| abstract |
The LiFePO 4 carbon composite material is satisfactorily single phase synthesized to achieve excellent cell characteristics. In preparing the positive electrode active material, the synthetic raw materials of the compound of formula 1 are mixed, ground and sintered, and carbon material is added to the resulting material at any point during the mixing, grinding and sintering. Li 3 PO 4 and Fe 3 (PO 4 ) 2 or its hydrate Fe 3 (PO 4 ) 2 · nH 2 O (where n is the number of hydrates) are used as a raw material for the synthesis of the compound of formula (1). When the sintered product is exposed to the atmosphere, the temperature of the sintered product is set to 305 ° C or lower. At the time of sintering, the oxygen concentration in the sintering atmosphere is set to 1012 ppm (volume) or less.n n n Formula 1n n n Li x FePO 4 n n n In Formula 1 above,n n n x is 0 <x≤1. |