Two-dimensional ZnS@N-doped carbon nanoplates for complete lithium ion batteries

Metal sulfides are attractive anode materials for lithium ion batteries due to the high specific capacities and better electrochemical kinetics comparing to their oxide counterparts. In this paper, novel monocrystalline wurtzite ZnS@N-doped carbon (ZnS@N-C) nanoplates, whose morphology and phase are different from the common ZnS particles with cubic phase, are successfully synthesized. The ZnS@N-C nanoplates exhibit good cycling stability with a high reversible specific capacity of 536.8 mAh∙g-1 after 500 cycles at a current density of 500 mA∙g-1, which is superior to the pure ZnS nanoplates, illustrating the obvious effect of the N-doped carbon coating for alleviating volume change of the ZnS nanoplates and enhancing the electronic conductivity during charge/discharge processes. Furthermore, it is revealed that the ZnS single crystals with wurtzite phase in the ZnS@N-C nanoplates are transformed to the polycrystalline cubic phase ZnS after charge/discharge processes. In particular, the ZnS@N-C nanoplates are combined with the commercial LiNi0.6Co0.2Mn0.2O2 cathode to fabricate a new type of LiNi0.6Co0.2Mn0.2O2/ZnS@N-C complete battery, which exhibits good cycling stability up to 120 cycles at 1C rate after the prelithiation treatment on the ZnS@N-C anode, highlighting the potential of the ZnS@N-C nanoplates as an anode material for lithium ion battery.