Spin relaxation studies of Li+ ion dynamics in polymer gel electrolytes

M. BRINKKOTER; M. GOUVERNEUR; PEDRO J. SEBASTIÃO; F. VACA CHAVEZ; M. SCHOENHOFF

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2017

1463-9076

Two ternary polymer gel electrolyte systems are compared, containing either polyethylene oxide (PEO) or the poly-ionicliquid poly(diallyldimethylammonium) bis(trifluoromethyl sulfonyl)imide (PDADMA-TFSI). Both gel types are based on theionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl)imide (P14TFSI) and LiTFSI. We study the influence ofthe polymers on the local lithium ion dynamics at different polymer concentrations using 7Li spin-lattice relaxation data independence on frequency and temperature. In all cases the relaxation rates are well described by a Cole-Davidsonmotional model with Arrhenius dependence of the correlation time and a temperature dependent quadrupole couplingconstant. For both polymers the correlation times are increasing with polymer concentration. The activation energy oflocal motions is slightly increasing for increasing PEO concentration, and slightly decreasing for increasing PDADMA-TFSIconcentration. Thus the local Li+ motion is reduced by the presence of either polymer, however, the reduction is lesseffective in the PDADMA+ samples. We thus conclude that mechanical stabilization of a liquid electrolyte by a polymer canbe achieved at a lesser drawback of Li+ motion when a cationic polymer is used instead of PEO.