Synergistic Prelithiation and In Situ Nitrogen Doping via Li3N in SiO Anodes: A Dual-Benefit Pathway to Achieving Enhanced Li+ Kinetics and High Initial Coulombic Efficiency

Silicon monoxide (SiO) has garnered significant attention as a promising anode material for high-energy-density lithium-ion batteries due to its lower volume expansion relative to pure silicon (Si) and its higher capacity compared to graphite. Nevertheless, the poor intrinsic electronic/ionic conductivity and the low initial Coulombic efficiency (ICE) of SiO result in inferior rate capability and inadequate practical energy density, hindering its commercial viability. Here, a simultaneous prelithiation and in situ nitrogen (N) doping approach for SiO utilizing lithium nitride (Li₃N), which significantly enhances both the ICE and lithium-ion (Li⁺) diffusion kinetics, is proposed. N atoms are not only incorporated into the carbon layer on the surface of SiO but also form a uniformly distributed amorphous Li₂SiN₂ phase within the SiO, facilitating Li⁺ transport. Molecular dynamics simulations demonstrate that the Li⁺ diffusion coefficient of amorphous Li₂SiN₂ is significantly higher than that of other crystalline phases present in the prelithiated SiO matrix. The 1.5 Ah pouch cells further validate that the SiON-0.175/graphite||NCM811 exhibits a high ICE of 88.06%, and it retains 51.5% of its capacity even under 4C fast charging conditions. This study offers new insights into the development of next-generation SiO anode materials with high ICE and high-rate performance.