Analysis of anodic nanotubular oxide on homogeneous Ti-Si alloys for Li-ion battery anodes

• Published in: Journal of alloys and compounds Vol. 888; p. 161659
• Main Authors: Valente, Renato C., Falqueto, Juliana B., Bocchi, Nerilso, Maltez, Rogerio L., Dick, Luís F.P.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.12.2021; Elsevier BV
• Subjects: Anodes; Barrier layers; Current efficiency; Dissolution; Electric arc melting; Electrical surges; Li-ion batteries; Lithium; Lithium-ion batteries; Martensite; Nanoporous anodizing; Oxygen evolution reactions; Precipitates; Rechargeable batteries; Silicon base alloys; TiSi alloy; Titanium oxide; TiSi alloy; Nanoporous anodizing; Titanium oxide; Li-ion batteries
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.161659

•Porous anodizing of homogeneous TiSix alloys was studied in an HF-NH4F electrolyte.•Formulated E/∂t expression of barrier anodizing was applied to TiSix/HF+NH4F system.•Voltage slope ∂E/∂t points to higher oxide formation current efficiency at higher %Si.•The adhesion of porous oxides to substrate decreases with Si%.•Specific Li charge increases by 15% by 2 at% Si addition. The porous anodization of pure Ti and arc melted Ti2Si, and Ti4Si alloys were studied, aiming to produce novel anodes for lithium-ion batteries. The annealed and quenched Ti2Si alloys were homogeneous β-martensite, while Ti4Si close to the maximal Si solubility presented Ti3Si and Ti5Si3 precipitates. The alloys anodized in standard HF + NH4F electrolyte showed an increasing tendency to detach the oxide layer with the Si content increase. The slope of the cell voltage transient ∂E/∂t was used to evaluate each material's current efficiency. Si addition decreases the oxide's electronic conductivity and the oxygen evolution reaction but increases the oxide dissolution rate due to a higher Si dissolution rate. Consequently, higher current efficiency of oxide formation is observed during the barrier layer and a lower one during the porous layer formation. Nevertheless, the specific Li mass capacity increased by around 15% with 2 at% Si addition to Ti.