Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Advanced Materials and Technology , University of Science and Technology Beijing , Beijing 100083 , China.
International Center for Quantum Materials, and Electron Microscopy Laboratory, School of Physics , Peking University , Beijing 100871 , China.
Inorg Chem. 2019 Oct 7;58(19):12724-12732. doi: 10.1021/acs.inorgchem.9b01626. Epub 2019 Sep 11.
Designing electrode materials with engineered exposed facets provides a novel strategy to improve their electrochemical properties. However, the controllability of the exposed facet remains a daunting challenge, and a deep understanding of the correlation between exposed facet and Li-transfer behavior has been rarely reported. In this work, single-crystal α-FeO hexagonal nanosheets with an exposed (001) facet are prepared with the assistance of aluminum ions through a one-step hydrothermal process, and structural characterizations reveal an Al-concentration-dependent-growth mechanism for the α-FeO nanosheets. Furthermore, such α-FeO nanosheets, when used as lithium-ion battery anodes, exhibit high specific capacity (1261.3 mAh g at 200 mA g), high rate capability (with a reversible capacity of approximately 605 mAh g at 10 A g), and excellent cyclic stability (with a capacity of over 900 mAh g during 500 cycles). The superior electrochemical performance of α-FeO nanosheets is attributed to the pseudocapacitive behavior, Al-doping in the α-FeO structure, and improved Li-transfer property across the (001) facet, as elucidated by first-principles calculations based on density functional theory. These results reveal the underlying mechanism of Li transfer across different facets and thus provide insights into the understanding of the excellent electrochemical performance.
设计具有工程暴露晶面的电极材料为改善其电化学性能提供了一种新策略。然而，暴露晶面的可控性仍然是一个艰巨的挑战，并且很少有关于暴露晶面和 Li 转移行为之间相关性的深入了解。在这项工作中，通过一步水热法，在铝离子的协助下制备出具有暴露（001）晶面的单晶α-FeO 六方纳米片，结构表征揭示了α-FeO 纳米片的 Al 浓度依赖性生长机制。此外，将这种α-FeO 纳米片用作锂离子电池阳极时，表现出高比容量（在 200 mA g 时为 1261.3 mAh g）、高倍率性能（在 10 A g 时可逆容量约为 605 mAh g）和优异的循环稳定性（在 500 次循环中容量超过 900 mAh g）。α-FeO 纳米片的优异电化学性能归因于赝电容行为、α-FeO 结构中的 Al 掺杂以及通过基于密度泛函理论的第一性原理计算阐明的（001）晶面之间改进的 Li 转移性质。这些结果揭示了不同晶面之间 Li 转移的潜在机制，从而深入了解了优异的电化学性能。
