Ultrafast biphasic Na5V3(PO4)2(P2O7)2/C composite cathode for sodium-ion batteries

A biphasic Na₅V₃(PO₄)₂(P₂O₇)₂/C composite is developed via a composition-regulation strategy as an ultrafast cathode for rechargeable sodium-ion batteries. It achieves a high practical capacity of 82.4 mA h g^-1 at the large current of 1000 mA g^-1 and obtains an impressive capacity retention of 88% after 1500 cycles.