LiFePO4/C composites were prepared by using organo-phosphonates as a single source of iron, phosphorus and carbon. Fe[RPO3]·H2O (R = methyl or phenyl group) was heated in the presence of Li2CO3 at high temperature and under nitrogen flux. Elemental carbon is formed on the surface of LiFePO4 particles leaving a carbon coated material. The materials were characterized by elemental analysis, TG/DTA, XRPD and SEM. Coulometric titration showed that some impurities are present in the final products. The material prepared starting from the iron(II) phenyl phosphonate showed higher discharge capacity, specific energy, and specific power. The specific energy evaluated at C/10 rate was about 520 Wh kg-1. The specific power calculated at 3C rate was in excess at 1400 W kg-1 while the specific energy was about 63% of the energy delivered at C/10. No capacity fading was observed upon cycling. The performance of LiFePO4 prepared from the iron(II) methyl phosphonate was found to be slightly lower, probably due to the lower carbon content.
A versatile method of preparation of carbon-rich LiFePO4. A promising cathode material for Li-ion batteries
Bauer EM;Bellitto C;Righini G;
2005
Abstract
LiFePO4/C composites were prepared by using organo-phosphonates as a single source of iron, phosphorus and carbon. Fe[RPO3]·H2O (R = methyl or phenyl group) was heated in the presence of Li2CO3 at high temperature and under nitrogen flux. Elemental carbon is formed on the surface of LiFePO4 particles leaving a carbon coated material. The materials were characterized by elemental analysis, TG/DTA, XRPD and SEM. Coulometric titration showed that some impurities are present in the final products. The material prepared starting from the iron(II) phenyl phosphonate showed higher discharge capacity, specific energy, and specific power. The specific energy evaluated at C/10 rate was about 520 Wh kg-1. The specific power calculated at 3C rate was in excess at 1400 W kg-1 while the specific energy was about 63% of the energy delivered at C/10. No capacity fading was observed upon cycling. The performance of LiFePO4 prepared from the iron(II) methyl phosphonate was found to be slightly lower, probably due to the lower carbon content.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
