Facile Fabrication of Multivalent VOx/Graphene Nanocomposite Electrodes for High‐Energy‐Density Symmetric Supercapacitors. Issue 26 (3rd June 2021)

• Record Type: Journal Article
• Authors: Huang, Ailun; El‐Kady, Maher F.; Chang, Xueying; Anderson, Mackenzie; Lin, Cheng‐Wei; Turner, Christopher L.; Kaner, Richard B.
• Is Part Of: Advanced energy materials. Volume 11:Issue 26(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-03
• Subjects: high energy density -- redox‐active electrodes -- reduced graphene oxide -- supercapacitors -- vanadium oxides; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202100768
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Supercapacitors have emerged as one of the leading energy‐storage technologies due to their short charge/discharge time and exceptional cycling stability; however, the state‐of‐the‐art energy density is relatively low. Hybrid electrodes based on transition metal oxides and carbon‐based materials are considered to be promising candidates to overcome this limitation. Herein, a rational design of graphene/VO x electrodes is proposed that incorporates vanadium oxides with multiple oxidation states onto highly conductive graphene scaffolds synthesized via a facile laser‐scribing process. The graphene/VO x electrodes exhibit a large potential window with a high three‐electrode specific capacitance of 1110 F g –1 . The aqueous graphene/VO x symmetric supercapacitors (SSCs) can reach a high energy density of 54 Wh kg –1 with virtually no capacitance loss after 20 000 cycles. Moreover, the flexible quasi‐solid‐state graphene/VO x SSCs can reach a very high energy density of 72 Wh kg –1, or 7.7 mWh cm –3, outperforming many commercial devices. With R ct < 0.02 Ω and Coulombic efficiency close to 100%, these gel graphene/VO x SSCs can retain 92% of their capacitance after 20 000 cycles. The process enables the direct fabrication of redox‐active electrodes that can be integrated with essentially any substrate including silicon wafers and flexible substrates, showing great promise for next‐generation large‐area flexible displays and wearable electronic devices. Abstract : The vanadium oxides/graphene hybrid electrodes fabricated by a facile laser irradiation method have a high specific capacitance and a wide electrochemical window due to the presence of multiple vanadium oxidation states. The aqueous and gel symmetric supercapacitors based on the electrodes show high energy densities and power densities, excellent cycling stability and outstanding Coulombic efficiencies.