Three-dimensional nano-folded transition-metal oxide electrode materials for high-performing electrochemical energy-storage devices

Abstract

The local structure of an electrochemical interface plays a dominant role in electrochemical reactions, and significantly influences the electrochemical performance of electrochemical energy-storage devices due to the variable electrochemical kinetics. Previously reported strategies for manipulating the geometry of electrode materials usually involve complex processes, where their versability is also greatly limited to certain kinds of material. Here, a three-dimensional (3D) nano-folded transition-metal oxide with a well-defined structure is prepared by oxidizing the corresponding transition-metal via a fast and scalable dynamic thermal oxidation route. With the prototypical model of Ni foam, the obtained NiO exhibits a 3D nano-folded configuration covering the Ni scaffold (i.e., 3D nano-folded Ni@NiO), where the folding degree can be adjusted by altering the oxidation parameters. Moreover, the 3D nano-folded Ni@NiO reveals a superior electrochemical performance with a specific capacitance of 0.23 F cm⁻² (at a scan rate 2 mV s⁻¹) and an outstanding rate capability of 50% (with the scan rate increasing to 50 mV s⁻¹) when working as a supercapacitor cathode. Such a superior performance results from the enhanced electrochemical accessible active sites and facilitated electrolyte ion kinetics in the nano-folded architecture. The strategy proposed here may benefit the scalable fabrication of transition-metal oxide electrode materials for high-performing electrochemical energy-storage devices.