Confinement Effects on the Thermal and Conductivity Properties of LiPF6-Dimethyl Carbonate Solutions Relevant to Lithium Rechargeable Batteries

Abstract

Solutions of lithium hexafluorophosphate dissolved in dimethyl carbonate (DMC) are confined within a nano-porous silica matrix (MCM-41). Thermal measurements indicate that the melting points of pure DMC and a 1.0 m LiPF6 DMC solution are significantly reduced when confined within the nanopores compared to bulk samples; an observation that is consistent with the Gibbs-Thompson equation. Temperature-dependent conductivity measurements of the confined solution show a sharp decrease in solution conductivity between 0 and -10oC. The measured conductivity values below -10oC are not sufficient to operate a lithium ion battery at sub-zero temperatures.