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Abstract
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In this study, LiFePO4-
carbon (LFP-C) and LFP-C/reduced graphene oxide (rGO) nanocomposites were prepared by ultrasonic
spray pyrolysis technique in different calcination conditions to be used as the cathode-active materials for lithium ion
battery (LIB). The structure, morphology and composition of the obtained materials were analyzed by X-ray diffraction
(XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HR-TEM) and energydispersive
X-ray spectroscopy (EDX). The XRD results reveal that the olivine pure phase was obtained after calcination of
the LFP-C. The SEM images of the prepared materials exhibit the spherical morphology with nanometer size and also change
in the morphology by applying the calcination step. The electrochemical performances of cathode-active materials were
investigated by charge–discharge test, electrochemical impedance spectroscopy and cyclic voltammetry. The obtained results
for LFP-C show that the electrochemical performance was improved by adding carbon precursor and calcining step; in the
optimum calcination conditions; 700 °C for 3 h, the LFP-C shows good results in terms of electrochemical performance in
comparison with LFP alone. The LFP-C/rGO nanocomposite exhibits the best electrochemical performance however: highest
rechargeable capacity and cycle stability; discharge capacity (168 mAh/g at 0.1 C and 123.5 mAh/g at 10 C) and capacity
retention of 100% after 50 cycles with maximum reversibility and lithium ion (
Li+) diffusion coefficient.
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