(Invited) Composite Electrodes – the Challenge of Characterizing Ionic Transport on the Liquid Side of the Solid-Liquid Interface

Abstract

Composite electrodes are at the hart of modern batteries, since they overcome critical limitations of the solid active materials including volume changes as well as poor electronic and ionic conduction. Due to the very nature of the composite electrodes the solid-liquid interface of electron transfer reaction become buried within the bulk. Moreover, the bulk of the electrode has a complex internal structure, which is exceeding difficult to characterize using even advanced electron and X-ray techniques. This is in part due the nanometric size of the carbon black used to improve electron transport. In this talk, we will present some of our latest development based on scanning electrochemical microscopy and synchrotron radiation to characterize the electrolyte side of the composite electrode. Specifically, we will present data to suggest that the canonical electrolyte transport can be determined in a single sided measurement, greatly simplifying analysis in quality control and providing experimental data for this critical parameter in battery modeling. Moreover, we will present operando measurements of the electrolyte concentration gradient within the composite electrode. This matrix is particularly changeling due to its paramagnetic, conducting and opaque nature. The talk will conclude with an outlook on opportunities and challenges related to these techniques.