A combined salt-hard templating approach for synthesis of multi-modal porous carbons used for probing the simultaneous effects of porosity and electrode engineering on EDLC performance

A new approach, based on a combination of salt and hard templating for producing multimodal porous carbons is demonstrated. The hard template, silica nanoparticles, generate mesopores (similar to 22 nm), and in some cases borderline-macropores (similar to 64 nm), resulting in high pore volume (similar to 3.9 cm(3)/g) while the salt template, zinc chloride, generates borderline-mesopores (similar to 2 nm), thus imparting high surface area (similar to 2100 m(2)/g). The versatility of the proposed synthesis technique is demonstrated using: (i) dual salt templates with hard template resulting in magnetic, nanostructured-day embedded (similar to 27% clay content), high surface area (similar to 1527 m(2)/g) bimodal carbons (similar to 2 and 70 nm pores), (ii) multiple hard templates with salt template resulting in tri-modal carbons (similar to 2, 12 and 28 nm pores), (iii) low temperature (450 degrees C) synthesis of bimodal carbons afforded by the presence of hygroscopic salt template, (iv) easy coupling with physical activation approaches. A selected set of thus synthesized carbons were used to evaluate, for the first time, the simultaneous effects of carbon porosity and pressure applied during electrode fabrication on EDLC performance. Electrode pressing was found to be more favorable for carbons containing hard-templated mesopores (similar to 87% capacitance retention at current density of 40 A/g) as compared to those without (similar to 54% capacitance retention). (C) 2015 Elsevier Ltd. All rights reserved.