Versatile Synthesis of Carbon-Rich LiFePO4
The surface engineering and the optimization of particle morphology have enhanced the LiFePO4 electrochemical performance, making this cathode material one of the most promising candidates to replace lithiated metal oxides in lithium-ion batteries. Many authors have attempted to improve the electrochemical performance of LiFePO4 by coating the surface with conducting particles (N. Ravet, J.B. Goodenough, S. Besner et al., Improved iron based cathode material. In Proceeding of 196th ECS Meeting, Hawaii, 17–22 Oct, 1999), or co-synthesizing the compound with conductive additives (Huang et al., Electrochem. Solid St. 4:A170–A172, 2001; Prosini et al., Electrochim. Acta 46:3517–3523, 2001). In both cases the conductive particles interfered with the grain coalescence determining the reduction of the grain size. Both particle size minimization and intimate carbon contact were claimed to be necessary to optimize the electrochemical performance. In this chapter we stress this concept reporting on a new reproducible synthetic route to prepare nano-particle LiFePO4/C composites, in which the phosphorus, iron and carbon atoms all originate from the same precursor. LiFePO4/C composites were prepared from thermal decomposition of Fe(II)organo-phosphonates Fe[(RPO3)(H2O)] (R = methyl or phenyl group) in presence of Li2CO3 at high temperature and under inert atmosphere (Bauer et al., Electrochem. Solid St. 7:A85–A87, 2004). The compounds were characterized by chemical analysis, TGA, DSC, X-ray powder diffraction, and SEM technique. Electrodes were fabricated for the electrochemical characterization. The cathode material obtained from Fe[C6H5PO3(H2O)] showed a specific energy evaluated at C/10 rate of about 550 Wh kg?1. The specific power calculated at 30C rate was in excess at 14000 W kg?1, while the specific energy was about 28% of the theoretical one. No capacity fading was observed upon cycling.
KeywordsElectrochemical Performance Cathode Material Composite Cathode Conductive Particle Phenyl Phosphonate
- 1.N. Ravet, J.B. Goodenough, S. Besner et al., Improved iron based cathode material. In Proceeding of 196th ECS Meeting, Hawaii, 17–22 Oct 1999Google Scholar