Journal Article

FZJ-2023-01300

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Coordinating Anions “to the Rescue” of the Lithium Ion Mobility in Ternary Solid Polymer Electrolytes Plasticized With Ionic Liquids

Hoffknecht, J.-P. ; Wettstein, A. ; Atik, J. ; Krause, C. ; Thienenkamp, J.FZJ* ; Brunklaus, G.FZJ* ; Winter, M.FZJ* ; Diddens, D. (Corresponding author)FZJ* ; Heuer, A. (Corresponding author)FZJ* ; Paillard, E.

2023
Wiley-VCH Weinheim

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Please use a persistent id in citations: doi:10.1002/aenm.202202789  doi:10.34734/FZJ-2023-01300

Abstract: Lithium salts with low coordinating anions such as bis(trifluoromethanesulfonyl)imide (TFSI) have been the state-of-the-art for polyethylene oxide (PEO)-based “dry” polymer electrolytes for 3 decades. Plasticizing PEO with TFSI-based ionic liquids (ILs) to form ternary solid polymer electrolytes (TSPEs) increases conductivity and Li+ diffusivity. However, the Li+ transport mechanism is unaffected compared to their “dry” counterparts and is essentially coupled to the dynamics of the polymer host matrix, which limits Li+ transport improvement. Thus, a paradigm shift is hereby suggested: the utilization of more coordinating anions such as trifluoromethanesulfonyl-N-cyanoamide (TFSAM), able to compete with PEO for Li+ solvation, to accelerate the Li+ transport and reach a higher Li+ transference number. The Li–TFSAM interaction in binary and ternary TFSAM-based electrolytes is probed by experimental methods and discussed in the context of recent computational results. In PEO-based TSPEs, TFSAM drastically accelerates the Li+ transport (increases Li+ transference number by a factor 6 and the Li+ conductivity by 2–3) and computer simulations reveal that lithium dynamics are effectively re-coupled from polymer to anion dynamics. Last, this concept of coordinating anions in TSPEs is successfully applied in LFP||Li metal cells leading to enhanced capacity retention (86% after 300 cycles) and an improved rate performance at 2C.

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Contributing Institute(s):

1. Helmholtz-Institut Münster Ionenleiter für Energiespeicher (IEK-12)

Research Program(s):

1. 1222 - Components and Cells (POF4-122) (POF4-122)
2. 1223 - Batteries in Application (POF4-122) (POF4-122)

Appears in the scientific report 2023

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; DEAL Wiley ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 25 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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