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@INPROCEEDINGS{Ahrens:1021033,
      author       = {Ahrens, Lara and Vettori, Kilian and Basak, Shibabrata and
                      Eichel, Rüdiger-A. and Mayer, Joachim},
      title        = {{I}nvestigation of the {D}egradation {M}echanism of
                      {N}i-rich {NMC} {C}athode {M}aterial in {L}ithium-{I}on
                      {B}atteries},
      reportid     = {FZJ-2024-00493},
      year         = {2023},
      abstract     = {Lithium-ion batteries (LIBs) are state-of-the-art battery
                      systems for electrical vehicles (EVs) and thus a
                      key-technology for an emission-reduced future [1]. Besides
                      anode and electrolyte, the cathode site plays an important
                      role for the performance of a battery. Ni-rich NMC
                      (LixNiyMnzCo1-y-zO2, with x > 0, y > 0.6) is the most
                      promising candidate of cathode materials due to its high
                      capacity, high energy density and low costs [1]. However,
                      structural instability is a drawback of a high nickel
                      content leading e.g., to phase transition under high
                      voltages, washing and heat treatment [1,2]. Although it is
                      clear, that a phase transition from layered structure (space
                      group R-3m) over an intermediate spinel-phase (space group
                      Fd-3m) to rocksalt structure (space group Fm-3m) takes
                      place, it is controversially discussed how fast and thick
                      the rocksalt layer grows and if it has a positive influence
                      on the electrochemical performance up to a certain thickness
                      [3-5].One urgent question is, how fast and heavily Ni-rich
                      NMC degrades if it is held at high voltages for long
                      timespans. To answer this question, battery cells were set
                      to 4.5 V for a varying number of days.The formed rocksalt
                      layers were imaged at the atomic scale using scanning
                      transmission electron microscopy (STEM) to obtain valuable
                      information about the phase transition occurring at the
                      surface of the particles. Figure 1 shows STEM images of a
                      battery cell after 30 days, where a pronounced rocksalt
                      layer of roughly 20 nm is visible, indicating degradation of
                      the cathode.The time-dependent study provides a better
                      understanding of the aging of Ni-rich NMC cathodes caused by
                      cut-off voltages.},
      month         = {Sep},
      date          = {2023-09-10},
      organization  = {The 20th of International Microscopy
                       Congress, Busan (South Korea), 10 Sep
                       2023 - 15 Sep 2023},
      subtyp        = {After Call},
      cin          = {IEK-9 / ER-C-2},
      cid          = {I:(DE-Juel1)IEK-9-20110218 / I:(DE-Juel1)ER-C-2-20170209},
      pnm          = {1223 - Batteries in Application (POF4-122)},
      pid          = {G:(DE-HGF)POF4-1223},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1021033},
}