High-performance pyrrolidinium-based poly(ionic liquid) binders for Li-ion and Li-air batteries

The role of binders is crucial to achieve high performance and long cycle lifes in next-generation elec-trodes for lithium batteries. Currently used binders in electrode configurations, such as poly(vinylidene difluoride) (PVDF) are inactive polymers that do not transport lithium ions themselves, causing re-strictions for high-power applications. Thus, developing innovative binders with an affinity towards lithium mobility is important for both lithium-ion and lithium-air batteries. In this work, we present for the first time the use of PDADMA poly(ionic liquid)s with fluorinated anions (FSI, TFSI, BETI, and CFSO) as cathode binders in Li-ion and Li-air batteries. The high-voltage NMC 532 cathodes with fluorinated PDADMA binders showed improved cells performances as: capacity values, rate performance, and cycling stability in accelerating aging conditions dedicated for more environmental-friendly mobility applica-tions. Especially, PDADMA-CFSO binder in cathodes shows a cell capacity increase of 26% at 5C (12 min charge), when compared to PVDF one. Moreover, the fluorinated PDADMA binders in cathode improve the discharge capacities in Li-O2 cells, both with liquid and solid gel polymer electrolytes. Impressively, the Coulombic efficiency improves by 146% and the cycling capacity by 70% in solid-state Li-O2 cells using PDADMA-CFSO binder in the cathode, instead of common lithiated Nafion. All in all, the proposed fluorinated PDADMA Poly(ionic liquid)s can be a highly competitive alternative to conventional binders used nowadays in Li-ion and Li-air batteries.(c) 2022 Elsevier Ltd. All rights reserved.