Computational insight into the capacitive performance of graphene edge planes

Abstract

Recent experiments have shown that electric double-layer capacitors utilizing electrodes consisting of graphene edge plane exhibit higher capacitance than graphene basal plane electrodes. However, theoretical understanding of this capacitance enhancement is still limited. Here we applied a self-consistent electronic calculation on the electrode/electrolyte interface and found that the capacitance of graphene edge plane depends on the edge type: zigzag edge has higher capacitance than armchair edge. We further examined the quantum, dielectric, and electric double-layer (EDL) contributions to the total capacitance of the edge-plane electrodes. Through classical molecular dynamics simulation, we found that the edge planes have higher electric double-layer (EDL) capacitance than the basal plane due to better adsorption of counter-ions and higher solvent accessible surface area, indicating the importance of surface morphology in affecting EDL capacitance. Our work therefore has elucidated the capacitive energy storage in graphene edge planes that take into account both the electrode's electronic structure and the EDL structure.

Substrate Effects in Graphene‐Based Electric Double‐Layer Capacitors: The Pivotal Interplays between Ions and Solvents

“…With the presence of solid electrode, an evidently multilayer structure of electrolytes was recognized at the interface, principally triggered by the VDW and coulombic interactions. To be specific, the first layer of Na + populations preferred to gather at the valley of neighboring O atoms, while Cl − ions accumulated farther away from the electrified surface where they could maintain a full hydration shell ,. Nevertheless, the density oscillations became vanished about ∼12 Å away from the electrode surface, consistent with previous theoretical studies ,.…”

Computational Insights into Materials and Interfaces for Capacitive Energy Storage

“…However, since the graphene edges also exhibit typical dielectric behavior, it is necessary to include the dielectric screening contribution in total capacitance with the three‐contribution model . To this end, JDFT was used to study the capacitance of graphene edge planes in contact with an implicit aqueous electrolyte: the electronic chemical potential shift and the electrostatic potential drop across the interface show that armchair and zigzag edges have distinct dielectric screening; the zigzag edge has much higher total capacitance than armchair edge due to its very high C Q ; CMD simulation was also used to study the influence of surface morphology on the C EDL …”

Highly Loaded Mildly Edge‐Oxidized Graphene Nanosheet Dispersions for Large‐Scale Inkjet Printing of Electrochemical Sensors

“…The reduction of capacitive signals could further suggest that the edge functionalities/defects on the graphene sites were reduced with partial restoration of the sp 2 structure. It has been shown that the capacitance of graphene is higher at the edges than the basal planes as the edges provide greater accessibility to the solvent ions and large inhomogeneities of the charges allow greater ion adsorption . It must be noted that the temperature of the EOGN film during the photonic curing process is unknown due to the lack of temperature sensors that operate on microsecond time scales.…”

“…It has been shown that the capacitance of graphene is higher at the edges than the basal planes as the edges provide greater accessibility to the solvent ions and large inhomogeneities of the charges allow greater ion adsorption. [71][72][73] It must be noted that the temperature of the EOGN film during the photonic curing process is unknown due to the lack of temperature sensors that operate on microsecond time scales. The thermal treatment in a furnace is limited by the thermal properties of the plastic substrates.…”