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Enhanced Supercapacitive Performance of MnCO 3 @rGO in an Electrolyte with KI as Additive
Author(s) -
Li Hua,
Wu Xiaozhong,
Zhou Jin,
Liu Yuxiang,
Huang Ming,
Xing Wei,
Yan Zifeng,
Zhuo Shuping
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201801290
Subject(s) - pseudocapacitance , electrolyte , crystallinity , supercapacitor , graphene , capacitance , cyclic voltammetry , electrochemistry , x ray photoelectron spectroscopy , current density , materials science , oxide , redox , analytical chemistry (journal) , chemical engineering , electrode , chemistry , nanotechnology , chromatography , metallurgy , composite material , physics , quantum mechanics , engineering
Abstract MnCO 3 @rGO (GM) was synthesized through a facile one‐pot hydrothermal process with graphene oxide and KMnO 4 as precursors. X‐ray diffraction analysis reveals that the prepared MnCO 3 possesses a high crystallinity with a grain size of 28.4 nm. To improve the capacitive performance of GM, KI was added to the Na 2 SO 4 electrolyte as a redox additive. Electrochemical measurements show that the specific capacitance of GM in KI additive electrolyte could reach up to 546 F g −1 at the current density of 0.5 A g −1 . This value is 8 times larger than that (61 F g −1 ) in Na 2 SO 4 electrolyte at the same current density. The elevated specific capacitance is attributed to the presence of I − , which can bring about significant pseudocapacitance through the redox couples of I − /I 3 − and I − /IO 3 − as confirmed by X‐ray photoelectron spectroscopy. GM also possesses a capacitance retention ratio of around 103 % after 2000 cyclic voltammetry measurements, suggesting a superior cycling stability.