In-situ growth of Cu(2-methylimidazole imidazole)2 on Cu2O polyhedrons for high-performance potassium-ion batteries

Abstract

In this work, Cu2O/Cu(2-MeIm)2 core–shell structure was designed and used as an anode for potassium-ion batteries. The Cu2O core not only ensured a high energy density through surface redox reactions, but also served as a copper-ion reservoir to keep the stability of skeleton structure of Cu(2-MeIm)2 shell during electrochemical process. The Cu(2-MeIm)2 shell, in turn, not only provided high power through rapid K+ adsorption/desorption, but also acted as an artificial solid electrolyte interphase layer and accommodated volumetric change during K+ intercalation/de-intercalation. The as-designed composite material was studied by X-ray diffraction, thermo gravimetric, Fourier transform infrared, nitrogen adsorption–desorption, X-ray photoelectron spectroscopic and electron microscopic characterizations. As an anode for potassium-ion batteries, it was galvanostatically discharged and charged to study its electrochemical properties, such as Coulombic efficiency, capacity retention and rate performance, and cyclic voltammetry curves were also tested to reveal its K-storage mechanism.