Porous active carbon derived from lotus stalk as electrode material for high-performance supercapacitors

Abstract

Porous active carbon electrode (PACE) materials in this work were prepared by a two-step method, which includes carbonization and KOH activation of dried lotus stalk at relatively high temperatures in an argon atmosphere. These processes produced a great number of disordered micropores and mesopores, thereby significantly increasing the specific surface area, up to 1022 m² g⁻¹. Those pores offered a more favorable pathway for electrolyte penetration and transportation, and thus improved the performance of supercapacitors. The electrochemical properties of PACE materials were tested in 6 M KOH electrolyte, and the results indicated that the specific capacitance reached 248.5 F g⁻¹ at the current density of 1 A g⁻¹. The PACE showed a rate capability with specific capacitance retained over 82.5% at a current density of 10 A g⁻¹ and a good long-term cycling stability with the specific capacitance retained 90.6% after 5000 cycles. Meanwhile, the energy density of PACE-based supercapacitors is 34.51 Wh kg⁻¹ at a corresponding power density of 496.94 W kg⁻¹. Lotus stalk manifests itself as a good carbon source candidate for the development of supercapacitor devices, and the facile synthetic process has a bright future for practical applications.

Keywords:

• Porous active carbon electrode
• lotus stalk
• carbonization
• activation
• electrochemical performance
• supercapacitor

Additional information

Funding

This work was financially supported by the Key Research and Development Project of Sichuan Province, China [Grant No. 2017GZ0396], the Fundamental Research Funds for Central Universities, the 11th Group of Outstanding Young Scientific and Technological Talents of Guizhou Province, China [Grant No. QKHPTRC[2017]5604], and Guizhou Science and Technology Program [Grant No. QKHZC[2020]2Y063].