The Research Of The Lini_1/3co_1/3mn_1/3o₂ For The Cathode Material Of Li-ion Battery

Two methods, solid-state method and molten-salt method, were adopted to synthesize LiNi1/3Co1/3Mn1/3O2 cathode materials. XRD, SEM/TEM and LAND battery test system were used to study microstructure and electrochemical performances (charge-discharge capacity, cycling performance, and so on) of the materials.LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized by solid-state method at different calcination temperature and different calcination time with LiOH·H2O, H2C2O4·2H2O, Ni(AC)2·4H2O, Co(AC)2·4H2O and Mn(AC)2·4H2O as the raw materials. The result shows that all the samples are layered materials with typicalα-NaFeO2 structure. With synthysis temperature and time increasing, the particle size increases. The sample prepared at 850℃for 15h has the highest discharge capacity and best cycling performance. At current density of 120mA/g and in the voltage range 2.75-4.5V, this powder possesses the initial discharge capacity of 173.2mAh/g. After 30 cycles, the discharge capacity is 163.5mAh/g and the capacity retention is 94%. After 50 cycles, it still has the discharge capacity of 157.2mAh/g and the capacity retention is 90.8%.LiNi1/3Co1/3Mn1/3O2 cathode materials were prepared by molten-salt method with LiOH·H2O, Ni(AC)2·4H2O, Co(AC)2·4H2O and Mn(AC)2·4H2O as raw materials and KCl as molten salt. The analysis show that all the materials are typicalα-NaFeO2 structure.The particle size of the materials is larger than that of the materials synthesized by solid-state method under the same calcination temperature and time. The material synthesized at 850℃for 15h with nKCl/nLi+=6/1 presents the best electrochemical performance. At current density of 120mA/g and in the voltage range 2.75-4.5V, the material delivers an initial discharge capacity of 161.1mAh/g during the first charge-discharge cycle. After 30 cycles, it still has the discharge capacity of 138.5mAh/g and the capacity retention is 86%.In the voltage range 2.75-4.5V, the materials prepared by solid-state method and molten-salt method have good cycling performances. The charge-off-resistant property of the materials is better than that of the commercial LiCoO2(4.2V).During the cycling process, Redox reaction of Ni2+/Ni3+ and Ni3+/Ni4+ occurred for the materials prepared by the two methods. But oxidation reaction of Co3+/Co4+ occurred only for the material prepared by molten-salt method.