Method for recycling natural graphite fine powder as negative pole material

Abstract

The invention provides a method for recycling natural graphite fine powder as a negative pole material. The method comprises the following steps: step A) taking 'tail material' produced in the production process of the natural graphite negative pole material of a lithium battery as raw material, adding a bonding agent and a pore-forming agent, performing kneading and granulation at a certain temperature, further performing roller pressing or pressing and performing carbonization at high temperature; step B) crushing, shaping and nodulizing the material after carbonization to obtain spherical or oval graphite powder which is in line with the requirement on particle size range, further performing high-temperature graphitizing and meanwhile, adding the 'tail material' which is re-collected in the crushing / nodulizing process into the step A) for recycling as the raw material; and step C) performing particle size allocation on the powder after nodulizing treatment and filling the powder into gaps between particles. The preparation method provided by the invention is safe and controllable in process; and by adopting the preparation method, the recycling of the low-value graphite 'tail material' is realized, and the prepared negative pole material has the advantages of good performances, and good recycling, rate charge and discharge and low-temperature performances.

Description

technical field [0001] The invention belongs to the field of energy, and relates to a method for negative electrode materials, in particular to a method that uses ultrafine graphite powder produced in the production process of natural graphite negative electrode materials—"tailing" as raw material, which is recycled and reused through treatment, and used as A method for lithium-ion battery anode materials. Background technique [0002] With the development of the automobile industry, the depletion of non-renewable fossil fuels such as oil and natural gas has attracted increasing attention, and air pollution and room temperature effects have also become global problems. In order to solve energy problems and achieve low-carbon environmental protection, based on the current level of energy technology development, electric vehicle technology has gradually become the focus of global economic development. The United States, Japan, Germany, China and other countries have successive...

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Problems solved by technology

However, the affinity between resin materials and graphite is poor, so the carbon materials obtained by pyrolysis and graphite are not firmly bonded, and the yield of carbon materials obtained by pyrolysis of resin is low, brittle, and the volatile content in the process of resin pyrolysis is high. , the specific surface area is high, the cohesive force of the resin is strong, it is easy to cause the coated particles to stick together, and the coating layer is easily damaged when crushed after heat treatment. At the same time, during the heat treatment process of the resin, there are too many small molecules in the resin , in the overflow process, it will cause too many voids on the surface of the coated material, resulting in an excessively large specific surface area of ​​the coated graphite, resulting in an excessively large initial irreversible capacity

[0006] The above problems affect the cycle efficiency, cycle stability and compressibility of graphite electrodes of resin-coated graphite materials.

However, when pitch, petroleum tar, coal tar or their mixtures are used to coat graphite, the specific surface area of ​​pitch pyrolytic carbon is smaller than that of resin pyrolytic carbon coated graphite, and the affinity with graphite is better, and the structure is firmer. During the heating process, it will be deformed due to melting. If the amount is too much, it will easily cause the mutual bonding of the coated graphite particles. If the amount is too small, it will easily cause uneven coating, and it will easily expand during the heating process, which will affect the electrical properties of graphite.

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