Ionic liquid/ether-plasticized quasi-solid-state electrolytes for long-life lithium–oxygen cells

Abstract

Rechargeable lithium–oxygen (Li–O₂) cells have aroused great attention due to their high theoretical energy density. However, a great challenge remains for the practical applications of Li–O₂ cells. One of the obstacles is the instability of the Li anode with organic electrolytes, even for relatively stable ether-based electrolytes. In this work, a quasi-solid state electrolyte, composed of a polymer, an inorganic ceramic electrolyte, Li salt and a plasticizer, was prepared. The quasi-solid state electrolyte plasticized by a hybrid of an ether and ionic liquid exhibits a stable interfacial contact with the metallic Li anode. At a limited capacity of 1000 mA h g⁻¹, the Li–O₂ cell with the quasi-solid-state electrolyte can be stably cycled for 196 cycles at 400 mA g⁻¹. The good cycling stability of the cell can be attributed to the stable metallic Li/electrolyte interface enabled by the F-containing protective layer formed in situ from the decomposition of the ionic liquid during cycling. This work provides a new design of solid state electrolytes for long-life Li–O₂ cells.