Progress and Challenges of Solid Electrolytes for High-Performance Sodium Ion Batteries

Sodium-ion batteries (SIBs) have become a promising candidate for large-scale energy storage applications, owing to the abundant availability and economic advantages of sodium resources. However, their progress is impeded by constraints in liquid electrolytes, including safety concerns and instability while cycling. Solid-state electrolytes (SSEs) offer a disruptive alternative, overcoming these problems while enabling the production of sophisticated solid-state SIBs. This review presents a complete overview of SSE technologies, divided into inorganic, polymeric, and composite materials, and discusses their specific advantages and limits. Issues such as inadequate ionic conductivity, restricted interfacial stability, and mechanical fragility are rigorously investigated. To address these difficulties, we highlight developing technologies, including crystal structure engineering, targeted doping, and advanced interface modification techniques, which jointly promote ion transport, inhibit dendrite development, and improve overall battery performance. Moreover, the review underlines the importance of balancing performance criteria with scalability and cost-effectiveness to encourage commercial adoption. This work highlights the crucial importance of SSEs in developing the next generation of sustainable and high-performance energy storage systems by incorporating insights from recent advancements and pinpointing future research directions. This assessment intends to encourage innovation in SSE development and reinforce its status as a cornerstone technology for future energy solutions.