“…The low capacitance of C-500 may be attributed to its negative characters such as the wide pore size distribution (2.0$28 nm), low N content (3.44%) and low N-Q percentage (8.51%). As previously reports, the micropores (<2 nm) are the most effective in a double-layer formation, and N groups (especially N-Q group) help in electron transfer through the carbon to increase the pseudocapacitive interactions [22,28,33]. H 3 PO 4 /C-500 presents the highest performance for 260, 206, 187, 175, 169 and 156 F g À1 at the current density of 0.05, 0.1, 0.2, 0.5, 1.0 and 2.0 A g À1 , respectively.…”