Evaluation of physical and electrochemical performances of hardwood and softwood derived activated carbons for supercapacitor application

This study is conducted to perceive evaluation of physical and electrochemical performances between activated carbons (ACs) derived from hardwood (HW) and softwood (SW). Here, ACs (HW-AC and SW-AC) are prepared by applying a cheap and easy-to-prepare method via chemical impregnation of H3PO4 at one-step integrated high-temperature carbonization process. The prepared HW-AC reveals large specific surface area of 1291.4 m2g−1 with 3.6 nm of pore size, which are larger than those of SW-AC having 1024.3 m2g−1 of specific surface area with 2.0 nm of pore size. However, both ACs do not exhibit high electrochemical properties. Therefore they are composited with MnO2 in three ratios of AC to MnO2 (1:1, 1:2 and 2:1) which resulted in remarkably enhanced electrochemical performances. Among the three composites, 1:1 hybrid-composite of HW-AC exhibits best electrochemical performances with specific capacitance of 484.3 Fg−1 at current density of 1 Ag−1, cycle life of 98.3 % (1000 cycles at 3 Ag−1) and specific energy density of 24.2 Whkg−1 at specific power density of 150.4 Wkg−1 in 6 M KOH electrolyte in 3 electrode set-up in a working voltage of 1.2 V. While, there is a significant improvement in performances of 1:1 hybrid SW-AC as compared to only SW-AC. It shows the specific capacitance of 309.2 Fg−1, cycle life of 94.3 % and specific energy density of 16.8 Whkg−1 at specific power density of 148.4 Wkg−1 related to specific capacitance of 104.3 m2g−1, cycle life 83.3 % and specific energy density of 2.3 Whkg−1 at specific power density of 79 Wkg−1 of SW-AC. The findings have been interpreted based on the lignocellulosic content of the precursors