Recent Development of Phosphate Based Polyanion Cathode Materials for Sodium-Ion Batteries

Abstract

Sodium-ion batteries (SIBs) are regarded as next-generation secondary batteries and complement to lithium-ion batteries (LIBs) for large-scale electrochemical energy storage applications due to the abundant availability, even distribution, and cost-effectiveness of raw sodium resources. The phosphate-based polyanions stand out of various cathode material owing to their high operation voltage, stable structure, superior safety, and excellent sodium-storage properties. The undesirable electric conductivities and specific capacities limit their large-scale industrialization. Herein, a recent research development of phosphate-based polyanion cathodes including orthophosphate, oxyphosphate, pyrophosphate, and mixed phosphates is thoroughly reviewed. Subsequently, the effect of modification strategies including element doping, surface coating, morphology control, and electrode design toward high-performance cathode materials for SIBs are systematically explored. Finally, the future research directions of phosphate-based polyanion cathodes based on electrochemical performance including reversible capacity, voltage, energy density, rate capacity, cycling stability, and commercial applications are comprehensively concluded. It is believed that current review will present instructive perspectives into developing practicable phosphate-based polyanion cathode materials for SIBs.