Confining CoSe/MoSe Heterostructures in Interconnected Carbon Polyhedrons for Superior Potassium Storage.

Metal selenides hold promise as feasible anode materials for potassium-ion batteries (PIBs), but still face problems such as poor potassium storage kinetics and dramatic volume expansion. Coupling heterostructure engineering with structural design could be an effective strategy for rapid and stable K storage. Herein, CoSe/MoSe heterojunction encapsulated in nitrogen-doped carbon polyhedron and further interconnected by three-dimensional nitrogen-doped carbon nanofibers (CoMoSe@NCP/NCFs) is ingeniously constructed. The abundant CoSe/MoSe heterointerfaces equipped with built-in electric fields and unique interconnected carbon polyhedrons (convenient electron/ion transfer pathway and robust mechanical buffer) promote the reaction kinetics and bolster the structural robustness. Accordingly, the CoMoSe@NCP/NCFs composite exhibits outstanding cycle life, with a capacity of 206 mAh g preserved after 2500 cycles at 2 A g. Besides, CoMoSe@NCP/NCFs also achieves decent rate performance with 161 mAh g at 10 A g. This research demonstrates a viable approach for constructing superior PIB anodes with both fast kinetics and high stability.