Mapping Li-Ion Transport Through a Ceramic Electrolyte by X-Ray Computed Tomography

Abstract

Low values of critical-current-densities are a significant shortcoming in the performance of Li^6.25La³Zr²A1^0.25O¹², a ceramic electrolyte. X-ray Computed Tomography (CT) images obtained from pristine and "exhausted" cells constructed with lithium metal electrodes, are used to map the spatial non-uniformity of lithium transport. The current is shown to be concentrated in a limited area of the interface, ostensibly producing low engineering values of the critical-current-density. The total volume of Li-ion transfer calculated from the CT scans, is consistent with Faradaic transport. A qualitative analysis of the maps suggests a current concentration factor of at least ten, and most likely even higher.

Keywords: LLZO, lithium ion electrolytes, ceramic electrolyte, critical current density, dendrites