Spent graphite as promising carbon matrix for high performance SiO/C anode material of Li-ion battery

Commercialization of SiO/graphite (SiO/G) composite anode material has been partially conducted in modern-model Li-ion batteries but is still limited by its relatively high cost and inferior stability. Improving the Li-ion storage performance as well as lowering the manufacturing cost of SiO/G anode has been the ongoing target of many studies. Herein, a low cost SiO/G anode with good Li-ion storage performance is developed by facilely integrating SiO nanoparticles into spent graphite (SG) extracted from used LiFePO4 batteries. The loose SG particles after repeated charge/discharge cycles can be easily exfoliated and combined with the SiO nanoparticles during the mechanical ball-milling treatment. Further processing the composite into spherical structure by spray-drying and pyrolysis results in practically applicable anode materials. The SiO/SG/C anode with a SiO mass ratio of 30 % exhibits the best overall performance including an excellent rate capability (385 mAh g−1 at 3 A g−1) and encouraging cycle stability (442 mAh g−1 after 300 cycles at 1 A g−1). The coin-type full cells coupling the pre-lithiated spherical SiO/SG anode and NCM811 cathode delivers a high energy density of 461 Wh kg−1 (based on the active masses of both electrodes) and good cycle performance (74.4 % capacity retention at 0.5C after 100 cycles). This work not only provides a high performance yet low cost SiO/G anode material, but explores a high value added way for the reuse of SG, thus can practically push forward the development of LIBs.