Salt-template assisted synthesis of cornstalk derived hierarchical porous carbon with excellent supercapacitance

Abstract

An effective and sustainable two-step route including a pre-carbonization and the subsequent pyrolysis/activation to improve pre-carbonization process was developed for synthesizing cornstalk derived hierarchical porous carbons (CHPCs), which showed high porosity (1.498 cm3 g−1 pore volume) and were rich in oxygen groups (15.63 %). The addition of LiCl/ZnCl2 as a green and non-toxic template led to tunable pore structure of carbon materials, which could tailor the pore structure by acting as a pore padding agent and minimizing the collapse of pore channels. Moreover, the subsequent activation further endowed the carbons with enlarged porosity, significantly improving the supercapacitance. The obtained CHPCs exhibited a satisfying specific mass capacity of 375 F g-1 at 0.5 A g−1 in 1 M H2SO4, and the corresponding symmetric supercapacitor set out a superior energy density of 21.6 W h kg−1 while power density is equal to 300 W kg−1, which could make a green light emitting diode (LED) bright for more than 3 min. This salt-template assisted synthesis can effectively enhance the energy storage capacity of HPCs by regulating the pore structure.