Resumo

DIOSSA, Giovanna; CASTRO, Chris Daniela; ZAPATA-BENABITHE, Zulamita  e  QUINTANA, Germán. Storage energy capacity evaluation of activated carbon xerogels from lignin. Rev. ion [online]. 2017, vol.30, n.2, pp.17-30. ISSN 0120-100X.  https://doi.org/10.18273/revion.v30n2-2017002.

In this work two types of organic xerogels were prepared from sol-gel solutions using resorcinol (R), formaldehyde (F), lignin (L) and NaOH (C) as catalyst. The mass ratio L/(R+L) was set at 0.27 and the amount of catalyst was varied on two mass ratios (R+L)/C, 90.3 (G series) and 72.1 (D series). Organic xerogels are chemically activated with phosphoric acid with a mass ratio of acid to xerogel 0.85/1, 1h of impregnation and 2h of activation and activation temperature is fixed at 450°C. Activated carbon xerogels are electrochemically evaluated as electrodes for supercapacitors using different techniques such as cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) in a configuration of two and three electrodes. The value of the gravimetric capacity from cyclic voltammetry curves at 0.5mV/s (0 - 0.75V) for samples GA27 and DA27 were 222 and 226F/g, respectively. The DA27 sample showed more retention of energy than GA27, which is attributable to an increase in the presence of mesopores in the sample compared GA27. The mesopores are formed due to the degradation of lignin in activation with phosphoric acid; the DA 27 sample has more crosslinking than GA27 sample and this produces that inside the organic xerogel be less accessible. The sample with a higher content of catalyst showed better electrochemical behavior for use as electrodes for supercapacitors.

Palavras-chave : Lignin; Activated carbon xerogels; electrochemical properties; Phosphoric acid.

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