Synthesis of Porous and Mechanically Compliant Carbon Aerogels Using Conductive and Structural Additives

Abstract

We report the synthesis of conductive and mechanically compliant monolithic carbon aerogels prepared by sol-gel polycondensation of melamine-resorcinol-formaldehyde (MRF) mixtures by incorporating diatomite and carbon black additives. The resulting aerogels composites displayed a well-developed porous structure, confirming that the polymerization of the precursors is not impeded in the presence of either additive. The aerogels retained the porous structure after etching off the siliceous additive, indicating adequate cross-linking of the MRF reactants. However, the presence of diatomite caused a significant fall in the pore volumes, accompanied by coarsening of the average pore size (predominance of large mesopores and macropores). The diatomite also prevented structural shrinkage and deformation of the as-prepared monoliths upon densification by carbonization, even after removal of the siliceous framework. The rigid pristine aerogels became more flexible upon incorporation of the diatomite, favoring implementation of binderless monolithic aerogel electrodes.

Recent Progress on Electrochemical Capacitors Based on Carbon Nanotubes

“…Recently, much attention has been paid to novel ultralight mesoporous carbon materials named carbon aerogels (CAGs) [15,[166][167][168][169][170][171][172][173] or carbon xerogels [8,[174][175][176][177][178]. Carbon aerogels exhibit many interesting properties such as low mass density, continuous porosity, high surface area, and high electrical conductivity.…”

Designing micro- and mesoporous carbon networks by chemical activation of organic resins

“…As opposed to carbon aerogels prepared by supercritical drying (Pekala 1989), the fragile polymeric structure of the xerogels usually undergoes an outstanding shrinkage and/or structural collapse during the carbonization step to obtain more dense carbon gels. Further activation of the RF xerogel to develop the nanoporous structure exerts a similar effect; whereas the microporosity is easily tuned by the activation procedure, the mesoporosity of the polymeric organic resins is typically destroyed during the activation process, due to the above-mentioned fragile structure of the xerogel dried under subcritical conditions (Zubizarreta et al 2008;Conceição et al 2009;Lozano-Castelló et al 2002;Contreras et al 2010;IsaacsPaez et al 2015;Hayashi et al 2002;Macias et al 2013Macias et al , 2016.…”

Preparation and characterization of a nitrogen-doped mesoporous carbon aerogel and its polymer precursor

“…The intensity ratio of the D/G peaks evaluates the graphitic nature of the sample. In our case, that ratio is 1.20, indicating that the carbon aerogel is amorphous [27]. It was not possible to record Raman spectrum for the polymer aerogel, it showed no Raman activity, neither when it was measured with 532 nm laser, nor when with 633 nm laser.…”

“…According to the powder XRD diffractograms (Fig. 6), both aerogels are amorphous, but some reflections from the graphite planes can be seen belonging to the Miller indices of 002 (at 23°) and 100 (at 44°) of the disordered carbon [27]. Table 1 shows the elemental composition of the polymer and carbon aerogels calculated from EDX spectra.…”