Recent Progress on the Self-Discharge of Lithium–Sulfur Batteries

Given the inherent limitation of intercalation chemistry-based Li-ion batteries, much research attention has been focused on the next-generation batteries with a Li metal anode. Lithium–sulfur (Li–S) batteries have become the spotlight of battery research due to the ultrahigh energy density of the sulfur cathode (2600 Wh kg–1). However, the notorious shuttle effect of polysulfides leads to a rapid loss of active materials, which results in the rapid decay of Li–S batteries. Consequently, various strategies have been proposed to improve the cycle stability, and prolonged cycle life has been achieved even under a low electrolyte-to-sulfur ratio. Nevertheless, the self-discharge of Li–S batteries, which influences the shelf life of Li–S batteries, has not received adequate attention. To push Li–S batteries for practical application, there is an urgent need to solve the issues of self-discharge. In this review, we initially introduce the working mechanism of Li–S batteries and discuss the origin of self-discharge of Li–S batteries. Subsequently, we summarize the recent advances in suppressing the self-discharge of Li–S batteries from the perspectives of structured sulfur host design, electrolyte optimization, functionalized separators, and solid-state electrolyte construction. Eventually, we propose a future research direction for prolonging the shelf life of Li–S batteries.