Robust Silicon–Carbon Composites Enabled by Nonmetal Doped Graphite from Post-Treatment Spent Graphite for Superior Lithium-Ion Batteries

Currently, the recycling of valuable metals from spent lithium-ion batteries has generated a large amount of post-treatment spent graphite (PSG), which contains various trace electrolytes and metal elements and is basically abandoned as solid waste. Some carbon-based materials used in Si/C anodes have the disadvantages of inactive surface atoms and weak interactions to the Si phase, leading to unstable interfacial chemical bonds, unsatisfactory electronic/ionic conductivity, and fragile interfaces. Herein, novel Si/RG composites are prepared by ball milling of nano-Si with regenerated graphite (RG) derived from PSG. The well-preserved non-metal elements in RG form strong bonds with nano-Si reducing the interfacial resistance and improving the electronic and ionic conductivity. As a result, the Si/RG exhibits excellent cycling performance, maintaining a reversible capacity of 1325.4 mAh g^–1 after 100 cycles at a discharging current density of 0.2 A g^–1. It also shows remarkable rate performance with a capacity of 681.1 mAh g^–1 at 3.0 A g^–1. This work provides a new strategy for recycling and green application of graphite in spent LIBs in the future.