All Solid-State Lithium Cells Employing Hybrid Solid Electrolytes Containing Li+-Conducting Inorganic Electrolyte

Abstract

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices, electric vehicles and energy storage systems, due to their high energy density and long cycle life.1 However, safety issues still prevent full utilization of these batteries owing to the use of flammable liquid electrolytes, and thus safety problems have become a significant concern especially in large capacity applications such as electric vehicles and energy storage systems. In this respect, the development of all solid-state lithium batteries with non-flammable solid electrolytes may provide a fundamental solution to the safety issue of lithium batteries.2 As solid electrolytes, inorganic electrolytes have been actively studied for solid-state lithium battery applications. They usually exhibit relatively high ionic conductivity, wide electrochemical stability window and good chemical stability in contact with lithium metal. However, their hard and brittle mechanical properties do not allow easy construction of large-scale lithium batteries. In addition, lack of flexibility results in high interfacial resistance and poor interfacial contacts with electrode materials. Therefore, developing the flexible hybrid solid electrolyte with high ionic conductivity is an attractive and urgent work for all solid-state lithium batteries. In this study, the hybrid solid electrolytes composed of Li+-ion conducting inorganic electrolyte and polymer electrolyte were prepared in the form of flexible thin film, and their electrochemical properties were investigated. The hybrid solid electrolytes were applied to the all solid-state Li/LiNi0.6Co0.2Mn0.2O2cells, and their electrochemical performance was evaluated.