Two-dimensional metal carbides as high-performance cathode materials for aqueous zinc-ion hybrid capacitors: synthesis, characterization and electrochemical performance

Abstract

This study focuses on the preparation of few-layered two-dimensional (2D) transition metal carbides (TMCs)based sheets using a simple wet-chemical etching and delamination process. The investigation explores MXenemimetic TMCs 2D lamellar materials, including titanium carbide (Ti3C2Tx), vanadium carbide (V2CTx), and nickel carbide (Ni3C2Tx), synthesized through selective etching followed by exfoliation using an organic solvent. The resulting Ti3C2Tx, V2CTx and Ni3C2Tx materials serve as electrode components in rechargeable zinc-ion hybrid capacitors (ZIHCs). These ZIHC devices, configured as Zn//Ti3C2Tx, Zn//V2CTx, and Zn//Ni3C2Tx exhibit higher electrochemical behavior and overall performance. At a constant current density of 0.5 A/g, the devices deliver specific discharge capacities of 119.20 mAh/g, 198.41 mAh/g, and 86.91 mAh/g, respectively. Among these, the Zn//V2CTx device demonstrates superior performance, achieving high capacity and excellent electrochemical characteristics. Furthermore, the V2CTx - based ZIHC shows remarkable cycling stability, retaining 88.32 % of its capacity after 10,000 cycles. This work highlights the potential of vanadium carbidebased few-layer TMCs electrodes for high-performance aqueous zinc-ion hybrid capacitors, offering a promising avenue for next-generation battery-type energy storage systems.