Atomic layer deposited aluminum oxynitride coating for high-performance Si anode in lithium-ion batteries

Silicon (Si) has received great attention as a promising anode material for lithium-ion batteries (LIBs) due to its high gravimetric capacity and large abundance. However, the use of Si anodes in LIBs has been hindered by their inferior electrochemical performance, resulting from its vast volume expansion and unstable solid electrolyte interphase (SEI). To address these problems, a novel surface coating material, aluminum oxynitride (AlOxNy), was developed using a plasma-enhanced atomic layer deposition technique with trimethylaluminum and plasma N2/H2 as the precursors. The effects of AlOxNy surface coatings on the electrochemical properties of Si electrodes were investigated. With the optimal AlOxNy coating (∼2 nm), the reversible capacity after 140 cycles was improved from 331 mAh g−1 for bare Si electrode to 1297 mAh g−1 for AlOxNy-coated one, and the capacity retention was elevated from 13% to 72%. Post-cycling analysis revealed that the AlOxNy coating significantly suppressed the charge transfer and SEI resistances and maintained the structural integration of Si electrodes by suppressing continuous electrolyte decomposition and electrode delamination from the current collector. This study provides a new perspective on designing advanced functional coating materials for atomic layer deposition for lithium-ion batteries.