Method for recovering a lithium ion battery anode material

Abstract

The invention relates to a method for recovering a lithium ion battery anode material. The method comprises the following steps: S1: collecting, crushing and sifting the graphite slag left after recovering metal of the lithium ion battery to obtain finer and more uniform graphite slag; S2: mixing graphite slag: asphalt: catalyst at a mass ratio of 100:1-20:1-10 to obtain a mixture; S3: under the protection of an inert gas atmosphere, carbonizing the graphite slag mixture at 500-1100 DEG C for 2-20 hours; then at 1500 DEG C-2250 DEG C graphitizating for 10-35 hours to obtain a graphite material. The method can obtain graphite anode material with excellent performance by using less asphalt, lower graphitization temperature and shorter graphitization time, and the performance of the obtainedgraphite anode material can directly meet the requirements for manufacturing a new lithium ion battery anode.

Description

technical field [0001] The invention relates to a treatment technology for waste lithium ion batteries, in particular to a method for recycling waste negative electrode materials of lithium ion batteries. Background technique [0002] Lithium-ion batteries have been widely used in electric vehicles, 3C, energy storage batteries and other fields. In recent years, with the promotion of the national new energy vehicle policy, it has developed rapidly. It is estimated that the demand for power lithium batteries will reach 125Gwh by 2020. The amount of scrapping will reach 32.2Gwh, about 500,000 tons; by 2023, the amount of scrapping will reach 101Gwh, about 1.16 million tons. At present, the recycling technology of lithium-ion batteries mainly focuses on the recycling of nickel, cobalt, manganese, aluminum, copper, lithium and other metal elements in the battery, while there are few studies on the recycling of negative electrode graphite materials. [0003] There are many kinds...

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Problems solved by technology

However, this method is not actually graphite recycling, but a silicon-carbon composite material. The treatment temperature is not enough to reach the graphitization temperature, and the process of ball milling the powder containing copper foil in the method also affects the graphite raw material. The structure was damaged to a certain extent, and the graphitization treatment was not carried out in the end, resulting in an average first-time efficiency of the composite material used in batteries of only 88%. If it is directly used in lithium-ion batteries, the electrochemical performance is slightly insufficient

[0004] In addition, in some existing technologies for preparing graphite anode materials, the temperature for graphitization treatment of carbon powder in an inert gas atmosphere is as high as 2500-3200 ° C, and the graphitization treatment time is as long as 40-60 hours, which puts forward very strict requirements on the corresponding equipment. requirements, the production efficiency is very low

[0005] In other existing technologies for preparing graphite negative electrode materials, a large amount of pitch (accounting for 20 to 50% by mass of carbon powder) is added to carbon powder or graphite powder, and the large amount of pitch will cause mutual interaction between coated graphite particles / carbon powder. Transitional bonding, not only the expansion is obvious during the heating process, but also the difficulty of graphitization becomes greater

The surface-coated low-crystallinity carbon is characterized by low reversible capacity and low compaction density; therefore, if the proportion of surface-coated asphalt is high, the surface coating of the particles is thicker, which affects the gram capacity and pressure of the negative electrode material. The solid density has a greater negative impact, and the physical rebound is greater, which affects the electrochemical performance of its coated graphite

In other existing technologies, the binder is invalidated by chemically immersing the negative electrode for a long time (up to several days), so as to obtain graphite powder or carbon powder, etc., and the recovery cycle is too long

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