Hierarchically porous-structured ZnxCo1−xS@C–CNT nanocomposites with high-rate cycling performance for lithium-ion batteries

Abstract

Transition metal sulfides are of great interest as anodes for lithium-ion batteries (LIBs) due to their high theoretical capacity and low cost. However, the poor cycling stability and rate performance are the critical problems that hinder their practical applications. In this work, a unique hybrid nanocomposite constructed from starfish-like Zn_xCo_1−xS rooted in porous carbon and strongly coupled carbon nanotubes (Zn_xCo_1−xS@C–CNTs) is demonstrated to address this concern. The designed nanocomposite integrates the high theoretical capacity of Zn_xCo_1−xS and the excellent conductivity as well as the excellent mechanical stability of CNTs. When evaluated as anode materials for LIBs, Zn_xCo_1−xS@C–CNTs exhibited a high reversible capacity of 635 mA h g⁻¹ at a current density of 1.2 A g⁻¹ after 1000 cycles and excellent high-rate capability (890 mA h g⁻¹ and 750 mA h g⁻¹ at current densities of 3.2 and 6.4 A g⁻¹, respectively). The excellent electrochemical performance of Zn_xCo_1−xS@C–CNTs can be ascribed to its hierarchically porous structure design and the synergistic effect between Zn_xCo_1−xS@C and CNTs.