Vanadium-based polyanionic compounds as cathode materials for sodium-ion batteries: Toward high-energy and high-power applications

Sodium ion batteries (SIBs) have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources. However, they face serious challenges of low energy & power density and short cycling lifespan owing to the heavy mass and large radius of Na+. Vanadium-based polyanionic compounds have advantageous characteristic of high operating voltage, high ionic conductivity and robust structural framework, which is conducive to their high energy & power density and long lifespan for SIBs. In this review, we will overview the latest V-based polyanionic compounds, along with the respective characteristic from the intrinsic crystal structure to performance presentation and improvement for SIBs. One of the most important aspect is to discover the essential problems existed in the present V-based polyanionic compounds for high-energy & power applications, and point out most suitable solutions from the crystal structure modulation, interface tailoring and electrode configuration design. Moreover, some scientific issues of V-based polyanionic compounds shall be also proposed and related future direction shall be provided. We believe that this review can serve as a motivation for further development of novel V-based polyanionic compounds and drive them toward high energy & power applications in the near future.