Ultra-Fast Activated Nh4+-Intercalated Vanadium Oxide Cathode for High-Performance Aqueous Zinc-Ion Batteries

Abstract

Vanadium-based oxides hold immense promise as cathodes for aqueous zinc-ion batteries (AZIBs), but a prevalent challenge hindering their practical implementation is the often-overlooked prolonged activation period exhibited by many of these materials. This sluggish activation, often requiring hundreds of cycles to reach peak performance, stems from the inherent properties of mixed-valence vanadium systems. Here, we present an effective and straightforward electrical activation strategy to address this critical bottleneck. By applying a simple pre-cycling charging protocol to NH4+-intercalated from vanadium oxide (VON), we demonstrate unprecedented activation speed, achieving peak capacity within mere cycles, even at high current densities. This electrochemically activated VON (E-VON) exhibits remarkable performance, delivering a high specific capacity of 359.1 mAh g-1 at 0.1 A g-1, outstanding rate capability (155.5 mAh g-1 at 10 A g-1), and impressive cycling stability. The electrical activation process not only facilitates faster ion transport within the VON structure but also triggers a unique Zn2+/H+ co-insertion mechanism during cycling. This co-insertion is intricately linked to the formation and dissolution of a basic zinc sulfonate by-product, providing new insights into charge storage processes within vanadium-based AZIB cathodes. This study highlights a practical pathway for circumventing the limitations of traditional vanadium oxide cathodes.

Keywords: Aqueous Zinc-Ion Batteries, Vanadium Oxide Cathode, Electrical Activation, Fast Activation, High Capacity