Hierarchical microstructure of CNTs interwoven ultrathin Co3S4 nanosheets as a high performance anode for sodium-ion battery

In this work, Co3S4/CNTs three-dimensional hierarchical microstructure has been synthesized through a facile sulfidation method with Co3O4/CNTs as precursor. Particularly, by controlling hydrothermal time, the optimized Co3S4/CNTs-9 composite consists of ultrathin and rich mesoporous Co3S4 nanosheets (< 10 nm) with CNTs firmly intertwined inside microstructures. Benefitting from the porous and robust secondary-structure, as well as the intertwined CNTs among ultrathin active materials Co3S4 nanosheets, Co3S4/CNTs-9 electrode provides fast efficient ways of ion and electron transportation. As a result, it exhibits an excellent rate performance. Charge capacity retention at 1 Ag-1 is up to 80% compared with 0.1 Ag-1. The enhanced extrinsic pseudocapacitive contribution is confirmed at higher rate through the cyclic voltammetry analysis at different scan rates of Co3S4/CNTs-9 electrode. Importantly, Co3S4 electrode also exhibits a high initial coulombic efficiency of 82.89%, which suggests that Co3S4 is a promising anode candidate for sodium-ion batteries.