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@INPROCEEDINGS{Karaca:890158,
      author       = {Karaca, Ali and Galkina, Irina and Glüsen, Andreas and
                      Sohn, Yoo Jung and Wippermann, Klaus and Müller, Martin and
                      Carmo, Marcelo and Stolten, Detlef},
      title        = {{S}elf-{S}tanding {S}pray-{D}eposited {N}afion {M}embranes
                      for {F}uel {C}ell {O}perations},
      issn         = {2151-2043},
      reportid     = {FZJ-2021-00747},
      year         = {2020},
      note         = {Online verfügbar:
                      https://doi.org/10.1149/MA2020-02352248mtgabs},
      abstract     = {AbstractThe characteristics of a polymer electrolyte
                      membrane (PEM) are crucial for the success of PEM based fuel
                      cells and electrolyzers. Membranes play a significant role
                      regarding ohmic losses, fuel permeability and mechanical
                      stability. For the resulting catalyst coated membrane (CCM),
                      it is important to create an ideal contact between membrane
                      and electrode to avoid gaps and enhance interfacial surface
                      area. Production of CCMs for fuel cells or electrolyzers is
                      mainly based on two techniques:Decal Transfer: Fabrication
                      of an electrode onto a carrier substrate and subsequent
                      transfer by hot-pressing it onto a membrane [1].Direct
                      deposition: Spray-deposition onto heated and vacuum fixed
                      membranes [2] or doctor-blade coating onto pre-swollen
                      membranes [3].Both techniques bear several problems:During
                      hot-pressing membranes are exposed to high temperatures and
                      pressure. This can lead to deformations or cracks within the
                      membrane. At the same time, transfer of electrode material
                      can be insufficient and membrane electrode interface can
                      suffer from delamination which causes gaps in terms of
                      proton conductivity.Direct deposition of electrode material
                      onto membranes entails difficult processing. Swelling and
                      shrinking during coating and drying can result in
                      inhomogeneous electrodes.Instead of coating membranes with
                      electrodes, ultrasonic spray-deposition was employed to
                      produce self-standing membranes. Being able to produce
                      membranes allows the consecutive fabrication of all layers
                      in a CCM and makes commercial membranes obsolete. It also
                      reduces problems when an electrode is spray-deposited
                      because the membrane is usually produced just before the
                      electrode that is supposed to be spray-deposited. Thus, the
                      membrane is attached to either a carrier substrate (PTFE) or
                      another electrode that was spray-deposited at the very
                      beginning.Fabricating membranes by spray-deposition gives
                      freedom in terms of several processing aspects:Modification
                      of the ionomer solution composition. The following
                      variations were used: Solutions based on water/alcohol and
                      water/alcohol + high boiling point solvents such as ethylene
                      glycol, dimethyl sulfoxide, dimethylformamide and
                      dimethylacetamide.Application of thermal treatmentsVariation
                      of the membrane thicknessesThis approach reveals
                      possibilities that would not be available with commercial
                      Nafion membranes with predefined properties. Self-standing
                      Nafion membranes, based on different ionomer solution
                      compositions and thermal treatments were produced (120-130
                      µm). All samples were employed for CCM fabrication (Anode:
                      3.0 mg/cm² PtRu; Cathode: 0.7 mg/cm² PtNi). Further, they
                      were characterized, regarding hydrogen permeability, ohmic
                      resistances and single-cell polarization curves in direct
                      methanol fuel cell (DMFC) operation. All samples were
                      compared to commercial Nafion 115 membranes.With some
                      samples the performances of CCMs using spray-deposited
                      membranes could be matched with Nafion 115. At the same time
                      they showed lower ohmic resistances and partly lower
                      hydrogen crossover values. Additionally, thinner membranes
                      equivalent to Nafion 212 (50 µm) and Nafion 211 (25 µm)
                      were fabricated and tested. They showed even better
                      performances. While 50 µm thick membranes had moderate
                      permeability levels comparable to 127 µm thick membranes,
                      25 µm samples showed high permeabilities. To reach high
                      performances with relatively low permeation values, thin
                      composite membranes (25 µm) were produced. These consisted
                      of Nafion and graphene oxide, where graphene oxide was
                      supposed to work as a blocking layer against permeation [4]
                      while supporting proton conductivity.It is also possible to
                      deposit Nafion solutions or Nafion (composite) dispersions
                      directly onto electrodes instead of producing self-standing
                      membranes [5]. This would allow the fabrication of a whole
                      CCM consecutively [6]. Even though this technique was used
                      for fabrication of CCMs for DMFCs, it can also be
                      transferred to hydrogen-based fuel cells (PEMFC) [6] or
                      water-electrolysis (PEMWE) [7].X. Ren, M. Wilson, S.
                      Gottesfeld, J. Electrochem. Soc., 143 (1996) L12–L15.L.
                      Sun, R. Ran, Z. Shao, Int. J. Hydrogen Energy, 35 (2010)
                      2921–2925.I.-S. Park, W. Li, A. Manthiram, J. Power
                      Sources, 195 (2010) 7078–7082.L. Sha Wang, A. Nan Lai, C.
                      Xiao Lin, Q. Gen Zhang, A. Mei Zhu, Q. Lin Liu, J. Memb.
                      Sci., 492 (2015) 58–66.M. Klingele, M. Breitwieser, R.
                      Zengerle, S. Thiele, J. Mater. Chem. A, 3 (2015)
                      11239–11245.M. Klingele, B. Britton, M. Breitwieser, S.
                      Vierrath, R. Zengerle, S. Holdcroft, S. Thiele, Electrochem.
                      Commun., 70 (2016) 65–68.P. Holzapfel, M. Bühler, C. Van
                      Pham, F. Hegge, T. Böhm, D. McLaughlin, M. Breitwieser, S.
                      Thiele, Electrochem. Commun., 110 (2020) 106640.Figure 1},
      month         = {May},
      date          = {2020-05-10},
      organization  = {237th ECS Meeting, Montreal (postponed
                       to 2021) (Canada (postponed to 2021)),
                       10 May 2020 - 14 May 2020},
      cin          = {IEK-14 / IEK-3},
      ddc          = {540},
      cid          = {I:(DE-Juel1)IEK-14-20191129 / I:(DE-Juel1)IEK-3-20101013},
      pnm          = {134 - Electrolysis and Hydrogen (POF3-134)},
      pid          = {G:(DE-HGF)POF3-134},
      typ          = {PUB:(DE-HGF)1},
      doi          = {10.1149/MA2020-02352248mtgabs},
      url          = {https://juser.fz-juelich.de/record/890158},
}