HIGH-ENERGY-DENSITY ELECTRODE ON THE BASIS OF ACTIVATED CARBON MATERIAL FOR HYBRID SUPERCAPACITORS

•Electron microscopy and Raman spectroscopy indicate formation of the C*xI.•The entropy-related contribution to ΔGоf(C*хI) is dominate.•One-electron transfer of the C*xI formation and its reversibility were experimentally shown.•The obtained high values of parameters of GD are: P = 2.28 W g−1, C = 1254 C g−1, Cf = 7376 F g−1, W = 1426 J g−1.•Practical values of W and C are equal to 82% and 87% of the theoretical values respectively.

ABSTRACTThe “Norit DLC Supra 30” commercial activated carbon material (NS commercial ACM) has been investigated as a polarized electrode for a hybrid supercapacitor (HS) in aqueous ZnI2 solution. Energy-dispersive X-ray spectroscopy and Raman spectroscopy have shown that there is considerable increase in response of iodine atoms of the electrochemically adsorbed material as compared to that of the initial material. Thermodynamic functions of the process of the Cx*I formation have been determined; they indicate that the entropy-related contribution to Gibbs free energy dominates there. The drawn theoretical Langmuir isotherm and capacity-voltage characteristic were compared with corresponding experimental ones. One-electron transfers of the process of iodine electrosorption and the reversibility of this process have been experimentally shown. The obtained experimental value of the specific pseudocapacitive discharge (Cf) is equal to 7376 F g−1 at the efficiency of the cycle of 93 %. Practical discharge has the following parameters: specific power (P) is 2.28 W g−1, specific energy (W) is 1426 J g−1, specific capacity (C) is 1254 C g−1. The obtained practical values of specific energy and capacity are equal to 82 % and 87 % of the theoretical values respectively.

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