Pore structure and electrochemical performances of tannin-based carbon cryogels

Carbon cryogels have been obtained by freeze-drying and pyrolysis of a family of tannin – formaldehyde organic gels prepared at different pHs. Such new materials, cheap and derived from biomass at a mass fraction of 0.8, were completely characterised in terms of pore structure and density. Samples obtained at pH higher than 6 were extremely lightweight and presented surface areas higher than 1200 m2 g−1. Tested as electrodes for electric double-layer capacitors, specific capacitances as high as 100 F g−1 were obtained and an ideal, purely capacitive, behaviour was always evidenced. Correlations have been observed between capacitance and micropore volumes, unambiguously suggesting that the latter mainly contribute to the capacitance.

Low-cost tannin-derived carbon cryogels, natural at a mass fraction of 0.8, were prepared for the first time at different pHs. Tested as electrodes for electric double-layer capacitors, carbon cryogels prepared above pH 6 presented specific capacitances as high as 100 F g−1. Correlation between electrochemical performances and pore texture showed that micropores mainly contribute to capacitance.Figure optionsDownload as PowerPoint slideHighlights
► The first tannin - formaldehyde carbon cryogels were prepared at different pHs.
► These materials have very cheap and natural at a mass fraction of 0.8.
► Cryogels prepared above pH 6 have specific capacitances as high as 100 F g−1.
► Micropores mainly contribute to capacitance, unlike in most other porous carbons.