A kind of preparation method of high compacted carbon coated natural graphite material

Abstract

The invention provides a preparation method of a highly compacted carbon-coated natural graphite material. The method comprises the following steps: with expanded natural graphite of which the interlayer space is 0.3470-0.3700 as a raw material, dissolving the raw material with an organic solvent, carrying out suction filtration, and keeping high pressure constant; adding a proper amount of mixed liquid of potassium peroxodisulfate and sodium hydrogen sulfite at 50-70 DEG C to obtain a material for forming a polymeric membrane on the graphite end surface; and finally carrying out carbonization treatment at 900-1900 DEG C, so as to obtain the highly compacted carbon-coated natural graphite material. According to the method provided by the invention, the end surface of the natural graphite is cladded; no volatile organic solvent is adopted; the method is friendly to environment; the processing technology has the advantages of being energy-saving and short in processing period; the compaction density of the material can be effectively improved and the material resistivity can be lowered under the condition that the product prepared by the method provided by the invention does not generate an adverse effect on other electrical properties.

Description

technical field [0001] The invention relates to a preparation method of a graphite material, in particular to a preparation method of a high-pressure compacted carbon-coated natural graphite material. Background technique [0002] Natural graphite is a crystalline material with a well-developed layered structure. When used as an anode material for lithium-ion batteries, it has the characteristics of high capacity, high compaction, good electrical conductivity, and excellent low-temperature performance. However, natural graphite also has obvious defects when used as a negative electrode material for lithium-ion batteries: the electrolyte will form solvation with lithium ions, and then co-embedded in graphite to undergo a reduction reaction, and the gas generated by the reaction can cause graphite crystals to pulverize and fail. It will damage the service life of the battery. At present, simple solid-phase coating technology is mostly used. Although the cycle performance of th...

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Problems solved by technology

However, natural graphite also has obvious defects when used as a negative electrode material for lithium-ion batteries: the electrolyte will form solvation with lithium ions, and then co-embedded in graphite to undergo a reduction reaction, and the gas generated by the reaction can cause graphite crystals to pulverize and fail. It will damage the service life of the battery. At present, simple solid-phase coating technology is mostly used. Although the cycle performance of the obtained material can be guaranteed to be significantly improved, at the same time, the material will also suffer from problems such as reduced compaction and increased powder resistivity. Lead to poor material energy density and low temperature performance

Using spray-drying coating or other liquid-phase coating technology, although the cycle performance, energy density and low-temperature performance of natural graphite anode materials can be taken into account, the processing technology has the problem of environmental pollution caused by the volatilization of a large amount of organic solvents, and this type of coating technology Strict requirements on equipment and high processing costs