Zhao Shixi

Synthesis and performance of LiMnO2 as cathodes for Li-ion batteries

Two structure types of LiMnO2 were synthesized by sol-gel method and ion-exchange method respectively. The results indicate that orthorhombic phase LiMnO2 is more stable than layered LiMnO2, o-LiMnO2 can be synthesized directly by sol-gel methods followed by heat-treated in argon, but layered LiMnO2 was obtained only by indirect methods such as ion-exchange method. In this paper, we first synthesized layered NaMnO2 by the sol-gel method, and then obtained layered LiMnO2 by the ion-exchange method. The phase, constitution, chemical composition, and images of the products were tested by XRD, AAS (atomic absorption spectroscopy) and SEM. The electrochemical performances of the two structural types of LiMnO2 are obviously different during the initial few cycles, but later they both have a good capacity-retaining ability. The capacity of layered structure LiMnO2 is higher than that of o-LiMnO2.

纳米Al 2 O 3 包覆LiFePO 4 /C正极材料的结构和电化学性能

主要研究了纳米氧化铝包覆对磷酸铁锂/C复合正极材料结构和电化学特性的影响。采用溶胶-凝胶方法把纳米氧化铝包覆在商业LiFePO 4 /C颗粒表面。研究了Al 2 O 3 包覆层的量对LiFePO 4 电极在室温和高温充放电性能的影响。结果显示：2wt% Al 2 O 3 包覆层能有效增加电池的循环容量, 能延缓电池在高温条件下充放电的容量衰减, 减小电极的界面阻抗。这归因于氧化铝包覆层对磷酸铁锂晶粒的表面起保护作用, 减少电解液对磷酸铁锂晶粒表面的腐蚀, 从而改善循环过程中磷酸铁锂的表面结构的完整和稳定, 确保锂离子扩散通道的畅通。主要研究了纳米氧化铝包覆对磷酸铁锂/C复合正极材料结构和电化学特性的影响。采用溶胶-凝胶方法把纳米氧化铝包覆在商业LiFePO 4 /C颗粒表面。研究了Al 2 O 3 包覆层的量对LiFePO 4 电极在室温和高温充放电性能的影响。结果显示：2wt% Al 2 O 3 包覆层能有效增加电池的循环容量, 能延缓电池在高温条件下充放电的容量衰减, 减小电极的界面阻抗。这归因于氧化铝包覆层对磷酸铁锂晶粒的表面起保护作用, 减少电解液对磷酸铁锂晶粒表面的腐蚀, 从而改善循环过程中磷酸铁锂的表面结构的完整和稳定, 确保锂离子扩散通道的畅通。