In-situ electrochemical modification of pre-intercalated vanadium bronze cathodes for aqueous zinc-ion batteries

Vanadium bronzes have been well-demonstrated as promising cathode materials for aqueous zinc-ion batteries. However, conventional single-ion pre-intercalated V2O5 nearly reached its energy/power ceiling due to the nature of micro/electronic structures and unfavourable phase transition during Zn2+ storage processes. Here, a simple and universal in-situ anodic oxidation method of quasi-layered CaV4O9 in a tailored electrolyte was developed to introduce dual ions (Ca2+ and Zn2+) into bilayer δ-V2O5 frameworks forming crystallographic ultra-thin vanadium bronzes, Ca0.12Zn0.12V2O5·nH2O. The materials deliver transcendental maximum energy and power densities of 366 W h kg−1 (478 mA h g−1 @ 0.2 A g−1) and 6627 W kg−1 (245 mA h g−1 @ 10 A g−1), respectively, and the long cycling stability with a high specific capacity up to 205 mA h g−1 after 3000 cycles at 10 A g−1. The synergistic contributions of dual ions and Ca2+ electrolyte additives on battery performances were systematically investigated by multiple in-/ex-situ characterisations to reveal reversible structural/chemical evolutions and enhanced electrochemical kinetics, highlighting the significance of electrolyte-governed conversion reaction process. Through the computational approach, reinforced “pillar” effects, charge screening effects and regulated electronic structures derived from pre-intercalated dual ions were elucidated for contributing to boosted charge storage properties.