新型富锂锂离子电池正极材料的合成与研究
发布时间：2018-09-03 09:19
【摘要】：近阶段，新型富锂材料xLi2MnO3·(1-x)LiMO2（其中M代表金属离子Ni，Co，Mn等中的一种或多种）在增加Li含量的同时，减少了过渡金属离子的比例，过量的Li使得高电压下的容量大幅度提升，引起了研究者们极大的关注，有望成为新一代商业化锂离子电池正极材料。本论文选取富锂体系中综合性能较好的Li[Li0.2Ni0.15Mn0.55Co0.1]O2正极材料作为基材，对其进行阴阳离子单一掺杂和复合掺杂来优化材料性能，通过TG，XRD，SEM，CV，，EDS及充放电性能测试对合成材料进行各项表征。 采用正交法试验，以温度和时间作为正交因素，用溶胶-凝胶法合成正极材料Li[Li0.2Ni0.15Mn0.55Co0.1]O2，通过对材料样品形貌，晶型结构以及电化学性能的表征，得到900℃下煅烧12h的材料综合性能最优。分别采用Cr3+，Al3+，Mg2+对材料进行Co3+取代，发现掺杂并没有改变材料的层状结构和外观形貌，但材料的颗粒大小却发生改变：掺杂Cr3+，Al3+的材料，颗粒缩小，掺杂Mg2+材料一次颗粒增大。充放电性能测试表明，掺杂阳离子Cr3+，Al3+的材料虽然放电比容量在一定程度上有所降低，但循环性能得到改善。当Cr3+和Al3+掺杂量分别在0.05和0.03时，20℃下，2.0~4.8V电压范围，首次放电容量分别为230.6和224.2mAh·g-1，首次库伦效率为80.1和83.2%；55℃时，首次放电容量为293.1和274.8mAh·g-1，首次库伦效率为90.1和90.4%，0.1C下30次循环之后的容量保持率分别为97.9和94.7%。Mg2+掺杂的材料，材料一次颗粒团聚严重，材料的放电比容量降低较多，循环性能也不及未掺杂的材料。 阴离子F-和Cl-掺杂Li[Li0.2Ni0.15Mn0.55Co0.1]O2之后，材料层状结构更明显。当F-和Cl-掺杂量为0.05时，20℃，2.0~4.8V电压，首次放电容量由未掺杂的235.4mAh·g-1增大到249.8和238.9mAh·g-1，不同电流下50个循环后容量保持率为87.8和88.9%；55℃时，首次放电容量由未掺杂的282.7mAh·g-1增大到318.0和302.9mAh·g-1，50次循环后容量保持率为88.3和90.0%。 再对材料Li[Li0.2Ni0.15Mn0.55Co0.1]O2进行Al3+，Cl-和Cr3+，Cl-共掺杂，发现Li[Li0.2Ni0.15Mn0.55Co0.07Al0.03]O1.95Cl0.05和Li[Li0.2Ni0.15Mn0.55Co0.05Cr0.05]O1.95Cl0.05表现出较好的性能。常温20℃，2.0~4.8V电压范围内，首次放电比容量分别为242.6和239.8mAh·g-1；高温55℃，首次放电比容量分别是303.5和308.3mAh·g-1。1C下，50个循环后在常温和高温下仍有184.6和207.7mAh·g-1的放电容量。循环伏安表明，掺杂之后的材料氧化还原峰增强，电位差减小，表明掺杂减小了电极极化，增强了材料的结构稳定性，综合比较，发现Cr3+，Cl-共掺具有更优的电化学性能。
[Abstract]:In the near future, xLi2MnO3 _ (1-x) LiMO2 (where M represents one or more of metal ions Ni,Co,Mn etc.) increases the content of Li and decreases the ratio of transition metal ions. Excessive Li greatly increases the capacity at high voltage. Researchers have attracted great attention and are expected to become a new generation of commercial lithium ion battery cathode materials. In this paper, Li [Li0.2Ni0.15Mn0.55Co0.1] O _ 2 cathode material with good comprehensive properties in Li-rich system is selected as the substrate, which is characterized by TG,XRD,SEM,CV,EDS and charge-discharge performance tests by single doping and composite doping of anion and anion. The cathode material Li [Li0.2Ni0.15Mn0.55Co0.1] O _ 2 was synthesized by sol-gel method with temperature and time as orthogonal factors. The morphology, crystal structure and electrochemical properties of the material were characterized. The optimum comprehensive properties of the materials calcined at 900 鈩
本文编号：2219552
[Abstract]:In the near future, xLi2MnO3 _ (1-x) LiMO2 (where M represents one or more of metal ions Ni,Co,Mn etc.) increases the content of Li and decreases the ratio of transition metal ions. Excessive Li greatly increases the capacity at high voltage. Researchers have attracted great attention and are expected to become a new generation of commercial lithium ion battery cathode materials. In this paper, Li [Li0.2Ni0.15Mn0.55Co0.1] O _ 2 cathode material with good comprehensive properties in Li-rich system is selected as the substrate, which is characterized by TG,XRD,SEM,CV,EDS and charge-discharge performance tests by single doping and composite doping of anion and anion. The cathode material Li [Li0.2Ni0.15Mn0.55Co0.1] O _ 2 was synthesized by sol-gel method with temperature and time as orthogonal factors. The morphology, crystal structure and electrochemical properties of the material were characterized. The optimum comprehensive properties of the materials calcined at 900 鈩
本文编号：2219552
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