Research On Properties And Controlled Synthesis Of LiNi_0.5Mn_1.5O₄Cathode Material For Lithium-ion Battery

Spinel cathode LiNi0.5Mn1.5O4offers the advantages of both a high capacity andoperating voltage. These attractive features have made this material a top choice for thenext generation of high-power batteries. The influence on shape and properties ofdifferent preparation method and condition are studied to controlled synthesisLiNi0.5Mn1.5O4and improve its electrochemical performance.The influence on ethanol-assisted hydrothermal synthesis of LiNi0.5Mn1.5O4ofdifferent preparation condition is studied. Particle size decrease with the increase ofNH4HCO3. The prepared LiNi0.5Mn1.5O4has better rate performance when moreNH4HCO3is added. The particle size synthesized with largest concentration of Li+issmallest. The LiNi0.5Mn1.5O4has better discharge capacity and stability when theconcentration of Li+is0.4mol L-1. With the increase of calcination temperature, particlesize and degree of crystallinity increase, leading to better cycling performance.The comparison of ethanol-assisted hydrothermal method, precipitation methodand hydrothermal method indicates that the ethanol-assisted hydrothermal processdecreases the size and aggregation degree of particles, improves the crystallinity andmixes the reagents homogeneously, leading to low impurity and Mn3+ions contents.The LiNi0.5Mn1.5O4material synthesized by ethanol-assisted hydrothermal methodexhibits excellent rate capability with discharge capacities of81.7mAh g-1at rate20C.WhaX’X m We, afXeW1000cycleX aX5C diXchaWge WaXe, iXX diXchaWge caUaciXy iX102.1mAh g-1with capacity retention ratio of88.1%..The influence on shape of MnCO3of different preparation condition is studied.With the increase of calcination temperature, particle size and degree of crystallinityincrease. With the increase of reaction time, particle size and degree of crystallinityincrease. With the increase of ethanol, particle size decrease and degree of crystallinityincrease.Spherical and hollow LiNi0.5Mn1.5O4are synthesized by precursors with differentshapes. The spherical LiNi0.5Mn1.5O4is synthesized by MnCO3sphere. Besides, MnCO3is calcined at350oC and the outer layer is transformed into MnO2and MnCO3innercore remine after calcination. The MnO2outer layer remain and MnCO3inner core isdissolved after acid pickling. The hollow LiNi0.5Mn1.5O4is synthesized by the remainingMnO2. The hollow LiNi0.5Mn1.5O4has low impurity and Mn3+ions contents, beneficialto high discharge capacity and cycling stability. And the rate capability of hollowLiNi0.5Mn1.5O4is better.