Extraordinary pseudocapacitive energy storage triggered by phase transformation in hierarchical vanadium oxides

• Published in: Nature communications Vol. 9; no. 1; pp. 1375 - 9
• Main Authors: Liu, Bo-Tian, Shi, Xiang-Mei, Lang, Xing-You, Gu, Lin, Wen, Zi, Zhao, Ming, Jiang, Qing
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.04.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 140/133; 140/146; 147/135; 147/137; 147/143; 639/301; 639/301/357; 639/4077; 639/4077/4079; 639/4077/909; Accessibility; Aqueous electrolytes; Capacitance; Carbon; Corundum; Electric power; Electrochemistry; Electrodes; Electrolytes; Energy storage; Flux density; Humanities and Social Sciences; Laboratories; multidisciplinary; Oxides; Phase transitions; Rutile; Science; Science (multidisciplinary); Sodium; Tunnels; Vanadium; Vanadium dioxide; Vanadium oxides
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-03700-3

Pseudocapacitance holds great promise for improving energy densities of electrochemical supercapacitors, but state-of-the-art pseudocapacitive materials show capacitances far below their theoretical values and deliver much lower levels of electrical power than carbon-based materials due to poor cation accessibility and/or long-range electron transferability. Here we show that in situ corundum-to-rutile phase transformation in electron-correlated vanadium sesquioxide can yield nonstoichiometric rutile vanadium dioxide layers that are composed of highly sodium ion accessible oxygen-deficiency quasi-hexagonal tunnels sandwiched between conductive rutile slabs. This unique structure serves to boost redox and intercalation kinetics for extraordinary pseudocapacitive energy storage in hierarchical isomeric vanadium oxides, leading to a high specific capacitance of ~1856 F g –1 (almost sixfold that of the pristine vanadium sesquioxide and dioxide) and a bipolar charge/discharge capability at ultrafast rates in aqueous electrolyte. Symmetric wide voltage window pseudocapacitors of vanadium oxides deliver a power density of ~280 W cm –3 together with an exceptionally high volumetric energy density of ~110 mWh cm –3 as well as long-term cycling stability. Pseudocapacitive materials could enable high-performance electrochemical supercapacitors, but their practical capacitance and power density remain low. Here the authors show that in situ phase transformation triggers extraordinary pseudocapacitive energy storage in metallic isomeric vanadium oxides.