Back to Search Start Over

Polybenzimidazole functionalized electrolyte with Li‐wetting and self‐fluorination functionalities for practical Li metal batteries

Authors :
Dongjiang Chen
Yuanpeng Liu
Chuan Xia
Yupei Han
Qingwei Sun
Xuchang Wang
Wei Chen
Xian Jian
Weiqiang Lv
Jianyi Ma
Weidong He
Source :
InfoMat, Vol 4, Iss 5, Pp n/a-n/a (2022)
Publication Year :
2022
Publisher :
Wiley, 2022.

Abstract

Abstract Rough Li plating, low ionic conductivity, and low thermal stability of conventional electrolytes post‐primary challenges for achieving reliable high‐capacity rechargeable lithium batteries, for which lithium metal is frequently proposed as the most promising anode material. Conventional low‐polarity commercial polypropylene/polyethylene separators fail to support the application of high‐energy‐density Li anodes due to their rigid physicochemical properties and the high reactivity of Li metal, leading to fatal dendrite formation and vigorous exothermic reaction with electrolytes. Herein, we develop a Li‐wetting, flame‐retardant binary polymer electrolyte by functionalizing poly(vinylidene fluoride) (PVDF) separators with nonflammable polybenzimidazole (PBI) to build safe room‐temperature solid‐state electrolyte membranes. A dendrite‐free LiFePO4 cell with the solid polymer electrolyte (SPE) delivers a discharge capacity of 127 mAh g−1 at 25°C with a capacity retention of 87.5% after 500 cycles at 0.5°C (0.15 mA cm−2). Phase‐field simulations and density functional theory calculations demonstrate that the negatively charged benzimidazole chains of PBI own superior affinity to lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and shares overlapping electron density with Li anode, giving rise to accelerated Li+ conduction at room temperature and uniform Li electrodeposition at the electrolyte/Li metal interface. The SPE is also flame‐retardant since heat‐resistant polytetrafluoroethylene and a dense, heat‐blocking graphitized carbon layer are formed in intense heat through dehydrogenation/fluorination of PVDF under the catalysis of Lewis base imidazole rings and the decomposition of benzimidazole rings in PBI. No such fire‐resistant mechanism is ever reported in conventional electrolytes.

Details

Language :
English
ISSN :
25673165
Volume :
4
Issue :
5
Database :
Directory of Open Access Journals
Journal :
InfoMat
Publication Type :
Academic Journal
Accession number :
edsdoj.5c13187e84db4987621daf44792f6
Document Type :
article
Full Text :
https://doi.org/10.1002/inf2.12247