Preparation and properties of stat–copoly(oxyethylene/oxypropylene)–LiClO4 polymer electrolytes

Abstract

High-molar-mass statistical copolymers of ethylene oxide and propylene oxide with compositions in the range 60–90 mol% oxyethylene units have been prepared, mixed with lithium perchlorate, and studied by differential scanning calorimetry (DSC) and ac impedance spectroscopy. The observation by DSC of two glass transitions gave evidence of separation into salt-poor and salt-rich phases. A copolymer of 85 mol% oxyethylene mixed with LiClO₄ at an O:Li mole ratio of 24:1 had a conductivity at 25 °C of σ≈ 10^–5 S cm^–1, i.e. lower than the room temperature conductivities recorded for comparable non-crystalline polymer electrolytes formed from some alternative high-molar-mass linear copolymers.