Design of a belt-like single-phase solid-solution Cu-Zn selenide with superior potassium-ion storage properties via a facile cation-exchange process

Abstract

To produce high-performance potassium ion batteries (KIBs), it is essential to fabricate anode materials with an appropriately controlled structure and chemical composition. In this study, we successfully fabricate porous solid-solution Cu-Zn selenide nanobelts (NBs) coated with N-doped carbon (p-CZSe@NC NBs) using a facile cation-exchange process. The p-ZnSe@NC NBs are prepared using a polymer coating on ZnSe[diethylenetriamine]0.5 followed by carbonization. Because Zn and Cu have a similar atomic radius and electronegativity, the Zn in p-ZnSe@NC NBs is easily substituted with Cu in a spontaneous reaction without heating. The synergistic effect of the combination of the electrochemically active Zn and inactive Cu in response to K ions and the inner pores of the NBs is conducive to buffering the change in volume and improving ion accessibility. The N-doped carbon shell also provides additional conductive pathways and improves the structural robustness of the electrode. As a result, the p-CZSe@NC NB electrode achieves a high specific capacity of 288.3 mA h g−1 with superior cycling stability over 500 cycles at 0.5 A g−1 and 132.4 mA h g−1 at 3.0 A g−1. Our work thus outlines a facile method for the design of high-performance anodes for energy storage via the control of their chemical composition and structure.