Construction of Sugar‐Gourd‐Shaped Carbon Nanofibers Embedded with Heterostructured Zinc‐Cobalt Selenide Nanocages for Superior Potassium‐Ion Storage

Abstract

Transition metal selenides are considered as promising anode materials for potassium‐ion batteries (PIBs) due to their high theoretical capacities. However, their applications are limited by low conductivity and large volume expansion. Herein, sugar‐gourd‐shaped carbon nanofibers embedded with heterostructured ZnCo‐Se nanocages are prepared via a facile template‐engaged method combined with electrospinning and selenization process. In this hierarchical ZnCo‐Se@NC/CNF, abundant phase boundaries of CoSe2/ZnSe heterostructure can promote interfacial electron transfer and chemical reactivity. The interior porous ZnCo‐Se@NC nanocage structure relieves volume expansion and maintains structural integrity during K+ intercalation and deintercalation. The exterior spinning carbon nanofibers connect the granular nanocages in series, which prevents the agglomeration, shortens the electron transport distance and enhances the reaction kinetics. As a self‐supporting anode material, ZnCo‐Se@NC/CNF delivers a high capacity (362 mA h g−1 at 0.1 A g−1 after 100 cycles) with long‐term stability (95.9% capacity retention after 1000 cycles) and shows superior reaction kinetics with high‐rate K‐storage. Energy level analysis and DFT calculations illustrate heterostructure facilitates the adsorption of K+ and interfacial electron transfer. The K+ storage mechanism is revealed by ex situ XRD and EIS analyses. This work opens a novel avenue in designing high‐performance heterostructured anode materials with ingenious structure for PIBs.