Solid‐State Sodium‐Ion Batteries: Theories, Challenges and Perspectives

Abstract Sodium‐ion batteries have abundant sources of raw materials, uniform geographical distribution, and low cost, and it is considered an important substitute for lithium‐ion batteries. Thereinto, solid‐state sodium‐ion batteries have the advantages of low raw material cost, high safety, and high energy density, and it has shown great potential for application in the fields of mobile power, electric vehicles, and large‐scale energy storage systems. However, the commercial development and large‐scale application of solid‐state sodium‐ion batteries urgently need to address issues such as the low room‐temperature ionic conductivity of solid electrolytes, high interfacial charge transfer impedance, and poor compatibility and contact between the solid electrolytes and the electrodes. Herein, this paper systematically discusses the basic theories of solid‐state sodium‐ion batteries, including working principles and characteristics, electrode materials and components, and solid electrolytes. Then, focusing on solid electrolytes, the key scientific challenges faced by solid‐state sodium‐ion batteries were systematically discussed, and the application of interface modification in enhancing solid‐state electrolytes was reviewed. Finally, the future industrial development of solid‐state sodium‐ion batteries was prospected. This review helps to deepen the understanding of the interface scientific issues of solid‐state sodium‐ion batteries and provides theoretical guidance for its development and application. Furthermore, this review also provides the necessary engineering theoretical guidance to accelerate the large‐scale commercial application of solid‐state sodium‐ion batteries, which has significant scientific value and profound social significance.