Li Guocheng, Duan Xiangrui, Liu Xueting, Zhan Renming, Wang Xiancheng, Du Junmou, Chen Zihe, Li Yuanjian, Cai Zhao, Shen Yue, Sun Yongming
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China.
School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Adv Mater. 2023 Jan;35(2):e2207310. doi: 10.1002/adma.202207310. Epub 2022 Dec 4.
The creation of fluorinated interphase has emerged as an effective strategy for improving Li-metal anodes for rechargeable high-energy batteries. In contrast to the introduction of fluorine-containing species through widely adopted electrolyte engineering, a Li-metal composite design is reported in which LiF can locally redistribute on the Li-metal surface in liquid electrolytes via a dissolution-reprecipitation mechanism, and enable the formation of a high-fluorine-content solid electrolyte interphase (SEI). For validation, a Li/Li Sn /LiF ternary composite is investigated, where the as-formed LiF-rich SEI locks the active Li metal from corrosive electrolyte. The Li/Li Sn /LiF anode displays an impressive average Coulombic efficiency (ACE, ≈99.2%) at 1 mA cm and 1 mAh cm in a carbonate electrolyte and a remarkable cycling life of over 1600 h at 1 mA cm and 2 mAh cm . Applied to a LiCoO full cell with a high cathode areal capacity of 4.0 mAh cm , a high capacity retention of ≈91.1% is realized for 100 cycles at 0.5 C between 2.8 to 4.5 V with a low negative/positive (N/P) ratio of 2:1. This design is conceptually different from the design employing the widely used fluorine-containing electrolyte additive and provides an alternative approach to realize reliable Li-metal batteries.
构建氟化界面已成为一种改进用于可充电高能电池的锂金属负极的有效策略。与通过广泛采用的电解质工程引入含氟物种不同，本文报道了一种锂金属复合设计，其中LiF可通过溶解-再沉淀机制在液体电解质中的锂金属表面局部重新分布，并促使形成高氟含量的固体电解质界面（SEI）。为进行验证，研究了Li/LiSn/LiF三元复合材料，其中形成的富含LiF的SEI可保护活性锂金属免受腐蚀性电解质的侵蚀。Li/LiSn/LiF负极在碳酸盐电解质中，电流密度为1 mA cm²、面积容量为1 mAh cm²时，平均库仑效率（ACE，≈99.2%）令人印象深刻；在电流密度为1 mA cm²、面积容量为2 mAh cm²时，循环寿命超过1600 h。将其应用于正极面容量高达4.0 mAh cm²的LiCoO₂全电池时，在2.8至4.5 V之间以0.5 C的倍率进行100次循环，负/正（N/P）比低至2:1的情况下，可实现约91.1%的高容量保持率。这种设计在概念上与采用广泛使用的含氟电解质添加剂的设计不同，为实现可靠的锂金属电池提供了一种替代方法。
