Four carbon aerogels with varied micro/mesoporous texture were synthesized and their electrochemical response for the electro-adsorption of ions investigated in saline electrolyte. As a general trend, the ability of the electrodes to electrosorb ions depended on the microporosity, whereas the large pores (mesopores) had a strong influence on the kinetics of the electrosorption process. The aerogels exhibiting a well developed microporosity interconnected by a large mesoporous network showed large capacitance values and fast electro-adsorption kinetics. Indeed, the diffusion of the ionic species in solution controls the performance of the electrodes at high current loadings (or scan rates). We show that this pore size distribution is easily controlled by modifying the precursor/catalyst ratio in the carbon aerogel fabrication. Optimized electrode materials should combine pores within the micropore range to effectively electrosorb ions and large mesopore volumes for a fast diffusion of the ionic species in solution. An adequate meso/micropore ratio in the carbon aerogels here reported allowed to record a capacitance value of 76 F g−1.

The authors are indebted to the Spanish MARM (grant 083/RN08/03.3) and MICINN (grants CTM2008-01956 and CTM2011-23378) for financial support. Technical support of M.C. Mohedano is also acknowledged. MH thanks CSIC for a postdoctoral contract.

Peer reviewed