Exploring the limitations and unlocking the potential of sodium-ion battery cathodes

The increasing demand for sustainable energy solutions led to the advancement of alternative energy storage devices beyond lithium-ion batteries (LIBs). Sodium-ion batteries (SIBs) have emerged as a viable substitute for LIBs owing to sodium's abundance and electrochemical characteristics similar to those of lithium. However, the commercialization of SIBs is impeded by issues related to the performance of cathode materials, including phase instability, low energy density, and poor cycling performance. This review offers a comprehensive evaluation of the four main categories of cathode materials for SIB—Transition metal oxides, Polyanionic compounds, Prussian blue analogues, and Organic materials, highlighting their advantages and limitations comprising of instability and poor conductivity. Recent advancement in SIB cathode material along with improvement strategies such as element doping, surface coatings, and structural modifications, have significantly improved the energy density, structural stability, and cycle performance but challenges such as irreversible phase transitions, air sensitivity, and sluggish Na-ion diffusion remains. This study underscores techniques that alleviate these problems and enhance the electrochemical performance of SIBs. Furthermore, research avenues to improve energy density and cycle longevity are delineated. This review outlines potential strategies for optimizing cathode materials to accelerate the practical implementation of SIBs for sustainable energy storage applications. • Compares the advantages and disadvantages of SIB cathodes such as oxides, polyanions, PBAs, and organics. • Investigates critical difficulties like phase instability, air sensitivity, and Na-ion kinetics in SIB cathodes. • Analyzes advancements in doping, surface coatings, and structural modifications. • Identifies research gaps in stability, cycle life, and energy density improvements. • Outlines strategies to optimize SIB cathodes for commercial energy storage use.