Comparing Graphite and Graphene Oxide Supercapacitors with a Constant Potential Model

Author(s)

Lemos Pereira, Guilherme Ferreira ^[1] ; Fileti, Eudes Eterno ^[2] ; Amaral Siqueira, Leonardo Jose ^[1]

Affiliation

^[1] Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Dept Quim, Lab Mat Hibridos, BR-09913030 Diadema, SP - Brazil

^[2] Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12247014 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 125, n. 4, p. 2318-2326, FEB 4 2021.
• Web of Science Citations: 0

Abstract

Electric double-layer capacitors store energy because of the adsorption of ions on the surface of electrodes. A realistic model to describe the electrolyte-electrode interface is based on the constant potential method that allows the electrode charges to fluctuate in order to try to mimic the polarization of metallic electrodes {[}J. Phys. Chem. Lett. 2013, 4, 264-268]. We performed molecular dynamics simulations of graphene oxide (GO) electrodes using the constant potential model comparing carefully the interface structure, polarization, and charging processes of an ionic liquid with the respective properties calculated for graphite electrodes. The layered structure of the ions at the electrode-electrolyte interface is less organized in comparison with that observed for graphite electrodes, which reduces overscreening. With regard to performance in terms of energy storage, graphite performs better than GO in a wide range of applied voltages. The charging dynamics of GO is slower at low applied voltages. At high voltages, the stronger electrostatic interactions between the charged electrode and electrolyte prevail, allowing for similar charging times for both supercapacitors. (AU)

• FAPESP's process: 19/18125-0 - Computational study of materials with application in energy storage
• Grantee: Leonardo José Amaral de Siqueira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/11631-2 - CINE: computational materials design based on atomistic simulations, meso-scale, multi-physics, and artificial intelligence for energy applications
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Research Grants - Research Centers in Engineering Program