Cary Pint

Abstract:

One of the key obstacles in the realization of high energy density lithium batteries exceeding 500 Wh/kg is the development of scalable manufacturing methods to produce stable and high mass and areal loading sulfur cathodes. In this talk, I will discuss our recent efforts that have addressed the manufacturing challenges posed by thermal melt diffusion infiltration of sulfur, which remains the most widely used technique to produce carbon-sulfur composites, through the development of a scalable capillary force driven manufacturing technique. This technique enables thick carbon host materials to be site-selectively infiltrated with sulfur (over 70 wt.%) in a matter of minutes with low-temperature thermal processing below 170 oC. This is compared to melt infiltration methods that usually require over 12 hours of processing at similar temperatures, yield no control of sulfur morphology or location, and hence exhibit poor sample-to-sample reproducibility. By leveraging this technique, our team has been able to iterate across numerous studies that I will discuss evaluating and demonstrating critical performance criteria that can enable lithium-sulfur batteries with energy density in packaged battery systems exceeding 500 Wh/kg. This includes (1) stability enabled by nanoscale V2O5 binding materials that mitigate polysulfide dissolution that lowers Coulombic efficiency and leads to anode fouling, (2) high areal capacities exceeding 19 mAh/cm2 with sulfur mass loading exceeding 75 wt.%, and (3) high sulfur utilization and retention that is strongly associated with combined sulfur morphology and polar binding properties in a sulfur-carbon composite material. Our work gives promise to a route that bypasses the high cathode material and processing cost in Li-ion batteries, sustains the scalability, throughput, and reliability needed for battery manufacturing, and overcomes performance limitations of prior approaches described in the literature that rely heavily on melt diffusion processing of sulfur-carbon composite cathodes.