High-performance zinc-ion batteries enabled by electrochemically induced transformation of vanadium oxide cathodes

• Published in: Journal of energy chemistry 2021-09, Vol.60, p.233-240
• Main Authors: Li, Yang, Yang, Wang, Yang, Wu, Huang, Yongfeng, Wang, Guoxiu, Xu, Chengjun, Kang, Feiyu, Dong, Liubing
• Format: Article
• Language: English
• Subjects: Cathode material; Electrochemically induced transformation; Vanadium oxide; Zinc-ion battery
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2021.01.025

An electrochemically induced transformation of vanadium oxides is reported to realize high-capacity, fast-rate and long-life cathode materials for rechargeable aqueous zinc batteries. [Display omitted] •An electrochemically induced transformation of vanadium oxides is reported.•Such an in-situ transformation realizes high-capacity, high-rate and long-life cathode materials for zinc-ion batteries.•New insights into Zn2+-storage electrochemistry are provided. Rechargeable aqueous zinc-ion batteries (ZIBs) have become a research hotspot in recent years, due to their huge potential for high-energy, fast-rate, safe and low-cost energy storage. To realize good electrochemical properties of ZIBs, cathode materials with prominent Zn2+ storage capability are highly needed. Herein, we report a promising ZIB cathode material based on electrochemically induced transformation of vanadium oxides. Specifically, K2V6O16·1.5H2O nanofibers were synthesized through a simple stirring method at near room temperature and then used as cathode materials for ZIBs in different electrolytes. The cathode presented superior Zn2+ storage capability in Zn(OTf)2 aqueous electrolyte, including high capacity of 321 mAh/g, fast charge/discharge ability (96 mAh/g delivered in 35 s), high energy density of 235 Wh/kg and good cycling performance. Mechanism analysis evidenced that in Zn(OTf)2 electrolyte, Zn2+ intercalation in the first discharge process promoted K2V6O16·1.5H2O nanofibers to transform into Zn3+xV2O7(OH)2·2H2O nanoflakes, and the latter served as the Zn2+-storage host in subsequent charge/discharge processes. Benefiting from open-framework crystal structure and sufficiently exposed surface, the Zn3+xV2O7(OH)2·2H2O nanoflakes exhibited high Zn2+ diffusion coefficient, smaller charge-transfer resistance and good reversibility of Zn2+ intercalation/de-intercalation, thus leading to superior electrochemical performance. While in ZnSO4 aqueous electrolyte, the cathode material cannot sufficiently transform into Zn3+xV2O7(OH)2·2H2O, thereby corresponding to inferior electrochemical behaviors. Underlying mechanism and influencing factors of such a transformation phenomenon was also explored. This work not only reports a high-performance ZIB cathode material based on electrochemically induced transformation of vanadium oxides, but also provides new insights into Zn2+-storage electrochemistry.