Single lithium-ion conductors (SLICs), which have anions covalently bonded to polymers or immobilized by anion acceptors, have been intensively studied. SLICs are generally accepted to have advantages over conventional salt-in-polymer electrolytes for application in lithium batteries due to the unity transference number and the absence of detrimental effect of anion polarization. By now, many types of SLICs have been reported, including organic polymers, organic-inorganic hybrid polymers and anion acceptors. In this paper, progresses in SLICs are reviewed, which mainly focused on their electrochemical properties, especially those with high ionic conductivity and high lithium-ion transference number. The current challenges and future perspectives in this field are also prospected.

Contents
1 Introduction
2 Organic polymer-based single lithium-ion con-ductors
2.1 Single lithium-ion conductors based on lithium salts of ionomer without ion conduction matrix
2.2 Single lithium-ion conductors based on lithium salts of ionomer with ion conduction matrix
3 Organic-inorganic hybrid polymers
3.1 The siloxane-based single lithium-ion conductors
3.2 The aluminate and borate-based hybrid polymers
4 Anion acceptor
4.1 Lewis acid-based anion acceptor
4.2 Calixarene and their derivatives
5 Conclusions and outlook