北京大学庞全全团队报道了高溶剂化核壳结构电解质用于稀电解质锂硫电池。相关研究成果发表在2024年11月11日出版的国际知名学术期刊《德国应用化学》。

锂硫电池的实际能量密度受到贫电解质条件下低硫利用的限制。高溶剂化电解质（HSEs）有望在恶劣条件下解决这一问题，但自由基介导的硫氧化还原反应（SRR）的长期稳定性，和锂金属阳极（LMA）的稳定性差这两个相互矛盾的挑战削弱了这一努力。

研究人员提出了一种独特的核壳溶剂化结构的HSE，由经典的醚基溶剂和磷酰胺共溶剂配制而成。独特的核壳溶剂化结构将磷酰胺限制在第一个溶剂化壳中，这禁止了与LMA的严重接触反应，并赋予[S3]自由基更长的稳定性，有利于基于自由基的快速溶液介导的SRR。

所提出的电解质电池在5.5 mg硫 cm²的高硫负载和4μL mg硫^-1的低E/S比下，显示出864 mA h g硫^-1的高容量。该策略进一步实现了2.71-Ah袋式电池的稳定循环，其具有307 W h kg^-1的高比能。

该工作强调了调节溶剂化结构的基本化学概念，以同时实现金属硫电池的SRR和LMA稳定性，其中电极反应与电解质化学严重耦合。

附：英文原文

Title: Highly Solvating Electrolytes with Core-Shell Solvation Structure for Lean-Electrolyte Lithium-Sulfur Batteries

Author: Mengxue He, Lujun Zhu, Yatao Liu, Yongfeng Jia, Yizhou Hao, Guo Ye, Xufeng Hong, Zhitong Xiao, Yue Ma, Jianhao Chen, Muhammad Burhan Shafqat, Quanquan Pang

Issue&Volume: 2024-11-11

Abstract: The practical energy density of lithium-sulfur batteries is limited by the low sulfur utilization at lean electrolyte conditions. The highly solvating electrolytes (HSEs) promise to address the issue at harsh conditions, but the conflicting challenges of long-term stability of radical-mediated sulfur redox reactions (SRR) and the poor stability with lithium metal anode (LMA) have dimmed the efforts. We now present a unique core-shell solvation structured HSE formulated with classical ether-based solvents and phosphoramide co-solvent. The unique core-shell solvation structure features confinement of the phosphoramide in the first solvation shell, which prohibits severe contact reactions with LMA and endows prolonged stability for [S3]– radical, favoring a rapid radical-mediated solution-based SRR. The cell with the proposed electrolyte showing a high capacity of 864 mA h gsulfur1 under high sulfur loading of 5.5 mgsulfur cm2 and low E/S ratio of 4 μL mgsulfur1. The strategy further enables steady cycling of a 2.71-A h pouch cell with a high specific energy of 307 W h kg1. Our work highlights the fundamental chemical concept of tuning the solvation structure to simultaneously tame the SRR and LMA stability for metal-sulfur batteries wherein the electrode reactions are heavily coupled with electrolyte chemistry.

DOI: 10.1002/anie.202415053

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202415053