Shelf life of lithium–sulfur batteries under lean electrolytes: status and challenges

Abstract

Lithium–sulfur batteries (LSBs) with high theoretical energy density are considered as one of the most promising next-generation energy storage devices. In the past decade, strategies to improve electrochemical performance and the related mechanism have been extensively explored. Subsequently, the LSB research has entered a key stage of real-life applicability. To date, however, the self-discharge performance of LSBs, which is an essential factor affecting their shelf life for practical application, has not received adequate attention, and no reviews have comprehensively presented the causes and improvement strategies. This is because the strategy of inhibiting disproportionation, which is one of the major reasons for self-discharge, is consistent with that of improving cycle stability under nonpractical conditions; this consistency, however, cannot be maintained under practical conditions, especially when using lean electrolytes. Moreover, other factors that can affect the self-discharge, such as temperature, chemical corrosion, and galvanic corrosion, have also been unveiled recently. Hence, to push LSBs forward from the lab to the industry, sufficient attention should be devoted to these important issues. In this review, we summarize the advances achieved in prolonging the shelf life of LSBs based on the issues resulting in self-discharge and their remediation. Then, we review the advantages and deficiencies of current strategies toward practical LSBs. Finally, we propose research prospects and noteworthy testing conditions for LSBs with high performance and sustained shelf life under practical conditions.