Soluble and Perfluorinated Polyelectrolyte for Safe and High‐Performance Li−O2 Batteries

• Published in: Angewandte Chemie International Edition Vol. 61; no. 19; pp. e202116635 - n/a
• Main Authors: Xiong, Qi, Huang, Gang, Yu, Yue, Li, Chao‐Le, Li, Jian‐Chen, Yan, Jun‐Min, Zhang, Xin‐Bo
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 02.05.2022
• Edition: International ed. in English
• Subjects: Anodic protection; Dendrites; Dendritic structure; Electrolytes; Electrolytic cells; Electronic equipment; Flammability; High Li+ Transfer Number; LiF-Rich Solid Electrolyte Interface; Lithiated Nafion; Lithium; Lithium fluoride; Li−O2 Battery; Performance degradation; Polyelectrolyte Solution; Polyelectrolytes; Sulfonic acid
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202116635

The severe performance degradation of high‐capacity Li−O2 batteries induced by Li dendrite growth and concentration polarization from the low Li+ transfer number of conventional electrolytes hinder their practical applications. Herein, lithiated Nafion (LN) with the sulfonic group immobilized on the perfluorinated backbone has been designed as a soluble lithium salt for preparing a less flammable polyelectrolyte solution, which not only simultaneously achieves a high Li+ transfer number (0.84) and conductivity (2.5 mS cm−1), but also the perfluorinated anion of LN produces a LiF‐rich SEI for protecting the Li anode from dendrite growth. Thus, the Li−O2 battery with a LN‐based electrolyte achieves an all‐round performance improvement, like low charge overpotential (0.18 V), large discharge capacity (9508 mAh g−1), and excellent cycling performance (225 cycles). Besides, the fabricated pouch‐type Li–air cells exhibit promising applications to power electronic equipment with satisfactory safety. A novel design principle of polymerization and fluorination for salt anions has been proposed and lithiated Nafion (LN) was suggested as a representative soluble lithium salt for the polyelectrolyte solution to improve the Li+ transfer number and produce a LiF‐rich solid electrolyte interface (SEI). Furthermore, the perfluorinated backbone of LN delivers the polyelectrolyte solution low flammability. Thus, making the Li−O2 batteries realize all‐round performance amelioration.