Performance of Coconut Shell Activated Carbon in LiMn<sub>0.7</sub>Fe<sub>0.3</sub>PO<sub>4</sub>/CNT/C Composite for Lithium Ion Battery Cathode

Synthesis and characterization of LiMn 0.7 Fe 0.3 PO 4 /CNT/C composite used as lithium ion battery cathode has been carried out. The active materials of LiMn 0.7 Fe 0.3 PO 4 was synthesized via hydrothermal method from the precursors of LiOH, NH 4 H 2 PO 4 , FeSO 4 .7H 2 O and MnSO 4 .7H 2 O. The activated carbon was pyrolyzed from coconut shell whereas the carbon nanotube (CNT) was commercially available in the market. The composite was prepared using a ball-mill to mix the components homogeneously. Simultaneous thermal analysis STA was used to determine the formation temperature of LiMn 0.7 Fe 0.3 PO 4 to which the sintering process was conducted at 700 °C. After sintering, the materials in powder forms were characterized using scanning electron microscope (SEM) to examine the morphology, whereas X-ray diffraction (XRD) was used to identify the phases formed. The performance of the composite as lithium ion battery cathode was characterized using electrochemical impedance spectroscopy (EIS) and battery analyzer. Secondary electron image from SEM showed that the samples have homogeneous particle distribution. Examination result from X-ray diffraction indicated that LiMn 0.7 Fe 0.3 PO 4 phase has been successfully synthesized with small impurities from a secondary phase. Performance analysis showed that the presence of activated carbon and CNTs in LiMn 0.7 Fe 0.3 PO 4 to form LiMn 0.7 Fe 0.3 PO 4 /CNTs/C gives significant improvement in the conductivity; however, some more improvement is still needed for the capacity.