Polyester‐ZrO₂ Nanocomposite Electrolytes with High Li Transference Numbers for Ambient Temperature All‐Solid‐State Lithium Batteries

Abstract

Abstract Polyester‐ and polycarbonate‐based polymer electrolytes have attracted great interest after displaying promising functionality for solid‐state Li batteries. In this present work, poly(ϵ‐caprolactone‐ co ‐trimethylene carbonate) electrolytes are further developed by the inclusion of ZrO 2 particles, prepared by an in situ sol‐gel method. SEM micrographs show that the ZrO 2 particles are uniform and 30–50 nm in size. Contrary to many studies on filler‐polymer electrolytes, the changes in ionic conductivity are less significant upon addition of zirconia filler to the polymer electrolyte, but remain at ∼10 −5 S cm −1 at room temperature. This can be explained by the amorphous nature of the polymer. Instead, high lithium transference numbers (0.83–0.87) were obtained. Plating/stripping tests with Li metal electrodes show long‐term cycling performance for >1000 cycles at 0.2 mA cm −2 . Promising solid‐state lithium battery cycling results at ambient temperature using the material are also shown.