Characterization of LiFePO₄/C Cathode for Lithium Ion Batteries

Abstract

LiFePO 4 /C was synthesized from a mixture of different precursors of Li, Fe, and C by solid-state reaction. The initial mixture obtained was heated in different calcination conditions under inert atmosphere. The precursor of LiFePO 4 doped with carbon was studied using different techniques such as thermal analysis, chemical and physical characterizations, and Mösbauer spectroscopy. A calculation of the crystallinity of the final product with two different methods is also presented. The chemical analysis techniques used were IRTF, XRD, and SEM. This characterization confirmed that we obtained a well-crystallized LiFePO4/C in all the operating conditions tested. The SEM showed aggregation and sintering during the calcination process, which were confirmed by the particle-size distribution measurements and by the physical characterizations. Mösbauer spectroscopy was used to determine the quantity of Fe(II) and Fe(III) contained in the final product. Our calcination conditions did not significantly modify the quantity of the two oxidation states.