Achieving the synergy of intercalation and defect engineering in a Cu2−xTe anode for high-performance aqueous “rocking-chair” zinc-ion batteries

Abstract

Aqueous zinc ion batteries (AZIBs) have become one of the most promising energy storage systems because of their high theoretical capacity, low cost, safety and other advantages. However, several problems, such as the hydrogen evolution reaction, corrosion and zinc dendrite formation at the zinc anode during cycling, hinder the further development of AZIBs. Therefore, the research and development of zinc-free metal anodes is essential. In this paper, a novel self-supporting CTAB intercalated Cu_2−xTe nanotube anode with tellurium vacancies was successfully prepared on copper foil by a simple low-temperature growth process. It exhibits a low discharge plateau of 0.21 V (vs. Zn²⁺/Zn), a high specific capacity of 188.5 mAh g⁻¹ and long-term cycling stability. This excellent electrochemical performance is mainly attributed to the high conductivity and abundant active sites endowed by the tellurium defects in Cu_2−xTe, as well as the effective reduction of ion diffusion barriers by the nanotubular structure. Theoretical calculations also show that the intercalation of CTAB can adjust the electronic structure, optimize the Zn²⁺ adsorption behavior and improve the electrochemical performance. Moreover, the storage mechanism of Zn²⁺ in the Cu_2−xTe nanotubes was also revealed by ex situ XRD and in situ Raman spectroscopy. Furthermore, the novel “rocking-chair” aqueous Cu_2−xTe//Zn_xMnO₂ zinc-ion full cell assembled exhibits a high energy density of 187.5 Wh kg⁻¹, power density of 4002.8 W kg⁻¹ and high capacity retention (capacity fading per cycle is only 0.0015%). This study provides a reference for the development of zinc-free anode materials with an ultra-long voltage platform, stable structure and high specific capacity.