The advent of manganese-substituted sodium vanadium phosphate-based cathodes for sodium-ion batteries and their current progress: a focused review

Na 3 V 2 (PO 4 ) 3 (NVP) is a member of the sodium superionic conductor (NASICON) family and has been extensively studied as a cathode material for sodium-ion batteries (SIBs) for more than three decades due to its stable voltage platform, high capacity, and stable cycle life. However, the presence of toxic and expensive V elements restricts the utilization of NVP-based SIBs. To overcome this, energy researchers have employed a cation swapping approach, which resulted in new NASICON-type manganese-substituted sodium vanadium phosphate (MSVP) cathodes for SIBs. Na 4 MnV(PO 4 ) 3 (NMVP) is among the new generation of high-energy, risk-free NASICON-type MSVP cathodes, and its use for SIBs was documented in 2016. There has been strong acceptance of MSVP-based cathodes among materials researchers due to their cost and economic advantages. In a short period, considerable work has been done to increase the commercial potential of MSVP-based cathodes for SIBs. This review summarizes the pioneering developments made with MSVP-based cathodes, with a special focus on their structural and electrochemical evolution. This review can serve as a reference for future energy researchers fabricating highly efficient and safer NASICON cathodes not only for SIBs but also for other energy storage applications. This review summarizes the current status and advancements made in research on manganese-substituted sodium vanadium phosphate-based cathodes, with a focus on their structural evolution, composite formation, morphological tailoring, and fabrication protocols.