Designing Li-protective layer via SOCl2 additive for stabilizing lithium-sulfur battery

Lithium metal is among the most promising anode materials for high-energy batteries due to its high theoretical capacity and lowest electrochemical potential. However, uncontrolled lithium decomposition and dendrite formation have hindered its practical applications. Here, we propose a facile and effective strategy using thionyl chloride (SOCl2) as electrolyte additive to in-situ build a stable interfacial protective layer on lithium anode to prevent Li dendrite growth. Furthermore, the decomposition of SOCl2 could produce active sulfur to offer extra capacity for cathode in full battery. As a result, the as-assembled lithium-sulfur battery delivered an ultra-high discharge capacity (2202.3 mA h g−1 at 400 mA g−1) and excellent rate performance (1348.6 mA h g−1 at 3000 mA g−1), as well as remarkable cycling performance. This study reveals an effective avenue to suppress the Li-dendrites growth and provide a significant step towards safe and high-energy Li-S batteries.