A general strategy for embedding ultrasmall CoMx nanocrystals (M = S, O, Se, and Te) in hierarchical porous carbon nanofibers for high-performance potassium storage

Closely integrated transition-metal-based compounds/carbon nano-architectures are one of themost promising anodematerials for largescale energy storage applications because of the superior structural stability and the outstanding synergistic effect from the efficient combination of the two components. Herein, a versatile strategy is demonstrated for fabricating hierarchical porous carbon nanofibers (HCFs) with closely coupled Co-based ultrafine nanoparticles and a carbon matrix. The spatially restricted reactions of the synthetic method can not only prevent the agglomeration of the nanoparticles, but also provide extremely tight coupling interaction between CoMx (M = S, O, Se, and Te) nanoparticles and conductive carbon nanofibers. As a proof of concept, the as-fabricated CoS2@HCFs show high reversible capacity, excellent rate property, and ultralong cycling life when evaluated as an anode material for potassium-ion batteries (PIBs). Even after 1000 cycles, the charge capacity can be retained at 268 mA h g(-1) at an elevated current rate of 500 mA g(-1), one of the highest reported performances for Co-based anode materials in PIBs. Thiswork emphasizes the importance of designing andmanufacturing highly functionally coupled hybrid materials for improved energy storage implementation.

Automated summary

This study demonstrates a versatile strategy for fabricating hierarchical porous carbon nanofibers with closely coupled Co-based ultrafine nanoparticles and a carbon matrix to achieve high-performance anode materials for potassium-ion batteries.