Breaking the Cascade Dissolution Loop through Self-inhibition Mechanism for Zinc Vanadium Oxide Battery

Abstract

The pre-intercalation of foreign species into zinc-vanadium oxides battery cathode has been successfully demonstrated due to the pillar effect to enhance the V-O bond. Here, we challenge this claim and propose the self-inhibition mechanism of cathode dissolution in zinc-vanadium oxides battery through pre-intercalation of Ca2+ to break the cascade dissolution loop of vanadate cathode. With the help of the state-of-the-art 3D electron microscopic reconstruction technique, the minor while key intermediate phase of insoluble calcium vanadate (CaV2O6·2H2O) species is identified on the surface of the electrode at nanometer scale. In the initial dissolution of Ca-VO2 would release both Ca2+ and vanadium ions, while Ca2+ act as solution inhibitor to co-precipitate vanadium ions as protective layer to prevent further dissolution of vanadium oxide cathode. As a result, it exhibits ultrahigh cycling stabilities for over 140 cycles at 0.1 A g-1 and 16500 cycles at 30 A g-1. Particularly in high mass loading of 20 mg cm-2, the Ca-VO2 cathode yields a high areal capacity of 8.11 mAh cm-2 at 0.1 A g-1. As a demonstration of the practical applications, an Ah-level pouch cell delivers an average capacity of 1.15 Ah over 200 cycles at 0.5 A g-1. This work provides new insights into the role of pre-intercalated Ca2+ in mitigating vanadium dissolution, paving the way for the development of ultra stable cathodes in AZIBs.