Dry Coating with Hydrophilic and Hydrophobized Nanostructured Fumed Alumina (Al₂O₃) on SiO_<i>x</i>/C Anodes for Enhanced Lithium‐Ion Battery Performance

Silicon-based anode materials hold great promise for advancing lithium-ion battery technology due to their high specific capacity, low voltage platform, abundant resources, and environmental benefits. However, their inherent challenges, such as poor electrical conductivity, significant volume expansion, and instability of the solid-electrolyte interphase layer, hinder their widespread commercialization. This study addresses these issues using the dry particle coating method with nanostructured fumed aluminum oxide (Al₂O₃), a novel approach with significant potential for commercial scalability. The impact of surface wettability on performance is studied by applying metal oxide coatings, using hydrophilic and hydrophobized surfaces. Electrochemical evaluation shows a significant increase in rate performance and cycle life when the surface coating is applied, with improvements in discharge capacity of around 10% and 17% for hydrophobized and hydrophilic Al₂O₃ coatings, respectively, after 100 cycles. The Al₂O₃ coating protects the surface of the active material, preventing particle pulverization, reducing side reactions, and decreasing electrolyte decomposition and hydrofluoric acid content. While overall performance improves with coating, the best results are achieved with the hydrophilic coating, which fosters a more homogeneous microstructured electrode. These findings underscore the potential of the dry particle coating technique with Al₂O₃ to enhance Si-based anode performance and facilitate commercial application.