Mesoporous carbons derived from citrates for use in electrochemical capacitors

Two mesoporous carbons were prepared by simple pyrolysis of commercial magnesium or barium citrate and tested as electrode materials for electrochemical double-layer capacitors (EDLCs), denoted MgC and BaC, respectively. The as-prepared carbon materials were characterized by N2 adsorption, scanning electron microscopy and Fourier transform infrared spectrometry. Nitrogen adsorption measurements demonstrated that the porosity of the prepared carbons was related to the type of metal cation. BaC possesses a typical bimodal pore size distribution (PSD) at 3.8 and about 15 nm, while MgC was between small-size mesoporous and microporous. The carbons were tested as electrode materials using different electrochemical means such as cyclic voltammetry and constant current charge-discharge. Very high specific capacitance (180 F·g−1 for MgC and 171 F·g−1 for BaC) was achieved in an ionic liquid electrolyte. BaC proved to be an excellent electrode material with a high rate performance for EDLC application and exhibited an energy density up to 53.3 Wh·kg−1 and a high maximum specific power density of 20 kW·kg−1 in IL electrolyte. The good capacitive performance of BaC is attributed to its bimodal PSD and hydrophilic surface properties.