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 LiFePO4 powders with enhanced electrochemical properties. A direct precipitation process is described for preparing crystalline LiFePO4powder, 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(I), Fe(II) and P(V) as 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.

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 LiFePO4 powders with enhanced electrochemical properties. A direct precipitation process is described for preparing crystalline LiFePO4powder, 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(I), Fe(II) and P(V) as 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.