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Abstract

The present invention relates to lithium secondary batteries and more specifically to positive electrode materials operating at potentials greater than 2.8 V vs. Li/Li in nonaqueous electrochemical cells. In particular, the invention relates to crystalline nanometric carbon-free olivine-type LiFePOpowders with enhanced electrochemical properties. A direct precipitation process is described for preparing crystalline LiFePOpowder, comprising the steps of: —providing a water-based mixture having at a pH between 6 and 10, containing a water-miscible boiling point elevation additive, and Li, Feand Pas precursor components; —heating said water-based mixture to a temperature less than or equal to its boiling point at atmospheric pressure, thereby precipitating crystalline LiFePO4 powder. An extremely fine 50 to 200 nm particle size is obtained, with a narrow distribution. The fine particle size accounts for excellent high-drain properties without applying any carbon coating. This allows for a significant increase in the active material content of the electrode. The narrow distribution facilitates the electrode manufacturing process and ensures a homogeneous current distribution within the battery.