Invited Presentation: Addressing Capacity Fading Challenges in Li-S Batteries via Electrolyte/Cathode Design

The presentation will focus on recent work in our lab involving the development of new electrolytes for the Li-S cell along with new materials for the cathode and developing insightful in situ probes of redox processes for a working cell and understanding the cathode interface.   We consider these to be the most challenging issues in electrochemical energy storage cells that operate on the basis of chemical transformations, where the factors that govern capacity and cycling stability are difficult to access owing to the amorphous nature of the intermediate species.  I will present results on cathodes for the Li-S cell comprised of sulfur-imbibed robust spherical carbon shells with tailored porosity that exhibit excellent cycling stability. Their highly regular nanoscale dimensions and thin carbon shells allow highly uniform electrochemical response and enable direct monitoring of sulfur speciation within the cell over the whole redox range by operando X-ray absorption spectroscopy on the S K-edge.  These studies are coupled with solid state NMR investigations, and include investigations of novel electrolyte systems.  Functional tailoring of the surface of the shells will also be presented, and if time permits, comparison will be drawn with Li-O2 electrochemistry.