Activated carbon from tree bark (ACB) has been
synthesized by a facile and environmentally friendly activation
and carbonization process at different temperatures (600,
700 and 800 °C) using potassium hydroxide (KOH) pellets as
an activation agent with different mass loading. The physicochemical
and microstructural characteristics of the as-obtained
material revealed interconnected microporous/mesoporous architecture
with increasing trend in specific surface area (SSA)
as carbonization temperatures rises. The SSA values of up to
1018 m2 g−1 and a high pore volume of 0.67 cm3 g−1 were
obtained. The potential of the ACB material as suitable
supercapacitor electrode was investigated in both a three and
two-electrode configuration in different neutral aqueous electrolytes.
The electrodes exhibited electric double-layer capacitor
(EDLC) behaviour in all electrolytes with the Na2SO4
electrolyte working reversibly in both the negative (−0.80 V
to −0.20 V) and positive (0.0 V to 0.6 V) operating potentials.
A specific capacitance (Cs) of up to 191 F g−1 at a current
density of 1 A g−1 was obtained for the optimized ACB electrode
material in 1 M Na2SO4 electrolyte. A symmetric device
fabricated exhibited specific Cs of 114 F g−1 at 0.3 A g−1 and
excellent stability with a coulombic efficiency of a 100 % after
5000 constant charge–discharge cycles at 5.0 A g−1 and a low
capacitance loss for a floating time of 70 h.