Lithium ion conducting membranes for lithium-air batteries

► A number of materials that are potential candidates for making lithium ion conducting membranes are summarized and discussed. ► NASICON-type lithium ion conducting membranes are exclusively discussed in terms of their conductivity, stability, and the application for lithium-air batteries. ► Single-crystal silicon membranes are highlighted in terms of their conductivity and potential application in lithium-air batteries. ► Personal perspectives on the future direction of lithium ion conducting membranes are discussed.