Biochar Derived from Waste Momordica Cochinchinensis Seed Shell as High-Performance Supercapacitor Electrodes

For the purpose of making high-value use of Chinese medicine waste, the preparation of derived biochar was studied and used as an electrode for supercapacitors (SCs). High-temperature KOH activation was used to convert the seed shells of discarded traditional Chinese medicine (Mubiezi) into graded porous carbon electrode materials, and the optimal electrode (MCSSAC-3) was obtained by optimizing the KOH addition ratio in this work. The MCSSAC-3 electrode obtained has a high specific surface area (1288.55 m2 g–1) and significantly higher specific capacitance of 302.29 F g–1 at 0.5 A g–1. The MCSSAC-3//MCSSAC-3 symmetric device has a high energy density of 11.13 Wh kg–1 at a power density of 350 W kg–1. In addition, even after 10,000 consecutive cycles, the MCSSAC-3//MCSSAC-3 symmetric device exhibits ideal capacitance retention of 87.16% at 10 A g–1. This work offers an approach for the preparation of low-cost and high-performance SCs carbon-based electrodes from discarded traditional Chinese medicine.