Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6604221 | Electrochimica Acta | 2018 | 40 Pages |
Abstract
The fabrication of graphene oxide (GO) thin layer encapsulated SiO2 microspheres (SiO2@GO) were accomplished by sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO2 microspheres. Then, hierarchical mesoporous δ-MnO2 hollow microspheres (δ-MnO2 HMS) were prepared by hydrothermal treatment of SiO2@GO microspheres in the presence of KMnO4, followed by removal of the SiO2 inner core in another hydrothermal reaction. The synthesized δ-MnO2 HMS was systematically characterized and found to exhibit remarkable supercapacitive performances in a three-electrode setup with the highest specific capacitance of 216.4â¯Fâ¯gâ1 at the current density of 0.5â¯Aâ¯gâ1, satisfactory rate capability and outstanding cyclic performance with the capacitance retention of 91.2% after consecutive charge/discharge at the current density of 5â¯Aâ¯gâ1 for over 3000 cycles. Such electrochemical behaviors of δ-MnO2 HMS electrode in a three-electrode system outperform those of a number of MnO2-based electrodes reported previously. Furthermore, a symmetric supercapacitor device of δ-MnO2 HMS//δ-MnO2 HMS was assembled. It released the maximum specific capacitance of 58.8â¯Fâ¯gâ1 at the current density of 0.25â¯Aâ¯gâ1, possessed excellent rate capability and favorable cycling stability with the capacitance retention up to 86.4% after cycling at the current density of 3â¯Aâ¯gâ1 for 3000 cycles, and offered the highest energy density of 8.2â¯Wâ¯hâ¯kgâ1 at a power density of 125â¯Wâ¯kgâ1, which was superior to that of many existing MnO2-based symmetric and asymmetric supercapacitors. The impressive electrochemical properties of δ-MnO2 HMS make it a promising candidate for constructing high-performance energy storage devices.
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Authors
Wei Xiao, Wenjie Zhou, Hong Yu, Yong Pu, Yanhua Zhang, Chengbo Hu,