Extraordinary pseudocapacitive energy storage triggered by phase transformation in hierarchical vanadium oxides.
basic_science · Level V
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- Record sourced from PubMed, PMID 29636459.
- Also identified by DOI 10.1038/s41467-018-03700-3 and PMC identifier 5893573.
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Abstract
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<sup>-1</sup> (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<sup>-3</sup> together with an exceptionally high volumetric energy density of ~110 mWh cm<sup>-3</sup> as well as long-term cycling stability.