Department of Chemistry, Stony Brook University, Stony Brook, NY 11790, USA.
Phys Chem Chem Phys. 2013 Nov 14;15(42):18539-48. doi: 10.1039/c3cp52870g.
Magnetite (Fe3O4) is an abundant, low cost, environmentally benign material with potential application in batteries. Recently, low temperature coprecipitation methods have enabled preparation of a series of nanocrystalline magnetite samples with a range of crystallite sizes. Electrochemical cells based on Li/Fe3O4 show a linear increase in capacity with decreasing crystallite size at voltages ≥1.2 V where a 2× capacity improvement relative to commercial (26.2 nm) magnetite is observed. In this report, a combination of X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS) is used to measure magnetite structural changes occurring upon electrochemical reduction, with parent Fe3O4 crystallite size as a variable. Notably, XAS provides evidence of metallic iron formation at high levels of electrochemical reduction.
磁铁矿（Fe3O4）是一种丰富、低成本、环境友好的材料，具有在电池中应用的潜力。最近，低温共沉淀方法使得能够制备一系列具有不同晶粒尺寸的纳米晶磁铁矿样品。基于 Li/Fe3O4 的电化学电池在 1.2 V 以上的电压下显示出容量随晶粒尺寸减小而线性增加，与商业（26.2nm）磁铁矿相比，容量提高了 2 倍。在本报告中，结合 X 射线粉末衍射（XRD）和 X 射线吸收光谱（XAS）来测量电化学还原过程中发生的磁铁矿结构变化，以母体 Fe3O4 的晶粒尺寸作为变量。值得注意的是，XAS 提供了在高电化学还原水平下形成金属铁的证据。
