Water determination in composite PEO-based polymer electrolytes by volumetric Karl Fischer titration method

Abstract

The determination of water in composite poly(ethylene oxide) (PEO)-based polymer electrolytes by volumetric Karl Fischer (KF) titration is described. The measurements have been carried out on specimens (up to 10 g) of polymer electrolytes (as single components, their mixture and thin film) in a dry-room (relative humidity, RH, <0.2% at 20 °C). The use of a dry-room allowed to obtain a baseline drift (defined as the titration rate necessary to keep dry the cell) as low as 0.5 μg H 2O min −1. Working range is 0.001–0.5 wt.% H 2O and precision, expressed as relative standard deviation of seven replicates, is 5 at 0.5 wt.% level. Comparison of the gathered results with those obtained by oven methods are provided. Uptake water from surrounding environment can be detected at a level as low as 0.001 wt.%.