Abstract:
Binderless composite monolith (BCM) electrodes prepared from carbon nanotubes (CNTs)
and self-adhesive carbon grains (SACGs) were used in a symmetrical supercapacitor. The
SACGs were prepared from fibers of oil palm empty fruit bunches (EFBs) from oil palm tree
(Elaeis guineensis), Heliotropium dasycarpum (H. dasycarpum) and Guaiacum officinale (G. officinale).
For each biomass, the BCMs were prepared by the carbonization and activation of
green monoliths (GMs) containing SACGs treated with KOH and a mixture of SACGs and
CNTs treated with KOH. Thermal decomposition behavior of all SACGs was found to be
slightly different because of the difference in their compositions. In addition, BCMs from H.
dasycarpum and G. officinale were found to have SiO2. The BET surface areas were 1656, 1031
and 532 m2 g 1 for the BCMs from EFB, H. dasycarpum and G. officinale, respectively, and
these values decreased by 40, 50 and 31% upon CNTs addition. Consequently, the specific
capacitance decreased from w124 to w104 and w49 F g 1 to w111, w87 and w31 F g 1,
respectively. However, addition of CNTs reduced the equivalent series resistance (ESR) by a
factor of 83.9 (EFB), 90.6 (H. dasycarpum) and 38.8 (G. officinale) %. It was also found that CNTs
addition contributed to improving the decay of Csp with increasing scan rate if the electrode
surface area was sufficiently high.
