Encapsulating ultrafine cobalt sulfides into multichannel carbon nanofibers for superior Li-ion energy storage.

Developing high-capacity anode materials based on metal sulfides is of great importance for building advanced lithium-ion batteries (LIBs). Herein, we demonstrate rational encapsulation of cobalt sulfide (CoS x) nanoparticles into multichannel carbon nanofibers (CoS x /MCF) with substantially improved Li+ reactivity and durability. The unique multichannel and conductive carbon scaffold not only affords boosted electron/Li + transportation pathways for fast redox reaction with CoS x , but also stabilizes the electrode structure by buffering the volume change of CoS x. Impressively, the CoS x /MCF composite could serve as flexible anodes to deliver a high reversible capacity of 737 mAh g−1 at 0.2 A g−1 after 100 cycles, superior rate capacity of 374 mAh g−1 at 5 A g−1, and excellent operating stability over 1000 cycles. Practical feasibility is also demonstrated by a full cell based on the high-capacity CoS x /MCF anode and Li[Ni 0.8 Co 0.1 Mn 0.1 ]O 2 cathode. The present study may provide insights for the facile synthesis of advanced anode materials for high-performance LIBs. [Display omitted] • Multichannel carbon nanofibers are developed to encapsulate ultrafine CoS x. • Axial nanochannels buffer volume change of CoS x and boost the reaction kinetics. • Freestanding CoS x /MCF electrode shows superior performance of lithium storage. [ABSTRACT FROM AUTHOR]