Preparation of carbon microspheres from lignin-urea-formaldehyde resin for application in high-performance supercapacitor

In this paper, porous carbon materials were prepared from activating lignin-urea-formaldehyde resin microspheres. The nitrogen content, oxygen content, crystal structure, specific surface area, pore diameter distribution and electrochemical properties of the carbon materials were analyzed by investigating the amount of lignin added and carbon-alkali ratios. The addition of lignin brought in oxygen-containing groups to enhance surface wettability and pseudocapacitance. Multiplier properties, cycle life and specific capacitance were further studied. Urea-formaldehyde resin with 30% lignin addition could produce porous carbon materials with the most superior electrochemical performance, which had the highest specific surface area (3342 m(2) g(-1)), higher mesoporous rate (83%), larger specific capacitance (305 F g(-1)) and better cycling stability and had eminent characteristics of double-layer capacitance at all current densities and speeds. The above data showed that the urea-formaldehyde resin microspheres could prepare nitrogen-doped porous carbon materials after adding lignin, which could be used as promising electrode materials for supercapacitors.