Sputtered binder-free Cu₃N electrode materials for high-performance quasi-solid-state asymmetric supercapacitors

Developing high-efficiency electrode materials is of great importance in manufacturing supercapacitor devices with superior electrochemical performance. Herein, we for the first time report a binder-free method for controllable growth of Cu₃N electrode materials via magnetron sputtering for supercapacitor applications. Benefiting from their unique polyhedral structure and good electrical conductivity, Cu₃N electrodes can achieve an areal capacity of 90.7 mC cm^-2 at 1 mA cm^-2 and outstanding cycling stability with a capacity retention of 97.4% after 20 000 cycles. In particular, the assembled Cu₃N//active carbon quasi-solid-state asymmetric supercapacitor can exhibit a maximum energy density of 13.2 μW h cm^-2 and a power density of 4.8 mW cm^-2 with an operating voltage of 1.6 V. These remarkable performances demonstrate the great potential of sputtered Cu₃N electrode materials for future energy storage applications.