"A General Prelithiation Approach for Group IV Elements and Corresponding Oxides"

Jie Zhao: Jie Suna, Allen Pei, Guangmin Zhou, Kai Yan, Yayuan Liu, Dingchang Lin, Yi Cui; Energy Storage Materials, 07/05/17.

Additional Authors: Jie Suna, Allen Pei, Guangmin Zhou, Kai Yan, Yayuan Liu, Dingchang Lin, Yi Cui

Abstract:

Prelithiation of anode materials is an important strategy to compensate for lithium loss as a result of the formation of a solid electrolyte interphase (SEI) at the surface of anodes in lithium-ion batteries. Conventional prelithiation reagents often present serious safety concerns due to the high flammability and unstable chemical nature. Here, we successfully developed a general one-pot metallurgical process to prelithiate group IV elements and their corresponding oxides, yielding prelithiation capacity approaching the theoretical specific capacity. Assynthesized Li22Z5 alloys and Li22Z5-Li2O composites (Z = Si, Ge, Sn etc) can serve as prelithiation reagents to increase the first cycle Coulombic efficiency of both graphite and alloy-type anode materials. Among all lithiated group IV alloys, LixGe exhibits the best stability under ambient-air conditions, consistent with the simulation results showing the large binding energy between Li and Ge atoms in Li22Ge5 crystal. Metallurgical lithiation of ZO2 results in composites with homogeneously dispersed reactive LixZ nanodomains embedded in a robust Li2O matrix which effectively suppresses the oxidation process. Li22Z5-Li2O composites further improve the ambientair stability because the strong binding between O atoms in Li2O and Li atoms in Li22Z5 stabilizes the reactive Li22Z5 nanodomains. These results allow us to identify the prelithiation reagents with the optimal stability in air, thereby simplifying the requirement on the industrial electrode fabrication environment.