Sandwiched N-carbon@Co9S8@Graphene nanosheets as high capacity anode for both half and full lithium-ion batteries

Abstract Transition metal sulfides (TMSs) are promising candidates for replacing graphite anode in LIBs. However, the low conductivity and structural collapse caused by the large volume change during lithium insertion and extraction greatly limit its application. Herein, we report a unique design of a two-dimensional (2D) sandwich structure of N-doped carbon@Co9S8@graphene (N C@Co9S8@G) with multilayer structure. Electrochemical tests reveal that the N C@Co9S8@G nanosheets possess a high reversible capacity (1009 mA h g−1 at 0.1 A g−1), and excellent rate capability (422 mA h g−1 at 10 A g−1) and long cycle life (853 mA h g−1 at 1 A g−1 for 500 cycles). Experimental studies reveal that capacitive storage contributes to the high reversible capacity. The lithium storage kinetics are studied by Galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). Meanwhile, the potential of N C@Co9S8@G anode in a full cell using LiCoO2 as the cathode is also demonstrated, exhibiting a high reversible capacity of 300 mA h g−1 cycles at 0.1 A g−1. The strategy proposed in this work paves the way to engineering high performance anodes in LIBs.