Ultra-stable zinc-ion batteries by suppressing vanadium dissolution via multiple ion-bonded vanadate cathodes

Abstract

Layered vanadate cathodes hold promise for aqueous zinc-ion batteries (AZIBs) owing to their multiple redox reactions as well as large interlayer space for Zn²⁺ storage. However, they are limited by vanadium dissolution during cycling, in association with severe capacity fade and unsatisfactory cyclic life. To address this challenge, we herein report a pre-inserted dual-cation vanadate (NaₓZnyV₃O₈ nH₂O) cathode, which combines the Zn²⁺-reinforced cathode structure with the Naþ-enlarged lattice distance for fast and stable Zn²⁺ migration. Multiple ex situ analysis found that electrochemically active Zn₃(OH)₂V₂O₇ 2H₂O was generated after discharging, and this corresponds to the efficient suppression of vanadium dissolution by strong ionic bonding. As a result, a certain NaₓZnyV₃O₈ nH₂O cathode having a Na⁺ to Zn²⁺ ratio of 2:1 retains 99.6% of capacity after 418 cycles at 0.1A g¯¹, 90.5% after 6000 cycles at 1.0 A g¯¹, and 96.7% after 9499 cycles at 10.0A g¯¹. Our method paves a way for researchers to develop robust cathode materials for ultra-stable AZIBs.