Publisher： John Wiley & Sons Inc
E-ISSN： 1521-3765|21|19|7119-7126
ISSN： 0947-6539
Source： CHEMISTRY - A EUROPEAN JOURNAL, Vol.21, Iss.19, 2015-05, pp. : 7119-7126
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Abstract
AbstractA hierarchical hollow hybrid composite, namely, MnO2 nanosheets grown on nitrogen‐doped hollow carbon shells (NHCSs@MnO2), was synthesized by a facile in situ growth process followed by calcination. The composite has a high surface area (251 m2g−1) and mesopores (4.5 nm in diameter), which can efficiently facilitate transport during electrochemical cycling. Owing to the synergistic effect of NHCSs and MnO2, the composite shows a high specific capacitance of 306 F g−1, good rate capability, and an excellent cycling stability of 95.2 % after 5000 cycles at a high current density of 8 A g−1. More importantly, an asymmetric supercapacitor (ASC) assembled by using NHCSs@MnO2 and activated carbon as the positive and negative electrodes exhibits high specific capacitance (105.5 F g−1 at 0.5 A g−1 and 78.5 F g−1 at 10 A g−1) with excellent rate capability, achieves a maximum energy density of 43.9 Wh kg−1 at a power density of 408 W kg−1, and has high stability, whereby the ASC retains 81.4 % of its initial capacitance at a current density of 5 A g−1 after 4000 cycles. Therefore, the NHCSs@MnO2 electrode material is a promising candidate for future energy‐storage systems.
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