Pseudocapacitance-Induced High-Rate Potassium Storage in CoSe@NrGo Hybrid Nanosheets for Potassium-Ion Batteries

Abstract

Potassium-ion batteries (PIBs) are considered to be promising candidates for large-scale energy storage because of their cost-effective resources. However, the sluggish kinetics and large volume expansion have been great challenges hindering the development of PIBs. Herein, CoSe anchored on reduced graphene oxide (CoSe@NrGo) with nitrogen doping is synthesized as a hybrid anode to boost the kinetics and maintain the structure stability. Importantly, the CoSe@NrGo hybrid nanosheets as a whole anode display the advantage of buffering the volume expansion and enhancing the kinetics. Consequently, the CoSe@NrGo hybrid nanosheets with a suitable amount of reduced graphene oxides demonstrate an unprecedented capacity of 408 mA h g–1 at 50 mA g–1 and an outstanding rate ability with a capacity of 143 mA h g–1 at 2 A g–1. The combination of conductive nitrogen-doped graphene oxides and the metallic CoSe hybrid nanosheets could achieve an excellent performance of long cycling stability and fast kinetics.