STRUCTURAL AND ELECTROCHEMICAL STUDY OF OLIVINE TYPE LIFEPO4 AS CATHODE MATERIAL

Abstract

This study is intended to synthesize the olivine-type pristine LiFePO4 (LFP) using the solid-state ball milling method. The structural, electrical, and electrochemical properties of as synthesized pristine LiFePO4 has been analyzed. The synthesized sample was characterized using X-ray diffraction (XRD) to confirm the single/mixed phase formation of the olivine type LFP as a cathode material. Hence, the Rietveld refinement analysis of the observed XRD pattern indicates that olivine type orthorhombic single phase with the space group, Pnma is formed without any impurity. Fourier Transform Infrared Spectroscopy (FTIR) is also performed to see the groups developed, bond strength and bond stretching and bond vibrations in the LFP. The dc conductivity and activation energy were estimated by the source measurement unit using Arrhenius equation. The electrochemical performance of LFP has been carried using Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and Galvanostatic charge/discharge (GCD) methods. Here, it is found that the 1st cycle of pristine LFP delivers a specific discharge capacity of 52(±5) mAh g-1 at 0.5C rate and after 50 charge/discharge cycles a noticeable retention in the capacity is observed which implies that, the electrochemical Li+ insertion/extraction process is extremely reversible and that the structure of pristine LiFePO4 is quite stable and also the pristine LFP has a coulombic efficiency of greater than 99 %.