Macroporous nitrogen-containing carbon for electrochemical capacitors

Abstract

Polypyrrole-gelatin aerogels were synthesized by a one-step cryopolymerization approach and carbonized at various temperatures (100–700 °C). The mechanical integrity and macroporous morphology (pore size 4–16 µm) of materials carbonized at all studied temperatures were preserved after carbonization. Raman and X-ray photoelectron spectroscopies confirmed the aerogel conversion to carbon with gradually enhanced structural order at higher temperatures (300–600 °C). Change of the material conductivity with carbonization temperature follows the evolution of its molecular structure, reaching 2 × 10–5 S cm–1 for a fully carbonized aerogel (700 °C). Specific surface area and total pore volume values for the carbonized material were ⁓one order of magnitude higher (441.7 m2 g–1 and 0.21 cm3 g–1 at 600 °C, respectively) compared to the ones of the precursor. Cyclic voltammetry measurements showed that gravimetric capacitance of the products increased at higher carbonization temperatures up to 209 F g–1 (700 °C) and was stable for at least 1000 cycles. Galvanostatic charge-discharge method showed the highest capacitance 273 F g–1 (1 M HCl). The prepared nitrogen-containing carbon materials can be potentially used for supercapacitor applications.