Manipulating the Polytellurides of Metallic Telluride for Ultra-Stable Potassium-Ion Storage: A Case Study of Carbon-Confined CoTe_2 Nanofibers

摘要

Transition metal tellurides (TMTes) are promising anode materials for highenergy density potassium-ion batteries (PIBs) due to their high electronicconductivity and high theoretical volumetric capacity. Most reported TMTeselectrodes have limited lifespans, however, in this work, for the first time, it isrevealed that the dissolution and shuttling effect of polytellurides (K_5Te_3 andK_2Te) are the key reasons for the rapid deterioration of cycling stability inTMTe-based conversion- and alloy-type anodes. In light of this, a dual-typeN-doped carbon-confined CoTe_2 composite material (CoTe_2@NPCNFs@NC,where NPCNFs stands for N-doped porous carbon nanofibers and NCrepresents N-doped porous carbon) is proposed to suppress the dissolutionand shuttle effect of polytellurides, which boosts the cycling stability up to1000 cycles at 2 A g~(?1). Furthermore, various in situ and ex situ techniquesand theoretical calculations are employed to systematically clarify theformation and transformation of polytellurides and to reveal the good physicalconfinement of the dual-type carbon and the strong chemisorption ofpyridinic-N and pyrrolic-N on K5Te3 and K2Te. This work highlights theimportant role of manipulating polytelluride in the design of long-lifespanTMTe anodes for advanced PIBs.