All-Organic Sodium Hybrid Capacitor: A New, High-Energy, High-Power Energy Storage System Bridging Batteries and Capacitors

The development of hybrid capacitors (HCs) has become essential for meeting the rising demand for devices that simultaneously deliver high energy with high power. Although the challenge to develop high-performance HCs remains great, it is also simultaneously essential to develop an eco-friendly and cleaner energy storage system for sustainable future use. To date, hybrid capacitors utilize heavily toxic inorganic insertion electrodes and hazardous coke-derived porous carbon adsorption electrodes to host ions. Herein, we present a conceptually novel all-organic sodium hybrid capacitor (OHC), rationally designed by replacing the conventional electrodes with clean, green, and metal free organic molecules, to host ions. A high energy density of ∼95 Wh kg –1 and an ultrahigh power density of 7 kW kg –1 (based on active mass in both electrodes) are achieved with a low energy loss of ∼0.22% per 100 cycles (∼89% retention after 5000 cycles), outperforming conventional HCs. The outstanding energy–power behavior of OHC bridges the performance gap between batteries and capacitors. This research holds great promise for the development of next-generation eco-friendly, clean, green, and safer high-energy, high-power devices.