Discretized Analysis of Polysulfide Shuttle Dynamics in Lithium-Sulfur Batteries

The polysulfide shuttle effect remains a fundamental challenge in lithium-sulfur batteries, particularly for high-energy-density applications where conventional mitigation strategies prove insufficient. Here, we introduce a state-resolved methodology for quantifying shuttle current by analyzing Coulombic efficiency across discretized charging blocks, addressing limitations in traditional voltage-dependent measurement techniques. Through systematic analysis of cells with and without LiNO 3 additive, we demonstrate that shuttle activity peaks at 60%–70% state-of-charge (SOC), correlating with maximum Li 2 S 4 concentration as confirmed by UV–vis spectroscopy. The block efficiency analysis reveals distinct patterns: cells without LiNO 3 show efficiency dropping to 60% in the mid-SOC region, while LiNO 3 -containing cells maintain minimum efficiency around 80%, demonstrating approximately 70% suppression of peak shuttle current. Electrochemical impedance analysis further reveals how polysulfide evolution affects transport processes, with bulk resistance peaking at mid-SOC due to pore blockage, while interfacial resistance changes reflect the transition between different polysulfide species. By correlating block efficiency with polysulfide speciation, we establish that Li 2 S 4 drives shuttle activity through its optimal balance of solubility and mobility, while larger Li 2 S 8 species contribute less despite higher solubility. This work provides quantitative insights into shuttle current distribution across different SOC ranges while establishing a robust methodology for evaluating shuttle suppression strategies.