Deciphering the Species-Dependent Polysulfide Corrosion on Lithium Anode Toward Durable Lithium-Sulfur Batteries

Abstract

Lithium-sulfur (Li-S) batteries are promising next-generation energy storage systems due to their ultrahigh theoretical energy density of 2600 Wh kg^-1. However, soluble lithium polysulfides (LiPSs) violently corrode Li metal anodes, inducing rapid capacity decay and poor cycling lifespan of Li-S batteries. Herein, the corrosion of different LiPS species on the Li metal anode is systematically investigated. The corrosion rate of Li metal anode by Li₂S₈ and Li₂S₆ is higher than Li₂S₄. The discrepancy in corrosion rate is attributed to the continuous reaction between the LiPSs and Li metal, while the corrosion can hardly be prohibited by the LiPS-generated solid electrolyte interphase. Smaller Li nuclei size, more uniform Li deposition, and more durable cycling of Li metal anodes are found in Li₂S₄ electrolyte in comparison with Li₂S₈ and Li₂S₆ electrolytes. Consequently, a LiPS selection strategy is proposed to selectively inhibit the corrosion of high-order LiPSs and successfully prolong the cumulative capacity by 31% in Li-S batteries. This work clarifies the fundamentals of Li metal anode corrosion by different LiPS species and highlights the rational selection of favorable LiPS species for promoting the cycling durability of Li-S batteries.

Keywords: corrosion; lithium metal anode; lithium polysulfides; lithium–sulfur batteries; shuttle effect.