Journal Article

FZJ-2021-05231

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Understanding the Role of Commercial Separators and Their Reactivity toward LiPF 6 on the Failure Mechanism of High‐Voltage NCM523 || Graphite Lithium Ion Cells

Klein, S. ; Wrogemann, J. M. ; van Wickeren, S. ; Harte, P. ; Bärmann, P. ; Heidrich, B. ; Hesper, J. ; Borzutzki, K.FZJ* ; Nowak, S. ; Börner, M. ; Winter, M.FZJ* ; Kasnatscheew, J. (Corresponding author)FZJ* ; Placke, T. (Corresponding author)

2022
Wiley-VCH Weinheim

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Please use a persistent id in citations: http://hdl.handle.net/2128/30596  doi:10.1002/aenm.202102599

Abstract: NCM523 || graphite lithium ion cells operated at 4.5 V are prone to an early “rollover” failure, due to electrode cross-talk, that is, transition metal (TM = Mn, Ni, and Co) dissolution from NCM523 and deposition at graphite, subsequent formation of Li metal dendrites, and, in the worst case, generation of (micro-)short-circuits by dendrites growing to the cathode. Here, the impact of different separators on the high-voltage performance of NCM523 || graphite cells is elucidated focusing on the separators’ structural properties (e.g., membrane vs fiber) and their reactivity toward LiPF6 (e.g., ceramic-coated separators). First, the separator architecture has a major impact on cycle life. Fiber-structured separators can prevent the “rollover” failure by a more homogeneous deposition of TMs and formation of Li metal dendrites, thus, hindering penetration of dendrites to the cathode. In contrast, porous membrane-structured separators cannot prevent the cell failure due to inhomogeneous TM deposits/Li metal dendrites. Second, it is demonstrated that different types of ceramic-coated separators (Boehmite (γ-AlO(OH)) vs α-Al2O3) exhibit different reactivities toward LiPF6. While α-Al2O3 shows a minor reactivity toward LiPF6, the γ-AlO(OH) coating leads to in situ formation of the beneficial difluorophosphate anion in high amounts due the high reactivity toward LiPF6 decomposition, which significantly improves cycle life.

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Contributing Institute(s):

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

Research Program(s):

1. 1221 - Fundamentals and Materials (POF4-122) (POF4-122)

Appears in the scientific report 2022

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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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