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

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 multiwalled carbon nanotubes (V 2 Se 9 @MWCNTs) are successfully synthesized via a facile solvothermal method, followed by calcination. As a positive (cathode) material for AZIBs, the V 2 Se 9 @MWCNTs composite enhances ion insertion/extraction kinetics and control the positive material dissolution in the cycling process. The V 2 Se 9 @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 V 2 Se 9 @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 V 2 Se 9 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 V 2 Se 9 @MWCNTs composite electrode is controlled by the combination of both diffusion and capacitive behaviors. Furthermore, the scanning electron microscope measurements after 500 cycles the well-preserved morphology after Zn ion insertion, indicating good structural stability. Overall, this work provide a deep insight into the energy storage mechanism and application of V 2 Se 9 @MWCNTs in AZIBs. • V 2 Se 9 @MWCNTs nanocomposites are successfully synthesized via a solvothermal method. • The MWCNTs incorporation into the V 2 Se 9 nanosheets improves electrical conductivity and structural integrity. • The V 2 Se 9 @MWCNTs electrode delivered an excellent reversible capacity of 294.95 mA h g -1 over 500 cycles at 1 A g -1 . • The V 2 Se 9 @MWCNTs electrode reveals outstanding cycling stability (99% capacity retention after 3000 cycles at 15 A g -1 ).