二维纳米片组成的花状铁醇盐及其微纳结构三氧化二铁衍生物的储锂性能

Fe₂O₃作为锂电池负极材料具有诸多优点,但其较低的本征电导率和充放电循环过程中材料粉化使得其电化学储锂性能有待改善。 本文以具有花状微纳结构的铁醇盐为反应中间体,在空气气氛下烧结制备出具有花状微纳结构的铁基负极材料Fe₂O₃。 纳米花状的铁醇盐可以在低烧结温度下转化为目标产物,从而使得产物能够保持中间体的形貌。 300 ℃热处理条件下,所得样品在电流密度为200 mA/g时首次放电比容量为1360 mA·h/g,循环100次后的容量仍然达到515.6 mA·h/g;相比之下,450和800 ℃热处理所得样品100次循环后,比容量分别为247.6和206.7 mA·h/g。 微纳结构在增加材料的活性的同时,也能够抑制材料的粉化现象,因而所制得的材料表现出较大的比容量和良好的循环性能,为解决Fe₂O₃负极材料循环性能差的问题提供了思路。

Preparation and Performances of Nano-Micro Structural Ferric Oxide from Flower-Like Iron Alkoxides

Iron-based anode materials for lithium ion batteries has attracted wide attentions due to its high capacity, rich resource, environmentally friendly property, etc. However, its low-conductance(comparing to carbon-based anode materials) and high-volume change during charge/discharge cycles results in a poor rate performance and serious capacity fade after long-term cycles. In this paper, flower-like iron-based anode materials(Fe₂O₃) were synthesized by sintering the iron alkoxides precursor with the same nano-structure under the atmosphere of air. The as-obtained anode materials possess high reactivity from nanosheets of iron alkoxides, which can lower the sintering temperature and allow the product to keep the morphology of its precursor. The sample obtained by heating iron alkoxides precursor under 300 ℃ shows an initial specific discharge capacity of 1360 mA·h/g at a current density of 200 mA/g. Moreover, the specific capacity of the sample is 515.6 mA·h/g after 100 charge/discharge cycles at 200 mA/g, while the samples obtained after calcining the precursor under 450 and 800 ℃ present a capacity of 247.6 and 206.7 mA·h/g, respectively, after 100 charge/discharge cycles. The as-obtained Fe₂O₃ with micro/nano-structure not only improves high reactivity due to the high special surfaces, but also inhibits its pulverization during charge/discharge process. Therefore, the as-obtained materials with hollow micro/nano-structure show both high discharge capacity and good cycle performances, which affords us another method to solve the problem of the capacity fade of Fe₂O₃ as anode material for lithium ion battery.