Abstract:
Binderless monoliths of supercapacitor electrodes were prepared by the
carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from
mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches
and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The
electrodes from GMs containing CNTs were found to have lower specific BET surface area
(SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared
electrodes were investigated by electrochemical impedance spectroscopy (EIS) and
galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces
the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from
GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than
that from the others GMs containing CNT. The cell has steeper Warburg’s slope than that from
its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move
into pores of electrodes despite these electrodes having largest reduction in specific BET
surface area. The cell also has the smallest reduction of specific capacitance (Csp) and
maintains the specific power range despite a reduction in the specific energy range due to the
CNT addition.
