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

• Published in: Batteries & supercaps Vol. 4; no. 4; pp. 653 - 662
• Main Authors: Lee, Tian Khoon, Andersson, Rassmus, Dzulkurnain, Nurul Akmaliah, Hernández, Guiomar, Mindemark, Jonas, Brandell, Daniel
• Format: Journal Article
• Language: English
• Published: 01-04-2021
• Subjects: lithium transference number; one-pot in situ preparation; poly(trimethylene carbonate)-epsilon-caprolactone; poly(trimethylene carbonate)-ϵ-caprolactone; zirconia nanoparticles
• ISSN: 2566-6223; 2566-6223
• DOI: 10.1002/batt.202000254

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 ZrO2 particles, prepared by an in situ sol‐gel method. SEM micrographs show that the ZrO2 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.
Taking a detour: Synthesizing ZrO2 nanoparticles in situ in an amorphous polycarbonate‐polyester solid electrolyte is shown to increase the Li+ transference number and the mechanical properties of the resulting materials. Thereby, the cyclability is improved in different cell types. This indicates that the effect of the nanoparticles promotes alternative transport routes for the ions, highlighting aspects that are not related to the crystallinity of the polymer host.