State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou 730000, P. R. China.
University of Chinese Academy of Sciences , Beijing 100080, P. R. China.
ACS Appl Mater Interfaces. 2017 Aug 16;9(32):26907-26914. doi: 10.1021/acsami.7b07843. Epub 2017 Aug 2.
The electrochemical properties of the metal-organic framework (MOF)-based composite as electrode material can be significantly improved by means of partial destruction of the full coordination of linkers to metal ions and replacing with other small ions, which make metal centers become more accostable and consequently more effective for the lithiation/delithiation process. In this paper, F was chosen to replace some of the benzenedicarboxylate (BDC) linkers because of its better interaction with the Li than the oxide ion. What's more, the formed M-F bond promotes the Li to transfer at the active material interface and protects the surface from HF attacking. The as-synthesized F-doped Mn-MOF electrode maintains a reversible capacity of 927 mA h g with capacity retention of 78.5% after 100 cycles at 100 mA g and also exhibits a high discharge capacity of 716 mA h g at 300 mA g and 620 mA h g at 500 mA g after 500 cycles. Even at 1000 mA g, the electrode still maintains a high reversible capacity of 494 mA h g after 500 cycles as well as a Coulombic efficiency of nearly 100%, which is drastically increased compared with pure Mn-MOF material as expected.
通过部分破坏配体与金属离子的完全配位并替换为其他小离子，可以显著改善基于金属有机骨架（MOF）的复合材料作为电极材料的电化学性能，这使得金属中心更容易与锂离子发生相互作用，从而更有效地进行锂化/脱锂过程。在本文中，选择 F 来取代部分苯二甲酸酯（BDC）配体，因为 F 与 Li 的相互作用比与氧化物离子的相互作用更好。此外，形成的 M-F 键促进了活性材料界面处 Li 的转移，并保护表面免受 HF 的攻击。合成的 F 掺杂 Mn-MOF 电极在 100 mA g 下循环 100 次后，具有 927 mA h g 的可逆容量和 78.5%的容量保持率，在 300 mA g 和 500 mA g 下循环 500 次后，还具有 716 mA h g 和 620 mA h g 的高放电容量。即使在 1000 mA g 下，电极在 500 次循环后仍保持 494 mA h g 的高可逆容量和近 100%的库仑效率，与纯 Mn-MOF 材料相比有了显著提高，这是预期的。
