Interface Engineering Toward Expedited Li2S Deposition in Lithium-Sulfur Batteries: A Critical Review

Lithium-sulfur batteries (LSBs) with superior energy density are among the most promising candidates of next-generation energy storage techniques. As the key step contributing to 75% of the overall capacity, Li2S deposition remains a formidable challenge for LSBs applications because of its sluggish kinetics. The severe kinetic issue originates from the huge interfacial impedances, indicative of the interface-dominated nature of Li2S deposition. Accordingly, increasing efforts have been devoted to interface engineering for efficient Li2S deposition, which has attained inspiring success to date. However, a systematic overview and in-depth understanding of this critical field are still absent. In this review, the principles of interface-controlled Li2S precipitation are presented, clarifying the pivotal roles of electrolyte-substrate and electrolyte-Li2S interfaces in regulating Li2S depositing behavior. For the optimization of the electrolyte-substrate interface, efforts on the design of substrates including metal compounds, functionalized carbons, and organic compounds are systematically summarized. Regarding the regulation of electrolyte-Li2S interface, the progress of applying polysulfides catholytes, redox mediators, and high-donicity/polarity electrolytes is overviewed in detail. Finally, the challenges and possible solutions aiming at optimizing Li2S deposition are given for further development of practical LSBs. This review would inspire more insightful works and, more importantly, may enlighten other electrochemical areas concerning heterogeneous deposition processes.

Automated summary

Lithium-sulfur batteries are promising candidates for next-generation energy storage with superior energy density. The sluggish deposition of Li2S, which contributes to 75% of the overall capacity, remains a formidable challenge. Efforts have been made to optimize the interface for efficient Li2S deposition, but a comprehensive overview and understanding are still lacking.