| 摘要 |
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 non-aqueous electrochemical cells. In particular, the invention relates to crystalline nanometric olivine-type LiFeI-xMxPO4 powder with M is Co and/or Mn, and 0<x<1, with small particle size and narrow particle size distribution. A direct precipitation process is described, comprising the steps of: - providing a water-based mixture having at a pH between 6 and 10, containing a dipolar aprotic additive, and Li(I), Fe(II), P(V), and Co(II) and/or Mn(II) 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 LiFeI-xMxPO4 powder. An extremely fine particle size is obtained of about 80 nm for Mn and 275 nm for Co, both with a narrow distribution. The fine particle size is believed to accounts for excellent high-drain properties, while minimizing the need for conductive additives. The narrow distribution facilitates the electrode manufacturing process and ensures a homogeneous current distribution within the battery. |
