LaSrCoFeO₃ Thin Films Deposited by Sputtering for Battery Electrodes

The development of high-performance anode materials is essential to overcome the limitations associated with conventional graphite electrodes in lithium-ion batteries, and perovskite oxides emerge as promising alternatives due to their structural flexibility and defect chemistry. In this work, the potential of LaSrCoFeO₃ perovskite (LSCF) thin films as anode materials is investigated, with particular emphasis on the effect of the post-deposition annealing atmosphere. LSCF thin films were deposited by dc magnetron sputtering and then thermal-treated at 600 °C in air and vacuum. The structural, electrical and electrochemical characterizations show that vacuum annealing promotes a more efficient crystallization, leading to larger crystallites (~ 240 nm), and to reduced oxidation due to the formation of oxygen vacancies. This reduced state significantly reduces electrical conductivity to ~10-6 Ω·cm. When evaluated as a half-cell anode, the vacuum-annealed films exhibit a theoretical specific capacity of 121 mAh·g-1, high reversibility with anodic and cathodic charge ratio Qa/Qc ≈ 1 and a good cyclic stability, with a loss of discharge capacity of less than 10%. Raman spectroscopy confirmed that the film structure remains unchanged upon the electrochemical tests, evidencing their stability. These results show that the annealing atmosphere is a determining parameter to optimize the electrochemical performance of LSCF thin films, reinforcing their potential as anodes for future lithium-ion batteries.