Carbon nanocoatings for C/LiFePO4 composite cathode

• Carbon nanocoatings on LiFePO4 grains were obtained in simple and cheap process.
• Morphology of carbon nanocoatings depended on polymer precursor composition.
• Carbon nanocoatings significantly improved electrical conductivity of C/LiFePO4.
• C/LiFePO4 composites revealed very good cyclability and capacity retention.

Composite cathode C/LiFePO4 was successfully prepared through the simple process of wet impregnation of polymer carbon precursor followed by controlled pyrolysis. Two types of polymer carbon precursors were used: poly-N-vinylformamide (PNVF) and pyromellitic acid modified poly-N-vinylformamide (MPNVF). TEM studies as well as adsorption (BET) measurements indicate that the morphology of obtained conductive carbon layers (CCLs) strongly depends on the composition of polymer precursors. The obtained carbon nanocoatings reveal a complex microporous and mesoporous structure as well as thin film-like character. Electrical conductivity measurements as well as charge–discharge tests in Li/Li+/(C/LiFePO4) cells prove that obtained CCLs assure good electrical properties of the composites. C/LiFePO4 composites revealed good capacity retention (~ 130 mAh/g at 20 cycles) and perfect coulombic efficiency.