Bachelor of Chemistry, Lanzhou University (2013)
Doctor of Philosophy, Peking University (2018)
Incorporating the nanoscale encapsulation concept from liquid electrolytes into solid-state lithium-sulfur batteries.
Lithium-sulfur (Li-S) batteries are attractive due to their high specific energy and low-cost prospect. Most studies in the past decade are based on these batteries with liquid electrolytes, where many exciting material/structural designs are realized at the nanoscale to address problems of Li-S chemistry. Recently, there is a new promising direction to develop Li-S batteries with solid polymer electrolytes, although it is unclear whether the concepts from liquid electrolytes are applicable in the solid state to improve battery performance. Here we demonstrate that the nanoscale encapsulation concept based on Li2S-TiS2 core-shell particles, originally developed in liquid electrolytes, is very effective in solid polymer electrolytes. Using in situ optical cell measurement and sulfur K-edge X-ray absorption near edge spectroscopy, we find that polysulfides form and are well trapped inside individual particles by the nanoscale TiS2 encapsulation. This TiS2 encapsulation layer also functions to catalyze the oxidation reaction of Li2S to sulfur, even in solid-state electrolytes, proved by both experiments and density functional theory calculations. A high cell-level specific energy of 427 W∙h∙kg-1 at 60 °C (including the mass of the anode, cathode, and solid-state electrolyte, but excluding the current collector and packaging) is achieved by integrating TiS2 encapsulated Li2S cathode with ultrathin polyethylene oxide-based solid polymer electrolyte (10~20 m) and lithium metal anode. The solid-state cells show excellent stability over 150 charge/discharge cycles at 0.8 C at 80 °C. This study points to the fruitful direction of borrowing concepts from liquid electrolytes into solid-state Li-S batteries.
View details for DOI 10.1021/acs.nanolett.0c02033
View details for PubMedID 32515973