Characterization and performance of LiFePO₄ thin-film cathodes prepared with radio-frequency magnetron-sputter deposition

LiFeP O4 films with a thickness of 1 μm were deposited on a stainless steel substrate by radio-frequency magnetron sputtering of a LiFeP O4 /carbon composite target. Raman spectra revealed the presence of carbon in the film, which increased the electronic conductivity of the film relative to reports of the carbon-free material. X-ray diffraction revealed that the films were well crystallized, free of second phases, and may have a texture with a (011) orientation. The LiFeP O4 plus carbon film showed a good capacity and rate capability at 25° and -20°C when cycled as the cathode of a lithium battery, although the film was still inferior to the carbon-coated LiFeP O4 powder electrodes with 0.5 μm particle size.