Promising as high-performance supercapacitor electrode materials porous carbons derived from biological lotus leaf

The lotus leaf, a renewable source of biomass, was successfully explored as a low-cost crude carbon source for preparing high-value lotus leaf porous carbon (LLPC) via carbonization and KOH activation. The synthesis method is simple, inexpensive and easily scalable. Testing and analysis showed that LLPC is a good supercapacitor electrode material with a microporous and macroporous structure, a specific surface area (SSA) of up to 2488 m(2) g(-1), and a high content of oxygen heteroatoms. In a three-electrode system with 6 M KOH as the electrolyte, LLPC-800-1:3 exhibited a high specific capacitance of 379 F g(-1) at 1 A g(-1) and good rate performance. At a current density of 20 A g(-1), the specific capacitance still reached as high as 298 F g(-1). Furthermore, after 5000 charging/discharging cycles, the capacitance retention rate was 90%. When the energy density of the electrode was 9.2 W h kg(-1), the power density was 491 W kg(-1). The achieved electrochemical performance demonstrates that lotus leaves can function as a new biomass material for the production of high-performance supercapacitors and low-cost energy storage devices. (C) 2018 Elsevier B.V. All rights reserved.