锂离子正极材料LiCo1-xMgxMnO4与LiCo1-xAlxMnO4 (x = 0, 0.02, 0.05, 0.1)的制备及其电化学性能

采用固相法合成掺杂镁和铝尖晶石LiCoMnO₄材料，研究镁和铝掺杂量对尖晶石LiCoMnO₄电极的初始容量、放电平台以及循环性能的影响. 利用扫描电子显微镜、粉末X-射线衍射仪观察分析材料形貌及结构. 结果表明，所合成材料的粒径分布均匀，结晶性较佳. LiCoMnO₄电极初始容量为87.0 mAh.g^-1，少量镁或铝掺杂使电极初始容量有所增加，LiCo_0.98Mg_0.02MnO₄和LiCo_0.98Al_0.02MnO₄电极初始容量分别为91.3和93.6 mAh.g^-1，提高了其5 V放电平台的比例，过量掺杂则其容量降低. 此外，掺杂Al显著改善了LiCoMnO₄电极的循环性能，而掺杂镁对电极的循环性能其影响不明显.

Synthesis and Electrochemical Properties of LiCo1-xMgxMnO4 and LiCo1-xAlxMnO4 (x= 0, 0.02, 0.05, 0.1) as Positive Materials for Lithium-ion Batteries

The Al-doped and Mg-doped LiCoMnO₄ materials were synthesized through solid-state reaction. The effects of doping amounts of Mg and Al on the initial capacities, discharge plateaus, and cycle performances were investigated. The morphologies and structures of the as-prepared materials were studied by scanning electron microscopy and powder X-ray diffraction. The results indicate that the as-prepared samples were composed of uniform, well-crystallized particles. The pristine LiCoMnO₄ possessed an initial capacity of 87.0 mAh·g^-1, while LiCo_0.98Mg_0.02MnO₄ and LiCo_0.98Al_0.02MnO₄ delivered 91.3 and 93.6 mAh·g^-1, respectively. The proper doping amount increased the capacity and the ratio of discharge plateau at 5 V, while over-doping decreased the discharge capacity of LiCoMnO₄. In addition, Al doping significantly improved the cycle performance of LiCoMnO₄, while no apparent influence with Mg doping.