Interface engineering toward stable lithium-sulfur batteries

The lithium-sulfur battery, one of the most potential high-energy-density rechargeable batteries, has obtained significant progress in overcoming challenges from both sulfur cathode and lithium anode. However, the unstable multi-interfaces between electrodes and electrolytes, as well as within the electrodes themselves still limit their commercial application. In this review, typical interfaces in the lithium-sulfur battery system are classified as solid/solid and solid/liquid interfaces. Subsequently, the unique multi-interfacial issues in lithium-sulfur batteries and their impact on lithium-sulfur electrochemistry are carefully discussed. Recent progress in the understanding of lithium-sulfur electrochemistry, interface optimization strategies, and the corresponding electrochemical performance are discussed. In particular, we summarize some advanced characterization techniques to gain a deeper understanding of the basic mechanism of these core issues of lithium-sulfur electrochemistry and multi-interfacial problems. Finally, the interfacial challenges in practical lithium-sulfur batteries and feasible interfacial modification strategies are summarized for future research. We provide some insights on the interface structure design in high-performance liquid or solid-state lithium-sulfur batteries in the future. The interfaces, interfacial issues, and their impact on lithium-sulfur electrochemistry are overviewed for both coin cells and practical lithium-sulfur batteries.