From spent graphite to amorphous sp(2) + sp(3) carbon-coated sp(2) graphite for high-performance lithium ion batteries

Today, with the massive application of lithium ion batteries (LIBs) in the portable devices and electric vehicles, to supply the active materials with high-performances and then to recycle their wastes are two core issues for the development of LIBs. In this paper, the spent graphite (SG) in LIBs is used as raw materials to fabricate two comparative high-capacity graphite anode materials. Based on a microsurgery-like physical reconstruction, the reconstructed graphite (RG) with a sp(2)+sp(3) carbon surface is prepared through a microwave exfoliation and subsequent spray drying process. In contrast, the neural-network-like amorphous sp(2)+sp(3) carbon-coated graphite (AC@G) is synthesized using a self-reconfigurable chemical reaction strategy. Compared with SG and commercial graphite (CG), both RG and AC@G have enhanced specific capacities, from 311.2 mAh g(-1) and 360.7 mAh g(-1) to 409.7 mAh g(-1) and 420.0 mAh g(-1), at 0.1C after 100 cycles. In addition, they exhibit comparable cycling stability, rate capability, and voltage plateau with CG. Because the synthesis of RG and AC@G represents two typical physical and chemical methods for the recycling of SG, these results on the sp2+sp3 carbon layer coating bulk graphite also reveal an approach for the preparation of high-performance graphite anode materials derived from SG.