Tailoring Cathode Interfaces in Sodium‐Ion Batteries: Advanced Coating Strategies and Electrochemical Interface Regulation

Abstract Sodium‐ion batteries (SIBs) are emerging as a promising alternative to lithium‐ion batteries (LIBs) due to the abundance and cost‐effectiveness of sodium. However, their commercialization is hindered by challenges such as sluggish ion transport, structural degradation, and interfacial instability at the cathode. Effective interfacial engineering is crucial to overcoming these limitations and enhancing electrochemical performance. This review systematically explores both ex situ and in situ modification strategies for cathode interfaces in SIBs. Ex situ techniques, including protective coatings and conductive surface layers, serve to mitigate parasitic side reactions, improve ion transport, and enhance structural integrity. Meanwhile, in situ approaches, such as elemental doping, crystal facet engineering, and electrolyte‐induced interfacial stabilization, dynamically regulate the cathode‐electrolyte interface during cycling. By integrating recent advances in interface engineering, this work provides a comprehensive perspective on optimizing cathode stability, prolonging cycle life, and improving the commercial feasibility of SIBs. The insights presented herein offer valuable guidelines for the rational design of next‐generation SIB cathodes with enhanced durability and high‐rate capability.