Effect of deposition conditions on the electrochemical characteristics of SnO₂ thin films as anodes for lithium-ion batteries

Abstract

SnO₂ thin-film anodes were fabricated by RF magnetron sputtering of a metallic Sn target onto Ti–Pt-coated stainless-steel substrates. The films were deposited at room temperature (RT) and 300 °C in an Ar/O₂ atmosphere and subsequently annealed in air at 620 °C. The structural evolution, morphology, and electrochemical performance of the films were systematically investigated. X-ray diffraction (XRD) analysis confirmed the formation of phase-pure tetragonal rutile SnO₂ without detectable secondary phases. SEM observations revealed significant changes in grain size and surface uniformity depending on deposition temperature and thermal treatment. Electrochemical testing in CR2032 coin cells demonstrated a typical multistep lithiation mechanism of SnO₂ involving conversion and alloying reactions. Although annealing improved crystallinity and reduced polarization, the films deposited at RT exhibited superior long-term cycling stability compared to those deposited at elevated temperature. The results highlight the crucial role of deposition temperature and sublayer configuration in controlling structural integrity and electrochemical durability of SnO₂ thin-film anodes for lithium-ion batteries.