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Issue 28, 2015
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Integration of nickel–cobalt double hydroxide nanosheets and polypyrrole films with functionalized partially exfoliated graphite for asymmetric supercapacitors with improved rate capability

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Abstract

High-rate asymmetric supercapacitors (ASCs) made of abundant and low-cost electrode materials and operating in safe aqueous electrolytes can be attractive for electrochemical energy storage. Here, we design a new type of ASC by using pseudo-capacitive nanomaterials, Ni–Co double hydroxide (Ni–Co DH) nanosheets and polypyrrole (PPy) films, for the cathode and anode, respectively, which were integrated with a functionalized partially exfoliated graphite (FEG) current collector. Benefiting from the “super highway” for fast electron/ion transportation in hybrid systems, the as-prepared electrodes exhibit superior rate capability (2442 and 2039 F g−1 at 1 and 50 A g−1, with 83.5% retention for Ni–Co DH; 560 and 441 F g−1 at 1 and 50 A g−1, with 79% retention for PPy). The assembled ASC displays a high specific capacitance (261 F g−1 at 1 A g−1) and excellent rate capability; 77% of its initial capacitance can be retained when the current density increases 30 times from 1 to 30 A g−1. An energy density of 61.3 W h kg−1 can be achieved by the ASC at 0.65 kW kg−1. Even at an ultra-high power density of 19.5 kW kg−1, the ASC can still deliver a high energy density of 47.2 W h kg−1. Through careful control of charges which can be stored in the anode and cathode, the cycling stability of the ASC is much improved, and 91% capacitance retention can be achieved after 5000 charge/discharge cycles. These features demonstrate a new avenue for developing high-performance pseudo-capacitive electrodes and rational assembly strategies for high power/energy density charge storage devices with good cycling stability.

Graphical abstract: Integration of nickel–cobalt double hydroxide nanosheets and polypyrrole films with functionalized partially exfoliated graphite for asymmetric supercapacitors with improved rate capability

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Publication details

The article was received on 17 Apr 2015, accepted on 05 Jun 2015 and first published on 08 Jun 2015


Article type: Paper
DOI: 10.1039/C5TA02810H
J. Mater. Chem. A, 2015,3, 14712-14720

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    Integration of nickel–cobalt double hydroxide nanosheets and polypyrrole films with functionalized partially exfoliated graphite for asymmetric supercapacitors with improved rate capability

    Y. Song, X. Cai, X. Xu and X. Liu, J. Mater. Chem. A, 2015, 3, 14712
    DOI: 10.1039/C5TA02810H

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