MEET Battery Research Center, Corrensstr. 46, 48149 Münster, Germany. melanie.schroeder@uni-muenster,de.
Phys Chem Chem Phys. 2013 Dec 21;15(47):20473-9. doi: 10.1039/c3cp53606h. Epub 2013 Oct 30.
Lithium iron fluoride materials have attracted recent interest as cathode materials for lithium ion batteries. The electrochemical properties of the high energy density Li(x)FeF6 (x = 2, 3, 4) materials have been evaluated using a combination of potential-based and DFT computational methods. Voltages of 6.1 V and 3.0 V are found for lithium intercalation from Li2FeF6 to α-Li3FeF6 and α-Li3FeF6 to Li4FeF6 respectively. The calculated density of states indicate that Li2FeF6 possesses metallic states that become strongly insulating after lithium intercalation to form α-Li3FeF6. The large energy gain associated with this metal-insulator transition is likely to contribute to the associated large voltage of 6.1 V. Molecular dynamics simulations of lithium diffusion in α-Li3FeF6 at typical battery operating temperatures indicate high lithium-ion mobility with low activation barriers. These results suggest the potential for good rate performance of lithium iron fluoride cathode materials.
氟化亚铁锂材料作为锂离子电池的正极材料，近来引起了人们的关注。本文采用基于电位和密度泛函理论（DFT）计算相结合的方法，研究了高能量密度 Li(x)FeF6（x=2、3、4）材料的电化学性能。从 Li2FeF6 到 α-Li3FeF6 和从 α-Li3FeF6 到 Li4FeF6 的锂嵌入电压分别为 6.1V 和 3.0V。计算的态密度表明，Li2FeF6 具有金属态，在锂嵌入形成 α-Li3FeF6 后变为强绝缘态。这种金属-绝缘转变的巨大能量增益可能导致了 6.1V 的大电压。在典型电池工作温度下，α-Li3FeF6 中锂离子扩散的分子动力学模拟表明锂离子具有高迁移率和低活化能垒。这些结果表明氟化亚铁锂正极材料具有良好的倍率性能的潜力。
