Improvement of yield and electrical double layer capacitor performance of activated carbon from cellulose by melamine- or guanine-sulfate addition

Abstract Conventional methods for preparing activated carbon with excellent electrical double-layer capacitor (EDLC) performance result in low yields and high costs due to the need for a large-surface-area structure. The creation of micropores increases the surface area of activated carbon but requires gasification of the carbonaceous component of the raw material, which is a challenging process. In this study, the addition of melamine sulfate to the cellulose precursor increased the yield from 10.8% to 24.4%, whereas the addition of guanine sulfate increased the yield to 18.4%. The mesopore-to-total pore volume ratio varied from 9.7% to 60.7% with the addition of melamine sulfate or guanine sulfate; this ratio was controlled by adjusting the addition amounts and the thermal pre-treatment conditions. The activated carbon samples were subsequently used as electrodes in EDLCs, and their charge/discharge properties were evaluated. The specific capacitances of the active materials prepared with melamine sulfate reached ∼30 F g −1 at a current density of 0.5 A g −1 , which was approximately three times higher than those of other samples. Specific capacitance improved after nitrogen doping and after the mesopore proportion had been increased to 60.7%. Impedance spectroscopy indicated that the increased mesopore proportion facilitated ion migration into the pores. The proposed method provides a simple and effective means of producing mesoporous carbon with up to 60.7% mesopores and desirable electrochemical properties, achieving low internal resistance.