Recent research progress on Li29Zr9Nb3O40-based solid electrolytes for lithium batteries

All-solid-state batteries have become a research hotspot because of their high specific capacity and safety. Solid-state electrolytes are the key material of all-solid-state lithium-ion batteries, and their properties directly affect the overall performance of lithium-ion batteries. So far, many inorganic solid electrolytes have been reported, such as NASICON, LISICON, perovskite, and garnet-type solid electrolyte. However, some lithium-rich rock salt-structured electrolytes, such as Li 2 ZrO 3 , LiNbO 4 , and Li 6 Zr 2 O 7 , have been underappreciated in the field of solid-state electrolytes due to their lower ionic conductivity at room temperature. While investigating solid solution formation, Li 6 Zr[Formula: see text][Formula: see text]Nb[Formula: see text]O[Formula: see text][Formula: see text][Formula: see text], a new phase known as [Formula: see text][Formula: see text][Formula: see text][Formula: see text] with a rock-salt structure was discovered. After decades, it was not until a team prepared [Formula: see text][Formula: see text][Formula: see text][Formula: see text] ceramics by sol-gel method, which exhibited high ionic conductivity (10[Formula: see text]–10[Formula: see text]S cm[Formula: see text]) at room temperature, that the substance showed great potential as a solid electrolyte in all-solid-state lithium-ion batteries. In this paper, the crystal structure, lithium-ion transport mechanism, preparation method, and element doping of [Formula: see text][Formula: see text][Formula: see text][Formula: see text] are described comprehensively based on research progress in recent years. Then, development prospects and challenges of the concrete application of [Formula: see text][Formula: see text][Formula: see text][Formula: see text] in all-solid-state lithium-ion batteries are also discussed.