Realizing Environmentally Scalable Pre-Lithiation via Protective Coating of LiSi Alloys to Promote High-Energy-Density Lithium-Ion Batteries

Pre-lithiation using Li–Si alloy-type additives is a promising technical approach to address the drawbacks of Si-based anodes, such as a low initial Coulombic efficiency (ICE) and inevitable capacity decay during cycling. However, its commercial application is limited by the air sensitivity of the highly reactive Li–Si alloys, which demands improved environmental stability. In this work, a protective membrane is constructed on Li13Si4 alloys using low-surface-energy paraffin and highly conductive carbon nanotubes through liquid-phase deposition, exhibiting enhanced hydrophobicity and improved Li+/e− conductivity. The Li13Si4@Paraffin/carbon nanotubes (Li13Si4@P-CNTs) composite achieves a high pre-lithiation capacity of 970 mAh g−1 and superb environmental stability, retaining 92.2% capacity after exposure to ambient air with 45% relative humidity. DFT calculations and in situ XRD measurements reveal that the paraffin-dominated coating membrane, featuring weak dipole–dipole interactions with water molecules, effectively reduces the moisture-induced oxidation kinetics of Li13Si4@P-CNTs in air. Electrochemical kinetic analysis and XPS depth profiling reveal the enhancement in charge transfer dynamics and surface Li+ transport kinetics (SEI rich in inorganic lithium salts) in P-SiO@C pre-lithiated by Li13Si4@P-CNTs pre-lithiation additives. Benefitting from pre-lithiation via Li13Si4@P-CNTs, the pre-lithiated SiO@C(P-SiO@C) delivers high ICE (103.7%), stable cycling performance (981 mAh g−1 at 200 cycles) and superior rate performance (474.5 mAh g−1 at 3C) in a half-cell system. The LFP||P-Gr pouch-type full cell exhibits a capacity retention of 83.2% (2500 cycles) and an energy density of 381 Wh kg−1 after 2500 cycles. The Li13Si4@P-CNTs additives provide valuable design concepts for the development of pre-lithiation materials.