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高电压正极材料LiNi0.5Mn1.5O4的制备及离子掺杂改性研究 化学工程与工艺 孙加勇 指导教师 李世友 副教授 摘要 分别采用高温固相法和自蔓延燃烧法合成了LiNi0.5Mn1.5O4，通过对样品的电化学性能研究，得出了自蔓延燃烧法合成的LiNi0.5Mn1.5O4性能优于高温固相法的结论。对LiNi0.5Mn1.5O4进行了Cr3+掺杂，得到了LiCr0.1Ni0.45Mn1.45O4。对LiNi0.5Mn1.5O4和LiCr0.1Ni0.45Mn1.45O4进行了对比研究：通过X射线衍射（XRD）表明Cr3+掺杂未改变LiNi0.5Mn1.5O4 的晶型结构，扫描电镜（SEM）结果表明样品呈现规则正八面体外形，颗粒均匀。电化学性能测试结果表明，在1 C充放电倍率下，两种电池的首次放电比容量分别为111.0 mAh/g和121.5 mAh/g；以容量保持率为首次放电比容量85%为截止条件，分别可以实现32个和51个稳定循环。在此条件下，LiCr0.1Ni0.45Mn1.45O4/Li电池的平均中值电压为4.55 V，略高于 LiNi0.5Mn1.5O4/Li电池的4.51 V。结果表明Cr3+掺杂，明显改善了LiNi0.5Mn1.5O4材料的综合性能。 关键词：高电压;正极材料;LiNi0.5Mn1.5O4;离子掺杂 Abstract LiNi0.5Mn1.5O4 was synthesized by two different methods, high temperature solid phase method and self–combustion reaction method. From electrochemical performance study, it is shown that self–combustion reaction was better than high temperature solid phase method. Cr3+ ion was doped into LiNi0.5Mn1.5O4 to synthesize LiCr0.1Ni0.45Mn1.45O4. Doping Cr3+did not change the crystalline structure of LiNi0.5Mn1.5O4 from X-Ray Diffraction (XRD) study. The two samples presented regular octahedron and uniformity granule from Scanning Electron Microscope (SEM). When LiNi0.5Mn1.5O4/Li battery and LiCr0.1Ni0.45Mn1.45O4/Li battery were assembled, the discharge capacities of the first number were 111.0 mAh/g and 121.5 mAh/g respectively, at 1 C rate. The two batteries could realize 32 and 51 stable cycles respectively, before their capacities decayed lower than 85% of the first discharge number. In these stable cycles, their average median voltages were 4.51 V and 4.55 V respectively. The results shown that, doping Cr3+ prominent improved the combination property of the LiNi0.5Mn1.5O4 sample. Key words: high voltage; cathode material; LiNi0.5Mn1.5O4; ion doped 一、前言 锂离子电池因具有电压平台高，比容量高，无记忆效应，环境污染小等显著优点而成为近年来的研究热点。而锂离子电池正极材料之一的LiNi0.5Mn1.5O4更是因为具有较高的放电中压而受到广泛关注，如LiFePO4的中值电压在3.2 V左右，LiCoO2及LiMn2O4的中值电压也不过3.6 V，而LiNi0.5Mn1.5O4的中值电压能达到4.5 V以上。但其电化学性能依然可以通过离子掺杂进行改善。理想的LiNi0.5Mn1.5O4中