Solid Electrolytes Based on NASICON-Structured Phosphates for Lithium Metal Batteries

All-solid-state lithium batteries are a promising alternative to commercially available lithium-ion batteries due to their ability to achieve high energy density, safety, and compactness. Electrolytes are key components of all-solid-state batteries, as they are crucial in determining the batteries’ efficiency. Herein, the structure of LiM2(PO4)3 (M = Ti, Ge, Zr) and lithium-ion migration mechanisms are introduced as well as different synthetic routes and doping (co-doping), and their influence on conductivity is discussed. The effective methods of reducing electrolyte/electrode interface resistance and improving ion-conducting properties are summarized. In addition, different polymer/NASICON composites are considered. The challenges and prospects of practical applications of NASICON-type lithium phosphates as electrolytes for all-solid-state batteries are discussed.