Large-Area Reduced Graphene Oxide Composite Films for Flexible Asymmetric Sandwich and Microsized Supercapacitors

Asymmetric supercapacitors have attracted tremendous attention in energy storage devices since they have an enhanced energy density in comparison with symmetric supercapacitor devices. Furthermore, the development of diverse and flexible electronic devices requires the asymmetric supercapacitor devices to be flexible and in various configurations. However, it is still a challenge to develop a universal strategy to obtain both capacitive and Faradic electrodes with various architectures. Herein, a spontaneously reducing/assembling strategy in an alkaline condition is developed to fabricate large-area reduced graphene oxide (RGO) and RGO-metal oxide/hydroxide composite films or microsized structures. As a proof of concept, the large-area pure RGO and RGO/Mn3O4 composite films with porous structure and superior mechanical property are achieved by such strategy. These RGO-based films can directly serve as the anodes and cathodes of the flexible asymmetric film supercapacitors. Furthermore, the interdigital RGO and RGO/Mn3O4 patterns are also obtained via a selectively reducing/assembling process to achieve the asymmetric microsized supercapacitors. These asymmetric supercapacitors with different configurations possess good electrochemical performance and excellent flexibility. Therefore, such reducing and assembling strategy provides a route to achieve large-area RGO-based films and microsized structures for the applications in the various fields such as energy storage and photocatalysis.