Long-Term Charge/Discharge Cycling Stability of MnO2 Aqueous Supercapacitor under Positive Polarization
KAUST Grant NumberKUK-C1-014-12
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AbstractThe long-term charge/discharge cycling stability of MnO 2 electrode under positive polarization in aqueous KCl electrolyte has been studied over different potential windows spanning from the open circuit potential to varied higher-end potential limited by O 2 evolution. Cycling up to 1.2 V (vs Ag/AgCl (aq)) causes partial (35) capacitance fading to a plateau value within the initial cycles, accompanied by morphological reconstruction, reduction of surface Mn ions and oxygen evolution. The surface Mn-ion reduction has been attributed to a two-step oxidation-reduction mechanism involving OH oxidation in electrolyte, based on electrochemical analysis. When cycling potential extends to 1.4 V, extensive oxygen evolution takes place. The combination of surface passivation of current collector and extensive gas bubbling, which deteriorates electrical contact among the constituent particles within the electrode, results in further monotonic capacitance reduction. © 2011 The Electrochemical Society.
CitationAtaherian F, Wu N-L (2011) Long-Term Charge/Discharge Cycling Stability of MnO2 Aqueous Supercapacitor under Positive Polarization. J Electrochem Soc 158: A422. Available: http://dx.doi.org/10.1149/1.3555469.
SponsorsThis work is partially supported by the National Science Council of Taiwan (NSC 98- 2221-E-002-084-MY3; 98-3114-E-007-011), by National Taiwan University (NTU98R0066-09), and by King Abdullah University of Science and Technology under the GRP Award (award No. KUK-C1-014-12). One of the authors, F.A., would like to thank NTU post-doctor fellowship (NTU99R40044).
PublisherThe Electrochemical Society