Practical Lithium–Sulfur Batteries Enabled by a Six-Membered Cyclic Urea Solvent
Lin Peng, Yilu Liu, Pengcheng Xue, Chenxi Lei, Xiao Yang, Lishan Lin, Liang Ma, Luyi Chen, Yue‐Peng Cai, Jian Wang, Lingzhi Zhao, Qifeng Zheng
Abstract
Highly solvating electrolytes hold great prospects for achieving the goal of practically high-energy-density lithium–sulfur batteries, yet they suffer from short cycle life due to their poor compatibility with Li-metal anode (LMA). Herein, a new six-membered cyclic urea, N, N′-dimethylpropyleneurea (DMPU), was rationally proposed as an electrolyte solvent to conquer this longstanding contradiction. The DMPU with high electron donicity preferentially coordinates with Li + to dominate the inner-solvation shell, which not only initiates and stabilizes the S 3 •– radical to facilitate S redox kinetics and 3D Li 2 S deposition but also suppresses its contact reaction with LMA kinetically. More encouragingly, the DMPU molecule with a six-membered ring bears small ring strain, thus weakening their reactivity with LMA thermodynamically. Consequently, the DMPU-based electrolyte bestows an extremely high area capacity of 8.4 mAh cm –2 for a practical lithium–sulfur cell under a high S mass loading of 8.2 mg cm –2 and ultralow E/S ratio of 3.8 μL mg sulfur –1 .