Ion Transport Effects in a Solid Polymer Electrolyte Due to Salt Substitution and Addition Using an Ionic Liquid

Abstract

We investigated mass and charge transport in amorphous salt-in-poly(ethylene oxide) (PEO) electrolytes with NaI and/or the ionic liquid (IL) EMImTFSI (1-ethyl-3-methylimizadolium bis(trifluoromethylsulfonyl)imide) as salt component. Combining the results of ion conductivity, pulsed field gradient nuclear magnetic resonance, and radiotracer diffusion measurements, it is found that over wide temperature ranges both the cation and anion diffusion coefficients and the charge diffusivity are distinctly larger in PEO(20)EMImTFSI than in PEO(20)NaI complexes, where the monomer-to-salt mole ratio equals 20. In the mixed-salt complexes PEO(20)NaI(1)EMImTFSI(1) and PEO(20)NaI(0.5)EMImTFSI(0.5), we observe a slowing down of the IL ions EMIm and TFSI along with a diffusivity enhancement of the I anion compared to the single-salt base complexes. For the cation Na, a diffusivity increase is only effected by IL substitution, but because of the concomitant decrease of the Na concentration, it does not predict more effective charge transfer in a battery cell configuration.

Block copolymer electrolytes for rechargeable lithium batteries

“…Recently, BCPs containing ionic liquids (ILs) have drawn attention as alternative electrolytes for lithium batteries . ILs are room temperature molten salts that are composed mostly of organic ions, offering several advantages including reduced flammability, low vapor pressure, good thermal stability, low toxicity, and good ionic conductivity . In 2007, He et al reported a method for preparing ion gels through the self‐assembly of PS‐PEO‐PS triblock copolymers at high IL, 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIm‐PF 6 ), compositions for polymer electrolytes .…”

Ion Transport Through Polyelectrolyte Multilayers

“…They observed an increase of the ion mobility as the temperature and the charge increased. Currently established concepts for determining ion conductivity of solid materials include impedance spectroscopy (IS), the radiotracer diffusion technique (RD), and pulsed field gradient nuclear magnetic resonance (PFG‐NMR) . IS relies on the ability to have two electrodes in contact with the sample, which in the case of nanoscale samples raises the problem of electrical short circuits.…”

Ion Permeability of Free-Suspended Layer-by-Layer (LbL) Films Prepared Using an Alginate Scaffold

“…The construction of separation and purification membranes for ions and molecules has also been studied using LbL films and related systems [29][30][31][32]. LbL films composed of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS), which were deposited on the surface of porous supports (pore diameter 20-200 nm), exhibited a high flux of monovalent ions while the flux of multivalent ions was significantly suppressed as a result of enhanced Donnan exclusion, as well as hindered diffusion in the film [33][34][35].…”