Synthesis of polyhedral MoS@C hollow cages using a sacrificial template approach for improved reversible lithium storage.

Hierarchical polyhedral MoS@C (HP-MoS@C) hollow cages are controllably constructed using the KNaMoOF precursors as self-sacrificed templates. As an anode for lithium-ion batteries, HP-MoS@C cages deliver a reversible capacity of 1092.9 mA h g at 2 A g after 1000 cycles. The excellent performance of HP-MoS@C can be mainly attributed to its hierarchical structure and the synergistic effect between MoS and carbon. Beneficially, the robust carbon framework in MoS@C composites not only facilitates electron transfer among MoS particles but also alleviates the large volume expansion of MoS during the charging and discharging processes. Due to the difference in work function, a built-in electric field forms at the MoS/C interface, which facilitates Li-ion transfer across the heterojunction interface. Density functional theory calculations reveal that the expanded interlayer space of MoS, due to carbon insertion, reduces the energy barrier and is consequently beneficial for the insertion and removal of Li-ions during the electrode reaction. The local defects in the MoS lattice due to carbon doping could also facilitate electron migration and Li-ion diffusion in the MoS layer based on bound polarons theory. Moreover, HP-MoS@C‖LiCoO Li-ion pouch cells are successfully assembled and deliver good lithium storage capacity, indicating promising applications in high energy-density Li-ion batteries.