近日，清华大学张强团队研究了工作锂硫电池中锂多硫化物的两阶段溶剂化。这一研究成果于2025年4月22日发表在《美国化学会杂志》上。

锂硫（Li-S）电池有望实现高能量密度，但循环寿命较差，因为锂多硫化物（LiPS）会腐蚀锂金属阳极。减弱LiPS的电解质溶剂化能力（ESP）有效地减轻了阳极腐蚀，但不可避免地会减缓阴极反应动力学。研究组揭示了弱溶剂化电解质中ESP和LiPS氧化还原动力学之间的相关性，以实现高性能的锂硫电池。随着弱溶剂化溶剂（WSS）含量的增加，ESP呈现出两阶段变化趋势，其中转变取决于WSS是否进入LiPS内溶剂化壳。

一旦WSS直接与LiPS配位，LiPS电荷转移动力学就会急剧恶化，活化极化迅速增加。为了克服动力学迟缓，引入了先进的电催化剂，使锂硫电池的极化降低，循环寿命延长。在具有稳定循环寿命的10Ah级袋式电池中实现了607 W h kg^–1的超高能量密度。这项工作深化了目前对LiPS溶剂化和动力学的理解，突出了弱溶剂化电解质对高能量密度和长循环锂硫电池的重要性。

附：英文原文

Title: Two-Stage Solvation of Lithium Polysulfides in Working Lithium–Sulfur Batteries

Author: Xi-Yao Li, Bo-Quan Li, Shuai Feng, Zheng Li, Liang Shen, Shu-Yu Sun, Zi-Xian Chen, Tian Jin, Xiang Chen, Meng Zhao, Xue-Qiang Zhang, Jia-Qi Huang, Qiang Zhang

Issue&Volume: April 22, 2025

Abstract: Lithium–sulfur (Li–S) batteries are promising in achieving high energy density but inferior in cycling lifespan since Li polysulfides (LiPSs) corrode Li metal anode. Weakening the electrolyte solvating power (ESP) for LiPSs effectively mitigates anodic corrosion but inevitably retards cathodic reaction kinetics. Herein, the correlation between the ESP and the LiPS redox kinetics in weakly solvating electrolyte is unveiled for achieving high-performance Li–S batteries. The ESP exhibits a two-stage variation tendency as the weakly solvating solvent (WSS) content increases, where the transition depends on whether the WSS enters the LiPS inner solvation shell. Once the WSS directly coordinates with LiPSs, the LiPS charge-transfer kinetics deteriorate dramatically, with a rapid increase in activation polarization. To overcome the kinetic sluggishness, advanced electrocatalysts are introduced to endow Li–S batteries with reduced polarization and prolonged cycling lifespan. An ultrahigh energy density of 607 W h kg–1 is realized in 10 Ah-level pouch cells with a stable cycling lifespan. This work deepens the current understanding of LiPS solvation and kinetics, highlighting the significance of weakly solvating electrolytes toward high-energy-density and long-cycling Li–S batteries.

DOI: 10.1021/jacs.5c01588

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.5c01588