# Decoding NASICON and Its Metal Interface for Solid‐State Batteries

## TL;DR

This review paper explores NASICON solid electrolytes for solid-state batteries, focusing on their properties, interface challenges with metal anodes, and strategies to improve performance and commercial viability.

## Contribution

The paper provides a comprehensive top-down analysis of NASICON fundamentals and interfacial failure mechanisms, offering new insights and mitigation strategies for solid-state batteries.

## Key findings

- NASICON shows high ionic conductivity and air stability, making it a promising solid electrolyte for SSBs.
- Interfacial instability with metal anodes leads to dendrite formation and battery failure.
- Advanced characterization techniques and mitigation strategies are essential for improving NASICON-based SSBs.

## Abstract

Solid‐state batteries (SSBs) are among the most promising next‐generation energy storage technologies, offering exceptional safety, high energy density, and fast‐charging capability. Among all kinds of solid electrolytes, sodium super ionic conductor (NASICON) is one of the most promising candidates due to its inexpensive material precursors, air stability, and high ionic conductivity. However, it faces a critical challenge: interfacial instability with metal anodes, leading to dendrite formation and penetration that ultimately cause battery failure. Addressing this issue requires a systematic understanding of the solid electrolyte itself, interfacial failure mechanisms, and robust mitigation strategies. Therefore, this review focuses on NASICON as a model system for both sodium‐ and lithium‐based SSBs, providing a comprehensive overview and new insights into NASICON and its metal interfaces. A top‐down approach is adopted, beginning with the fundamentals of NASICON's crystallography, thermodynamics, and kinetics to elucidate its intrinsic properties and interfacial degradation behaviors. Advanced characterization techniques for probing such failures are then reviewed, followed by a comprehensive discussion of mitigation strategies targeting the electrolyte, electrode, and their interface, along with practical insights into NASICON manufacturing. Finally, future research directions are proposed to guide the advancement of NASICON‐based SSBs toward practical commercialization.

This review paper focuses on lithium‐ and sodium‐based NASICON solid electrolytes and their interfaces with metal anodes using a top‐down framework. It begins with NASICON fundamentals, elucidates anode‐induced failure mechanisms, surveys advanced characterization strategies to understand them, summarizes mitigation approaches, and concludes with a forward‐looking perspective on solid‐state batteries enabled by NASICON.