US: New solid state EV batteries capture sulfur cathode potential

Researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) have developed a novel one-step milling process to enhance the use of sulfur as a cathode material in solid-state batteries. Sulfur, abundant and low-cost, offers a high theoretical capacity (1675 mAh/g) but has been underutilized due to its insulating nature and poor electronic conductivity. The new process powders sulfur, solid-state electrolyte, and conductive carbon together, creating a metastable interphase that improves electrolyte interaction with sulfur, resulting in a discharge capacity of about 1500 mAh/g—close to sulfur’s theoretical maximum. This method addresses inefficiencies of previous mixing techniques and boosts battery performance without adding new materials or coatings. Additionally, the researchers tackled the issue of battery "breathing," where materials expand and contract during charge-discharge cycles, causing mechanical stress. They paired a silicon negative electrode with a lithium sulfide positive electrode, exploiting sulfur’s unique expansion behavior to offset the contraction of