Preparation of LiFePO4 as lithium intercalation compound by emulsion drying method

Abstract

Crystalline olivine type LiFePO4 as cathode material for Li-ion battery was prepared by emulsion drying method. By employing this method, difficulty of conventional preparation, that is, repeated recalculations and subsequent regrindings, was solved. This method replaced successfully relatively expensive divalent iron to cheaper trivalent iron as a starting material by burning out the emulsion-dried precipitates with carbon, which act as a strong reducing agent. High temperature calcination of the emulsion-dried precursor powders in an Ar atmosphere resulted in high crystalline olivine type LiFePO4 powders which was confirmed and refined by Rietveld method of X-ray diffraction data. The prepared material delivered a capacity as high as 120 and 140 mAh (g-phosphate)-1 at 25 and 50°C, respectively.