Abstract
A three-dimensional bi-continuous nanoporous gold (NPG)/nickel foam is developed though the electrodeposition of a gold–tin alloy on Ni foam and subsequent chemical dealloying of tin. The newly-designed 3D metal structure is used to anchor MnO2 nanosheets for high-performance supercapacitors. The formed ternary composite electrodes exhibit significantly-enhanced capacitance performance, rate capability, and excellent cycling stability. A specific capacitance of 442 Fg−1 is achieved at a scan rate of 5 mV s−1 and a relatively high mass loading of 865 μg cm−2. After 2500 cycles, only a 1% decay is found at a scan rate of 50 mV s−1. A high power density of 3513 W kg−1 and an energy density of 25.73 Wh kg−1 are realized for potential energy storage devices. The results demonstrate that the NPG/nickel foam hybrid structure significantly improves the dispersibility of MnO2 and makes it promising for practical energy storage applications.
Highlights
To overcome the aforementioned drawback, a variety of strategies have been employed to improve the conductivity of MnO2
We developed a mild two-step strategy to fabricate high quality nanoporous gold (NPG) films directly supported on Ni foam for the loading of MnO2 which acts as a high-performance supercapacitor
Few cracks were observed during the dealloying procedure because the initial Sn/Au ratio is not enough to cause a significant shrinkage of volume
Summary
To overcome the aforementioned drawback, a variety of strategies have been employed to improve the conductivity of MnO2. Professor Chen et al have proposed thick MnO2 layer on free-standing NPG films to close the theoretical gravimetric specific capacitance of MnO227 They fabricated these electrodes into nonaqueous symmetric supercapacitors for demonstrating the advantages of this structure[32]. The highest gravimetric specific capacitance can only be gained when the MnO2 layer is rather thin (very low mass-loading), which is far away from commercial application[33]. To resolve this problem, we developed a mild two-step strategy to fabricate high quality NPG films directly supported on Ni foam for the loading of MnO2 which acts as a high-performance supercapacitor. The proposed 3D bi-continuous metal structure may have the potential to be applied to many promising energy storage devices in which the performance is mainly limited by the low conductivity of materials
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