A comprehensive study on influence of Nd3 + substitution on properties of LiMn2O4

Abstract

LiNd x Mn 2−x O 4 samples are synthesized via co-precipitation technique. The activation energies computed from thermogravimetric analyses on the basis of Ozawa method have been observed to linearly increase with increase in dopant concentration. X-ray diffraction analyses indicate the cubic-spinel structure for all the samples. The lattice parameter has been observed to decrease with increasing concentration of Nd 3+ doping. The octahedral site preference of neodymium dopant in the LiMn 2 O 4 structure has been elucidated using XRD and FT-IR studies. The porosity and surface roughness obtained from SEM analysis have been observed to decrease with increase in Nd 3+ dopant concentration in LiMn 2 O 4 lattice. The electrochemical performances of the electrodes were analysed through cyclic voltammetry, chronopotentiometry and electrochemical impedance techniques. The specific capacity has been observed to decrease initially with increase in Nd 3+ dopant concentration, whereas the capacity retention has increased with increase in dopant concentration. The observed percentage capacity retention after 50 cycles of the electrodes LiNd 0·05 Mn 1·95 O 4 , LiNd 0·10 Mn 1·90 O 4 and LiNd 0·15 Mn 1·85 O 4 were 88·4%, 97·1% and 96·8%, respectively. The Li ion diffusion coefficient ascertained using electrochemical impedance spectroscopy was found to be higher for LiNd 0·10 Mn 1·90 O 4 around 3·74 × 10 −12 cm 2 s −1 .