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@PHDTHESIS{Yang:1019580,
      author       = {Yang, Aikai},
      title        = {{N}a5{YS}i4{O}12-type {N}a+ superionic conductors for
                      solid-state batteries},
      volume       = {618},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2023-05515},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {X, 150},
      year         = {2023},
      note         = {Dissertation, RWTH Aachen University, 2023},
      abstract     = {The development of high-performance solid-state batteries
                      (SSBs) has gained increasing attention in recent years as a
                      promising alternative to conventional liquid electrolyte
                      batteries. In this context, the Na5YSi4O12- type (NYS) Na+
                      superionic conductors have emerged as potential electrolyte
                      candidates due to their high Na+ ionic conductivity and
                      stability in solid-state Na batteries (SSSBs). This thesis
                      investigates the synthesis, characterization, and
                      electrochemical properties of NYS-type Na+ superionic
                      conductors, focusing on their applicability in large-scale
                      fabrication as well as in SSBs and the development of novel
                      compositions with higher ionic conductivity. The background
                      of the work is introduced in the first two chapters,
                      followed by an explanation of the preparation and
                      characterization methods applied. The results and discussion
                      are divided into three main parts: First, tape-casting of
                      thin NYS sheets using aqueous slurries has been developed.
                      The microstructure, crystal structure, electrochemical
                      performance and mechanical properties of the as-prepared NYS
                      tapes have been investigated. After sintering, the obtained
                      NYS tapes had high crystalline purity, dense microstructure
                      (relative density > $90\%),$ and favorable mechanical
                      properties (hardness H of 2 GPa andYoung’s modulus E of 45
                      GPa). The NYS tapes showed a total ionic conductivity of 1.0
                      mS cm‒1 at room temperature (RT), a low total activation
                      energy of 0.30 eV, and a wide electrochemical stability
                      window of over 8 V. The critical current density (CCD) of
                      NYS tape against Na metal electrodes reached 2.2 mA cm‒ 2
                      and the galvanostatic cycling time was over 280 h at 0.8 mA
                      cm‒2 and 0.8 mAh cm‒2. This work not only highlights the
                      potential of the scarcely studied silicate-based NYS ionic
                      conductor as a functional separator but also presents a
                      cost-efficient and eco-friendly continuous fabrication using
                      the aqueous tape casting technique, thus is expected to
                      boost the practical application of NYS as a solid-state
                      electrolyte (SSE) in SSSBs.},
      cin          = {IEK-1},
      cid          = {I:(DE-Juel1)IEK-1-20101013},
      pnm          = {899 - ohne Topic (POF4-899)},
      pid          = {G:(DE-HGF)POF4-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.34734/FZJ-2023-05515},
      url          = {https://juser.fz-juelich.de/record/1019580},
}