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_0.8Co_0.1Mn_0.1]O₂ cathode. The present study may provide insights for the facile synthesis of advanced anode materials for high-performance LIBs.