Activation-Free Synthesis of Chitin-Derived Porous Carbon: Application for Electrical Energy Storage

Chitin-derived porous carbons (CDPCs) are synthesized by simply carbonizing chitin at 850 °C for 1 h under a N2 atmosphere. This method is very simple and does not require any activation or washing processes. We study the effects of the heating rate (2–20 °C min–1) on their structural characteristics and electric double-layer capacitor performance. Pore development proceeds above 300 °C during heating chitin, and nitrogen in chitin remains in the CDPCs with nitrogen/carbon molar ratios of 0.053–0.055. Although their specific surface areas are only 300–327 m2 g–1, three-electrode cell measurements in 1 M H2SO4 reveal that their gravimetric and area-normalized capacitances at 0.05 A g–1 are as high as 173–177 F g–1 and 54–57 μF cm–2, respectively. The area-normalized capacitances exceed those reported for activated carbons derived from chitin. Moreover, they show high capacitance retentions of 49–52% at 10 A g–1. Their high area-normalized capacitances and capacitance retentions are attributed to the coexistence of ultramicropores and mesopores along with high electrical conductivity due to a large amount of quaternary nitrogen and the absence of activation. Symmetrical two-electrode cell measurements show the practical energy and power densities of 4.9 W h kg–1 at 11.3 W kg–1 and 1.1 W h kg–1 at 1.5 kW kg–1 with a long cycle lifetime of 10,000 cycles. Our study demonstrates the significant contribution of utilizing biomass for electrode materials, aligning with the objectives of both United Nation's Sustainable Development Goals 7 and 12. By enhancing clean energy accessibility (SDG 7) and promoting responsible consumption and production practices (SDG 12) through efficient resource utilization, we have paved the way for a more sustainable energy future.