Lithium Pre-Storage Enables High Initial Coulombic Efficiency and Stable Lithium-Enriched Silicon/Graphite Anode.

Abstract

Application of silicon-based anode is significantly challenged by low initial Coulombic efficiency (ICE) and poor cyclability. Traditional pre-lithiation reagents often pose safety concerns due to their unstable chemical nature. Achieving a balance between water-stability and high ICE in prelithiated silicon is a critical issue. Here, we present a lithium-enriched silicon/graphite material with an ultra-high ICE of ≥110% through a high-stable lithium pre-storage methodology. Lithium pre-storage prepared a nano-drilled graphite material with surficial lithium functional groups, which can form chemical bonds with adjacent silicon during high-temperature sintering. This results in an unexpected O-Li-Si interaction, leading to in-situ pre-lithiation of silicon nanoparticles and providing high stability characteristics in air and water. Additionally, the lithium-enriched silicon/graphite materials impart a combination of high ICE, high specific capacity (620 mAh g-1), and long cycling stability (> 400 cycles). This study opens up a promising avenue for highly air and water-stable silicon anode prelithiation methods.