(682g) Simulation of Electrochemical Double-Layer Capacitors Based On Carbon Nanotube Forests

Simulation of Electrochemical
Double-layer Capacitors based on Carbon Nanotube Forests

Xinli You, Peixi
Zhu, and Lawrence R. Pratt

Abstract      Unique
properties of nanomaterials, and specifically of
Carbon nanotube (CNT) forests based electrochemical double-layer capacitors
(EDLCs), arise from their large surface areas.¹ In recent
studies, we exhaustively studied propylene carbonate as a solvent for EDLCs,
reported experimental and molecular simulation results on PC interfaces. PC
wets graphite with a contact angle of 31° at ambient conditions.² Molecular
dynamics simulations agree with this contact angle after 40% reduction of the
strength of graphite-C atom Lennard-Jones
interactions with the solvent. This validation paves the way to direct
simulation of dynamical filling and performance of CNT-based EDLCs. Here, we
present all-atom molecular dynamics simulations of electrochemical double-layer
capacitors based on CNT forests with propylene carbonate tetraethylammonium-tetrafluoroborate
(PC:TEA-BF4) solutions. Preliminary results are showed in FIG. 1. We explicit
characterizations of the charging and discharging process, including electrolyte
composition in the pores, the rates that charging responses equilibrate, and
the possibility of bubble formation. Also, we consider the pore size dependence of EDLC characteristics and the
structural stability of CNT forests.

¹ L. Yang, et al., J. Am. Chem. Soc. 131,
12373-12376 (2009): "Molecular simulation of electric double-layer capacitors
based on carbon nanotube forests."

² X. You, et
al., J. Chem. Phys. 138, 114708 (2013): "Interfaces of
propylene carbonate."