Development of aqueous zinc ion battery cathode with heteroatom doped vanadium oxide materials

Among aqueous rechargeable batteries, zinc-ion batteries (ZIBs) have attracted colossal interest due to their high theoretical specific capacity, low redox potential, abundance of zinc metal, safety, and low cost. Due to the low cost and high safety, aqueous ZIBs are highly compelling platforms for large-scale applications like grid-scale energy storage. Despite being one of the oldest known battery types, rechargeable ZIBs still have not found use as expected. Aqueous ZIBs have difficulty finding suitable cathode materials to achieve high capacity, coulombic efficiency, and long-lasting cycle life. Although remarkable specific capacities have been obtained by using various cathode materials, the challenges arising from stability of cathode materials, have greatly hindered their practical applications. Thus, there is an urgent need for high-performance cathode materials to solve the low cycling stability and electrochemical performance of ZIBs. Vanadium dioxide (VO2) has attracted significant attention in recent years because of its high theoretical capacity and the structural properties. The layered structure of VO2 allows the ion-doping in the crystal unit cell. The metal-ion doping of VO2 has the potential to achieve its high capacity and cycle life. In this work, we designed metal-ion-doped VO2 cathodes and utilized them in high-performance aqueous ZIB devices. The selected Group 1A metal (lithium, sodium, and potassium) and transitional metal (niobium, molybdenum, and tungsten) ions were doped in VO2 in various amounts. The fabricated ZIBs had improved electrochemical energy storage properties due to the heteroatom doped VO2 cathodes. The metal-ion-doped vanadium dioxide-based materials were produced via hydrothermal method and used in aqueous ZIBs to obtain remarkable electrochemical properties, which was the main theme of this thesis. In this regard, aqueous Zn-ion batteries with metal-ion doped VO2 cathodes were fabricated and characterized to achieve high electrochemical performance and cycling stability.