Na4Co2.4Mn0.3Ni0.3(PO4)2P2O7: High potential and high capacity electrode material for sodium-ion batteries

Na4Co2.4Mn0.3Ni0.3(PO4)2P2O7 has been evaluated as a positive electrode for sodium-ion batteries. The novel material has two redox couples around 4.2 V and 4.6 V and can deliver the high capacity of ca. 103 mAh g− 1 at the high current density of 850 mA g− 1 (5 C). X-ray absorption spectroscopy (XAS) results show that the redox reactions of Co, Mn and Ni ions proceed simultaneously in the charge process and it is indicated the novel material provide high mixed potential by the redox reactions of Co, Mn and Ni ions. These findings suggest that the derivatives of Na4Co3(PO4)2P2O7 should be employed as high potential and high capacity electrode materials.