Synthesis and characterization of LiMxMn2−xO4 (M = Al, Bi and Cs ions) films for lithium ion batteries

Films of doped LiMxMn2−xO4 (M = Cs, Al and Bi) were deposited on Indium Tin Oxide (ITO) substrate using the Pechini method. X-ray diffraction (XRD) and differential thermal analysis (DTA) were used for structural characterization of the oxides. Their morphology was studied by scanning electron microscope (SEM) and their electrochemical properties by cyclic voltammetry, charge/discharge tests and electrochemical impedance spectroscopy in a 1.0 mol L−1 LiClO4/EC:PC 1:1 (v/v) electrolyte. A single-phase spinel structure was characterized from X-ray patterns of the as-grown films. The best electrochemical performance was obtained with a LiCs0.02Mn1.98O4 cathode. After 15 cycles, its specific capacity was 127 mA h g−1. This value was maintained up to the 30th cycle. The diffusion coefficient value determined by electrochemical impedance spectroscopy was 6.4 × 10−8 cm2 s−1, indicating that electrochemical processes were highly favored on the LiCs0.02Mn1.98O4 films.