Positive electrode material for sodium ion battery and preparation method of positive electrode material

The invention discloses a positive electrode material for a sodium ion battery. The positive electrode material is a P3 type oxide; the composition of the oxide is Na < 0.66 > Mn < 0.6 > Ni < 0.4-x > Mg < x > O < 2 >, wherein x < lt > is not less than 0.1; 0.4 part; according to the invention, the P3 structure of Na < 0.66 > Mn < 0.6 > Ni < 0.4-x > Mg < x > O < 2 > (0.1 < = xlt; according to the present invention, the material has characteristics of good charge-discharge performance, large reversible capacity and small capacity fading when the voltage range is 1.5-4.4 V (vs.Na < + >/Na) and the current density is 10-50 mA/g, the charge-discharge capacity is 100-180 mAh/g, 70-80% of the capacity can be maintained after 100 cycles, and the material has good reversibility. 本发明公开了一种钠离子电池用正极材料，所述正极材料为P3型氧化物；氧化物的组成为Na0.66Mn0.6Ni0.4-xMgxO2，0.1≤x