We address the physics of Ionic Liquids (IL) charged with lithium salts under confinement in polymer membranes made out of vertically aligned carbon nanotube (CNT). As this system shows no tortuosity and no friction at the electrolyte/CNT interface, electrolyte transport within the pore system (the interior of the CNTs) is expected to be tremendously enhanced. We have recently shown that, compared to the bulk situation, such 1D CNT nanometric confinement induces a conductivity gain of the electrolyte as high as 50.1 Then, ultra-fast transport of the electrolyte in between electrodes of a battery separator is an interesting route to directly boost the power density of batteries (Fig. 1). A patent has been filed.2 In this framework, where the CNTs diameter (4 nm) and their length (100 μm) are orders of magnitude different, a multiscale characterization of the confined electrolyte transport properties is essential. The competition between electrostatic and van der Waals interactions leads to a property original for pure liquids: they self-organize in fluctuating nanometric aggregates. So far, this transient structuration has escaped direct clear-cut experimental assessment. In bulk, we have taken advantage of the alliance of QENS (Time-of-flight, Spin-Echo), PFG-NMR, Electrochemical Impedance Spectroscopy and particle-probe rheology to i) catch this phenomenon and ii) highlight an unexpected consequence: a one order of magnitude difference of the transport quantities, depending whether they are inferred at the molecular or at the microscopic scale.3 We extend these results to the confined case.

Ionic liquids in bulk and under 1D CNT nanometric confinement

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.