Effect of Ni and Fe substitution on the thermal, structural, vibrational spectroscopic and electrochemical properties of LiMn2O4 cathode material

Spinel LiMn2O4, Li-1.025(Mn1.95Ni0.025Fe0.025)O-4, and Li-1.025(Mn1.9Ni0.025Fe0.05)O-4 cathodes were synthesized by a two-step solid-state reaction method. The thermal, structural, vibrational spectra and electrochemical properties of these materials were characterized by using TGA-DTA, XRD, SEM, EDS, Fourier-FT-IR spectroscopy, Raman spectroscopy, and charge-discharge test. The TGA-DTA analysis confirmed that 800 degrees C is the suitable temperature for synthesizing all the samples using Li2CO3, Fe2O3, MnO2, and NiO precursors. The XRD analysis revealed the formation of a single-phase cubic spinel structure with Fd (3) over barm space group. Two distinct strong absorption peaks were identified by FT-IR analysis in the wavenumber regions of 512 to 621 cm(-1). Enhancement of the discharge specific capacity due to Ni and Fe substitution into LiMn2O4 was observed. Among all samples, Li-1.025(Mn1.95Ni0.025Fe0.025)O-4 exhibited excellent cyclic performance (97.4%) after 50 cycles. (C) 2021 Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.