Fast-Charging High-Energy Battery-Supercapacitor Hybrid: Anodic Reduced Graphene Oxide-Vanadium(IV) Oxide Sheet-on-Sheet Heterostructure

다국어 초록 (Multilingual Abstract)

<P>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.</P>
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