The coulombic efficiency (ηc) of the electrodes lies in the range of 75-90% and follows the sequence GR-AC (87%) ≃ Y-AC (87%) > S-AC (81%) ≃ GS-AC (80%) > GP-AC (76%) ≃ BPL-AC (75 %) (Figure ). No correlation was found between ηc and any other parameter, suggesting that the ratio of charge recovered during discharging to the charge stored during charging depends specifically on the type of electrode material. Similarly, the energy efficiency (ηe) did not depend on any other performance metric and followed the sequence GR-AC (54.2%) ≃ Y-AC (54.1%) > S-AC (52.8%) > BPL-AC (52.4%) > GP-AC (49.6%) > GS-AC (16.7%) (Figure ). The exceptionally low ηe of GS-AC is due to the very high resistance (235 Ω.cm 2 ) of these electrodes (Figure ). The higher resistance may be due to modified synthesis conditions and greater sp 3 character of GS-AC compared to other biomass-derived carbons, as shown in XPS surface chemical state analysis. Despite the high resistance, GS-AC electrodes showed high specific capacitance and high adsorption capacity, comparable to GP-AC and GR-AC. Among commercial carbons, S-AC shows the highest resistance due to its highest sp 3 character and smallest sp 2 character. BPL-AC, GP-AC, Y-AC and GR-AC exhibit reasonable resistance values of 7.2 Ω.cm 2 , 9.2 Ω.cm 2 , 13.6 Ω.cm 2 , and 25.5 Ω.cm 2 , respectively. The energy loss is lowest for BPL-AC electrodes and highest for GS-AC electrodes and follows the sequence BPL-AC (1.84 J) ≃ GR-AC (1.88 J) < GP-AC (2.73 J) ≃ S-AC (2.74 J) < Y-AC (2.78 J) < GS-AC (5.40 J) (Figure and Table ).