Recent Progress in Surface Coatings for Sodium-Ion Battery Electrode Materials

Sodium-ion batteries (SIBs) are an emerging technology regarded as a promising alternative to lithium-ion batteries (LIBs), particularly for stationary energy storage. However, due to complications associated with the large size of the Na+ charge carrier, the cycling stability and rate performance of SIBs are generally inadequate for commercial applications. Due to their similar chemistry and operating mechanism to LIBs, many improvement strategies derived from extensive LIB research are directly translatable to SIBs. In addition to doping and tailoring of the particle morphology, applying coatings is a promising approach to improve the performance of existing electrode materials. Coatings can mitigate side reactions at the electrode- electrolyte interface, restrict active material dissolution, provide reinforcement against particle degradation, and/or enhance electrode kinetics. This review provides a comprehensive overview and comparison of coatings applied to SIB intercalation cathodes and anodes. Coatings are categorized based on their mechanism of action and deposition method. Key classes of SIB electrode materials are introduced, and promising coating strategies to improve the performance of each material are then discussed. These insights can help guide rational design of high-performance SIB electrodes.