Performance of Vanadium Doped and Carbon Bamboo/Carbon Black Coated Lithium Iron Phosphate for Battery Cathode

Synthesis of lithium iron phosphate (LiFePO₄) via wet chemical followed by a hydrothermal method has been carried out. The preparation of LiFePO₄ was begun with the precursor of LiOH, NH₄H₂PO₄, and FeSO₄.7H₂O mixed stoichiometrically. After the synthesis, LiFePO₄ was doped using vanadium and then coated using two types of carbon sources, i.e. carbon black blended with activated carbon pyrolyzed from bamboo, through a solid-state reaction. The materials were mixed using a ball-mill and subsequently characterized using a thermal analyzer (STA) to determine the sintering temperature. The result shows that LiFePO₄ formation temperature is at 639°C. The sintering process was performed for 4 hours and the characterization was done using X-ray diffraction (XRD) and electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX). The electrochemical impedance spectroscopy (EIS) testing was performed to show the conductivity of the formed materials. XRD result showed that LiFePO₄/V/C phase has formed with an olivine structure, while the SEM result showed fair distribution and small particle size with some agglomerated microstructures. The EIS results showed that carbon coating on the active material increases the conductivity, whereas the addition of vanadium increases the conductivity of up to 5 wt.% vanadium but decreases at 7 wt.% vanadium.