Preparation And Electrochemical Properties Of Iron/Cobalt Oxides

Lithium ion batteries have become the first choice as power sources for portable electronic devices and electric/hybrid vehicles, due to their high electromotive force and high energy density. In this paper, some transition-metal oxides as the anode materials with different morphology were prepared. XRD、SEM、BET et al were used to characterize the phase composition and microstructure. Meanwhile, the charge-discharge cyclic stability, the cyclic voltammetry（CV） and the electrochemical impedance（EIS） were examined. The main conclusions were as following:1. Octahedral, spherical and nanowire shape Fe₃O₄ and nanosheet, nanosphere, nanowire Co₃O₄ were synthesized by different methods. The initial capacity of Fe₃O₄ nanowire was 1184.5 mAh/g. The capacity remained 526.4 mAh/g after 25 charging-discharge cycles and the retention rate of capacity was 48.54%. As of Co₃O₄ nanowire, the initial capacity reached 1380.6 mAh/g. The capacity remained 720 mAh/g after 20 cycles, and the retention rate of capacity was 52.2%.2. Fe_xCo_3-xO₄ was prepared by different molar ratio of Fe and Co. XRD result showed it was composed of various oxidation products. When the molar ratio of Fe and Co was 2:1, it showed the best electrochemical performance. Herein, the discharge capacity maintained 815.8 mAh/g（I=100 mAh/g） after 30 cycles and the capacity retention rate was 63.3%.3. Needlelike and flaky-shape ferric oxyhydroxide（FeOOH） was prepared. They gave the different discharge capacity, initial coulombic efficiencies and rate capabilities due to the different morphology. The initial discharge capacity of the needlelike Fe OOH material was 1340 mAh/g at a current density of 100 mAh/g.