To mitigate self-discharge of lithium–sulfur batteries by optimizing ionic liquid electrolytes

Abstract

Li–S batteries generally suffer from severe self-discharge when resting due to an internal polysulfide shuttle effect. Soluble long-chain polysulfide species (Li₂S_x, 4 ≤ x ≤ 8) would continue to dissolve and migrate to the negative side to react with metallic Li. Here, we demonstrate pronounced suppression of polysulfide shuttle using an ionic liquid of the N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI)-based electrolyte. When working in combination with LiNO₃, zero self-discharge can be achieved to rest a full-charged Li–S cell for two days. The fascinating study clearly demonstrates that a promising practical Li–S battery with low self-discharge depends on both improvements on polysulfide diffusion control and Li-metal stabilization.