Abstract:Spherical LiNi_0.5Mn_1.5O₄ powder was synthesized from the coprecipitated Ni_0.25Mn_0.75CO₃ precursor. The effects of two synthesis routes, Ni_0.25Mn_0.75CO₃ precursor directly mixed with Li₂CO₃ and (Ni_0.25Mn_0.75)₂O₃ mixed with Li₂CO₃, on the morphology and electrochemical performance of LiNi_0.5Mn_1.5O₄ cathode material were investigated. XRD, SEM, charge-discharge tests and cyclic voltammetry were utilized to characterize the properties of samples. The XRD results indicate that the LiNi_0.5Mn_1.5O₄ samples synthesized from both methods exhibit spinel structure. The morphologies of the samples prepared from two routes are spherical. However, the LiNi_0.5Mn_1.5O₄ sample synthesized directly from mixture of Ni_0.25Mn_0.75CO₃ and Li₂CO₃ possesses larger primary particle size compared with the LiNi_0.5Mn_1.5O₄ synthesized from the (Ni_0.25Mn_0.75)₂O₃ and Li₂CO₃. Besides, the latter LiNi_0.5Mn_1.5O₄ shows more excellent electrochemical properties, delivers an initial discharge capacity 136.3 mA？h/g at the rate of 1C in the voltage range of 3.0-4.9 V. Particularly, its capacity is still 126.5 mA？h/g after 100 cycles. Furthermore, the sample performs excellent rate capability, even at 5C, the discharge capacity still keeps 120.7 mA？h/g.

Key words: lithium ion battery; LiNi_0.5Mn_1.5O₄; cathode material; electrochemical performance