Supercapacitors (electrochemical capacitors) are energy storage devices featuring high power density, fast charging and discharging, long cycle life, and high durability. Their energy storage mechanisms are mainly divided into electric double-layer capacitance (e.g., carbon-based materials) and pseudocapacitance (e.g., metal oxides or conducting polymers). Supercapacitors bridge the performance gap between conventional capacitors and batteries, making them ideal energy storage or buffering components for electric vehicles and renewable energy systems like wind and solar power. Our laboratory is dedicated to developing high-performance electrode materials for supercapacitors. Recently, we successfully transformed waste coffee grounds into KOH-activated, nitrogen- and oxygen-enriched porous carbon materials with high specific surface areas. When assembled into a symmetric supercapacitor, it exhibited an extremely high power density of 7500 W/kg and outstanding long-term stability (no decay after 10,000 cycles). Additionally, we embedded graphene oxide and carbon nanotubes into carbon nanofibers (GO-CNT/CNF) to achieve superior specific capacitance and cycle life in neutral aqueous electrolytes. We also pioneered the development of an asymmetric supercapacitor (ASC) using petal-shaped manganese dioxide (MnO2) nanosheets as the positive electrode and CNT-embedded carbon nanofibers as the negative electrode. Operating at a high voltage of 2.0 V, it achieved a high energy density of 52.22 Wh/kg and a specific capacitance of 93.99 F/g.