Electrochemically modified graphite paper as an advanced electrode substrate for supercapacitor application

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (29), p.17547-1756
• Main Authors: Mandal, Debasish, Routh, Parimal, Mahato, Ashok K, Nandi, Arun K
• Format: Article
• Language: English
• Subjects: Capacitance; Charge transfer; Contact resistance; Current density; Electrochemical impedance spectroscopy; Electrochemical oxidation; Electrochemistry; Electrodes; Exfoliation; Flux density; Graphite; Kinetics; Molybdenum oxides; Nanoparticles; Oxidation; Performance tests; Spectroscopy; Spectrum analysis; Substrates; Supercapacitors
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta04496e

Herein, a novel advanced electrode substrate, electrochemically modified graphite paper (ECM-GP) having a foam-like structure, was developed via the green electrochemical oxidation/exfoliation of pristine graphite paper (PGP). The exfoliation technique greatly enhanced the specific surface area from 28.6 m 2 g −1 for PGP to 560.9 m 2 g −1 for ECM-GP with a pore volume of 0.766 cm 3 g −1 . This structural improvement not only enhanced its capacitance (from 108 mF cm −2 for PGP to 156 mF cm −2 for ECM-GP) but also improved its charge storage kinetics from diffusion-controlled to a capacitive nature. These amazing characteristics of ECM-GP allowed it to be extended as an advanced electrode substrate by electrochemically depositing MoO 2 nanoparticles, resulting in a high capacitance value of 1409 mF cm −2 (19.6 F cm −3 ) at a current density of 2 mA cm −2 with 33.7% retention at a current density of 30 mA cm −2 . This capacitance value is very high compared to that of previously reported MoO 2 -based electrodes and other differently designed electrodes. Electrochemical impedance spectroscopy indicated low charge transfer resistance in ECM-GP and low contact resistance between ECM-GP and MoO 2 . The designed solid-state symmetric supercapacitor (SSC) using the MoO 2 -decorated ECM-GP electrode showed a high energy density of 0.212 mW h cm −2 (1.41 mW h cm −3 ) with a power density of 98.46 mW cm −2 (665.41 mW cm −3 ). The designed electrochemically modified graphite paper (ECM-GP) having a foam-like structure serves as an advanced electrode substrate of supercapacitors.