Synthesis And Properties Of The New Lithium-ion Battery Cathode Material Of Lini <sub> 0.5 </ Sub> The Mn <sub> 1.5 </ Sub> O <sub> 4 </ Sub>

Cubic spinel LiNi_0.5Mn_1.5O₄ has drawn great attention due to its highvoltage and high energy density. In the research, composite oxide ofnickel and manganese was prepared by calcination of composite oxalatesynthesised by solid-state reaction at low temperature firstly,LiNi_0.5Mn_1.5O₄ was then synthesised by firing the mixture of theas-prepared composite oxide and Li₂CO₃.The solid-state reaction at low temperature to synthesize compositeoxalate completed in about 2-5 minutes. The product was dried at 120℃for 6h, and then the composite nickel and manganese oxide was preparedat 390℃for 3 hours in air. The composite oxide was composed of severalphases with the even distribution of elements and small primary particalsize of 100-200nm.One-step solid-state method was adopted to synthesizeLiNi_0.5Mn_1.5O₄. The calcination temperature showed obvious effect on itsphysical properties and electrochemical performances. The calcinationtime didn't affect the physical properties; however apparently affect theelectrochemical performances. LiNi_0.5Mn_1.5O₄ synthesised in air at 700℃for 12h delivered specific capacity of 130mAh.g^-1, it also showed goodperformances at high charge/discharge rate and temperature. Theintroduction of pure oxygen is beneficial to the preparation ofLiNi_0.5Mn_1.5O₄ at high temperature and the particle size became smaller.LiNi_0.5Mn_1.5O₄ synthesised under oxygen at 800℃for 12h showed goodcycle performance and delivered specific capacity of 143.9mAh.g^-1.LiNi_0.5Mn_0.5O₄ synthesised in air at 700℃for 12h was investigated bycyclic voltammetry. The results indicated that the LiNi_0.5Mn_1.5O₄electrode possessed excellent stability.LiNi_0.5Mn_1.5O₄ was also synthesised by two-step solid-state method.The calcination temperature, time and annealing time showed obviouseffects on its physical properties and electrochemical performances. Theintroduction of annealing is beneficial to the preparation ofLiNi_0.5Mn_1.5O₄ at high temperature. In air, campared with LiNi_0.5Mn_1.5O₄ synthesised by one-step solid-state method, LiNi_0.5Mn_1.5O₄ synthesised at800℃for 6h and then annealing at 600℃for 24h delivered more specificcapacity of 138mAh.g^-1, and showed better cycle performance at highcharge/discharge rate.