Size effects on carbon-free LiFePO4 powders

C-free LiFePO4 crystalline powders were prepared by a synthesis method based on direct precipitation under atmospheric pressure. The particle size distribution is extremely narrow, centered on ca. 140 nm. A soft thermal treatment, typically at 500 degrees C for 3 h under slight reducing conditions was shown to be necessary to obtain satisfactory electrochemical Li+ deinsertion/insertion properties. This thermal treatment does not lead to grain growth or sintering of the particles, and does not alter the surface of the particles. The electrochemical performances of the powders obtained by this synthesis method are excellent, in terms of specific capacity (147 mAh g(-1) at 5C-rate) as well as in terms of cyclability (no significant capacity fade after more than 400 cycles), without the need of carbon coating. (c) 2006 The Electrochemical Society.