Exploiting the Li–N Interaction of Arginine Additive to In Situ Construct a Cathode Protective Layer for Lean Electrolyte Li–S Batteries

Abstract

Lithium–sulfur (Li–S) batteries represent a highly promising electrochemical energy storage technology for next-generation applications, yet their practical viability is critically limited by the shuttle effect of lithium polysulfides (LiPSs) and the requirement for high electrolyte dosage. The cathode electrolyte interface (CEI) strategy is recognized as a promising pathway to realize high electrochemical performance of Li–S batteries in lean electrolyte systems. Herein, via a feasible electrolyte regulation strategy, arginine (Arg) is introduced as an electrolyte additive for Li–S batteries. Comprehensive experimental investigations show that Arg can be readily dissolved in the electrolyte. It is proposed that Arg may undergo partial deprotonation and then interact with LiTFSI and LiPS to form the corresponding Arg–Li–TFSI and Arg–Li–PS complexes. Notably, the formed Arg–Li–PS complexes are insoluble in the electrolyte. It is inferred that these complexes participate in the construction of the CEI and help mitigate the dissolution of LiPS, which can weaken the dependence of electrochemical performance on electrolyte volume and enhance sulfur utilization under lean electrolyte conditions. Consequently, under a sulfur loading of ∼8.0 mg cm–2 and low electrolyte(μL)/sulfur(mg) (E/S) ratio with 5 μL mg–1, the Arg-modified Li–S batteries exhibit a discharge capacity of 886 mAh g–1 (7.1 mAh cm–2), and preserve 750 mAh g–1 (6.1 mAh cm–2) after 95 cycles at 0.1 C. This work provides a strategy for designing high-efficiency electrolyte additives and developing high-performance Li–S batteries under conditions of limited electrolyte availability.