Transport and Electrochemical Dynamics in the Li-S Battery Electrolyte

Abstract

Lithium-sulfur chemistry is a promising candidate beyond intercalation-based Li-ion batteries. In addition to an order of magnitude higher theoretical capacity, it provides some unique advantages such as being free of sluggish intercalation dynamics. On the flip side, the electrolyte phase description in such cells is quite intricate, and poorly understood till date. The identity of ionic charge carriers in the electrolyte phase changes upon pore-scale reactions. This alters the intrinsic ionic transport characteristics as the cell operation progresses. Interestingly this evolution of electrolyte phase exhibits hysteresis as reaction pathway differs for consecutive charge and discharge operations. Additional complexities arise from electrode microstructural evolution, which modifies the effectiveness of transport through porous electrodes. Such porosity changes introduce electrolyte level variations in the porous electrode. This flow is in response to pressure gradients in the electrolyte phase, and brings about further complexation. Current work explores the effects of such diverse electrolyte limitations and how they correlate to physicochemical behavior, microstructural and operational specifications of these cells.