A kind of purification method of anthracite-based microcrystalline graphite for preparing negative electrode material of lithium ion battery

Abstract

The invention discloses a method for purifying anthracite-based microcrystalline graphite for preparing negative electrode materials of lithium-ion batteries. Prepare ultra-fine powder with a particle size of less than 10 μm. At the same time, two kinds of inhibitors, self-made emulsified kerosene collector and 2# oil foaming agent are used to conduct one roughing and five times of refining to collect fixed carbon content of not less than 90.0 % concentrate as flotation ore; put the flotation ore into a mixed solution of one or more acids in a constant temperature water bath at 60-90°C, stir, and ultrasonically 30-60min, and wash the mixture until pH=7 , and then suction filtered, and dried at 110°C for 2 to 5 hours. The fixed carbon content of the purified microcrystalline graphite is not less than 99.0%. The anthracite-based microcrystalline graphite prepared by the present invention is used as the negative electrode material of the lithium ion battery, and the first reversible capacity is not less than 400mAh / g, which is higher than the theoretical capacity of graphite. After 100 cycles, the reversible capacity retention rate is not less than 90.0%. Compared with microcrystalline graphite before purification, it is significantly improved.

Description

technical field [0001] The invention belongs to the purification technology of high-purity anthracite-based microcrystalline graphite. The purified microcrystalline graphite is applied to the negative electrode material of lithium ion battery, and specifically relates to mechanical crushing, emulsified kerosene flotation, pickling process and the application of materials in new energy materials. Cross-cutting technologies in the fields of physics, chemistry and chemical power supplies. Background technique [0002] Anthracite-based microcrystalline graphite has low crystallinity and high ore grade. The ultrafine powder prepared by two-stage jaw crusher, one-stage impact hammer crushing, horizontal stirring mill-dry cyclone classification is isotropic, and the microcrystalline graphite grains Small, as a negative electrode material for lithium-ion batteries, the theoretical specific capacity is higher than that of flake graphite, but the high impurity content of natural micro...

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Problems solved by technology

[0002] Anthracite-based microcrystalline graphite has low crystallinity and high ore grade. The ultrafine powder prepared by two-stage jaw crusher, one-stage impact hammer crushing, horizontal stirring mill-dry cyclone classification is isotropic, and the microcrystalline graphite grains Small, as a negative electrode material for lithium-ion batteries, the theoretical specific capacity is higher than that of flake graphite, but the high impurity content of natural microcrystalline graphite leads to a decrease in the structural stability and electrical performance of lithium-ion batteries. Therefore, through deep processing of microcrystalline graphite, its purity is improved and improved Its structure becomes an urgent problem to be solved

[0003] There are five main purification processes for microcrystalline graphite. Chloride roasting method has the highest graphite recovery rate, but poor operation controllability, chlorine gas is poisonous, and high temperature method has the highest purity, but requires high raw materials, expensive equipment, and huge investment. , but the corrosion of the equipment is relatively serious. Some impurities in the flotation method are extremely fine and impregnated in the graphite, which cannot be completely dissociated from the monomer. Therefore, the purity of the obtained graphite is not high. Oxide impurities combine to form fluoride precipitates, resulting in a decrease in the fixed carbon content of microcrystalline graphite

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