Unlocking the High Capacity Ammonium‐Ion Storage in Defective Vanadium Dioxide

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-11, Vol.18 (47), p.e2204888-n/a
• Main Authors: Wu, Yulin, Dong, Shengyang, Lv, Nan, Xu, Zikang, Ren, Ruiqi, Zhu, Guoyin, Huang, Baoling, Zhang, Yizhou, Dong, Xiaochen
• Format: Article
• Language: English
• Subjects: ammonium‐ion storage; Anodes; defective vanadium dioxide; Diffusion coefficient; Electrochemical analysis; Electrode materials; Energy storage; high capacity; high stability; Hydrogels; Ion storage; Manganese dioxide; MnO 2; Nanotechnology; Safety; State of charge; Vanadium dioxide; Vanadium oxides
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202204888

Aqueous ammonium‐ion storage has been considered a promising energy storage competitor to meet the requirements of safety, affordability, and sustainability. However, ammonium‐ion storage is still in its infancy in the absence of reliable electrode materials. Here, defective VO2 (d‐VO) is employed as an anode material for ammonium‐ion batteries with a moderate transport pathway and high reversible capacity of ≈200 mAh g−1. Notably, an anisotropic or anisotropic behavior of structural change of d‐VO between c‐axis and ab planes depends on the state of charge (SOC). Compared with potassium‐ion storage, ammonium‐ion storage delivers a higher diffusion coefficient and better electrochemical performance. A full cell is further fabricated by d‐VO anode and MnO2 cathode, which delivers a high energy density of 96 Wh kg−1 (based on the mass of VO2), and a peak energy density of 3254 W kg−1. In addition, capacity retention of 70% can be obtained after 10 000 cycles at a current density of 1 A g−1. What's more, the resultant quasi‐solid‐state MnO2//d‐VO full cell based on hydrogel electrolyte also delivers high safety and decent electrochemical performance. This work will broaden the potential applications of the ammonium‐ion battery for sustainable energy storage. A high‐performance NH4+‐based full cell is assembled based on defective VO2 (d‐VO) anode and MnO2 cathode. Benefitt from the defective structure and moderate transport pathway, the MnO2//d‐VO full cell demonstrates a high energy density of 96 Wh kg−1, a peak energy density of 3254 W kg−1, and an impressive capacity retention of 70% after 10 000 cycles.