MANGANESE OXIDE CATHODES FOR TRANSPORTATION APPLICATIONS

摘要

The doubly substituted spinel lithium manganese oxides such as LiMn_(2-y-z)Ni_yLi_zO_4 show excellent performance characteristics that are appealing for electric and hybrid electric vehicle applications. They exhibit excellent cyclability at elevated temperatures, high rate capability, good storage performance, low irreversible capacity (IRC) loss, and low electrical resistance. The superior performance compared to the conventional LiMn2O4 spinel oxide is attributed to a smaller lattice parameter difference Aa between the two cubic phases formed around (1-x) ≈ 0.3 - 0.5 in Li_(1-x)Mn_(2-y)Ni_yLi_zO_4 during the charge-discharge process and the consequent low microstrain or lattice strain. Additionally, the electrochemical properties are found to bear a clear relationship to the initial Mn valence and the initial lattice parameter. The excellent electrochemical performance coupled with the inexpensive and environmentally benign nature of Mn and good structural and chemical stabilities may make optimized spinel oxide compositions viable candidates for lithium ion cells suitable for transportation applications.