Effect of carbon modification on the structure and electrochemical properties of recycled graphite anode materials

The recycled graphite (RG) and a new type of recycled graphite with multi-layer coating structure (RGC) were prepared by using spent graphite and asphalt. The electrochemical properties and coatings of RG and RGC were also investigated. The low graphitization degree of hard carbon and soft carbon was beneficial to improve the electrochemical properties of regenerated graphite, which was verified by first principles. The unique structure (soft carbon/ hard carbon/ graphite) limited the volume expansion of hard carbon and graphite when lithium ions were embedded or extruded, which improved the rate capability and cycling performance of the battery. Compared with spent graphite (SG) and recycled graphite (RG), the first charge-specific capacity of RGC at 0.1 C was 349.17 mAh·g − 1 , and the coulombic efficiency was 82.47%. Impressive reversible capacity was 263.38 mAh·g − 1 after 130 cycles at 0.5 C and discharge capacity of 188 mAh·g − 1 at 1 C. Due to the pre-lithiation of RGC, the first coulomb efficiency (99.49%) of the full battery (18,650) was higher than that of commercial graphite, and the energy conservation rate was 65.6% after 2000 cycles. This study provides a simple and effective scheme, and realizes the clean recovery and high value commercial application of spent graphite.