Page 29 - ILK Research Report 2020

PEM

Polymer electrolyte membranes for vanadium redox flow batteries

The increasing use of energy from renewable sources requires storage sys- Period
tems for this fluctuating energy. One possibility is the use of redox-flow-bat- 01.06.2019 – 31.05.2022
teries (RFB). In Vanadium based RFBs polymer electrolyte membranes (PEM)
are frequently used as separator. Particularly important is Nafion, which is a Project Director
sulfonated fluoropolymer. Nevertheless, there are some shortcomings asso- Dr. rer.-nat. Uwe Gohs
ciated with Nafion and the development of new PEM materials with superior
properties is of high importance. Within the interdisciplinary project novel PEM Contact Person
materials will be developed on the basis of commercially available fluoropoly- Mohsen Sadeghi Bogar
mer films and fabrics. The electron-induced activation of the fluoropolymers is
followed by a graft copolymerization to incorporate functional groups allowing Funding
for sulfonation into the material. The influence of the irradiation conditions German Research Foundation (DFG)
on type and concentration of trapped radicals as well as subsequently on the
graft copolymerization is studied by electron paramagnetic resonance (EPR) Project Partner
spectroscopy. After sulfonation the PEMs are electrochemically characterized TU Clausthal
and application tests in Vanadium based RFBs are performed. The experi-
mental results constitute the basis for establishing a correlation of process,
polymer, structure and the PEM properties. Moreover, the experiments are
accompanied by modelling with respect to determination of the radical types,
optimization of the polymerization process and description of mass transfer
through the membrane.

Simulated EPR spectra of alkyl radicals
(74,4 %) in comparison to the experimental
EPR spectrum of irradiated PVDF

Overview on electron induced generation of radicals in PVDF and simulation of EPR spectra

Funded by
Simulated EPR spectra of peroxy radicals
(20,7 %) in comparison to the experimental
German Research Foundation EPR spectrum of irradiated PVDF

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