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@INPROCEEDINGS{Daniel:911501,
      author       = {Daniel, Davis Thomas and Szczuka, Conrad and Eichel,
                      Rüdiger-A. and Granwehr, Josef},
      title        = {{EPR} spectroscopic investigation of {L}ithium-organic
                      batteries},
      school       = {KIT - Karlsruher Institut für Technologie},
      reportid     = {FZJ-2022-04763},
      year         = {2022},
      abstract     = {Electrochemical energy storage is of key importance to meet
                      future energy demands sustainably. The most used battery
                      technology utilizes lithium metal as the anode and
                      transition metal oxides or phosphates (LiCoO2, LiFePO4 etc.)
                      as cathode material. Owing to the toxicity of the metals,
                      production costs and poor recyclability, transition metal
                      oxides as cathode materials have a negative environmental
                      impact. Organic radical polymers are a promising
                      alternative, as they feature tuneable redox properties, fast
                      kinetics and are more environmentally sustainable.[1]EPR is
                      well suited to study these systems as the polymers comprise
                      of paramagnetic species as redox units. A common radical
                      polymer, bearing TEMPO radicals as redox units is PTMA
                      (poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl
                      methacrylate)).[2] Herein, we report EPR spectroscopic
                      characterization of PTMA polymers using cw-EPR and
                      pulsed-EPR techniques and study charge/discharge
                      characteristics of a Li-PTMA cell using in operando EPR
                      spectroscopy. Cw-EPR is primarily used for radical
                      quantification and to distinguish between nitroxide radicals
                      undergoing exchange and isolated nitroxides by lineshape
                      fitting. Laplace inverted pulsed-EPR relaxation offers
                      insight into electronic contact between the active material
                      (PTMA) and SuperP conductive carbon present in the composite
                      cathode. The redox state of the active material was
                      monitored by acquiring cw-EPR spectra during battery cycling
                      using an in operando EPR cell [3] with lithium metal as the
                      anode and a PTMA composite cathode(65 $wt\%$ PTMA, 30 $wt\%$
                      SuperP, 5 $wt\%$ CMC(Carboxymethyl cellulose)). The Li-PTMA
                      in operando cell shows good electrochemical reversibility of
                      the active material for over60 cycles and an irreversible
                      accumulation of mossy (microstructured) lithium is indicated
                      by the linewidth of the lithium resonance. In the
                      electrochemically oxidized state of the radical polymer, EPR
                      spectrum shows the presence of immobilised nitroxide
                      radicals arising from electrochemically inactive regions of
                      the cathode film. EPR serves as an optimal spectroscopic
                      technique for gaining insights into structural and
                      mechanistic features of organic radical batteries (ORB).
                      Comparative studies using pulsed-EPR techniques on pristine
                      and post-cycled battery materials would also reveal
                      degradation pathways and changes in the radical environment,
                      further aiding the optimization of the ORB setup.
                      Literature:[1] Muench, S. et al. Chem. Rev. 116, 9438–9484
                      (2016). [2] Nakahara, K. et al. Chem.Phys. Lett. 359,
                      351–354 (2002). [3] Niemöller, A. et al. J. Chem. Phys.
                      148, 014705(2018).},
      month         = {Sep},
      date          = {2022-09-12},
      organization  = {43rd FGMR Annual Discussion Meeting,
                       Karlsruhe (Germany), 12 Sep 2022 - 15
                       Sep 2022},
      subtyp        = {After Call},
      cin          = {IEK-9},
      cid          = {I:(DE-Juel1)IEK-9-20110218},
      pnm          = {1223 - Batteries in Application (POF4-122) / Insight into
                      doping mechanisms of polymer electrolyte / redox-active
                      organic radical polymer lamellar composites (441255373) /
                      HITEC - Helmholtz Interdisciplinary Doctoral Training in
                      Energy and Climate Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF4-1223 / G:(GEPRIS)441255373 /
                      G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/911501},
}