Structural, microstructural and electrochemical studies on LiMn2-x(GdAl)xO4 with spinel structure as cathode material for Li-ion batteries

Gd and Al co-doped LiMn2-x(GdAl)xO4 (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) materials with spinel structure were synthesized by sol-gel method. Powder X-ray diffraction results confirm the formation of cubic spinel structure and average particle sizes are found to be between 80 and 110 nm from FE-SEM and TEM analysis. Decrease in peak potential difference as a function of doping in Cyclic Voltammetry results establishes enhancement in Li+ intercalation and de-intercalation. Electrochemical Impedance Spectroscopy (EIS) results showed that accumulation of charges on electrode has improved with doping over pristine samples. At a doping of x = 0.02 charge transfer resistance values were found to be least. First cycle charge-discharge profiles for LiMn1.96(GdAl)0.02O4 shows 139.2 mAh/g discharge capacity over other doped derivatives and pure LiMn2O4 (119.6 mAh/g) in aqueous Li2SO4 electrolyte. Doping of x = 0.02 exhibit good cycling performance with only a total 4% capacity loss after 30 cycles.