Dry-Films Containing Vanadium Tetrasulfide as Cathode Active Material for Solid-State Batteries with High Rate Capability

This study presents a comprehensive investigation of vanadium tetrasulfide (VS4) cathodes for solid-state lithium batteries, utilizing innovative material characterization techniques, including time-of-flight secondary ion mass spectrometry (ToF-SIMS), Raman spectroscopy, scanning electron microscopy (SEM), and focused ion beam-SEM. The effects of milling intensity and solid electrolyte (SE) content on microstructural evolution and electrochemical performance are thoroughly examined. VS4 composites are analyzed, revealing significant morphological and structural transformations. Notably, ToF-SIMS provides unprecedented insights into the lithiation process, highlighting the formation of lithium sulfide species and structural changes during cycling. Electrochemical testing demonstrates that high energy ball-milled composites exhibit superior discharge rate capability and cycling stability, achieving discharge capacities of up to 1466 mAh gs-1 at 0.05 C and 1150 mAh gs-1 at 1.00 C. The study emphasizes the critical role of SE content in enhancing lithium ion conductivity and interfacial contact, contributing to improved electrochemical performance. Furthermore, the development of a scalable dry-film processing method is explored, showcasing its potential for high power density applications. Overall, this research underscores the viability of VS4 as a promising cathode material for fast charging solid-state batteries, paving the way for advanced sulfur-based energy storage technologies.