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 ~10−5 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 experiments confirm that the film structure remains unchanged upon the electrochemical tests, evidencing the stability of the perovskite structure. 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.