纳米Al_2O_3包覆LiFePO_4/C正极材料的结构和电化学性能(英文)

Structure and Electrochemical Performance of LiFePO_4/C Cathode Materials Coated with Nano Al_2O_3for Lithium-ion Battery

主要研究了纳米氧化铝包覆对LiFePO4/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LiFePO4/C颗粒表面。研究了Al2O3包覆层的量对LiFePO4电极在室温和高温充放电性能的影响。结果显示:2wt%Al2O3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。

The structure and electrochemical performance of Al2O3-coated LiFePO4 cathode materials were investigated. A nano Al2O3 coating on the surface of commercial LiFePO4/C particles （Aleees Inc.） was prepared by using the Sol-Gel method. The effect of the amount of Al2O3 coating on the electrochemical performance and structural stability of LiFePO4 electrodes at room temperature （25℃） and elevated temperatures （55℃） was studied. The results show that 2wt% Al2O3 coating can effectively enhance the cycling capacity, alleviate capacity fading at high temperature and reduce cell impedance. It is largely attributed to Al2O3 coating, which plays a regulatory role of lithium-ion inserting the lattice and preventing direct contact between the cathode material and the electrolyte, and improves the structural stability of LiFePO4 during cycles.