Microwave-Assisted Rapid Synthesis of NH₄V₄O₁₀ Layered Oxide: A High Energy Cathode for Aqueous Rechargeable Zinc Ion...

Aqueous rechargeable zinc ion batteries (ARZIBs) have gained wide interest in recent years as prospective high power and high energy devices to meet the ever-rising commercial needs for large-scale eco-friendly energy storage applications. The advancement in the development of electrodes, especially cathodes for ARZIB, is faced with hurdles related to the shortage of host materials that support divalent zinc storage. Even the existing materials, mostly based on transition metal compounds, have limitations of poor electrochemical stability, low specific capacity, and hence apparently low specific energies. Herein, NH₄V₄O₁₀ (NHVO), a layered oxide electrode material with a uniquely mixed morphology of plate and belt-like particles is synthesized by a microwave method utilizing a short reaction time (~0.5 h) for use as a high energy cathode for ARZIB applications. The remarkable electrochemical reversibility of Zn²⁺/H⁺ intercalation in this layered electrode contributes to impressive specific capacity (417 mAh g^-1 at 0.25 A g^-1) and high rate performance (170 mAh g^-1 at 6.4 A g^-1) with almost 100% Coulombic efficiencies. Further, a very high specific energy of 306 Wh Kg^-1 at a specific power of 72 W Kg^-1 was achieved by the ARZIB using the present NHVO cathode. The present study thus facilitates the opportunity for developing high energy ARZIB electrodes even under short reaction time to explore potential materials for safe and sustainable green energy storage devices.