%0 Journal Article
%A Klein, Sven
%A Wrogemann, Jens Matthies
%A van Wickeren, Stefan
%A Harte, Patrick
%A Bärmann, Peer
%A Heidrich, Bastian
%A Hesper, Jakob
%A Borzutzki, Kristina
%A Nowak, Sascha
%A Börner, Markus
%A Winter, Martin
%A Kasnatscheew, Johannes
%A Placke, Tobias
%T Understanding the Role of Commercial Separators and Their Reactivity toward LiPF 6 on the Failure Mechanism of High‐Voltage NCM523 || Graphite Lithium Ion Cells
%J Advanced energy materials
%V 12
%N 2
%@ 1614-6832
%C Weinheim
%I Wiley-VCH
%M FZJ-2021-05231
%P 2102599 -
%D 2022
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000725443500001
%R 10.1002/aenm.202102599
%U https://juser.fz-juelich.de/record/903576