Poly(vinyl alcohol)–LiBOB complexes for lithium–air cells

•Mobility and diffusivity can control conductivity even if charge carriers increase.•PVA–LiBOB electrolytes can produce high conductivity in wide temperature range.•Suitable packaging of Li–air cell can reduce moisture interaction with Li metal.

Poly(vinyl alcohol) or PVA complexes with lithium bis(oxalato)borate or LiBOB have been prepared by solution casting. X-ray diffraction reveals that the amorphousness of the polymer increased until 40 wt.% LiBOB salt concentration. The increase in amorphousness is accompanied by a decrease in the glass transition temperature, Tg. The diffusion coefficient of lithium ion obtained from cyclic voltammetry (CV) is 1.98 × 10−8 cm2 s−1. From infrared and impedance spectroscopic studies, it is inferred that conductivity is governed by charge carrier density, ionic mobility and diffusion coefficient for PVA incorporated with 10–40 wt.% LiBOB. However, for the sample with equal weight ratio of PVA and LiBOB, ionic mobility and diffusivity have a greater influence over charge carrier density in determining conductivity at room temperature (RT). PVA can solvate a large amount of salt and for the highest conducting composition of 60 wt.% PVA–40 wt.% LiBOB, conductivity extends from 10−4 S cm−1 at RT (25 °C) to 10−3 S cm−1 at 100 °C. This sample was tested as an electrolyte in a Li–air cell.