铝掺杂对Li_(1.2)Ni_(0.2)Mn_(0.6)O_2结构和电化学性能的影响

Effects of Al doping on structure and electrochemical performance of Li_(1.2)Ni_(0.2)Mn_(0.6)O_2

采用共沉淀法合成了球型前驱体Ni_(0.25)Mn_(0.75)(OH)_2,与锂源混合煅烧得到锂离子电池正极材料Li_(1.2)Ni_(0.2)Mn_(0.6)O_2,并对其进行铝掺杂改性,得到样品Li_(1.2)(Ni_(0.2)Mn_(0.6))_(1-x)Al_(0.8x)O_2(x=0~0.03)。利用X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试对各个样品的结构、形貌和电化学性能进行了表征,结果表明:掺杂铝后,样品具有规则的球形形貌,层状结构保持完整,阳离子混排程度降低,铝掺杂量为2%的样品(x=0.02)阳离子混排程度最小,结构最稳定,具有较高的首次充放电效率和最优异的循环性能,其首次充放电效率为84.2%,1C倍率下循环50次的容量保持率为95.7%。

The sphere prescursor Ni_(0.25)Mn_(0.75)(OH)_2was obtained by chemical co-precipitation reaction.The lithium-ion battery cathode material Li_(1.2)Mn_(0.6)Ni_(0.2)O_2 was synthesized by mixing and calcining Ni_(0.25)Mn_(0.75)(OH)_2and lithium source,and then the Al was doped on Li_(1.2)Ni_(0.2)Mn_(0.6)O_2 to obtain the samples Li1.2(Ni0.2Mn0.6)_(1-x)Al_(0.8x)O_2(x=0~0.03).Their structure,morphology,and electrochemical properties were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and electrochemical performance tests.Results showed that the Al-doped samples had regular spherical morphology,a perfect layered structure,and a lower cation mixing degree.The sample with 2% Al doping(x =2) had the lowest cation mixing degree,the most stable structure,higher charge-discharge efficiency for the first time,and the most excellent circulation performance,the initial charge and discharge efficiency was 84.2% at 1C rates,and the capacity retention rate was 95.7% after cycled50 times at 1C rates.