posted on 2020-03-31, 19:46authored byKatrina
Irene S. Mongcopa, Daniel A. Gribble, Whitney S. Loo, Madhusudan Tyagi, Scott A. Mullin, Nitash P. Balsara
We investigate the segmental dynamics
and ion transport in two chemically distinct polymer electrolytes,
poly(2-cyanoethyl acrylate) (PCEA) and poly(ethylene oxide) (PEO),
and their mixtures with lithium bis(trifluoromethane)sulfonimide (LiTFSI)
salt. Quasi-elastic neutron scattering experiments reveal slow dynamics
in PCEA/LiTFSI relative to that in PEO/LiTFSI, translating to monomeric
friction coefficients that are orders of magnitude different. In spite
of the enhanced salt dissociation in PCEA due to the presence of polar
groups, ion transport is largely dominated by the effect of increased
monomeric friction in the pure polymer. Conductivity in these systems
is quantified through a simple expression combining salt dissociation,
the monomeric friction in the pure polymer, and the effect of added
salt on the monomeric friction.