LiCo x Mn2-x O4 cathode materials for lithium ion batteries were synthesized by mechanical activation-solid state reaction at 750°C for 24 h in air atmosphere, and their crystal structure, morphology, element composition and electrochemical performance were characterized with XRD, SEM, ICP-AES and charge-discharge test. The experimental results show that all samples have a single spinel structure, well formed crystal shape and uniformly particle size distribution. The lattice parameters of LiCo x Mn2-x O4 decrease and the average oxidation states of manganese ions increase with an increase in Co content. Compared with pure LiMn2O4, the LiCo x Mn 2-x O4 (x=0.03-0.12) samples show a lower special capacity, but their cycling life are improved. The capacity loss of LiCo 0.09Mn1.91O4 and LiCo0.12Mn 1.88O4 is only 1.85% and 0.95%, respectively, after the 20th cycle. The improvement of the cycle performance is attributed to the substitution of Co at the Mn sites in the spinel structure, which suppresses the Jahn-Teller distortion and improves the structural stability.
|ジャーナル||Journal Wuhan University of Technology, Materials Science Edition|
|出版ステータス||出版済み - 6月 2007|
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