梯度材料LiNi0.8Co0.2O2的合成与表征

The gradient composite LiNi_0.8Co_0.2O₂ was synthesized using spherical Ni(OH)₂ particle coated by a sol-gel containing cobalt and lithium. The precursor was examined by DSC-TG. The gradient composite was characterized by SEM, EDS, XPS, XRD and ICP-AES. The XPS, EDS and ICP-AES results show that content of cobalt in the surface is higher than in the center of the spherical particle of the gradient composite. The first discharge specific capacity of the gradient composite sintered at 700 ℃ is 187.3 mAh·g^-1.     

Al、Co和Mn掺杂对LiNiO2结构的影响

本文采用XRD和EXAFS研究Al、Co和Mn原子掺杂对LiNiO₂材料结构的影响。XRD结果表明掺杂材料具有与LiNiO₂相同的晶体结构，都属于R3m点群，但是晶胞略微缩小，LiNiO₂的层状结构得到改善,阳离子有序度增强。从EXAFS数据拟合结果可以看出，引入掺杂原子Al、Co和Mn减弱了Jahn-Teller畸变，使得NiO₆八面对称性提高。掺杂Al和Co使得第一壳层Ni-O配位键长减小，掺杂Mn原子影响不明显。Al、Co和Mn掺杂使第二壳层Ni-Ni配位键长减小，Co和Mn掺杂使得第二壳层局域有序度提高，而Al的引入使得第二壳层局域有序度降低。