Multi-walled carbon nanotubes interlinked vanadium selenite nanocomposites as a positive electrode for high-performance aqueous zinc-ion batteries

Abstract

With the growing necessity for energy storage and/or resource, aqueous zinc (Zn) ion batteries (AZIBs) have attracted wide attention due to their safety, low price, stability, and eco-friendliness. Vanadium (V)-based materials have been prepared to be used as a positive electrode for AZIBs for several years. However, there are also various challenges to developing high-performance AZIBs. Herein, vanadium selenite nanosheet encapsulated multi-walled carbon nanotubes (V2Se9@MWCNTs) are successfully synthesized via a facile solvothermal method, followed by calcination. As a positive (cathode) material for AZIBs, the V2Se9@MWCNTs nanocomposite enhances ion insertion/extraction kinetics and control the positive material dissolution in the cycling process. The V2Se9@MWCNTs electrode exhibits enhanced specific capacity (294.95 mA h g−1 after 500 cycles at 1 A g−1) and outstanding cycling stability (99 % capacity retention after 3000 cycles at 15 A g−1). As expected, the rate performance of V2Se9@MWCNTs electrode (291.64 mA h g−1 at 1 A g−1 and 95.39 mA h g−1 at 10 A g−1) is better than that of V2Se9 electrode (258.69 mA h g−1 at 1 A g−1 and 82.84 mA h g−1 at 10 A g−1). It is found that the charge storage mechanism of V2Se9@MWCNTs electrode is controlled by the combination of both diffusion and capacitive behaviors. Furthermore, the high-resolution scanning electron microscope measurements after 500 cycles reveal the well-preserved morphology after Zn ion insertion, indicating good structural stability. Overall, this work provides a deep insight into the energy storage mechanism and application of V2Se9@MWCNTs in AZIBs.