Investigation of Underlying Reaction Mechanism in Li-S Battery Under Extreme Conditions

Abstract

Recent developments in electric vehicles (EVs) and portable electronics, lithium-sulfur (Li-S) battery has emerged as a promising candidate due to its high theoretical energy density. To achieve the practical high energy density (~500 Wh kg-1) in Li-S battery, high active material (sulfur) loading (> 6 mg cm-2), effective sulfur utilization, and low electrolyte-to-sulfur (E:S) ratio (<3 μL mg-1) should be achieved. Primarily, high sulfur loading, low E:S ratio, high sulfur content, and an optimum current rate are needed to achieve high energy and power density. In this work, we experimentally investigate polysulfide conversion mechanism that takes place in Li-S battery under extreme, both electrochemical and operating, conditions. An extreme threshold with respect to maximum and minimum sulfur loading and E:S ratio of below 3 or close to zero are thoroughly investigated. It is observed that the underlying polysulfide conversions altered when cell was operated at extreme conditions (e.g. E:S ratio). Furthermore, this work is expected to provide a critical scientific insight through advanced characterization techniques (e.g. in-situ Raman spectroscopy) to mechanistically understand the reaction kinetics in Li-S battery.