Lithium salt of a pro-mesogenic [closo-CB11H12]− derivative: anisotropic Li+ ion transport in liquid crystalline electrolytes

Abstract

Li⁺ ion conduction in two aligned liquid crystalline electrolytes consisting of 10 mol% Li⁺ salt of a pro-mesogenic anion derived from [closo-1-CB₁₁H₁₂]⁻ in non-ionic hosts was investigated. Using electrochemical impedance spectroscopy (EIS), the ionic conductivity in the parallel (σ_‖) and perpendicular (σ_⊥) directions of the electrolyte samples was determined using two types of cells: an interdigitated gold electrode and a nylon 6-coated ITO cell. The ratio of ionic conductivities σ_⊥/σ_‖ in the electrolyte with a nona(ethylene oxide) spacer was about 3 in the entire SmA phase, while in the shorter homologue, the ratio monotonically increases from about 0.4 to 2.9. The liquid crystalline behavior of the hosts and the electrolytes was investigated by optical, thermal, and powder XRD methods.