Effects of Oxygen-Containing Functional Groups on Supercapacitor Performance
Molecular dynamics (MD) simulations of the interface between graphene and the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIM OTf) were carried out to gain molecular-level insights into the performance of graphene-based supercapacitors and, in particular, determine the effects of the presence of oxygen-containing defects at the graphene surface on their integral capacitance. The MD simulations predict that increasing the surface coverage of hydroxyl groups negatively affects the integral capacitance, whereas the effect of the presence of epoxy groups is much less significant. The calculated variations in capacitance are found to be directly correlated to the interfacial structure. Indeed, hydrogen bonding between hydroxyl groups and SO3 anion moieties prevents BMIM+ and OTf- molecules from interacting favorably in the dense interfacial layer and restrains the orientation and mobility of OTf- ions, thereby reducing the permittivity of the ionic liquid at the interface. The results of the molecular simulations can facilitate the rational design of electrode materials for supercapacitors.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1136595
- Report Number(s):
- PNNL-SA-102736; 44591
- Journal Information:
- Journal of Physical Chemistry Letters, 5(13):2330-2334, Journal Name: Journal of Physical Chemistry Letters, 5(13):2330-2334
- Country of Publication:
- United States
- Language:
- English
Similar Records
Molecular Investigation of Oxidized Graphene: Anatomy of the Double-Layer Structure and Ion Dynamics
Temperature-programed time-of-flight secondary ion mass spectrometry study of 1-butyl-3-methylimidazolium trifluoromethanesulfonate during glass-liquid transition, crystallization, melting, and solvation