posted on 2021-09-22, 19:47authored byKie Hankins, Venkateshkumar Prabhakaran, Sungun Wi, Vaithiyalingam Shutthanandan, Grant E. Johnson, Swadipta Roy, Hui Wang, Yuyan Shao, Suntharampillai Thevuthasan, Perla B. Balbuena, Karl T. Mueller, Vijayakumar Murugesan
Delineating
intricate interactions between highly reactive Li-metal
electrodes and the diverse constituents of battery electrolytes has
been a long-standing scientific challenge in materials design for
advanced energy storage devices. Here, we isolated lithium polysulfide
anions (LiS4–) from an electrolyte solution
based on their mass-to-charge ratio and deposited them on Li-metal
electrodes under clean vacuum conditions using ion soft landing (ISL),
a highly controlled interface preparation technique. The molecular
level precision in the construction of these model interfaces with
ISL, coupled with in situ X-ray photoelectron spectroscopy
and ab initio theoretical calculations, allowed us
to obtain unprecedented insight into the parasitic reactions of well-defined
polysulfides on Li-metal electrodes. Our study revealed that the oxide-rich
surface layer, which is amenable to direct electron exchange, drives
multielectron sulfur oxidation (S0 → S6+) processes. Our results have substantial implications for the rational
design of future Li–S batteries with improved efficiency and
durability.