The Essence of Electrochemical Prelithiation for Silicon Anode: from Interface to Bulk Phase

Abstract

When Si anode is implemented in lithium ion cells, prelithiation is a prerequisite for improving Si anode’s electrochemical performances. In this situation, there is a great need to deeply comprehend the mechanisms relating to prelithiation. Herein, the essence of electrochemical prelithiation for Si anode is unveiled through combined studies of the full cells against NCM523 cathode. After 100 cycles against NCM523 cathode, the SEI formation makes up for 924.2 mAh g-1 of the capacity loss for the Si anode without prelithiation. After prelithiation, the lithium consumption aroused from SEI growth is significantly reduced by 61.4%. More importantly, prelithiation plays a significant role stabilizing the bulk phase of the Si anode, which is realized by the mitigated volume change with the prestored Li and the construction of a stable mosaic nanostructure by LiF and lithium silicate doping. For the full cell after 100 electrochemical cycles, 858.5 mAh g-1 of the trapped Li within Si particles without prelithiation is reduced down to 414.9 mAh g-1 after prelithiation. These results shed new light on the prominent roles of prelithiation on the interface and the bulk Si phase, which is of key importance for optimizing Si-based anodes.