Scalable fabrication of vanadium carbide/graphene electrodes for high-energy and flexible microsupercapacitors

In-plane microsupercapacitors (MSCs) hold great promise for microscale power source, due to the extremely high power density and ultra-long cycling life. However, the scalable fabrication of flexible MSCs with high energy density remains a major challenge. Here, we demonstrate the fabrication of vanadium carbide/reduced graphene oxide (V8C7/rGO) MSCs via laser scribing on ammonium metavanadate/graphene oxide (NH4VO3/GO) films, prepared by efficient continuous centrifugal casting method. More than 20 MSCs can be produced on a flexible substrate in 30 min, showing the potential for scalable fabrication. The laser-induced V8C7/rGO shows highly porous microstructure, where vanadium carbide nanoparticles are in-situ synthesized and uniformly decorated on graphene nanosheets. The well-defined architecture endows V8C7/rGO MSCs with excellent electrochemical performance. The areal capacitance of these devices can be as high as 49.5 mF cm−2, 11 times higher than that of rGO MSCs. The volumetric energy density and power density can be up to 3.4 mWh cm−3 and 401 mW cm−3, respectively, competitive with the commercially available energy storage devices and most reported MSCs. In addition, V8C7/rGO MSCs show excellent flexibility and integrability, as well as long cycling life, promising for practical applications.