50-60.

[0015] As a further description of the above technical solutions:

[0016] The ultrasonic reflux temperature in step S2 is 80-90°C.

[0017] As a further description of the above technical solutions:

[0018] The pH in step S2 is neutral at 7.0±0.2.

[0019] As a further description of the above technical solutions:

[0020] The mass ratio of CNTs and (NH4)2MoS4 in the step S3 is 5:3-8; and the inert atmosphere in the step S3 is one or more of nitrogen, argon, helium, etc.

[0021] As a further description of the above technical solution:

[0022] The D50 of the three-dimensional composite material MoSx-CNTs in the step S3 is less than 2.0 microns.

[0023] As a further description of the above technical solution:

[0024] The mass ratio of the three-dimensional composite material MoSx-CNTs and lithium oxalate in the step S4 is 5-12:100.

[0025] As a further description of the above technical solution:

[0026] The inert atmosphere in the step S4 is one or more of nitrogen, argon, helium, etc.

[0027] The present application has the following beneficial effects:

[0028] 1. Compared with the prior art, the preparation method of the high-efficiency lithium oxalate lithium supplementing agent reduces the decomposition voltage: the traditional Ni, Co catalyst is abandoned, and a unique MOFs material MoSx-CNTs is used, so that the lithium oxalate can be efficiently decomposed at a lower voltage, the lithium oxalate residue is reduced, and the battery safety is increased.

[0029] 2. Compared with the prior art, the preparation method of the high-efficiency lithium oxalate lithium supplementing agent optimizes the material microstructure: by accurately controlling the metal nodes and channel structure of the MOFs, the damage of the residual materials to the microstructure of the battery in the traditional process is effectively prevented, which helps to prolong the cycle life of the battery.

[0030] 3. Compared with the prior art, the preparation method of the high-efficiency lithium oxalate lithium supplementing agent uses (NH4)2MoS4 as a precursor to prepare a three-dimensional composite material MoSx-CNTs, compared with the molybdenum oxide, molybdenum carbide, molybdenum nitride and other materials used as catalysts for improving the performance of the lithium oxalate lithium supplementing agent in the prior art, (NH4)2MoS4 has obvious differences with these materials in chemical properties, preparation process and finally formed material structure, etc. For example, molybdenum oxide is usually a metal oxide, while (NH4)2MoS4 is a precursor of sulfide, which will form MoSx phase with different electronic structures in the preparation process, and the valence of molybdenum is not equal to +2 to +6, and the Mo in the prior art is fixed valence. Such differences may result in significant differences in key properties such as catalytic activity and electrical conductivity of the prepared composite material, thereby enabling the lithium oxalate lithium supplementing agent of the present application to have unique performance advantages.

[0031] 4、Compared with the prior art, the preparation method of the high-efficiency lithium oxalate lithium supplementing agent, through specific process steps, MoSx-CNTS is compounded with lithium oxalate, and lithium oxalate@MoSx-CNTS composite material is successfully prepared. The composite structure not only realizes physical mixing, but also makes lithium oxalate uniformly distributed on the surface or inside the pores of MoSx-CNTS by precisely controlling process parameters such as solid content, sanding time, spray drying conditions, etc. Compared with the existing technology, the composite mixing of lithium oxalate and conductive carbon, catalyst is processed by high-speed mechanical dispersion, and the compounding of lithium oxalate and MoSx-CNTS in the application is realized by sanding and spray drying in ethanol solution. This process can better control the size and distribution of particles, and further improve the activity and stability of the lithium supplementing agent. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The lithium oxalate for the preparation method of the high-efficiency lithium oxalate lithium supplementing agent provided by the application

[0033] The SEM diagram of MoSx-CNTS;

[0034] Figure 2 The Raman test diagram of CNTs before and after acid treatment for the preparation method of the high-efficiency lithium oxalate lithium supplementing agent provided by the application. DETAILED DESCRIPTION

[0035] Reference Figure 1 and Figure 2 The application provides a preparation method of a high-efficiency lithium oxalate lithium supplementing agent, which comprises the following steps:

[0036] S1, CNTs are added into an organic solvent for ultrasonic cleaning for 1-2 hours, wherein the organic solvent is ethanol, propylene glycol, acetone or the like; then the solution is transferred to a centrifuge for dealcoholization treatment, and the CNTs are cleaned with pure water; finally, the cleaned wet material is placed in a vacuum drying box at 85 DEG C for drying treatment;

[0037] S2, the concentrated sulfuric acid and concentrated nitric acid are mixed to form a mixed acid solution, wherein the ratio of the concentrated sulfuric acid to the concentrated nitric acid in the mixed acid solution is 3-5:1, and the CNTs cleaned and dried in step S1 are added, wherein the mass ratio of the CNTs to the mixed acid solution is 1:50-60, and ultrasonic reflux is performed for 2-4 hours at a temperature of 80-90°C; then the solution is transferred to a centrifuge for deacidification treatment, and the CNTs are repeatedly washed with pure water until the washing water is neutral, i.e., the pH value is 7.0±0.2, and finally, the washed CNTs are placed in a vacuum drying box at 85°C for drying treatment to obtain oxidized CNTs. Specifically, by precisely controlling the ratio of the concentrated sulfuric acid to the concentrated nitric acid in the mixed acid solution, the ultrasonic reflux temperature, and the pH value, the oxidation treatment of the CNTs can be more efficiently realized, the surface activity of the CNTs is significantly improved, the reaction of the CNTs with (NH4)2MoS4 is more sufficient, and then the three-dimensional composite material MoSx-CNTS is formed.

[0038] S3, the oxidized CNTs and (NH4)2MoS4 in step S2 are dissolved in water, and the solid content is controlled to be 15%-25%, wherein the mass ratio of the CNTs to (NH4)2MoS4 is 5:3-8; the precursor solution is atomized into micron-sized droplets by ultrasonic waves, and pyrolysis is performed in an inert atmosphere, which is one or more of nitrogen, argon, and helium, at a cavity temperature of 325-385°C to obtain the three-dimensional composite material MoSx-CNTS, wherein the D50 of the three-dimensional composite material MoSx-CNTS is less than 2.0 μm. Specifically, the three-dimensional MoSx-CNTS composite material (D50<2.0 μm) is directly synthesized in an inert atmosphere by using the ultrasonic atomization pyrolysis technology, and atomic-level coupling of MoSx and CNTS is realized. Compared with the ball milling method used in the prior art to mix the materials, this method can improve the uniformity and structural stability of the materials.

[0039] S4, the three-dimensional composite material MoSx-CNTS and lithium oxalate in step S3 are dissolved in an ethanol solution, and the solid content is controlled to be 20%-30%, wherein the mass ratio of the three-dimensional composite material MoSx-CNTS to lithium oxalate is 5-12:100, and sand milling is performed for 1-2 hours. The solid content of the material is adjusted to 10%-15% by supplementing pure water, and then drying is performed in a high-pressure spray dryer under the protection of an inert atmosphere, which is one or more of nitrogen, argon, and helium, at an air outlet temperature of 100-110°C to obtain the lithium oxalate@MoSx-CNTS composite material. Specifically, the high-pressure spray drying method is used to precisely control the composite structure of lithium oxalate and MoSx-CNTS in an inert atmosphere, and the performance of the composite material is further optimized.

[0040] Example 1:

[0041] 100 g of carbon nanotubes (CNTs) were added to a propylene glycol solution and subjected to ultrasonic treatment at a frequency of 45 Hz for 2 h. Subsequently, the solution was transferred to a centrifuge for dealcoholization treatment, and the CNTs were washed with pure water. Finally, the washed wet material was placed in a vacuum drying oven at 85°C for drying treatment.

[0042] Concentrated sulfuric acid and concentrated nitric acid were mixed in a ratio of 4:1 by volume to configure a mixed acid solution. 80 g of dried CNTs were added to 4000 g of the mixed acid solution, and ultrasonic reflux treatment was performed at 80°C for 2.5 hours. After the treatment was completed, the solution was transferred to a centrifuge for acid removal treatment, and the carbon nanotubes were repeatedly washed with pure water until the washing water was neutral. Finally, the washed carbon nanotubes were placed in a vacuum drying oven at 85°C for drying treatment.

[0043] CNTs and (NH4)2MoS4 were mixed in a mass ratio of 5:3 and dissolved in water, and the solid content of the solution was controlled to be 18%. Under a nitrogen protective atmosphere, three-dimensional composite MoS x -CNTs were prepared by ultrasonic spray pyrolysis at 360°C.

[0044] The three-dimensional composite MoS x -CNTs and lithium oxalate were dissolved in pure water in a mass ratio of 10:100, the solid content was controlled to be 20%, sand milling was performed for 2 h, the solid content of the material was adjusted to 10% by supplementing pure water, and drying was performed in a high-pressure spray dryer under a nitrogen atmosphere protection at an air outlet temperature of 105°C to obtain lithium oxalate@MoSx-CNTs.

[0045] Example 2:

[0046] 100 g of carbon nanotubes (CNTs) were added to a propylene glycol solution and subjected to ultrasonic treatment at a frequency of 45 Hz for 2 h. Subsequently, the solution was transferred to a centrifuge for dealcoholization treatment, and the CNTs were washed with pure water. Finally, the washed wet material was placed in a vacuum drying oven at 85°C for drying treatment.

[0047] Concentrated sulfuric acid and concentrated nitric acid were mixed in a ratio of 4:1 by volume to configure a mixed acid solution. 80 g of dried CNTs were added to 4000 g of the mixed acid solution, and ultrasonic reflux treatment was performed at 80°C for 2.5 hours. After the treatment was completed, the solution was transferred to a centrifuge for acid removal treatment, and the carbon nanotubes were repeatedly washed with pure water until the washing water was neutral. Finally, the washed carbon nanotubes were placed in a vacuum drying oven at 85°C for drying treatment.

[0048] CNTs and (NH4)2MoS4 were mixed in a mass ratio of 5:4 and dissolved in water to control the solid content of the solution to 18%. Under nitrogen protection atmosphere, the three-dimensional composite material MoS was prepared by ultrasonic spray pyrolysis at 360 ° C. x -CNTs.

[0049] The three-dimensional composite material MoS x -CNTs and lithium oxalate were dissolved in pure water in a mass ratio of 10:100, with the solid content controlled at 20%. The mixture was sand-milled for 2 hours, and the solid content of the material was adjusted to 10% by adding pure water. The mixture was then dried in a high-pressure spray dryer under nitrogen atmosphere at an outlet temperature of 105°C to obtain lithium oxalate@MoSx-CNTs.

[0050] Example 3:

[0051] 100g of carbon nanotubes (CNTs) were added to a propylene glycol solution and ultrasonically treated at 45Hz for 2 hours. The solution was then transferred to a centrifuge for dealcoholization, and the CNTs were washed with pure water. Finally, the washed wet material was dried in a vacuum oven at 85°C.

[0052] Concentrated sulfuric acid and concentrated nitric acid were mixed in a 4:1 volume ratio to create a mixed acid solution. 80g of dried CNTs were weighed and added to 4000g of the mixed acid solution. The solution was then ultrasonically refluxed at 80°C for 2.5 hours. After treatment, the solution was transferred to a centrifuge for deacidification. The carbon nanotubes were then repeatedly rinsed with pure water until the rinse water was neutral. Finally, the rinsed carbon nanotubes were dried in a vacuum drying oven at 85°C.

[0053] CNTs and (NH4)2MoS4 were mixed in a mass ratio of 5:5 and dissolved in water to control the solid content of the solution to 18%. Under nitrogen protection atmosphere, the three-dimensional composite material MoS was prepared by ultrasonic spray pyrolysis at 360℃. x -CNTs.

[0054] The three-dimensional composite material MoS x -CNTs and lithium oxalate were dissolved in pure water in a mass ratio of 10:100, with the solid content controlled at 20%. The mixture was sand-milled for 2 hours, and the solid content of the material was adjusted to 10% by adding pure water. The mixture was then dried in a high-pressure spray dryer under nitrogen atmosphere at an outlet temperature of 105°C to obtain lithium oxalate@MoSx-CNTs.

[0055] Example 4:

[0056] 100 g of carbon nanotubes (CNTs) were added to a propylene glycol solution and subjected to ultrasonic treatment at a frequency of 45 Hz for 2 h. Subsequently, the solution was transferred to a centrifuge for dealcoholization treatment, and the CNTs were washed with pure water. Finally, the washed wet material was placed in a vacuum drying oven at 85°C for drying treatment.

[0057] Concentrated sulfuric acid and concentrated nitric acid were mixed in a ratio of 4:1 by volume to configure a mixed acid solution. 80 g of dried CNTs were added to 4000 g of the mixed acid solution, and ultrasonic reflux treatment was performed at 80°C for 2.5 hours. After the treatment was completed, the solution was transferred to a centrifuge for acid removal treatment, and the carbon nanotubes were repeatedly washed with pure water until the washing water was neutral. Finally, the washed carbon nanotubes were placed in a vacuum drying oven at 85°C for drying treatment.

[0058] CNTs and (NH4)2MoS4 were mixed in a mass ratio of 5:6 and dissolved in water, and the solid content of the solution was controlled to be 18%. Under a nitrogen protective atmosphere, three-dimensional composite MoS x -CNTs were prepared by ultrasonic spray pyrolysis at 360°C.

[0059] The three-dimensional composite MoS x -CNTs and lithium oxalate were dissolved in pure water in a mass ratio of 10:100, the solid content was controlled to be 20%, sand milling was performed for 2 h, the solid content of the material was adjusted to 10% by supplementing pure water, and drying was performed in a high-pressure spray dryer under a nitrogen atmosphere protection at an air outlet temperature of 105°C to obtain lithium oxalate@MoSx-CNTs.

[0060] Example 5:

[0061] 100 g of carbon nanotubes (CNTs) were added to a propylene glycol solution and subjected to ultrasonic treatment at a frequency of 45 Hz for 2 h. Subsequently, the solution was transferred to a centrifuge for dealcoholization treatment, and the CNTs were washed with pure water. Finally, the washed wet material was placed in a vacuum drying oven at 85°C for drying treatment.

[0062] Concentrated sulfuric acid and concentrated nitric acid were mixed in a ratio of 4:1 by volume to configure a mixed acid solution. 80 g of dried CNTs were added to 4000 g of the mixed acid solution, and ultrasonic reflux treatment was performed at 80°C for 2.5 hours. After the treatment was completed, the solution was transferred to a centrifuge for acid removal treatment, and the carbon nanotubes were repeatedly washed with pure water until the washing water was neutral. Finally, the washed carbon nanotubes were placed in a vacuum drying oven at 85°C for drying treatment.

[0063] CNTs and (NH4)2MoS4 were mixed in a mass ratio of 5:7 and dissolved in water, with the solid content of the solution controlled at 18%. A three-dimensional composite MoS x -CNTs.

[0064] The three-dimensional composite MoS x CNTs and lithium oxalate were dissolved in pure water in a mass ratio of 10:100, with the solid content controlled at 20%, sand milling for 2 h, and the solid content of the material adjusted to 10% by adding pure water. Drying was performed in a high-pressure spray dryer under a nitrogen atmosphere, with the outlet temperature controlled at 105°C, to obtain lithium oxalate@MoSx-CNTs.

[0065] Example 6:

[0066] 100 g of carbon nanotubes (CNTs) were added to a propylene glycol solution and subjected to ultrasonic treatment at a frequency of 45 Hz for 2 h. Subsequently, the solution was transferred to a centrifuge for dealcoholization treatment, and the CNTs were washed with pure water. Finally, the washed wet material was placed in a vacuum drying oven at 85°C for drying treatment.

[0067] Concentrated sulfuric acid and concentrated nitric acid were mixed in a volume ratio of 4:1 to prepare a mixed acid solution. 80 g of dried CNTs were added to 4000 g of the mixed acid solution, and ultrasonic reflux treatment was performed at 80°C for 2.5 h. After the treatment, the solution was transferred to a centrifuge for acid removal treatment, and the carbon nanotubes were repeatedly washed with pure water until the wash water was neutral. Finally, the washed carbon nanotubes were placed in a vacuum drying oven at 85°C for drying treatment.

[0068] CNTs and (NH4)2MoS4 were mixed in a mass ratio of 5:8 and dissolved in water, with the solid content of the solution controlled at 18%. A three-dimensional composite MoS x -CNTs.

[0069] The three-dimensional composite MoS x CNTs and lithium oxalate were dissolved in pure water in a mass ratio of 10:100, with the solid content controlled at 20%, sand milling for 2 h, and the solid content of the material adjusted to 10% by adding pure water. Drying was performed in a high-pressure spray dryer under a nitrogen atmosphere, with the outlet temperature controlled at 105°C, to obtain lithium oxalate@MoSx-CNTs.

[0070] Comparative Example 1:

[0071] CNT, NiO, lithium oxalate were added into ethanol with a mass ratio of 6:3:91, the solid content was controlled at 20%, sand mill sand mill for 2h treatment, then spray drying in high pressure spray dryer, nitrogen atmosphere protection, with the outlet temperature of 85℃ for drying, to get composite lithium oxalate.

[0072] The test results are shown in Table 1:

[0073]

[0074]

[0075] Table 1

[0076] Working principle: first, the CNTs were refluxed with concentrated sulfuric acid and concentrated nitric acid mixed solution, then the oxidized CNTs were mixed with (NH4) 2MoS4 solution and prepared into three-dimensional composite material MoSx-CNTs by ultrasonic spray pyrolysis method. Finally, with ethanol as solvent, the three-dimensional composite material MoSx-CNTs and lithium oxalate were sand milled by sand mill, and then lithium oxalate@MoSx-CNTs were prepared by high pressure spray dryer.

[0077] Finally, it should be pointed out that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the foregoing embodiments of the present application are described in detail, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement, within the spirit and principles of the present application, any modification, equivalent replacement, improvement, etc., should be included in the scope of protection of the present application.

Claims

1. A method for preparing a high-efficiency lithium oxalate lithium supplement, characterized in that: The following steps are involved: S1. Add CNTs to an organic solvent and perform ultrasonic cleaning for 1 to 2 hours; then transfer the solution to a centrifuge for dealcoholization, and wash the CNTs with pure water; finally, place the washed wet material in a vacuum drying oven at 85°C for drying; S2, preparing a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, adding the CNTs cleaned and dried in step S1, and performing ultrasonic reflux for 2 to 4 hours; The solution was then transferred to a centrifuge for deacidification, and the CNTs were repeatedly washed with pure water until the washing water became neutral. Finally, the washed CNTs were placed in a vacuum drying oven at 85°C for drying to obtain oxidized CNTs. S3. Dissolve the oxidized CNTs and (NH4)2MoS4 from step S2 in water, controlling the solid content to 15% to 25%. Atomize the precursor solution into micron-sized droplets using ultrasound, and pyrolyze them in an inert atmosphere at a chamber temperature of 325-385°C to produce the three-dimensional composite material MoSx-CNTs. S4. Dissolve the three-dimensional MoSx-CNTs composite material and lithium oxalate prepared in step S3 in an ethanol solution to a solid content of 20% to 30%, and sand-mill for 1 to 2 hours. Adjust the solid content of the material to 10% to 15% by adding pure water, and then dry the material in a high-pressure spray dryer under an inert atmosphere at an outlet temperature of 100-110°C to obtain a lithium oxalate@MoSx-CNTs composite material.

2. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: The organic solvent in step S1 is ethanol, propylene glycol, or acetone.

3. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: In the step S2, the ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3-5:1; and the mass ratio of CNTs to the mixed acid solution in the step S2 is 1:50-60.

4. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: The ultrasonic reflux temperature in step S2 is 80-90°C.

5. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: The pH in step S2 is neutral at 7.0±0.

2.

6. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: In step S3, the mass ratio of CNTs to (NH4)2MoS4 is 5:3-8; and in step S3, the inert atmosphere is one or more of nitrogen, argon, helium, etc.

7. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: The D50 of the three-dimensional composite material MoSx-CNTs in step S3 is less than 2.0 μm.

8. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: In step S4, the mass ratio of the three-dimensional composite material MoSx-CNTs to lithium oxalate is 5-12:

100.

9. The method for preparing a high-efficiency lithium oxalate lithium supplement according to claim 1, characterized in that: The inert atmosphere in step S4 is one or more of nitrogen, argon, helium, etc.

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