Self-template/activation nitrogen-doped porous carbon materials derived from lignosulfonate-based ionic liquids for high performance supercapacitors.

A simple ion exchange reaction of sodium lignosulfonate (SLS) and 1-allyl-3-methyl imidazolium chloride ([Amim]Cl) produced a new polymeric ionic liquid [Amim]LS and NaCl, and the mixture was successfully used as a precursor to prepare a nitrogen-doped porous carbon material via direct carbonization without any additional activation agent or template. It was believed that the in situ produced NaCl during the precursor synthesis process acted as the self-template and in self-activation. The introduction of imidazolium ionic liquid into the precursor raised the nitrogen content of the obtained carbon material up to 4.68% for a high yield of [Amim]LS-700 carbon material up to 34.6%. The effect of carbonization temperature on the structures and electrochemical properties of the prepared carbon were also studied systematically. It was found that the carbon material exhibits a superior gravimetric capacitance up to 230 F g -1 (0.1 A g -1 ) at the carbonization temperature of 700 °C, a good energy density of 7.99 W h kg -1 at the power density of 25 W Kg -1 , and an excellent cycling stability of 90.3% after 20 000 cycles. This work provides a new path for the value-added utilization of biomass coupled with the field of electrochemical energy storage.