Hierarchically porous carbon derived from potassium-citrate-loaded poplar catkin for high performance supercapacitors

A simple one-step preparation of biomass derived carbon materials with hierarchical pore structure for supercapacitor application is proposed. Briefly, potassium citrate is loaded onto poplar catkin, a forestry and agricultural residue, for carbonization at different temperature (750-900 degrees C). With the confined effect of poplar catkin and pore-forming role of potassium compounds, interconnected carbon networks combining of macropores, small mesopores and micropores are obtained. The product carbonized at 850 degrees C (S-850) processes large surface area of 2186 m(2)/g with two main micropore ranges distributed in 0.5-0.7 nm and 0.7-1.5 nm, and the sample of S-900 processes relatively high electrical conductivity because of the high degree of graphitization. The electrodes based on these carbon materials show main electrical double-layer capacitors with small part of pseudo-capacitors due to O-doping. The S-850 sample displays superior specific capacity at low charge-discharge current density while the electrode based on S-900 shows high specific capacity under high current density. The symmetrical devices based on S-850 give a superb stability and high energy and power densities in alkaline electrolyte. Within a voltage window of 1.4 V, the device can deliver a 13.3 Wh/kg energy density at a power density of 720 W/kg and maintain 7.8 Wh/kg at 14040 W/kg. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

A simple one-step method for preparing biomass derived carbon materials with hierarchical pore structure for supercapacitor application is proposed. The carbon materials exhibit interconnected carbon networks with macropores, small mesopores and micropores, and different temperature carbonization results in varying properties such as surface area and electrical conductivity. The electrodes based on these carbon materials show high specific capacity and stability, with S-850 sample displaying superior specific capacity at low charge-discharge current density and S-900 electrode showing high specific capacity under high current density. The symmetrical devices based on S-850 demonstrate superb stability and high energy and power densities in alkaline electrolyte.