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@INPROCEEDINGS{Flammia:852611,
      author       = {Flammia, Ivan and Mester, Achim and Niemöller, Arvid and
                      Granwehr, Josef and van Waasen, Stefan},
      title        = {{O}ptimization of {C}urrent {C}ollector {D}esign for
                      {O}perando {X}-band-{EPR} {I}nvestigations of
                      {L}ithium-{I}on {B}atteries {U}sing {N}umerical
                      {S}imulations},
      reportid     = {FZJ-2018-05515},
      pages        = {3A0-28},
      year         = {2018},
      abstract     = {Monitoring the operation of lithium-ion batteries using
                      electron paramagnetic resonance (EPR) is a powerful tool for
                      gaining a better understanding of the redox processes and
                      degradation mechanisms in anode and cathode materials. For
                      this purpose, a complete operational cell, including current
                      collectors, must be placed into the region of maximum
                      magnetic field and minimum electric field of the specific
                      resonance mode established in the EPR cavity. The
                      homogeneity of the microwave (MW) magnetic field in the
                      measurement region is essential to perform accurate
                      quantitative measurements. Furthermore, the samples, the
                      current collectors, and the dielectric holders should be
                      confined within a region with negligible electrical field,
                      to prevent unwanted power dissipation and to avoid a
                      reduction of the cavity quality factor. Current collectors
                      represent a major problem in the EPR characterization of
                      battery cells, as the introduction of conducting elements
                      into the resonator affects the electromagnetic field
                      distribution, thus altering the EPR spectra, or prevents
                      their acquisition altogether.Furthermore, the collectors
                      should not excessively cover the battery surface, as this
                      would shield the MW field at the position occupied by the
                      active materials in the cell. On the other hand, they should
                      be evenly distributed over the surface of the cell to
                      prevent the establishment of transversal electrical
                      gradients and guarantee a homogenous development of
                      electrochemical processes. In this paper, we discuss the
                      simulation results for various circular current collector
                      geometries with a diameter of 7 mm, suitable for operando
                      X-band-EPR measurements of battery cells in a Bruker Elexsys
                      E540 spectrometer. A commercial 4108 TMHS cylindrical
                      resonator is operated using the TM110 mode in order to
                      excite and monitor the EPR resonances. The designs take into
                      account practical manufacturability considerations: The
                      collectors are specifically engineered to be easily
                      integrated into the assembly, using substrates which are EPR
                      silent and chemically inert against the battery materials.},
      month         = {Aug},
      date          = {2018-08-01},
      organization  = {The 40th Progress In Electromagnetics
                       Research Symposium, Toyama (Japan), 1
                       Aug 2018 - 4 Aug 2018},
      cin          = {ZEA-2 / IEK-9},
      cid          = {I:(DE-Juel1)ZEA-2-20090406 / I:(DE-Juel1)IEK-9-20110218},
      pnm          = {131 - Electrochemical Storage (POF3-131)},
      pid          = {G:(DE-HGF)POF3-131},
      typ          = {PUB:(DE-HGF)8},
      doi          = {10.23919/PIERS.2018.8597984},
      url          = {https://juser.fz-juelich.de/record/852611},
}