Recent Advances in High-Entropy NASICON-Type Polyanionic Cathode Materials for Sodium-Ion Batteries

NASICON-type polyanionic compounds (NTPCs) have emerged as a notable class of cathode materials for sodium-ion batteries (SIBs), featuring distinct structural integrity, tunable redox potentials, and favorable thermodynamic stability. Nevertheless, their practical application is impeded by low electronic conductivity, sluggish Na+ diffusion kinetics, substantial volume changes, interfacial instability, and restricted theoretical capacity. Fortunately, the emerging high-entropy strategy in the field of energy storage offers a transformative pathway to overcome the bottlenecks of NTPCs. This review elucidates the fundamental concepts underlying high-entropy materials and includes an overview of the structural characteristics, persistent challenges, and conventional modification strategies associated with typical NTPCs. Subsequently, it comprehensively surveys the latest research progress on various high-entropy NTPC systems, including phosphates, fluorophosphates, and mixed-polyanion types, with particular emphasis on their performance enhancement mechanisms. Finally, future research directions are outlined to guide the rational design of high-performance high-entropy NTPC cathodes and accelerate the commercialization of SIBs.