Synergetic impact of high-entropy microdoping modification in Na 3 V 2 (PO 4 ) 3 .

High entropy polyanionic Na 3 V 1.9 (Ca,Mg,Cr,Ti,Mn) 0.1 (PO 4 ) 3 was synthesized, which activated a reversible redox reaction of V 4+ /V 5+ and reached a remarkable capacity of 116 mA h g -1 at 1C and maintained 90% capacity retention after 1000 cycles at 10C. Structure evolution and sodium storage mechanisms were revealed by an in situ XRD method, which disclosed the high-entropy effect of material design. Together with the full battery tests, these findings promote the wide applications of high-entropy polyanionic cathodes in SIBs.