Low‐Cost Polyanion‐Type Sulfate Cathode for Sodium‐Ion Battery

Abstract Recently, environmental degradation along with the energy crisis has led to an urgent necessity to develop renewable and clean energy storage devices. The sodium ion batteries (SIBs) have become promising candidates in the whole energy storage system, due to its rich and low‐cost sodium resources. To accelerate the commercialization of SIBs, the energy density of SIBs needs to be further improved. Increasing the operating voltage of SIBs is considered to be an effective method, which requires stable and high‐voltage cathode materials. Comparatively, polyanionic sulfate materials (PSMs) with stable skeletons, adjustable structures, operational safety, and the high electronegativity of SO 4 2− are believed to be the most promising high‐energy‐cathodes. In this review, recent progresses on several typical sulfates for SIBs are summarized. What's more, based on their intrinsic characteristics, the structures and kinetic behaviors of PSMs are also discussed. Reported measures to optimize their electrochemical performances and structural stability are summarized and reviewed. The key challenges and corresponding opportunities for PSMs are also discussed. The insights presented in this review may be a guide for designing and developing stable and practical PSMs for room‐temperature SIBs, which is conducive to promoting their industrialization.