Atomic Layer Deposition for Sodium‐Ion Batteries

Abstract Sodium (Na)‐ion batteries (SIBs) have emerged as a sustainable alternative to lithium (Li)‐ion counterparts due to sodium's abundance and cost‐effectiveness. However, the larger ionic radius and higher mass of Na + compared to Li⁺ induce sluggish Na⁺ intercalation kinetics within electrode materials, compromising energy density, rate capability, and lifespan. Atomic layer deposition (ALD) presents a promising approach for addressing these issues. This technique can not only synthesize favorable nanostructured coatings/electrodes to accelerate Na + diffusion but also precisely control their thickness to reduce unnecessary mass loading. Over the past five years, research on ALD in SIBs has surged, particularly in cathode applications. However, a comprehensive review focusing specifically on ALD in SIBs remains absent. This review aims to bridge that gap by analyzing key studies published in recent years. First, the ALD techniques as applied in SIBs are outlined, covering their fundamental process, key parameters, common coating materials, and historical development. Next, the applications of ALD on various anodes, cathodes, and solid‐state electrolytes are categorized and summarized, with a particular emphasis on ALD's roles in enhancing SIBs' performance. Finally, the challenges and possible future directions of ALD in SIBs are discussed, aiming to accelerate R&D for practical applications and the commercialization of SIBs.