AlTiMgLiO medium entropy oxide additive for PEO-based solid polymer electrolytes in lithium ion batteries

Abstract

Solid polymer electrolytes (SPE) have attracted considerable attention as electrolytes for solid-state batteries due to their toughness, high safety, and ionic conductivities that can be comparable with liquid electrolytes, especially at higher temperatures. However, polymers have low elastic moduli, which decrease at higher temperatures, limiting their ability to reduce dendrite formation. Mechanical blocking is one method of improving the interfacial layer and reducing dendritic growth but requires the elastic modulus of the polymer to be high enough to suppress lithium dendrites growth. Previous studies have focused on using unary metal oxides, which are limited by the percent of additives that can be included in the polymer before causing negative effects on electrochemical properties. In this study, we demonstrate a new strategy for improving the performance of polymers by synthesizing a multielement oxide (MEO) filler, AlTiMgLiO, to create a composite SPE with enhanced electrochemical performance. The synthesized AlTiMgLiO-containing SPE resulted in a voltage window of 0–6.18 V and a lithium transference number of 0.42. The overpotential voltage during galvanostatic cycling was reduced due to the improvements made to the morphology. The improvement of the interfacial layer reduced Li dendritic growth, resulting in a capacity of 99.68 mAh g−1 after 500 cycles, and a capacity retention of 78.69 %. The possible reasons for the improvement are discussed, providing a direction for future studies on the use of multielement materials as fillers in solid polymers electrolytes.