The invention relates to a technology on a
cathode material for a
lithium ion secondary battery, and in particular relates to an iron-based
composite oxide cathode material ZnFe2O4 / C with a hollow sphere structure and a preparation method thereof. The iron-based
composite oxide cathode material is characterized in that the general formula is ZnFe2O4 / C, wherein the content of carbon element is 1-10%; and a solvothermal one-
step method is utilized to prepare the ZnFe2O4 / C
composite cathode material with the hollow sphere structure and narrower
particle size distribution. The ZnFe2O4 / C
composite cathode material is high in purity; and the mean particle size of the ZnFe2O4 / C
composite cathode material is 500 nanometers and the wall thickness is 150 nanometers. An electrochemical test proves that the charging specific capacity of the ZnFe2O4 / C composite
cathode material at the first cycle can be 911mAh / g and the charging specific capacity of the ZnFe2O4 / C composite
cathode material can be 826mAh / g after being circulated for 30 times as well as the
retention rate of the capacity can be 91%. In addition, the ZnFe2O4 / C composite
cathode material can keep good charge-
discharge reversibility under different charge-
discharge current densities. The charge-
discharge capacity of the ZnFe2O4 / C composite cathode material is superior to that of an existing commonly-used carbon cathode material (theoretical specific capacity is 372mAh / g). The ZnFe2O4 / C composite cathode material is low in price of raw materials, simple in process and easy to industrialize, and has wider application prospects as well as meets practical production.