Sustainable Porous Carbon from Waste Fungal Substrates of Gastrodia Elata: A Dual-Function Material for High-Performance Supercapacitors and Lithium Batteries

In this work, waste fungal substrates materials of a traditional Chinese medicine Gastrodia elata were used to produce porous carbon for high-performance supercapacitors and lithium batteries. The porous carbon exhibited ultrahigh specific capacitances of 550 F/g at 1.0 A/g and 280 F/g at 20 A/g in a 6 M KOH electrolyte in a three-electrode system. In the assembled supercapacitors using 6 M KOH, 1 M Na₂SO₄, and 1 M Et₄NBF₄/AN electrolytes, it showed remarkably high specific energies of 11.6 Wh kg⁻¹, 28.2 Wh kg⁻¹, and 44 Wh kg⁻¹, respectively along with excellent long cycle stabilities. In addition, it has a high reversible lithium storage capacity of 1059.7 mAh g⁻¹ at 0.2 C, long cycle stability of 658.7 mAh g⁻¹ after 300 cycles, and great rate performance of 332.1 mAh g⁻¹ at 3.2 C. The capacity went as high as 241.2 mAh g⁻¹ after 1000 cycles under 3.2 C with a capacity retention of 72.6%. These excellent results proved that it is advantageous to use the discarded substrates of the Chinese medicine Gastrodia elata as a sustainable source to prepare porous carbon for multiple energy storage functions with high specific capacity and energy density.