Facing the Ionic Conductivity of Solid Polymer Electrolytes for Sodium–Metal Batteries: A Mini Review

Polymer-based solid electrolytes have good prospects in the arena of sodium-metal batteries (SMBs) because of their high stability and safety. However, it has problems, including insufficient ion conductivity and narrow voltage windows, which may reduce performance and hinder its practical application. The existing research has not thoroughly investigated the problem of poor ionic conductivity in solid polymer electrolytes (SPEs). This review focuses on improving the low ionic conductivity of SPEs. A comprehensive approach is proposed, which includes the introduction of inorganic fillers, the dissociation of different salts, and the electrode/electrolyte interface affinity regulation. At last, we presented several crucial prospects for promoting the future progress of SPEs and SMBs.