Preparation method for synthesizing lithium battery positive electrode material by solvent-free solid-phase method

Abstract

The invention discloses a preparation method for synthesizing a lithium battery positive electrode material by a solvent-free solid-phase method, particularly relates to the technical field of electrochemistry, and relates to the preparation method for synthesizing the lithium battery positive electrode material by the solvent-free solid-phase method. The lithium battery positive electrode material synthesized by the solvent-free solid-phase method is prepared from lithium acetate, nickel cobaltate, manganese cobaltate and a composite functional agent; the preparation raw materials of the lithium battery positive electrode material synthesized by the solvent-free solid phase method comprise the following components in parts by mass: 100 parts of lithium acetate, 74.3-97.2 parts of nickel cobaltate, 4.0-18.5 parts of manganese cobaltate and 6.8-14.6 parts of a composite functional agent, by adopting lithium acetate as a clean lithium source and combining with a solvent-free solid-phase synthesis method assisted by a composite functional agent, organic solvent pollution and harmful gas emission are eliminated from the source, and the lithium acetate is decomposed at a low temperature without solid residues by utilizing the characteristic of lithium acetate without solid residues and cooperating with a reducing atmosphere generated by decomposition of organic components in the functional agent, so that the lithium-ion battery cathode material is obtained. And the problem of pollution caused by high-temperature decomposition of the lithium salt in the traditional process is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and more specifically, to a method for preparing lithium battery cathode materials using a solvent-free solid-phase synthesis method. Background Technology

[0002] Lithium-ion batteries, as a highly efficient and clean electrochemical energy storage device, are widely used in portable electronic devices, electric vehicles, and large-scale smart grid energy storage. Their performance directly depends on the technological level of their cathode materials, anode materials, and electrolytes. Among these, cathode materials are the key to improving battery energy density, power density, and safety.

[0003] The preparation method of lithium battery cathode materials in related technologies relies on high-temperature solid-state reaction, including lithium source, transition metal source and organic solvent; among them, lithium source provides lithium ions during sintering, which constitute the main framework of cathode material and realize reversible insertion and extraction; transition metal source constitutes the crystal skeleton of material, which determines the specific capacity, working voltage and stability of material; organic solvent is used to wet and disperse precursor powder, and ball milling is used to achieve preliminary physical mixing of each component.

[0004] However, in practical use, it still has some drawbacks, such as being environmentally unfriendly, as the use of organic solvents requires subsequent drying and solvent recovery processes, posing safety risks of flammability and explosion and environmental pollution problems; poor uniformity, as the solute will undergo local recrystallization during solvent evaporation, resulting in uneven distribution of elements at the microscale, affecting the electrochemical performance of the final product; and low purity, as traditional methods mostly rely on organic solvent reaction media, and the solvent is difficult to completely remove and easily remains in the product, affecting electrochemical performance. Summary of the Invention

[0005] To improve the above-mentioned problems and reduce the issues of environmental unfriendliness, poor uniformity, and low purity in the synthesis of lithium battery cathode materials in related technologies, this invention provides a solvent-free solid-phase method for preparing lithium battery cathode materials, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A solvent-free solid-state synthesis method for preparing lithium battery cathode materials includes the following steps: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 20-30:1; the mixture is ball-milled for 6-12 hours at a speed of 300-600 r / min under an argon atmosphere to obtain the mixture. S2. Place the mixture obtained in S1 in a tube furnace and heat it to 200-300℃ under a flowing nitrogen atmosphere at a heating rate of 2-5℃ / min. Hold it at this temperature for 1-4 hours. Then, heat it again to 400-500℃ at a heating rate of 1-3℃ / min and hold it at this temperature for 3-6 hours to obtain the precursor. S3. The precursor obtained in S2 is placed in an alumina crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 750-850℃ within 8 minutes using a microwave power of 4-8kW, and then reacted at this temperature for 10-30 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. Transfer the quenched material to an atmosphere sintering furnace, introduce a SiF4 / Ar mixed gas with a volume concentration of 0.8%, and keep it at 400-500℃ for 1-3 hours. Then wash it repeatedly with pure water until the conductivity of the filtrate is less than 5μS / cm. Finally, dry it in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0007] Preferably, the components and mass fractions of the raw materials for preparing the solventless solid-phase synthesis of lithium battery cathode materials are as follows: 100 parts lithium acetate, 74.3-97.2 parts nickel cobalt oxide, 4.0-18.5 parts manganese cobalt oxide, and 6.8-14.6 parts composite functional agent.

[0008] Preferably, the composite functional agent is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate.

[0009] Preferably, the preparation method of the composite functional agent is as follows: Nanofiber silica powder was added to a mixed solvent of deionized water and anhydrous ethanol to prepare an initial suspension; the suspension was placed in an ultrasonic cell disruptor and ultrasonically dispersed for 30 minutes at a power of 600W and a frequency of 20kHz to obtain a nanofiber silica suspension for later use. In another container, citric acid powder and polyethylene glycol 6000 were dissolved together in deionized water at 60°C to prepare a clear mixed solution; then sodium polyacrylate, accounting for 0.5% of the total mass of citric acid and polyethylene glycol, was added as a dispersing agent, and the mixture was stirred until it was completely dissolved and homogeneous to obtain a citric acid-polyethylene glycol mixed solution. Basic magnesium carbonate powder was dried at 120℃ for 2 hours; the dried powder was added into a nano silica suspension, and then the mixture was transferred to a high-speed shear dispersion emulsifier and continuously sheared and dispersed at 8000 r / min for 15 min to obtain an activated composite suspension. Under continuous mechanical stirring at 500 r / min, a citric acid-polyethylene glycol mixed solution was added dropwise to the activated composite suspension at a rate of 10 mL / min using a constant flow pump. After the addition was complete, the entire mixture was transferred to a high-pressure homogenizer and homogenized five times under a pressure of 60 MPa before drying to obtain the composite functional agent.

[0010] Preferably, the composite functional agent is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 4.5-6:2.5-3.5:1.4-2:0.1-0.5.

[0011] Preferably, the initial suspension is an initial suspension of nanofiber silica powder with a solid content of 10 wt%.

[0012] Preferably, the mixed solvent of deionized water and anhydrous ethanol is composed of deionized water and anhydrous ethanol in a volume ratio of 3:1.

[0013] Preferably, the clarified mixed solution is a clarified mixed solution of citric acid powder and polyethylene glycol 6000 at a total concentration of 25 wt%.

[0014] 1. This invention uses lithium acetate as a clean lithium source and combines it with a solvent-free solid-phase synthesis method assisted by composite functional agents to eliminate organic solvent pollution and harmful gas emissions from the source. It utilizes the characteristic of lithium acetate decomposing at low temperature without solid residue, and combines it with the reducing atmosphere generated by the decomposition of organic components in the functional agents to effectively avoid the pollution problems caused by the high-temperature decomposition of lithium salts in traditional processes. 2. This invention utilizes the synergistic effect of mechanochemical solid-phase coordination reaction and the steric hindrance of composite functional agents. The solid-state coordination of citric acid and transition metal ions ensures elemental-level dispersion, while the composite template system formed by nano-silica and polyethylene glycol prevents particle agglomeration through steric hindrance effect, thereby improving uniformity. 3. This invention achieves complete decomposition and volatilization of organic components through segmented temperature control, and then promotes complete crystallization by utilizing the heating characteristics of microwave body. At the same time, the magnesium ions generated by the decomposition of basic magnesium carbonate achieve uniform doping and stable lattice during the rapid crystallization process, thereby improving the purity of the product. 4. This invention constructs a synergistic system of a three-dimensional multi-level porous structure and a surface gradient protective coating. The interconnected porous network constructed by the nanotemplate greatly promotes ion transport dynamics. At the same time, the fluorine oxysilicon coating formed by vapor deposition and the bulk carbon network jointly construct a stable interface. Combined with the lattice stabilization effect of magnesium ion doping, the electrochemical performance of the product is improved. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the embodiments of the present invention. Unless otherwise specified below, the raw materials used in the various examples and embodiments of the present invention are all commercially available common materials. Preparation Examples 1-5 A solvent-free solid-state synthesis method for lithium-ion battery cathode materials is described. The composition and their proportions are shown in Table 1, and the material is prepared using the following method: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. The functional agent is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 5:3:2:0.5. The specific preparation method of the composite functional agent is as follows: Nanofiber silica powder was added to a mixed solvent prepared by deionized water and anhydrous ethanol at a volume ratio of 3:1 to obtain an initial suspension with a solid content of 10 wt%. The suspension was placed in an ultrasonic cell disruptor and ultrasonically dispersed for 30 min at a power of 600 W and a frequency of 20 kHz to obtain a nanofiber silica suspension for later use. In another container, citric acid powder and polyethylene glycol 6000 were dissolved together in deionized water at 60°C to prepare a clear mixed solution with a total concentration of 25wt%. Then, sodium polyacrylate, accounting for 0.5% of the total mass of citric acid and polyethylene glycol, was added as a dispersant and stirred until completely dissolved and homogeneous to obtain a citric acid-polyethylene glycol mixed solution. Basic magnesium carbonate powder was dried at 120℃ for 2 hours; the dried powder was added into a nano silica suspension, and then the mixture was transferred to a high-speed shear dispersion emulsifier and continuously sheared and dispersed at 8000 r / min for 15 min to obtain an activated composite suspension. Under continuous mechanical stirring at 500 r / min, a citric acid-polyethylene glycol mixed solution was added dropwise to the activated composite suspension at a rate of 10 mL / min using a constant flow pump. After the addition was complete, the entire mixture was transferred to a high-pressure homogenizer and homogenized five times under a pressure of 60 MPa before drying to obtain the composite functional agent.

[0016] S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0017] Table 1: Components and their mass ratios (g) of the raw materials used in Preparation Examples 1-5

[0018] Preparation Example 6 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 20:1; and ball milled for 6 hours at a speed of 300 r / min under an argon atmosphere to obtain a mixture; S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0019] Preparation Example 7 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 30:1; and ball milled for 12 hours at a speed of 600 r / min under an argon atmosphere to obtain a mixture; S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0020] Preparation Example 8 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. S2. The mixture obtained in S1 is placed in a tube furnace and heated to 200°C at a heating rate of 2°C / min under a flowing nitrogen atmosphere. The temperature is held for 1 hour, and then heated to 400°C again at a heating rate of 1°C / min. The temperature is held for 3 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0021] Preparation Example 9 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. S2. The mixture obtained in S1 is placed in a tube furnace and heated to 300°C at a heating rate of 5°C / min under a flowing nitrogen atmosphere. The temperature is held for 4 hours, and then heated to 500°C again at a heating rate of 3°C / min. The temperature is held for 6 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0022] Preparation Example 10 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 750°C within 8 minutes using a microwave power of 4kW, and then reacted at this temperature for 10 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0023] Preparation Example 11 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 850°C within 8 minutes using a microwave power of 8kW, and then reacted at this temperature for 30 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 450℃ for 2 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0024] Preparation Example 12 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 400℃ for 1 hour, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0025] Preparation Example 13 A solvent-free solid-state method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the preparation method is as follows: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 25:1; the mixture is ball-milled for 8 hours at a speed of 500 r / min under an argon atmosphere to obtain the mixture. S2. The mixture obtained in S1 is placed in a tube furnace and heated to 280°C at a heating rate of 3°C / min under a flowing nitrogen atmosphere. The temperature is held for 2 hours, and then heated to 420°C again at a heating rate of 2°C / min. The temperature is held for 4 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into a corundum crucible and placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 800°C within 8 minutes using a microwave power of 6kW, and then kept at this temperature for 20 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. The quenched material is transferred to an atmosphere sintering furnace, and a SiF4 / Ar mixed gas with a volume concentration of 0.8% is introduced. After being kept at 500℃ for 3 hours, it is repeatedly washed with pure water until the conductivity of the filtrate is lower than 5μS / cm. Finally, it is placed in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

[0026] Preparation Example 14 A solventless solid-phase method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the composite functional agent in S1 is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 6:2.5:1.4:0.1.

[0027] Preparation Example 15 A solventless solid-phase method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the composite functional agent in S1 is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 4.5:3.5:1.5:0.5.

[0028] Preparation Example 16 A solventless solid-phase method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the composite functional agent in S1 is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 5.5:2.5:1.9:0.1.

[0029] Preparation Example 17 A solventless solid-phase method for synthesizing lithium battery cathode materials differs from Preparation Example 1 in that the composite functional agent in S1 is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 4.5:3.2:1.8:0.5.

[0030] Performance testing The solvent-free solid-state synthesized lithium battery cathode materials obtained in each embodiment were selected for testing. The test subjects were 170 samples of solvent-free solid-state synthesized lithium battery cathode materials, with 10 samples in each group. Their contamination level, uniformity, purity, and electrochemical performance were tested. The specific testing steps are as follows: Pollution level: Samples were taken during the solvent-free solid-phase synthesis of lithium-ion battery cathode materials prepared in the examples, and the entire preparation process was tracked. The exhaust gas from the sintering stage was collected and qualitatively and semi-quantitatively analyzed using gas chromatography-mass spectrometry. The wastewater generated during the washing process was tested for its chemical oxygen demand, total organic carbon, and heavy metal ion content to characterize the pollution level of the solvent-free solid-phase synthesis of lithium-ion battery cathode materials. The test results and evaluation criteria are as follows: Pass: No solvents are involved, the main components of the exhaust gas are carbon dioxide and water, and there are no sulfur or nitrogen oxides; the content of organic matter and heavy metals in the wastewater is lower than the detection limit (considered as low pollution level). Non-compliant: The main process uses a large amount of organic solvents; the exhaust gas or wastewater contains toxic and harmful substances (considered as a high level of pollution).

[0031] Uniformity: First, samples of the solvent-free solid-state synthesized lithium battery cathode material obtained in the examples were taken and analyzed using dispersive X-ray spectroscopy. The distribution maps of nickel, cobalt, manganese, and magnesium were observed, and the average relative standard deviation (RSD) of the four elements was calculated to characterize the defect control capability of the solvent-free solid-state synthesized lithium battery cathode material. The test results and evaluation criteria are as follows: RSD < 10% (considered as high uniformity); RSD > 10% (considered as low uniformity).

[0032] purity: First, samples of the solvent-free solid-state synthesized lithium battery cathode material obtained in the examples were taken, and X-ray diffraction was used to analyze the phase composition of the samples and calculate the impurity phase content, thereby characterizing the purity of the solvent-free solid-state synthesized lithium battery cathode material. The test results and evaluation criteria are as follows: Impurity phase content ≤1% (considered high purity); Impurity phase content >1% (considered low purity).

[0033] Electrochemical performance: First, samples of the solvent-free solid-state synthesized lithium battery cathode material obtained in the examples were taken and subjected to constant current charge-discharge tests at 4V and a low rate of 0.1C to obtain its charge-discharge efficiency and specific capacity; this was used to characterize the purity of the solvent-free solid-state synthesized lithium battery cathode material; the test results and evaluation criteria are as follows: Charge-discharge efficiency ≥80%, discharge specific capacity ≥150mAh / g (considered as having strong electrochemical performance); Charge-discharge efficiency <80%, discharge specific capacity <150mAh / g (considered as weak electrochemical performance).

[0034] It should be specifically noted that the solvent-free solid-state synthesized lithium battery cathode material obtained above is a solvent-free solid-state synthesized lithium battery cathode material produced in accordance with normal production methods. Defective solvent-free solid-state synthesized lithium battery cathode materials produced are discarded and disregarded.

[0035] Examples 1-5 A solvent-free solid-state method for synthesizing lithium battery cathode materials is shown in Table 2. The corresponding relationships of the preparation methods used are illustrated in Table 2.

[0036] Table 2: Comparison of the usage of solvent-free solid-state synthesized lithium battery cathode materials in Examples 1-5

[0037] The solvent-free solid-state synthesized lithium battery cathode materials from Examples 1-5 were extracted and their contamination level, average relative standard deviation (RSD), impurity phase content, charge / discharge efficiency, and discharge specific capacity were tested according to the above measurement steps and standards. The average value of the test results was recorded in Table 3.

[0038] Table 3: Performance test results of pollution level, mean relative standard deviation (RSD), mean relative standard deviation, charge / discharge efficiency, and discharge specific capacity in Examples 1-5

[0039] As shown in Table 3, the solvent-free solid-state synthesis of lithium-ion battery cathode materials in Examples 1-5 all effectively improve the production efficiency of the solvent-free solid-state synthesis of lithium-ion battery cathode materials. Using lithium acetate as a clean lithium source, its low-temperature decomposition characteristics enable efficient lithiation without introducing any solid residues, ensuring high purity of the product from the source and avoiding pollution from lithium salt decomposition. Using pre-synthesized nickel cobalt oxide and manganese cobalt oxide as transition metal sources, their spinel structure provides a uniform atomic-level mixing substrate, laying a solid foundation for subsequent molecular-level uniform reactions. The core composite functional agent system uses nanofiber silica as a rigid template, and subsequent selective etching constructs a three-dimensional interconnected mesoporous network within the material, greatly enhancing the ion transport rate. Citric acid plays a dual role. On the one hand, its carboxyl groups undergo solid-phase coordination reactions with transition metal ions, achieving uniform mixing at the atomic scale. On the other hand, the amorphous carbon network generated by its thermal decomposition coats the grains, inhibiting excessive grain growth and improving electronic conductivity. Polyethylene glycol 6000, as a soft template and dispersant, introduces micron-level primary channels into the material through its mild decomposition process, and forms a multi-level channel structure in synergy with citric acid decomposition. At the same time, its steric hindrance effect effectively prevents the agglomeration of raw materials. Basic magnesium carbonate, as a key structural stabilizer, generates highly active nano-magnesium oxide through thermal decomposition, which can enter the crystal lattice to achieve uniform bulk doping of magnesium ions, effectively inhibiting harmful phase transitions and cation mixing during cycling, and significantly enhancing lattice stability. Thus, the goal of improving the production efficiency of lithium battery cathode materials synthesized by solvent-free solid-phase method is achieved. All of them meet the pollution level requirements and are considered to have low pollution levels; the RSD is 3.2-4.5%, which is considered to have high uniformity; the impurity phase content is 0.34-0.52%, which is considered to have high purity; the charge-discharge efficiency is 87.2-91.5% and the discharge specific capacity is 185-218mAh / g, which is considered to have strong electrochemical performance. It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be improved by adjusting the proportions of these materials. Based on the data in Table 3, it is clear that the solvent-free solid-state synthesis of lithium-ion battery cathode materials using 100 parts lithium acetate, 88 parts nickel cobalt oxide, 5 parts manganese cobalt oxide, and 7.7 parts composite functional agent yields the highest uniformity, purity, and charge / discharge efficiency. This is attributed to the appropriate cobalt content effectively enhancing the material's electronic conductivity and providing a stable framework for the crystal lattice. The precisely controlled manganese content further enhances structural stability; on this basis, uniform magnesium ion doping significantly suppresses cation mixing and harmful phase transitions during charging and discharging; the optimized amount of composite functional agent is sufficient to ensure atomic-level mixing uniformity through the coordination effect of citric acid, and also constructs an ideal ion transport channel with the help of nano-silica template, while avoiding the residual carbon problem that may be caused by excessive organic components; the clean lithium acetate source and reasonable lithium ratio together ensure the completeness of the reaction and minimize the formation of impurity phases such as residual lithium, as obtained from Examples 1-5.

[0040] It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be increased by adjusting the proportions of these materials. Based on the data in Table 3, it is clear that the solvent-free solid-state synthesis of lithium-ion battery cathode materials using 100 parts lithium acetate, 97.2 parts nickel cobalt oxide, 4 parts manganese cobalt oxide, and 12.1 parts composite functional agent yields the highest discharge specific capacity. This is because the ultra-high content of nickel-cobalt-manganese composite oxide provides abundant redox reaction centers, allowing for the extraction and insertion of more lithium ions per unit mass of material, directly increasing the theoretical capacity limit. Simultaneously, it significantly increases the complex... The functional agent constructs a more developed three-dimensional mesoporous structure through a nano-silica template, which greatly shortens the solid-state diffusion path of lithium ions. The continuous carbon network formed by the decomposition of citric acid ensures the rapid conduction of electrons. This superior conductive framework effectively activates the deep active material inside the high-nickel material and significantly reduces the electrode polarization effect. The magnesium ion doping introduced by an appropriate amount of basic magnesium carbonate partially stabilizes the crystal structure without excessively sacrificing capacity. The clean lithium acetate source and sufficient lithium ratio ensure that the cathode material forms a complete and less defective layered structure during high-temperature crystallization, providing sufficient insertion and extraction channels for lithium ions, as obtained from Examples 1-5.

[0041] Examples 6-13 A solvent-free solid-state method for synthesizing lithium battery cathode materials is shown in Table 4.

[0042] Table 4: Comparison of the usage of lithium battery cathode materials synthesized by solvent-free solid-state method in Examples 6-13

[0043] The solvent-free solid-state synthesized lithium battery cathode materials from Examples 6-13 were extracted and their contamination level, average relative standard deviation (RSD), impurity phase content, charge / discharge efficiency, and discharge specific capacity were tested according to the above measurement steps and standards. The average value of the test results was recorded in Table 5.

[0044] Table 5: Performance test results of pollution levels, mean relative standard deviation (RSD), charge / discharge efficiency, and discharge specific capacity in Examples 1 and 6-13

[0045] As shown in Table 5, the solvent-free solid-state synthesis of lithium-ion battery cathode materials in Examples 1 and 6-13 effectively improves the production efficiency of the solvent-free solid-state synthesis of lithium-ion battery cathode materials. Using lithium acetate as a clean lithium source, its low-temperature decomposition characteristics enable efficient lithiation without introducing any solid residues, ensuring high purity of the product from the source and avoiding pollution from lithium salt decomposition. The pre-synthesized nickel cobalt oxide and manganese cobalt oxide are used as transition metal sources; their spinel structure provides a uniform atomic-level mixing substrate, laying a solid foundation for subsequent molecular-level uniform reactions. The core composite functional agent system uses nanofiber silica as a rigid template, and subsequent selective etching constructs a three-dimensional interconnected mesoporous network within the material, greatly enhancing the ion transport rate. Citric acid plays a dual role... On the one hand, its carboxyl groups undergo solid-phase coordination reactions with transition metal ions, achieving uniform mixing at the atomic scale. On the other hand, the amorphous carbon network generated by its thermal decomposition coats the grains, inhibiting excessive grain growth and improving electronic conductivity. Polyethylene glycol 6000, as a soft template and dispersant, introduces micron-level primary channels into the material through its mild decomposition process, and forms a multi-level channel structure in synergy with citric acid decomposition. At the same time, its steric hindrance effect effectively prevents the agglomeration of raw materials. Basic magnesium carbonate, as a key structural stabilizer, generates highly active nano-magnesium oxide through thermal decomposition, which can enter the crystal lattice to achieve uniform bulk doping of magnesium ions, effectively inhibiting harmful phase transitions and cation mixing during cycling, and significantly enhancing lattice stability. Thus, the goal of improving the production efficiency of lithium battery cathode materials synthesized by solvent-free solid-phase method is achieved. All of them have qualified pollution levels, which is considered to be low pollution levels; RSD is 3.8-4.5%, which is considered to be high uniformity; impurity phase content is 0.42-5.50%, which is considered to be high purity; charge-discharge efficiency is 88.7-90.2%; discharge specific capacity is 200-208mAh / g, which is considered to be strong electrochemical performance. It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be increased by adjusting the preparation conditions. Based on the data in Table 5, it is clear that during the preparation of solvent-free solid-state synthesis of lithium-ion battery cathode materials, the ball milling process at a ball-to-material mass ratio of 25:1 and a milling speed of 500 r / min for 8 hours yielded the highest uniformity, purity, charge-discharge efficiency, and discharge specific capacity. This is because this ball-to-material ratio ensures sufficient impact force while avoiding excessive collisions that introduce impurities. Furthermore, this milling speed and duration provide a continuous and gentle environment for the mechanochemical solid-state coordination reaction. The energy field can effectively disrupt the crystal structure of raw material particles, exposing fresh active surfaces to promote the coordination and bonding of citric acid and transition metal ions to achieve atomic-level uniform mixing. However, it will not cause excessive lattice defects or local overheating due to excessive impact, which would lead to premature decomposition of the raw materials. This controlled mechanical force allows the components of the composite functional agent to be uniformly dispersed and embedded in the reaction system, laying the foundation for the subsequent formation of a regular layered structure and a three-dimensional mesoporous network. At the same time, the appropriate energy input ensures that the decomposition of lithium acetate and the reaction of transition metal oxides can proceed synchronously and in a coordinated manner, thereby significantly improving the crystal integrity, elemental distribution uniformity and reaction conversion rate of the material, as obtained from Examples 1 and 6-7.

[0046] It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be improved by adjusting the preparation conditions. Based on the data in Table 5, it is clear that during the solvent-free solid-state synthesis of lithium-ion battery cathode materials, the following step-heating process—raising the temperature to 280℃ at a rate of 3℃ / min, holding for 2 hours, and then raising it again to 420℃ at a rate of 2℃ / min and holding for 4 hours—results in lithium-ion battery cathode materials prepared using this method exhibiting superior uniformity, purity, and charge / discharge efficiency. The highest discharge specific capacity was observed. The reason for this is that the first-stage conditions allowed polyethylene glycol 600 to fully melt and slowly decompose and volatilize, forming a continuous and uniformly distributed micron-scale initial pore framework within the material, while simultaneously reserving sufficient gas diffusion channels for subsequent decomposition reactions. The second-stage conditions ensured that citric acid could simultaneously complete the entire process of coordination bond breaking, carbonization reconstruction, and nano-carbon network coating, highly matching the decomposition sequence of basic magnesium carbonate—newly formed nano-magnesium oxide achieved atomic-level dispersion on the transition metal oxide surface, laying the foundation for subsequent lattice doping. This controlled thermal decomposition mechanism avoided pore collapse and component segregation caused by rapid heating, and through staged heat preservation, ensured the clean decomposition of lithium acetate and the pre-reaction of transition metal oxides were fully carried out. This eliminated organic residues while promoting the migration of magnesium ions to the shallow lattice layer, ultimately forming an intermediate with a complete carbon-coated network, a uniform magnesium-doped precursor, and a three-dimensional multi-level pore structure, as obtained in Examples 1 and 8-9.

[0047] It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be increased by adjusting the preparation conditions. Based on the data in Table 5, it is clear that during the preparation of solvent-free solid-state synthesis of lithium-ion battery cathode materials, the following conditions were observed: heating the precursor to 800℃ within 8 minutes using a microwave power of 6kW, followed by a second heating to 420℃ after a 20-minute isothermal reaction, and then holding at this temperature for 4 hours. These conditions resulted in the highest uniformity, purity, charge / discharge efficiency, and discharge specific capacity of the prepared solvent-free solid-state synthesized lithium-ion battery cathode material. This is attributed to the selective heating of polar molecules by microwaves. The material achieves uniform heating in the bulk phase, effectively avoiding the lag in heat conduction from the surface to the interior in traditional resistance furnaces, eliminating the component segregation problem caused by temperature gradients, and suppressing the formation of intermediate phases by rapidly crossing the low-temperature decomposition range. This reaction time ensures sufficient growth of the layered lattice and stable doping of magnesium ions, shortens the high-temperature duration, reduces the risk of lithium volatilization loss and abnormal grain growth, and allows the material to maintain ideal stoichiometry and microstructure while obtaining a complete crystal structure. At the same time, the carbon network pre-constructed in the precursor plays a microwave absorption and enhancement role in the microwave field, promoting uniform heat distribution and accelerating reaction kinetics, as obtained in Examples 1 and 10-11.

[0048] It is evident that, given a fixed amount of raw materials, the production efficiency of lithium-ion battery cathode materials can be increased by adjusting the preparation conditions. Based on the data in Table 5, it is clear that during the preparation of lithium-ion battery cathode materials using the solvent-free solid-state method, the highest uniformity, purity, charge / discharge efficiency, and discharge specific capacity were obtained when the temperature was raised to 420°C for 4 hours after holding at 400°C for 1 hour during crystallization. This is because the temperature and duration promote sufficient diffusion and surface reaction of the precursors for vapor deposition, forming a complete and dense protective layer on the outer edge of the cathode material particles. This inhibits crystallization of the coating structure caused by excessively high temperatures, ensuring the maintenance of its amorphous characteristics with high ionic conductivity. Simultaneously, this mild heat treatment condition allows the mesoporous framework and carbon network formed in the early stages of the material to be stabilized and solidified, avoiding pore collapse and structural stress concentration that may be caused by rapid heating, as observed in Examples 1 and 12-13.

[0049] Examples 14-17 A solvent-free solid-state method for synthesizing lithium battery cathode materials is shown in Table 6.

[0050] Table 6: Comparison of the usage of solvent-free solid-state synthesized lithium battery cathode materials in Examples 14-17

[0051] The solvent-free solid-state synthesized lithium battery cathode materials from Examples 14-17 were extracted and their contamination level, average relative standard deviation (RSD), impurity phase content, charge / discharge efficiency, and discharge specific capacity were tested according to the above measurement steps and standards. The average value of the test results was recorded in Table 7.

[0052] Table 7: Performance test results of pollution levels, mean relative standard deviation (RSD), charge / discharge efficiency, and discharge specific capacity for Examples 1, 14-17

[0053] As shown in Table 7, the solvent-free solid-state synthesis of lithium-ion battery cathode materials in Examples 1 and 14-17 effectively improves the production efficiency of the solvent-free solid-state synthesis of lithium-ion battery cathode materials. Using lithium acetate as a clean lithium source, its low-temperature decomposition characteristics enable efficient lithiation without introducing any solid residues, ensuring high purity of the product from the source and avoiding pollution from lithium salt decomposition. The pre-synthesized nickel cobalt oxide and manganese cobalt oxide are used as transition metal sources; their spinel structure provides a uniform atomic-level mixing substrate, laying a solid foundation for subsequent molecular-level uniform reactions. The core composite functional agent system uses nanofiber silica as a rigid template, and subsequent selective etching constructs a three-dimensional interconnected mesoporous network within the material, greatly enhancing the ion transport rate. Citric acid plays a dual role... On the one hand, its carboxyl groups undergo solid-phase coordination reactions with transition metal ions, achieving uniform mixing at the atomic scale. On the other hand, the amorphous carbon network generated by its thermal decomposition coats the grains, inhibiting excessive grain growth and improving electronic conductivity. Polyethylene glycol 6000, as a soft template and dispersant, introduces micron-level primary channels into the material through its mild decomposition process, and forms a multi-level channel structure in synergy with citric acid decomposition. At the same time, its steric hindrance effect effectively prevents the agglomeration of raw materials. Basic magnesium carbonate, as a key structural stabilizer, generates highly active nano-magnesium oxide through thermal decomposition, which can enter the crystal lattice to achieve uniform bulk doping of magnesium ions, effectively inhibiting harmful phase transitions and cation mixing during cycling, and significantly enhancing lattice stability. Thus, the goal of improving the production efficiency of lithium battery cathode materials synthesized by solvent-free solid-phase method is achieved. All of them meet the pollution level requirements and are considered to have low pollution levels; the RSD is 3.2-4.8%, which is considered to have high uniformity; the impurity phase content is 0.32-0.55%, which is considered to have high purity; the charge-discharge efficiency is 86.5-92.0% and the discharge specific capacity is 185-215mAh / g, which is considered to have strong electrochemical performance. It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be improved by adjusting the proportions of these materials. Based on the data in Table 7, it is clear that when preparing solvent-free solid-state synthesis of lithium-ion battery cathode materials, the composite functional agent prepared using 5.5 parts of nanofiber silica, 2.5 parts of citric acid, 1.9 parts of polyethylene glycol hexahydrate, and 0.1 parts of basic magnesium carbonate exhibits the highest uniformity, purity, and charge-discharge efficiency. This is because the moderately increased content of nanofiber silica effectively constructs a more developed and stable mesoporous framework structure, facilitating lithium-ion transport. This provides ample channels and maintains the structural integrity of the material. The citric acid ratio ensures sufficient metal coordination to achieve atomic-level uniform mixing. The moderate carbon coating layer formed by its thermal decomposition effectively promotes electron conduction and avoids the negative impact of excessive carbon residue on purity. The polyethylene glycol 6000 content generates a spatial synergistic effect with the silica template through its decomposition process, jointly constructing a through-hole multi-level pore system and optimizing the particle dispersion state of the precursor. The addition of trace amounts of basic magnesium carbonate effectively enhances lattice stability with magnesium ion doping while avoiding phase separation or impurity generation problems that may be caused by excessive magnesium elements. This was obtained from Examples 1 and 14-17.

[0054] It is evident that, given a fixed amount of raw materials, the production efficiency of solvent-free solid-state synthesis of lithium-ion battery cathode materials can be improved by adjusting the proportions of these materials. Based on the data in Table 7, it is clear that when preparing solvent-free solid-state synthesis of lithium-ion battery cathode materials, the composite functional agent prepared using 4.5 parts of nanofiber silica, 3.2 parts of citric acid, 1.8 parts of polyethylene glycol hexahydrate, and 0.5 parts of basic magnesium carbonate exhibits the highest uniformity, purity, and charge-discharge efficiency. This is attributed to the significantly increased proportion of citric acid, which enhances the chelation with transition metal ions, ensuring uniform elemental distribution. Furthermore, the sufficient thermal decomposition of citric acid forms a more complete and continuous carbon coating. The network effectively suppressed abnormal grain growth and improved electronic conductivity. Its reducing atmosphere reduced the oxidation of nickel ions and the volatilization of lithium during high-temperature sintering, and reduced the degree of cation mixing and the generation of impurity phases. An appropriate amount of nanofiber silica and a moderate amount of polyethylene glycol hexane synergistically constructed a stable multi-level porous template system, which ensured both ion transport efficiency and maintained the integrity of the particle structure. Meanwhile, basic magnesium carbonate achieved sufficient bulk magnesium ion doping through active magnesium oxide generated by thermal decomposition. These magnesium ions incorporated into the lattice effectively stabilized the layered structure like pinning points, suppressed phase transitions and oxygen evolution during cycling, and formed a synergistic protection mechanism with the surface carbon layer, greatly reducing interfacial side reactions, as obtained in Examples 1 and 14-17.

[0055] This specific embodiment is merely an explanation of the present invention and not a limitation thereof. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for preparing lithium battery cathode materials using a solvent-free solid-state synthesis method, characterized in that, Includes the following steps: S1. Lithium acetate, nickel cobalt oxide, manganese cobalt oxide, and composite functional agents are mixed and added to a ball mill, with the ball-to-material mass ratio controlled at 20-30:1; the mixture is ball-milled for 6-12 hours at a speed of 300-600 r / min under an argon atmosphere to obtain the mixture. S2. Place the mixture obtained in S1 in a tube furnace and heat it to 200-300℃ under a flowing nitrogen atmosphere at a heating rate of 2-5℃ / min. Hold it at this temperature for 1-4 hours. Then, heat it again to 400-500℃ at a heating rate of 1-3℃ / min and hold it at this temperature for 3-6 hours to obtain the precursor. S3. The precursor obtained in S2 is placed into an alumina crucible and then placed in a microwave sintering furnace. Under an oxygen atmosphere, the precursor is heated to 750-850℃ within 8 minutes using a microwave power of 4-8kW, and then reacted at this temperature for 10-30 minutes. After the reaction is completed, the precursor is immediately immersed in liquid nitrogen for rapid quenching to obtain the quenched precursor. S4. Transfer the quenched material to an atmosphere sintering furnace, introduce a SiF4 / Ar mixed gas with a volume concentration of 0.8%, and keep it at 400-500℃ for 1-3 hours. Then wash it repeatedly with pure water until the conductivity of the filtrate is less than 5μS / cm. Finally, dry it in a vacuum drying oven at 85℃ for 10 hours to obtain the solvent-free solid-phase synthesis of lithium battery cathode material.

2. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 1, characterized in that: The components and mass fractions of the raw materials for the solvent-free solid-state synthesis of lithium battery cathode materials are as follows: 100 parts lithium acetate, 74.3-97.2 parts nickel cobalt oxide, 4.0-18.5 parts manganese cobalt oxide, and 6.8-14.6 parts composite functional agent.

3. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 1, characterized in that: The composite functional agent is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate.

4. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 1, characterized in that: The specific preparation method of the composite functional agent is as follows: Nanofiber silica powder was added to a mixed solvent of deionized water and anhydrous ethanol to prepare an initial suspension; the suspension was placed in an ultrasonic cell disruptor and ultrasonically dispersed for 30 minutes at a power of 600W and a frequency of 20kHz to obtain a nanofiber silica suspension for later use. In another container, citric acid powder and polyethylene glycol 6000 were dissolved together in deionized water at 60°C to prepare a clear mixed solution; then sodium polyacrylate, accounting for 0.5% of the total mass of citric acid and polyethylene glycol, was added as a dispersing agent, and the mixture was stirred until it was completely dissolved and homogeneous to obtain a citric acid-polyethylene glycol mixed solution. Basic magnesium carbonate powder was dried at 120℃ for 2 hours; the dried powder was added into a nano silica suspension, and then the mixture was transferred to a high-speed shear dispersion emulsifier and continuously sheared and dispersed at 8000 r / min for 15 min to obtain an activated composite suspension. Under continuous mechanical stirring at 500 r / min, a citric acid-polyethylene glycol mixed solution was added dropwise to the activated composite suspension at a rate of 10 mL / min using a constant flow pump. After the addition was complete, the entire mixture was transferred to a high-pressure homogenizer and homogenized five times under a pressure of 60 MPa before drying to obtain the composite functional agent.

5. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 1, characterized in that: The composite functional agent is prepared from nanofiber silica, citric acid, polyethylene glycol 6000 and basic magnesium carbonate in a mass ratio of 4.5-6:2.5-3.5:1.4-2:0.1-0.

5.

6. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 4, characterized in that: The initial suspension is an initial suspension of nanofiber silica powder with a solid content of 10 wt%.

7. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 4, characterized in that: The mixed solvent of deionized water and anhydrous ethanol is composed of deionized water and anhydrous ethanol in a volume ratio of 3:

1.

8. The method for preparing lithium battery cathode material by solvent-free solid-state synthesis according to claim 4, characterized in that: The clarified mixed solution is a clarified mixed solution of citric acid powder and polyethylene glycol 6000 at a total concentration of 25 wt%.

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