Electrolyte Structure of Lithium Polysulfides with Anti‐Reductive Solvent Shells for Practical Lithium–Sulfur Batteries

• Published in: Angewandte Chemie 2021-07, Vol.133 (28), p.15631-15637
• Main Authors: Zhang, Xue‐Qiang, Jin, Qi, Nan, Yi‐Ling, Hou, Li‐Peng, Li, Bo‐Quan, Chen, Xiang, Jin, Zhe‐Hui, Zhang, Xi‐Tian, Huang, Jia‐Qi, Zhang, Qiang
• Format: Article
• Language: English
• Subjects: Anodes; Chemistry; electrolyte structure; Electrolytes; Intermediates; Lithium; lithium metal anode; Lithium sulfur batteries; Molecular dynamics; NMR; Nuclear magnetic resonance; polysulfide encapsulation; Polysulfides; Shells; solvent shell; Solvents; Storage batteries; Sulfur
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202103470

The lithium–sulfur (Li–S) battery is regarded as a promising secondary battery. However, constant parasitic reactions between the Li anode and soluble polysulfide (PS) intermediates significantly deteriorate the working Li anode. The rational design to inhibit the parasitic reactions is plagued by the inability to understand and regulate the electrolyte structure of PSs. Herein, the electrolyte structure of PSs with anti‐reductive solvent shells was unveiled by molecular dynamics simulations and nuclear magnetic resonance. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether (DIPE) as a cosolvent, DIPE molecules tend to distribute in the outer solvent shell due to poor solvating power. Furthermore, DIPE is more stable than conventional ether solvents against Li metal. The reactivity of PSs is suppressed by encapsulating PSs into anti‐reductive solvent shells. Consequently, the cycling performance of working Li–S batteries was significantly improved and a pouch cell of 300 Wh kg−1 was demonstrated. The fundamental understanding in this work provides an unprecedented ground to understand the electrolyte structure of PSs and the rational electrolyte design in Li–S batteries. The electrolyte structure of lithium polysulfides (PSs) with anti‐reductive solvent shells was unveiled. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether as a cosolvent, the reactivity of PSs is suppressed by encapsulating PSs into anti‐reductive solvent shells. The stability of practical Li–S batteries was improved and a pouch cell of 300 Wh kg−1 was demonstrated.