posted on 2022-09-07, 12:03authored byKuilin Peng, Jie Lin, Deshuai Yang, Fangjia Fu, Zhongyang Dai, Guobing Zhou, Zhen Yang
Here, we performed classical molecular dynamics simulations
to
systematically explore the relationships between interfacial interactions
and nanostructures of an imidazolium-based ([BMIM][BF4])
ionic liquid (IL) electrolyte around single-walled carbon nanotube
electrodes with various charge densities and nanotube diameters. Our
simulation results showed that the aggregation of [BMIM]+ cations around the negative electrodes is dominated by the Coulombic
interactions. Meanwhile, it is unexpectedly found that a certain amount
of [BMIM]+ cations is distributed near the positive electrode
surface, which is attributed to the combined effect of their attractive
Coulombic interactions with anions and π–π stacking
interactions with nanotubes. Further analysis reveals that the imidazolium
rings of cations around the negative (or positive) electrodes with
a lower charge density exhibit more ordered orientations compared
to the counterparts with a higher charge density. Such phenomena mainly
occur because a lower charge density is favorable to form stronger
π–π stacking interactions between cations and nanotube
electrodes as well as stronger hydrogen bonds within interfacial cations
and anions. Hereto, our findings present a crucial step to interpret
complicated interactions and nanostructures at the electrolyte–electrode
interface, which would benefit experiments in designing high-performance
supercapacitors based on carbon electrodes and IL electrolytes.