Reduction pretreatment to the precursor of LiNi0.5Mn1.5O4 was carried out by adding hydrazine to a solution of NaOH during precursor synthesis.The effect of reduction agent on the performance of LiNi0.5Mn1.5O4 was obtained by comparing the structure and electrochemical properties of the reduction pretreated sample with those of pristine samples (LiNi0.5Mn1.5O4 without hydrazine pretreatment).Results of electrochemical experiments showed that the LiNi0.5Mn1.5O4 from the precursor pretreated with hydrazine had a much higher special capacity than the pristine sample at 2C charge/discharge rate.Moreover,the former showed a better capacity keeping activity than the later (pristine sample).Results from powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that the LiNi0.5Mn1.5O4 from the hydrazine pretreated precursor showed a much pure spinel phase (no impurity phase detected),high degree of crystallinity and well-distributed diameter of grains,while the pristine sample contains a minor impurity phase and showed a low degree of crystallinity.In this paper,the reduction pretreatment to the precursor of LiNi0.5Mn1.5O4 was proved to be beneficial to electrochemical performances of LiNi0.5Mn1.5O4,which should be helpful in the following studies on the mass production of LiNi0.5Mn1.5O4.%在用二次干燥共沉淀法制备锂离子电池正极材料LiNi0.5Mn1.5O4的前驱体时,加入还原剂水合肼,对前驱体进行还原处理,进而对比还原处理与不加还原剂的样品在结构和电化学方面的区别.实验结果发现,还原处理的前驱体所制备的LiNi0.5Mn1.5O4的充放电比容量远高于不加还原剂的样品,而且还原处理的前驱体所制备的正极材料在高温条件下(55℃)电化学性能保持较好,50次充放电循环后容量保持率更高.X粉末衍射(XRD)和扫描电镜测试结果表明,用还原剂水合肼处理的前驱体所合成的样品具有较好的结晶度,晶粒呈规则的八面体形貌,杂质含量很少；而未处理的前驱体所合成的样品则含有少量的杂质,结晶度较差.研究结果表明,添加还原剂水合肼对所制备的LiNi0.5Mn1.5O4正极材料的结构和性能有较好的促进作用,对进一步的改性研究具有重要的指导意义.
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