Electro-deposition and dissolution of MnO2 on a graphene composite electrode for its utilization in an aqueous based hybrid supercapacitor

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DOIResolve DOI: http://doi.org/10.1149/2.064208jes
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TypeArticle
Journal titleJournal of the Electrochemical Society
ISSN0013-4651
Volume159
Issue9
PagesA1554A1561
SubjectAqueous electrolyte; Charge/discharge cycle; Electrode reactions; Electrodissolution; Graphene composites; High surface area; Hybrid supercapacitors; Potential windows; Capacitors; Deposition; Dissolution; Electrolytes; Graphene; Hybrid systems; Manganese oxide
AbstractThe electro-deposition and dissolution of MnO2 is studied for its potential utilization in hybrid supercapacitors. A commercially available graphene powder is used as high surface area substrate and capacitive type electrode. An aqueous electrolyte composed of 0.5 M H2SO4 + 0.5 M MnSO4 is used. The deposition-dissolution reaction of MnO2 is shown to provide the bulk of the charge storable in the battery type electrode. Furthermore, the potential window of stability of this electrode reaction is compatible with the aqueous electrolyte. Two complete systems were assembled and tested for their charge/discharge behavior. It is shown that energy and power densities of 25 Wh kg-1 and 980 W kg -1, respectively, can be achieved for at least 5000 cycles. Limitations of the system in terms of cycle numbers and electrolyte volume are discussed in more detail. The electrolyte volume to electrode mass ratio is shown to be a critical factor in determining the charge/discharge cycle number of the device. This is believed to be due to the fact that the efficiency of the MnO2 electro-dissolution/deposition process is less than 100%. This, in turn, could result in gradual pH changes and a lower Mn2+ concentration in the electrolyte during continues charging and discharging. This eventually results in lowering the energy and power density of the system. However, it is shown that an energy density of 25 Wh kg-1 is achievable, thus being comparable with similar hybrid systems. © 2012 The Electrochemical Society. All right reserved.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Institute for Chemical Process and Environmental Technology (ICPET-ITPCE)
Peer reviewedYes
NPARC number21269421
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Record identifier4fb5ba18-4d3a-4ae1-ba58-c994bc0d9516
Record created2013-12-12
Record modified2016-05-09
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