MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, Key Laboratory of Environment and Energy Chemistry of Guangdong Higher Education Institutes, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China.
Analytical and Testing Center, South China University of Technology , Guangzhou 510640, P. R. China.
ACS Appl Mater Interfaces. 2017 Jan 11;9(1):354-361. doi: 10.1021/acsami.6b12150. Epub 2016 Dec 29.
Transition metal oxides caused much attention owing to the scientific interests and potential applications in energy storage systems. In this study, a free-standing three-dimensional (3D) chestnut-like TiO@α-FeO core-shell nanostructure (TFN) is rationally synthesized and utilized as a carbon-free electrode for lithium-ion batteries (LIBs). Two new interfaces between anatase TiO and α-FeO are observed and supposed to provide synergistic effect. The TiO microsphere framework significantly improves the mechanical stability, while the α-FeO provides large capacity. The abundant boundary structures offer the possibility for interfacial lithium storage and electron transport. The as-prepared TFN delivers a high capacity of 820 mAh g even after 1000 continuous cycles with a Coulombic efficiency of ca. 99% at a current of 500 mA g, which is better than the works reported previously. A thin gel-like SEI (solid electrolyte interphase) film and Fe phase yielded during charge/discharge cycling have been confirmed which makes it possible to alleviate the volumetric change and enhance the electronic conductivity. This confirmation is helpful for understanding the mechanism of lithium-ion storage in α-FeO-based materials. The as-prepared free-standing TFN with excellent stability and high capacity can be an appropriate candidate for carbon-free anode material in LIBs.
过渡金属氧化物由于其在储能系统中的科学兴趣和潜在应用而引起了广泛关注。在本研究中，我们合理合成了一种独立的三维（3D）板栗状 TiO@α-FeO 核壳纳米结构（TFN），并将其用作无碳锂离子电池（LIB）的电极。观察到了锐钛矿 TiO 和 α-FeO 之间的两个新界面，它们被认为可以提供协同效应。TiO 微球骨架显著提高了机械稳定性，而α-FeO 则提供了大容量。丰富的边界结构为界面锂存储和电子传输提供了可能性。所制备的 TFN 在 500 mA g 的电流下，经过 1000 次连续循环后，仍具有 820 mAh g 的高容量，且库仑效率约为 99%，优于之前的报道。在充放电循环过程中形成的薄凝胶状 SEI（固体电解质界面）膜和 Fe 相已得到证实，这使得缓解体积变化和提高电子电导率成为可能。这一证实有助于理解基于α-FeO 的材料中锂离子存储的机制。所制备的具有优异稳定性和高容量的独立 TFN 可以作为无碳 LIB 阳极材料的合适候选材料。
