A few case studies on the correlation of particle network and its stability on the ionic conductivity of solid–liquid composite electrolytes

Abstract

We discuss here the crucial role of the particle network and its stability on the long-range ion transport in solid–liquid composite electrolytes. The solid–liquid composite electrolytes chosen for the study here comprise nanometer sized silica (SiO₂) particles having various surface chemical functionalities dispersed in nonaqueous lithium salt solutions, viz. lithium perchlorate (LiClO₄) in two different polyethylene glycol based solvents. These systems constitute representative examples of an independent class of soft matter electrolytes known as “soggy sand” electrolytes, which have tremendous potential in diverse electrochemical devices. The oxide additive acts as a heterogeneous dopant creating free charge carriers and enhancing the local ion transport. For long-range transport, however, a stable spanning particle network is needed. Systematic experimental investigations here reveal that the spatial and time dependent characteristics of the particle network in the liquid solution are nontrivial. The network characteristics are predominantly determined by the chemical makeup of the electrolyte components and the chemical interactions between them. It is noteworthy that in this study the steady state macroscopic ionic conductivity and viscosity of the solid–liquid composite electrolyte are observed to be greatly determined by the additive oxide surface chemical functionality, solvent chemical composition, and solvent dielectric constant.