Effect of Anions on Lithium Ion Conduction in Poly(ethylene carbonate)-based Polymer Electrolytes

Abstract

Poly(ethylene carbonate)-based polymer electrolytes with lithium salts (LiX; X=TFSI, ClO4, BF4 and PF6) were prepared and measured their lithium transference numbers (t +) for the comparison between different anion radius and salt concentrations. The LiTFSI electrolytes showed highest t + and Li-ion conductivities of all samples at 80 oC, and these values increased with increasing salt concentration. From the results of FT-IR measurements for all concentrated samples, it was revealed that the changes of a band fraction divided at around 1720 cm-1 for interacted carbonyl groups with Li+ (C=O --- Li+) strongly relate to the mobility of Li+.

Use of Solid-State NMR Spectroscopy for the Characterization of Molecular Structure and Dynamics in Solid Polymer and Hybrid Electrolytes

“…Polymer electrolytes tend to have good mechanical stability, minimal interfacial resistance with solid electrolytes, and are suitable for use in flexible battery applications [ 10 ]. However, lithium ion conductivity tends to be much lower in most polymer systems at room temperature than in liquid or some ceramic electrolytes (on the order of 10 −8 to 10 −6 S/cm at room temperature with lithium transference numbers below 0.5) and dendrite formation may still occur [ 11 ]. Hybrid electrolytes, which contain both solid polymers and ceramic particles, were created to capitalize on the advantages of both of these systems: they have higher lithium conductivities (on the order of 10 −5 to 10 −4 S/cm at ambient temperature) [ 12 , 13 , 14 , 15 ] than polymer electrolytes and are more flexible and interface compatible than ceramic electrolytes [ 16 ].…”