Lithium Sulfur (Li-S) batteries are a promising energy storage technology with very high theoretical limits in terms of specific capacity and specific energy. However, these batteries suffer from high self-discharge rates, associated with a low coulombic efficiency due to the polysulfide shuttle mechanism. A better understanding of the self-discharge characteristics and suppression of the self-discharge is of great interest for most applications. Hence, a continuous self-discharge current measurement method is applied to evaluate the self-discharge behavior of a Li-S battery, based on a corrected reference open-circuit voltage. The result is a continuous self-discharge current measurement method, that investigates the self-discharge in the upper plateau of a Li-S battery at 10 °C and 25 °C. This self-discharge current displays a plateau and extended balancing times directly before this plateau and is validated by a discrete self-discharge current measurement method at 10 °C and 25 °C. Furthermore, the activation energy is continuously calculated for the upper plateau and compared to a discrete reference measurement.

Lithium sulfur batteries have a promisingly high theoretical specific energy density of about 2600 Wh/kg and an expected practical specific energy density of about 500-600 Wh/kg. Therefore, it is a highly promising future energy storage technology for electric vehicles. Beside these advantages, this technology shows a low cell capacity at high discharge currents. Due to the capacity recovery effect, up to 20% of the total cell capacity becomes available again with some rest time. This study shows a newly-developed capacity recovery model for lithium sulfur batteries. Due to the long rest periods of electric vehicles, this effect has an important influence on the usable cell capacity and depth of discharge in lithium sulfur batteries.

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