Supercapacitors have attracted increasing research interests and industrial usage over the past decade for their merits like high power density and outstanding cycling stability. Due to their unique charge-storage mechanism, the energy-power metrics of supercapacitors complement those of conventional batteries; however, the state-of-the-art energy density is undesirably low. Pseudocapacitive materials that undergo surface-controlled redox reactions at rates similar to those of non-Faradaic processes are considered to be promising candidates to overcome this limitation. Herein, we present a hybrid VOx/graphene electrode material that incorporates vanadium oxides with multiple oxidation states onto highly conductive graphene scaffolds. The synthesis features a facile laser-scribing of GO/VCl3 precursor mixture and enables the fabrication of large-area pseudocapacitive electrodes that can be integrated with various substrates. The as-prepared thin-filmVOx/graphene electrodes exhibit a large potential window with a high three-electrode specific capacitance of 1110 F/g. The aqueous VOx/graphene symmetric supercapacitors can reach a high energy density of 54 Wh/kg with virtually no capacitance loss after 20,000 cycles. Moreover, the flexible quasi-solid-state VOx/graphene SSCs can reach a very high energy density of 72 Wh/kg (or 7.7 mWh/cm3), outperforming many commercial devices. With very small Rct and near-100% Coulombic efficiency, these gel VOx/graphene SSCs can reach 92% capacitance retention after 20,000 cycles. Therefore, the pseudocapacitive VOx/graphene electrode can potentially enable highly desirable energy storage properties such as fast charging and grid storage.

Multivalent VOx/graphene nanocomposite electrodes for high-energy-density symmetric supercapacitors

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.