Cation- deficient Zn0.3(NH4)0.3V4O10•0.91H2O for rechargeable aqueous zinc battery with superior low- temperature performance

Abstract

The development of aqueous zinc batteries (AZBs) has attracted great attention owing to intrinsic safety, environmental friendliness and low cost. Cathode materials with high capacity and long cycle life at both room temperature and low temperature are urgently needed for practical application of AZBs. Herein, we report cation-deficient nonstoichiometric Zn0.3(NH4)0.3V4O10·0.91H2O (ZNV) cathode materials for AZBs. The pre-intercalated Zn2+ and structural water act as “pillars” to improve the structure stability. The structural water molecules also provide charge shielding for Zn2+ insertion/extraction. Both experiments and theoretical simulations demonstrate that the presence of cation vacancies facilitates Zn2+ diffusion during cycles. As a result, the ZNV exhibits a high discharge capacity of 461.1 mAh g−1 at 0.1 A g−1, and negligible decay after 2000 cycles at 2 A g−1. Superior cyclability is also achieved at the low temperature (0, -15, and -30 ℃) with more than 90% capacity retentions over 3500 cycles at 2 A g−1. In addition, the reversible Zn2+ (de)intercalation reaction mechanism in ZNV is confirmed. Our work may shed a light on the electrode materials designing and development for wide-temperature AZBs.