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Issue 20, 2019
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Co2+ induced phase transformation from δ- to α-MnO2 and their hierarchical α-MnO2@δ-MnO2 nanostructures for efficient asymmetric supercapacitors

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Abstract

MnO2 possesses multiple crystal phases and various geometrical morphologies, so there remains a big challenge to simultaneously control the crystal phases and geometrical morphologies of MnO2 by a facile process. Indeed, these controllable syntheses will provide material bases to investigate their effects on the specific capacitance. Herein, benefiting from the first attempt of using Co2+ as a phase transformation-inducing agent and a doping ion, we present an interesting report on controllable phase transformation from δ- to α-MnO2 and their morphology evolution from nanosheets to nanowires. These transformations need the synergistic effect between MnCO3 and Co2+. Furthermore, three dimensional hierarchical α-MnO2@δ-MnO2 core–shell heterophase nanostructures were fabricated to improve capacitance performance. Impressively, the specific capacitance of α-MnO2@δ-MnO2 reaches up to 206 F g−1, which is higher than those of the corresponding single components. An asymmetric supercapacitor device based on the α-MnO2@δ-MnO2 cathode exhibits a good energy density of 12.9 W h kg−1 at a power density of 230 W kg−1 and excellent cycle lives with a decrease of 26% capacitance after 10 000 charge/discharge cycles.

Graphical abstract: Co2+ induced phase transformation from δ- to α-MnO2 and their hierarchical α-MnO2@δ-MnO2 nanostructures for efficient asymmetric supercapacitors

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Publication details

The article was received on 21 Feb 2019, accepted on 24 Apr 2019 and first published on 25 Apr 2019


Article type: Paper
DOI: 10.1039/C9TA01918A
J. Mater. Chem. A, 2019,7, 12661-12668

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    Co2+ induced phase transformation from δ- to α-MnO2 and their hierarchical α-MnO2@δ-MnO2 nanostructures for efficient asymmetric supercapacitors

    Y. Guo, L. Li, L. Song, M. Wu, Y. Gao, J. Chen, C. Mao, J. Song and H. Niu, J. Mater. Chem. A, 2019, 7, 12661
    DOI: 10.1039/C9TA01918A

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