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@INPROCEEDINGS{Kaghazchi:1048387,
      author       = {Kaghazchi, Payam and Winkler, Lars},
      title        = {{Z}r {I}ncorporation into {L}ithium {N}ickel {O}xides:
                      {S}olid {S}olution or {T}wo-{P}hase {S}ystem},
      reportid     = {FZJ-2025-04602},
      year         = {2025},
      abstract     = {Ni-rich cathodes such as LiNiO2 (LNO) offer high
                      theoretical capacities for Li-ion batteries, but their
                      performance degrades upon cycling due to limiting factors
                      such as microcracking, electrolyte decomposition, cation
                      mixing and/or oxygen loss. A common strategy to mitigate
                      these degradation mechanisms involves the use of doping
                      and/or coating agents to enhance structural stability and
                      capacity retention. Cobalt, alumina, and manganese – used
                      in NCA and NCM cathodes – are well-known examples that
                      improve cycling performance, although they reduce the
                      overall theoretical capacity compared to pure LNO.
                      Therefore, ongoing research aims to identify alternative
                      doping and coating agents that can stabilize LNO while
                      preserving its high theoretical capacity. Zirconium is a
                      promising candidate, with studies reporting improved
                      capacity retention when LNO is doped with small amounts of
                      Zr. However, incorporating Zr into the LNO lattice remains
                      challenging, even with low doping concentrations. This study
                      focuses on the incorporation of Zr into LNO using
                      electrostatic analysis and ab-initio density functional
                      theory (DFT) calculation. We analysed the synthesis route
                      using common precursor materials, which can yield either a
                      mixture of pure LNO and Li2ZrO3 (LZO), or Zr-doped LNO
                      (LixNiyZrZO2), potentially accompanied by second phases. Our
                      DFT calculation demonstrate that both cases, namely LNO +
                      LZO and Zr-doped LNO (+ second phase) are energetically
                      favoured over the precursor materials. We proposed several
                      chemical reactions pathways for Zr-concentrations ranging
                      from $1\%$ up to $7\%.$ The results suggest that low amounts
                      $(1-3\%)$ of Zr can be incorporated into LNO if a Ni-rich
                      secondary phase is also present. For higher Zr
                      concentrations $(4\%),$ stabilization within LNO requires an
                      oxygen-rich environment, such as high partial oxygen
                      pressure during synthesis. This observation holds true even
                      for elevated synthesis temperatures (~ 750°C) as confirmed
                      by ab-initio thermodynamic calculations. At Zr
                      concentrations above $4\%,$ we find phase separation into
                      LNO and LZO rather than Zr doped LNO. This phase separation
                      is likely detrimental, as LZO exhibits a large band gap (> 5
                      eV), whereas $3\%$ Zr-doped LNO and pure LNO have
                      significantly lower band gaps (~0.2 eV and 0.4 eV
                      respectively). Electrostatic calculation for large
                      particle-like atomistic structures with more than 3000 atoms
                      further reveal that Zr-doped LNO is energetically more
                      stable in elongated particle geometries compared to
                      spherical ones. Additionally, Zr ions tend to stay segregate
                      towards the particle surface. This preference could explain
                      experimental observations of elongated primary particles in
                      Zr-doped LNO and may correlate with improved mechanical
                      integrity and enhanced capacity retention.In summary, this
                      study provides theoretical insights into the synthesis
                      challenges and structural advantages of Zr doping into LNO
                      cathode materials. Our results indicate that Zr
                      concentrations between $1-4\%$ can be successfully
                      incorporated under appropriate conditions, such as Ni-rich
                      secondary phases or high oxygen partial pressure. These
                      findings support the potential of Zr as a stabilizing dopant
                      that retains the high capacity of LNO, offering guidance for
                      future experimental efforts to further understand and
                      develop advanced cathode materials for Li-ion batteries.},
      month         = {Sep},
      date          = {2025-09-29},
      organization  = {Material Development for Batteries
                       (MDB), Seoul (South Korea), 29 Sep 2025
                       - 3 Oct 2025},
      cin          = {IMD-2},
      cid          = {I:(DE-Juel1)IMD-2-20101013},
      pnm          = {1221 - Fundamentals and Materials (POF4-122) / AdamBatt -
                      Fortschrittliche Materialien für die Anwendung in Hybriden
                      Festkörperbatterien (13XP0305A)},
      pid          = {G:(DE-HGF)POF4-1221 / G:(BMBF)13XP0305A},
      typ          = {PUB:(DE-HGF)1},
      doi          = {10.34734/FZJ-2025-04602},
      url          = {https://juser.fz-juelich.de/record/1048387},
}