Elucidating the Role of Prelithiation in Si-based Anodes for Interface Stabilization

摘要

Prelithiation as a facile and effective method to compensate the lithiuminventory loss in the initial cycle has progressed considerably both on anodeand cathode sides. However, much less research has been devoted to theprelithiation effect on the interface stabilization for long-term cycling ofSi-based anodes. An in-depth quantitative analysis of the interface that formsduring the prelithiation of SiO_x is presented here and the results arecompared with prelithiaton of Si anodes. Local structure probe combined withdetailed electrochemical analysis reveals that a characteristic mosaic interfaceis formed on both prelithiated SiO_x and Si anodes. This mosaic interfacecontaining multiple lithium silicates phases, is fundamentally different fromthe solid electrolyte interface (SEI) formed without prelithiation. The idealconductivity and mechanical properties of lithium silicates enable improvedcycling stability of both prelithiated anodes. With a higher ratio of lithiumsilicates due to the oxygen participation, prelithiated SiO1.3 anode improvesthe initial coulombic efficiency to 94 in full cell and delivers good cyclingretention (77) after 200 cycles. The insights provided in this work can beused to further optimize high Si loading (>70 by weight) based anodes infuture high energy density batteries.