Synergistic effects of salt concentration and polymer blend composition on the crystal phases, dielectric relaxation, and ion conduction in PVDF/PEO/LiCF3SO3 solid polymer electrolytes

摘要

Effects of lithium triflate (LiCF3SO3) salt concentration and compositional weight ratio of poly(vinylidene fluoride) (PVDF)/poly(ethylene oxide) (PEO) blend host matrix on the structural, dielectric relaxation, and ion transport properties of PVDF/PEO/LiCF3SO3 solid polymer electrolyte (SPE) films have been investigated. Variations in the amounts of constituents in these SPEs enormously alter the characteristic crystal phases of polymers and their chain segmental dynamics. Ionic conductivity increases by more than five orders of magnitude on loading LiCF3SO3 amount up to 30 wt% in the 75PVDF/25PEO blend matrix, and by about two orders with the increase of PEO amount from 25 to 90 wt% in the polymer blend host matrix of PVDF/PEO-25 wt% LiCF3SO3 films. Correlation between ionic conductivity and relaxation time confirms that the transport of ions is coupled to the polymer chain segmental motions in these SPEs. Total ion transference number, electrochemical voltage stability, and cyclic performance of these electrolyte materials are determined and appropriately explained.