Electrostatic self-assembly of hierarchical porous carbon microparticles

By Balach, Juan; Bruno, Mariano M.; Cotella, N. Gustavo; Acevedo, Diego F. & Barbero, César A.
Published in Journal of Power Sources NULL 2012

Abstract

Hierarchical porous carbon microparticles (HPCMs) are produced by milling and sieving porous monolithic carbon, which was obtained by carbonization of a resorcinol-formaldehyde gel in the presence of surfactant as a pore stabilizer. The obtained HPCMs has a surface area of 536 m2 g-1 and maximum specific capacitance and areal capacitance, measured at slow scan rates, of 194 F g-1 and 152 mF cm-2 respectively. Moreover, the carbon surface remains accessible at 100 mV s-1 with large values of specific capacitance (154 F g-1) and areal capacitance (121 mF cm-2), making the material suitable for fast supercapacitors. The HPCMs are then built into electrostatic self-assembled (ESA) adsorbed layers by sequential immersion of a planar electrode in HPCMs dispersions and a cationic polyelectrolyte. Using soluble redox molecules, it is possible to detect the finite (inside the pores) and semi-infinite (outer surface) diffusion of redox species. The specific capacitance of the HPCMs could be increased up to 5 times (to ca. 900 F g-1 in acid media) by adsorption of naphthoquinone molecules on the carbon surface. Using the ESA process, it is possible to build a layer with three different quinones in a single electrode. The specific capacitance of those layers is more than 4 times higher and maintained nearly constant in a wide range of potential.

Read Article » Back