Advancing NASICON solid-state electrolytes for lithium metal batteries: interfacial challenges, engineering strategies, and future directions

Abstract

Solid-state lithium metal batteries (SSLMBs) have emerged as a highly promising next-generation energy storage technology due to their superior safety and high energy-density. Among all solid-state electrolytes, sodium superionic conductor (NASICON) electrolytes are particularly noteworthy, offering high ionic conductivity, excellent air stability, and wide electrochemical window, making them one of the most extensively studied and technologically viable options. However, critical interfacial challenges persist between NASICON electrolytes and lithium metal anodes, including poor physical contact, insufficient chemical/electrochemical stability, and detrimental side reactions, all of which significantly hinder battery performance. These interfacial phenomena involve multifaceted complexities, such as intrinsic material properties, dynamic side reactions, and spatiotemporal evolution-processes, which are inherently difficult to observe using conventional characterization techniques. Here, this review systematically analyzes the interfacial issues between NASICON electrolytes and Li anodes, evaluating existing modification strategies (e.g., inorganic coatings, organic/polymer coatings, composite coatings, and anode protection mechanisms) and highlighting advanced characterization techniques which provide deeper insights into the dynamic interactions occurring at the interface, facilitating the rational design and optimization of solid-state batteries. Advanced characterization techniques are discussed for interfacial analysis. By leveraging advanced interfacial engineering strategies and characterization techniques, researchers can accelerate the development of safer, more efficient, and longer-lasting solid-state lithium batteries.