Cathodic deposition of Ni(OH)2 and Co(OH)2 for asymmetric supercapacitors: Importance of the electrochemical reversibility of redox couples
This work demonstrates the influences of electrochemical reversibility of the pseudocapacitive materials on the performances of an asymmetric supercapacitor consisting of a pseudocapacitive cathode and an anode of the double-layer type. Thanks for the simple, one-step, cathodic deposition of nickel...
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Published in | Journal of power sources Vol. 221; pp. 128 - 133 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Amsterdam
Elsevier B.V
01.01.2013
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | This work demonstrates the influences of electrochemical reversibility of the pseudocapacitive materials on the performances of an asymmetric supercapacitor consisting of a pseudocapacitive cathode and an anode of the double-layer type. Thanks for the simple, one-step, cathodic deposition of nickel and cobalt hydroxide (denoted as Ni(OH)2 and Co(OH)2, respectively) films from their chloride precursor in aqueous media with the addition of 40 mM NO3− as the OH-donating agent. The specific capacitances of Ni(OH)2 and Co(OH)2 films (ca. 0.4 mg cm−2) deposited at 1.0 mA cm−2 for 1000 s are equal to 2217 and 549 F g−1, respectively while the electrochemical reversibility of Co(OH)2 is better than that of Ni(OH)2 based on peak potential difference and symmetry of charge/discharge curves. The Co(OH)2-graphene asymmetric supercapacitor shows higher capacitance retention and higher energy efficiency of charge–discharge than the Ni(OH)2-graphene system although the latter system exhibits higher energy and power densities than the former one. The microstructures of as-deposited Ni(OH)2 and Co(OH)2 films have been examined by scanning electron microscopic (SEM), transmission electron microscopic (TEM), and X-ray diffraction (XRD) analyses.
► Reversibility of redox materials determines CS retention and energy capture efficiency of asymmetric ECs. ► CS of Ni(OH)2 and Co(OH)2 prepared by cathodic deposition are 2217 and 549 F g−1, respectively. ► Ni(OH)2-graphene is an energy-oriented EC of the asymmetric type. ► Co(OH)2-graphene is a power-oriented EC of the asymmetric type. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0378-7753 1873-2755 |
DOI: | 10.1016/j.jpowsour.2012.07.111 |