Enhancing lithium-ion storage performance of hollow CoS2/MoS2 nanospheres via N-doped carbon-coating

Abstract

Transition metal sulfides (TMSs) have been considered as up-and-coming anode materials for lithium-ion batteries (LIBs) owing to their large theoretical capacity and good reversibility. However, obvious volume variation and sluggish kinetics greatly limit their practical application. To address this issue, we successfully design and fabricate hollow CoS2/MoS2 nanospheres and effectively enhance their lithium storage performance via N-doped carbon-coating (CoS2/MoS2@N-C). The unique hollow structure provides shortened ion-diffusion path, while the N-doped carbon shells buffer the severe volume changes during cycling and improve the electronic conductivity of the electrode. When used as an anode material for LIBs, the CoS2/MoS2@N-C displays high specific capacity (1056.9 mA h g−1 at 100 mA g−1), excellent cycling stability (653.9 mA h g−1 after 250 cycles at 1000 mA g−1), and rate capability (685 mA h g−1 at 2000 mA g−1). The CoS2/MoS2@N-C||LiFePO4 full-cell LIB is also assembled and exhibits remarkable performance. The remarkable electrochemical performance of CoS2/MoS2@N-C electrode could be assigned to the synergistic enhancement effect of the N-doped carbon coating and hollow structure, which efficiently shorten the ion diffusion path, boost the charge transfer rate, and alleviated the volume changes of the electrode upon cycling.