State Key Laboratory of Silicon Materials, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, P. R. China.
Adv Mater. 2017 Dec;29(48). doi: 10.1002/adma.201606499. Epub 2017 Feb 23.
Boosting power density is one of the primary challenges that current lithium ion batteries face. Alloying anodes that possess suitable potential windows stand at the forefront in pursuing ultrafast and highly reversible lithium storage to achieve high power/energy lithium ion batteries. Herein, ultrafast lithium storage in Sn-based nanocomposite anodes is demonstrated, which is boosted by pseudocapacitance benefitting from a high fraction of highly interconnected interfaces of Fe/Sn/Li O. By tailoring the voltage window in the range of 0.005-1.2 V for the alloying/dealloying reactions, such Sn-based nanocomposite anodes achieve simultaneous ultrahigh rate capability, superlong cycling performance, and close-to-100% Coulombic efficiency. The nanocomposite anode delivers a high reversible capacity (≈420 mAh g ) at 1 A g for more than 1200 cycles, corresponding to only 0.016% per cycle of capacity decay. A reversible capacity of 350 mAh g can be maintained at an ultrahigh current density of 80 A g , with 67.3% capacity retention relative to the capacity at 1 A g . This combination of pseudocapacitive lithium storage and spatially confined electrochemical reactions in Sn-based nanocomposite anode materials may pave the way for the development of high power/energy and long life lithium ion batteries.
提高能量密度是当前锂离子电池面临的主要挑战之一。在追求超快和高度可逆的锂存储以实现高功率/能量锂离子电池时，具有合适电位窗口的合金化负极处于前沿。本文展示了基于 Sn 的纳米复合材料负极的超快锂存储，得益于高比例的高度互连的 Fe/Sn/LiO 界面，赝电容得到了增强。通过将合金化/去合金化反应的电压窗口调整到 0.005-1.2 V 的范围内，这种基于 Sn 的纳米复合材料负极实现了超高倍率性能、超长循环性能和接近 100%的库仑效率。该纳米复合材料负极在 1 A g 的电流密度下具有高可逆容量（≈420 mAh g），超过 1200 次循环后，其容量衰减率仅为 0.016%/循环。在 80 A g 的超高电流密度下，可逆容量可保持在 350 mAh g，与 1 A g 时的容量相比，容量保持率为 67.3%。基于 Sn 的纳米复合材料负极中赝电容式锂存储和空间受限的电化学反应的这种组合可能为开发高功率/能量和长寿命锂离子电池铺平道路。
