FePO4 nanoparticles supported on mesoporous SBA-15:: Interesting cathode materials for Li-ion cells

Exploiting the properties of stability, low cost and low toxicity of iron phosphates, we have tried to enhance the performance of FePO4 as cathode material for Li-ion cells. We adopted the strategy of obtaining FePO4, via a typical preparation, onto the channels of an ordered mesoporous SBA- 15 silica, a low cost mesoporous material commonly used in industry, which possesses larger pores, thicker walls and higher thermal stability as compared with other mesoporous silicas like MCM-41. Characterizations with ICP-AES, XRPD, BET and HRTEM suggest that the supported iron phosphate species, with loading amounts as high as 30 wt%, are located and dispersed in the mesopores of SBA- 15. Iron phosphate can be reduced/oxidized more readily than the unsupported iron phosphate at room temperature, and in fact, cycling at C/10, the supported phosphate shows a utilization of 70% with respect to a value of 30% for the unsupported solid. The result is interesting from the scientific viewpoint but not suitable for application at the moment. Indeed, the amount of active material does not exceed 30% of the electrode mass and the total electrode capacity, though the active material is very efficient, is largely insufficient. Researches are being developed trying to increase the performances of the materials and also to eliminate the support after the dispersion of the active material. (c) 2007 Elsevier B.V. All rights reserved.