High surface area porous carbon for ultracapacitor application by pyrolysis of polystyrene containing pendant carboxylic acid groups prepared via click chemistry

Strategic designing and synthesis of polystyrene derivative is performed via click chemistry to achieve micro/meso-porous conducting carbon with high surface area (1860 m2 g−1) by controlled pyrolysis. The design is done with the objective to get graphene-like framework (by polystyrene backbone), nitrogen doping (by triazole ring) and high porosity (salt of carboxylic acid). Potassium hydroxide is reacted with the carboxylic acid groups of the polymer to achieve uniform in situ molecular activation. The obtained hierarchically porous carbon is characterized and studied for the electric double layer capacitor in organic electrolyte as well as lithium ion hybrid electrochemical capacitor (Li-HEC) performance. A specific capacitance of 137.8 F g−1 is obtained for the applied current density of 0.5 A g−1 using tetraethyl ammonium tetrafluoroborate in propylene carbonate as an electrolyte, in the potential range of 0–2.7 V. The Li-HEC cell is found to deliver the maximum energy and power densities of 61 Wh kg−1 and 10,015 W kg−1, respectively, with ∼70% capacitance retention after 2000 charge–discharge cycles at the current density of 2 A g−1.