Supercapacitor electrodes from activation of binderless green monoliths of biomass self-adhesive carbon grains composed of varying amount of graphene additive

• Published in: Ionics 2018-04, Vol.24 (4), p.1195-1210
• Main Authors: Jasni, M.R.M., Deraman, M., Suleman, M., Zainuddin, Z., Othman, M.A.R., Chia, C.H., Hashim, M.A.
• Format: Article
• Language: English
• Subjects: Activated carbon; Activation; Carbon; Carbonization; Charge transfer; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrical resistivity; Electrochemistry; Electrodes; Energy Storage; Grains; Graphene; Optical and Electronic Materials; Original Papers; Porosity; Renewable and Green Energy; Response time; Supercapacitors
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-017-2283-7

Binderless electrodes of activated carbon monoliths (ACMs) and its composites with graphene are prepared by carbonization and activation of green monoliths consisting of self-adhesive carbon grains and 0–10 wt% KOH-treated graphene. Compared with ACMs, the optimized composite containing 6 wt% graphene exhibits more ordered micro-structures with increased crystallite height, and graphitic sp 2 carbons ( I D / I G  = 0.49 vs. 0.91) along with enhanced porosity; as revealed by X-ray diffraction, Raman, and N 2 adsorption-desorption studies. These modifications lead to increased electrical conductivity (13 vs. 9 S cm −1 ) through improved interconnections of carbon particles by graphene, and surface area ~ (800 vs. 456 m 2  g −1 ) due to increased inter-particle spacing. Further, contrary to ACMs, the composite electrodes can offer faster delivery of energy in almost 50% less response time (5 vs. 8 s) due to reduced equivalent series resistance (1.67 vs. 2.65 Ω) and charge transfer resistance (0.55 vs. 1.33 Ω).