Structural and Electrochemical Properties of Li(LaAl)xMn2−xO4 Based Composite Cathodes

Spinel oxides lanthanum (La) and aluminium (Al) doped Li(LaAl) x Mn 2− x O 4 ( x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) compounds were prepared by a sol–gel method. Lanthanum and aluminium showed an influence on the structural, morphological and electrochemical properties. An x-ray diffraction study revealed that all the samples are in the cubic spinel phase. The grain size from the Debye–Scherrer and Williamson–Hall methods is comparable at lower doping concentration. Field emission scanning electron microscopy shows that the particle size of the samples increased with increasing dopant concentration, and the particle sizes were found to be between 50 nm and 200 nm. Cyclic voltammetry studies show two sets of well separated redox peaks due to the formation of Li + extraction/insertion into the spinel framework at a scan rate of 0.5 mV/s in the potential range of 0.2–1.2 V. Electrochemical impedance spectroscopy studies show that (LaAl) 0.01 doping improved charge transfer resistance. Li(LaAl) 0.01 Mn 1.98 O 4 showed better discharge capacity (68.2 mAh/g) over other doped derivatives and pristine LiMn 2 O 4 in saturated Li 2 SO 4 aqueous electrolyte.