Twin-cocoon-derived self-standing nitrogen-oxygen-rich monolithic carbon material as the cost-effective electrode for redox flow batteries

Developing cost-effective and environmental-friend electrode material is critical to accelerate the large-scale commercialization of the all-vanadium redox flow batteries . Herein, we propose and develop a twin-cocoon-derived self-standing carbon material by a green and safe preparation method. This facile degumming and carbonization process allows the twin-cocoon-derived monolithic carbon material to be decorated with nitrogen defects and oxygen functional groups. It has been demonstrated that this nitrogen-oxygen-rich monolithic carbon electrode material yields a promoted electrochemical activity for both V 2+ /V 3+ and VO 2+ /VO 2 + couples, causing a 50% decrease in redox potential difference and a 192% increase in diffusion slope as compared with the commercial carbon paper , thereby improving the electrochemical reversibility and enhancing the mass transfer kinetics. It is also found that the flow battery using nitrogen-oxygen-rich monolithic carbon electrode material shows 83% higher average discharge capacity and 20% higher energy efficiency than that with carbon paper at the current density of 100 mA cm −2 , promising a high-performance and low-cost all-vanadium redox flow battery . This work opens a new way to developing monolithic carbon electrode material that possesses great potential applications in flow battery and other electrochemical energy conversion and storage systems.