Electrochemical methods for the removal of impurities from the graphite anode in spent ternary lithium-ion batteries

The use of lithium-ion batteries (LIBs) is becoming increasingly widespread, and a large number are reaching their end of life. The recycling and re-use of spent LIBs has attracted great attention. Because of the unchanged layer structure of the graphite anode in these batteries, their recycling does not require high-temperature graphitization, and only focuses on the removal of internal impurities. We used electrochemical treatment for the deep removal of internal metal impurities after the heat treatment, ultrasonic separation, and acid leaching of spent graphite. By comparing and analyzing the graphite in different recovery stages, it was found that the presence of organic impurities seriously affects the electrochemical performance. The presence of trace inorganic impurities such as Cu and Fe has little effect on the initial discharge specific capacity, but reduces the cycling stability of graphite. The content of the main metal impurities in the final recycled graphite was less than 20 mg/kg. The discharge specific capacity reached 358.7 mAh/g at 0.1 C, and the capacity remained at 95.85% after 150 cycles. Compared with the reported methods for recycling spent graphite, this method can efficiently remove impurities in the graphite, solve the current problems of high acid and alkali consumption, incomplete impurity removal and high energy consumption. The recycled graphite anode has a good electrochemical performance. Our work provides a new recycling and regeneration path for spent LIB graphite anodes.