富锂正极材料 Li1+x Ni0.36 Mn0.641-x O2的制备及电化学性能研究∗

摘要

采用氢氧化物共沉淀-高温固相焙烧法合成了富锂正极材料 Li1+x [Ni0.36 Mn0.64]1-x O2(x=0.12,0.15,0.18,0.2)。采用 XRD 表征其结构,SEM 表征其形貌,恒电流充放电和循环伏安测试其电化学性能。其中,XRD 结果表明各样品都具有α-NaFeO2型层状结构。结果表明：室温下以30 mA/g 的电流密度,在4.6~2.75 V 的电压范围内充放电,x=0.15的首次放电比容量为237.9 mAh/g,经50次循环后容量保持率为98%。研究发现,层状富锂镍锰正极材料中的 Li2 MnO3组分在充放电过程中会逐渐向尖晶石相转变,这是容量衰减的主要原因。%Lithium rich Li1 +x [Ni0.3 6 Mn0.64 ]1 -x O2 (x=0.12,0.1 5,0.18,0.2)cathode materials were synthe-sized via co-precipitation and high temperature sintering.The crystal structure,morphology,and electrochemical per-formance were characterized by XRD,SEM,galvanostatic charge-discharge cycling and cyclic voltammetry,respec-tively.The XRD results indicated that all samples were based on anα-NaFeO2 layered structure.The electrochemical performance utilizing this as-prepared optimum sample material as the cathode generated high specific discharge capaci-ty 237.9 mAh/g and capacity retention ratio 98% at 30 mA/g after 50 cycles at room temperature,in the voltage range of 4.6-2.75 V.The study emphasized that,Li2 MnO3 doping stabilizes layered lithium rich nickel and manga-nese oxide cathode material transforms into spinel phase during the cycling,which leads to poor cycling stability.