Fast-Charging High-Energy Battery-Supercapacitor Hybrid: Anodic Reduced Graphene Oxide-Vanadium(IV) Oxide Sheet-on-Sheet Heterostructure.
basic_science · Level V
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- Record sourced from PubMed, PMID 31432663.
- Also identified by DOI 10.1021/acsnano.9b05605.
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Abstract
The battery-supercapacitor hybrid (BSH) device has potential applications in energy storage and can be a remedy for low-power batteries and low-energy supercapacitors. Although several studies have investigated electrode materials (particularly for a battery-type anode material) and design for BSHs, the energy density and power density are insufficient (far from the levels required for practical applications). Herein, a hierarchical vanadium(IV) oxide on reduced graphene oxide (rGO@VO<sub>2</sub>) heterostructure as an anode and activated carbon on carbon cloth (AC@CC) as a cathode are proposed for fabricating an advanced BSH. The mixed valency of V ions inside the as-prepared VO<sub>2</sub> matrix (V<sup>3+</sup> and V<sup>4+</sup>) facilitates redox reactions at a low potential, giving rise to rGO@VO<sub>2</sub> as a typical anode with a working potential of 0.01-3 V (<i>vs</i> Li/Li<sup>+</sup>). The sheet-on-sheet heterostructured rGO@VO<sub>2</sub> yields a high specific capacity of 1214 mAh g<sup>-1</sup> at 0.1 A g<sup>-1</sup> after 120 cycles, with a high rate capability and stability. The rGO@VO<sub>2</sub>//AC@CC BSH device exhibits a maximum gravimetric energy density of 126.7 Wh kg<sup>-1</sup> and a maximum gravimetric power density of ∼10 000 W kg<sup>-1</sup> within a working voltage range of 1-4 V. Moreover, it exhibits fast charging times of 5 and 834 s with energy densities of 15.6 and 82 Wh kg <sup>-1</sup>, respectively.