Abstract
Mesoporous carbons were synthesized using thermoplastic phenolic resin (PF) as carbonaceous precursor and magnesium citrate as template precursor. Pore structure was determined as ink-bottle-like geometry through TEM, N2 adsorption analysis combined with TG curves. The porous carbons prepared were then applied as electrode material for electric double-layer capacitors. The capacitor performance was examined in 30 wt% KOH aqueous solution by cyclic voltammetry and galvanostatic charge/discharge measurements. The carbon prepared with MgO/PF mass ratio of 8/2 had a BET surface area of 1920 m2 g−1 and exhibited a capacitance of 220 F g−1 at a current density of 50 mA g−1. Besides, the carbon with the ratio of 4/6 had the optimize proportion of mesopores, which ensures its good rate performance that up to 98.3%, expressed as the ratio of the capacitance measured at 1000 mA g−1 against that at 50 mA g−1.
Highlights
Porous carbons have attracted great attention because of their hydrophobic surface nature, high surface area, large pore volumes, chemical inertness, as well as good thermal and mechanical stability [1]
For the excellent physical and chemical property, porous carbons have been used in various fields, the nature of which depends on the pore size of carbon materials
Three weight loss peaks for MgCi pyrolysis are evident, between 100–200°C, 300–400°C, and 400–600°C, respectively: the first peak indicates the removal of crystal water, the second one the decomposition of MgCi to Mg carbonate, and the third one the formation of MgO
Summary
Porous carbons have attracted great attention because of their hydrophobic surface nature, high surface area, large pore volumes, chemical inertness, as well as good thermal and mechanical stability [1]. MgO and organic magnesium salt, such as magnesium citrate, magnesium acetate, magnesium gluconate, were proved to be ideal because the pyrolysis product, MgO, exhibit perfect performance: chemical and thermal stability, no structural and compositional changes, no reaction with carbon up to carbonization temperature of carbon precursors, and dissolving into a diluted acidic solution [9,10]. Many carbon precursors have been selected to investigate various kinds of MgO-templated carbons, the interaction between carbon precursors and magnesium precursors during carbonization has not been properly discussed and the pore morphology of resultant carbons has not formed final conclusion. Magnesium citrate (MgCi, reagent grade, Tianjin Guangfu Fine Chemical Research Institute, China) with phenol formaldehyde resin (PF, novolac-type, Tianjin Daying Resin Co., Tianjin, China) was mixed in anhydrous ethanol, with mass ratios varying from 2/8 to 8/2, which were calculated on the basis of the mass of MgO, which was expected to be formed from MgCi, against PF itself
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