O3-type na(Fe_1/3Mn_1/3Co_1/3)O₂ as a cathode material with high rate and good charge-discharge cycle performance for sodium-ion batteries

O3-Na(Fe_1/3Mn_1/3Co_1/3)O₂ has been reported as a cathode material with a reversible capacity of 84mAh/g. This cathode active material shows excellent electrochemical performance with a high capacity retention of 95.0% after 100 cycles at 1C rate, and a discharge rate capability of 37mAh/g (47% of the initial capacity of 1C rate) at 50C rate. From the results of electrochemical impedance spectroscopy, an increase in reaction resistance was not confirmed between before and after the charge/discharge cycle test. TEM observation revealed that the crystal structure change on the surface of O3-Na(Fe_1/3Mn_1/3Co_1/3)O₂ after the charge/discharge cycle test was slight, and the change in the crystal structure was small compared with that of the lithium ion battery, so O3-Na(Fe_1/3Mn_1/3Co_1/3)O₂ has high crystal structure stability.