Amorphous Mixed‐Valence Vanadium Oxide/Exfoliated Carbon Cloth Structure Shows a Record High Cycling Stability

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2017-04, Vol.13 (16), p.np-n/a
• Main Authors: Song, Yu, Liu, Tian‐Yu, Yao, Bin, Kou, Tian‐Yi, Feng, Dong‐Yang, Liu, Xiao‐Xia, Li, Yat
• Format: Article
• Language: English
• Subjects: Carbon; carbon cloth; Charging; Cycles; cycling stability; Discharge; Dissolution; electrochemical exfoliation; Electrodes; Electrolytes; Energy storage; Heat detection; Nanotechnology; supercapacitors; vanadium oxide; Vanadium oxides
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201700067

Previous studies show that vanadium oxides suffer from severe capacity loss during cycling in the liquid electrolyte, which has hindered their applications in electrochemical energy storage. The electrochemical instability is mainly due to chemical dissolution and structural pulverization of vanadium oxides during charge/discharge cyclings. In this study the authors demonstrate that amorphous mixed‐valence vanadium oxide deposited on exfoliated carbon cloth (CC) can address these two limitations simultaneously. The results suggest that tuning the V4+/V5+ ratio of vanadium oxide can efficiently suppress the dissolution of the active materials. The oxygen‐functionalized carbon shell on exfoliated CC can bind strongly with VO x via the formation of COV bonding, which retains the electrode integrity and suppresses the structural degradation of the oxide during charging/discharging. The uptake of structural water during charging and discharging processes also plays an important role in activating the electrode material. The amorphous mixed‐valence vanadium oxide without any protective coating exhibits record‐high cycling stability in the aqueous electrolyte with no capacitive decay in 100 000 cycles. This work provides new insights on stabilizing vanadium oxide, which is critical for the development of vanadium oxide based energy storage devices. Both the structural pulverization and chemical dissolution of vanadium oxide electrodes are simultaneously suppressed by an integrated approach without the need of protective coating. The electrode achieves an outstanding cycling stability with no capacitive decay in 100 000 charging/discharging cycles. This value sets a new record for the cycling stability of vanadium oxide for energy storage applications.