U Texas team reports composite sulfur/lithium insertion cathode boosts performance over pure sulfur material
In a paper in the Journal of Power Sources, Yu-Sheng Su and Arumugam Manthiram from the University of Texas report that a composite cathode material of titanium disulfide (TiS2) and sulfur delivered 252 mAh g−1 more than that of pristine sulfur cathode (1334 mAh g−1 vs. 1082 mAh g−1). The increased capacity is not only due to the contribution by TiS2 itself but also due to a better active-material dispersion and utilization, they found.
In their study, they replaced a portion of the carbon additives in sulfur cathodes with lithium-insertion compounds (VO2(B) and TiS2). These can work within the same voltage window as that of sulfur.
The found VO2(B) to be incompatible with the glyme-based electrolytes that are usually used in Li–S cells, but TiS2 performed well while coupled with sulfur.
Serving as active reaction sites during cycling, TiS2 suppresses agglomeration of sulfur and facilitates better ionic/electronic transport within the cathode structure. This composite cathode design provides another direction for Li–S batteries to improve the overall energy density.—Su and Manthiram
Yu-Sheng Su, Arumugam Manthiram, Sulfur/lithium-insertion compound composite cathodes for Li–S batteries, Journal of Power Sources, Volume 270, Pages 101-105 doi: 10.1016/j.jpowsour.2014.07.099