正极材料LiNi_(0.5)Mn_(1.5)O_4的制备及离子掺杂改性研究

Synthesis and electrochemical performance of cathode material LiNi_(0.5)Mn_(1.5)O_4 and its ion doped

采用溶胶-凝胶-自蔓延燃烧法合成了LiNi0.5Mn1.5O4和LiCr0.1Ni0.45Mn1.45O4两种高电压正极材料。通过X射线衍射(XRD)表明铬离子掺杂未改变LiNi0.5Mn1.5O4的晶型结构,但改善了其晶型生长。扫描电镜(SEM)表明两种样品呈规则正八面体外形,颗粒较均匀,LiNi0.5Mn1.5O4平均粒径大约为400 nm,LiCr0.1Ni0.45Mn1.45O4平均粒径大约为200 nm。电化学性能测试结果表明,在1 C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4.51 V。倍率性能测试结果表明,LiCr0.1Ni0.45Mn1.45O4/Li电池及LiNi0.5Mn1.5O4/Li电池在0.5 C、1 C下放电比容量分别可保持0.2 C时的91.9%、87.1%和91.1%、83.6%。铬离子掺杂可明显改善LiNi0.5Mn1.5O4的综合性能。

LiNi0.5Mn1.5O4 and LiCr0.1Ni0.45Mn1.45O4 were synthesized through self-combustion reaction. The XRD result shows that Cr3＋ doped does not change the structure of LiNi0.5Mn1.5O4, and improve its growth. The SEM result shows that two samples present regular octahedron and uniformity granule. The average particle size of LiNi0.5Mn1.5O4, is larger than that of LiNi0.5Mn1.5O4.The electrochemical performance test of LiNi0.5Mn1.5O4/U battery and LiCr0.1Ni0.45Mn1.45O4 battery show that the first discharge specific capacity is 111.0 rnAh/g and 121.5 mAh/g at 1 C rate respectively, with 85% capacity retention of the first discharge specific capacity, and two samples can realize 32 and 51 stable cycles respectively. Under these conditions, their average median voltages are 4.51 V and 4.55 V. The rate performance testing results show that LiNi0.5Mn1.5O4/Li battery and LiCr0.1Ni0.45Mn1.45O4 battery at 0.5 C and 1 C can retain 91.9%, 87.1% and 91.1%, 83.6% of at 1 C discharge capacity. In conclusion, chromium ion doping can greatly improve the comprehensive performance of LiNi0.5Mn1.5O4.