Influence of plasma atmosphere on the sputter deposition of Li–Mn–O cathodes

This study delves into the influence of plasma gas composition on the properties of Li–Mn–O cathode coatings deposited using radio-frequency sputtering. The research systematically explores the effects of varying Ar/O2 gas mixtures on the deposition process, revealing significant differences in microstructural, structural, chemical, and electrochemical performance. Key findings include the formation of amorphous LiMn2O4 coatings under pure oxygen plasma, partial crystallization under pure argon plasma, and well-crystallized coatings with superior electrochemical properties under mixed Ar/O2 plasma. The study highlights the importance of precise control over deposition parameters to tailor the desired chemistry and functionality of the sputtered coatings. Electrochemical characterization, including cyclic voltammetry, charge–discharge cycling, and impedance spectroscopy, consistently identifies the 50O50Ar coating as the most promising composition, exhibiting the highest specific capacity, efficient lithium diffusion, and robust cycling stability. The presence of secondary surface phases, such as lithium oxide and lithium carbonate, is also discussed, along with their potential impact on electrochemical behavior. Overall, this research provides valuable insights into the synthesis and optimization of lithium-ion battery cathode materials, contributing to the development of scalable, cost-effective, and environmentally sustainable battery manufacturing processes.