SOL-GEL SYNTHESIS AND CHARACTERIZATION OF LiMn2-2XNdXCoXO4 CATHODE MATERIALS

Abstract

The spinel LiMn1.9Nd0.05Coo.o5O4 and LiMn1.8Nd0.1Co0.1O4 cathode materials are synthesized by sol-gel method for the purpose of investigating the effect of Co and Nd substitution on the structural, electrical and dielectric properties of LiMn2O4 cathode material. Structural analysis of these cathode materials is performed by X–ray powder Diffraction (XRD), Ecanning Electron Microscopy (SEM), Dispersive X-ray Spectroscopy (EDS) and Fourier Transform Infrared (FT-IR) spectroscopy. Moreover, the electrical and dielectric properties of both synthesized cathode materials are investigated by using Complex Impedance Spectroscopy (CIS). The XRD analysis confirms that LiMn1.9 Nd0.05Co0.05O4 and LiMn1.8 Nd0.1Co0.1O4 cathode materials belong to a cubic structure with space group of Fd3m at room temperature. No impurities are detected, indicating the successful synthesis of both materials. SEM analysis coupled with EDS shows that the synthesized cathode materials possess fairly uniform distribution of particles, porous and agglomeration of particles, indicating well developed crystallinity. Further, EDS analysis confirms the presence of cations anions in the samples. No other elements are detected in both samples, which is consistent with the result obtained in the XRD patterns. The FT-IR spectra reveals two absorption bands in the range 515.31 – 626.87cm-1 arising due to stretching vibrations between cations and oxygen. From the electrical properties study, the Cole-Cole plot analysis shows grain contributions towards conductivity along with polarization and conductivity relaxation behavior in both synthesized materials. The conductivity is found to be 2.5 × 10-5 and 2.2 × 10-5 S.cm-1 for LiMn1.9Nd0.05Co0.05O4 and LiMn1.8Nd0.1Co0.1O4, respectively. The frequency dependent dielectric response is also studied in the frequency range 1 Hz to 1 MHz. It is found that the dielectric constant is relatively high at low frequency and decreases with increase in applied frequency and showed almost frequency independent behavior at higher frequency region.