Probing Charge Transport and Microstructural Attributes in Solvent‐ versus Water‐Based Electrodes with a Spotlight on Li–S Battery Cathode

Abstract

AbstractIn the quest for environmentally benign battery technologies, this study examines the microstructural and transport properties of water‐processed electrodes and compares them to conventionally formulated electrodes using the toxic solvent, N‐Methyl‐2‐pyrrolidone (NMP). Special focus is placed on sulfur electrodes utilized in lithium‐sulfur batteries for their sustainability and compatibility with diverse binder/solvent systems. The characterization of the electrodes by X‐ray micro‐computed tomography reveals that in polyvinylidene fluoride (PVDF)/NMP, sulfur particles tend to remain in large clusters but break down into finer particles in carboxymethyl cellulose‐styrene butadiene rubber (CMC‐SBR)/water and lithium polyacrylate (LiPAA)/water dispersions. The findings reveal that in the water‐based electrodes, the binder properties dictate the spatial arrangement of carbon particles, resulting in either thick aggregates with short‐range connectivity or thin films with long‐range connectivity among sulfur particles. Additionally, cracking is found to be particularly prominent in thicker water‐based electrodes, propagating especially in regions with larger particle agglomerates and often extending to cause local delamination of the electrodes. These microstructural details are shown to significantly impact the tortuosity and contact resistance of the sulfur electrodes and thereby affecting the cycling performance of the Li‐S battery cells.