Sumitomo Chemical Company, Limited

Maiko Sakai

Takeshi Hattori

Taketsugu Yamamoto

Satoru Kuze

Masami Makidera

Disclosed are a positive electrode active material and a method for producing an olivine-type phosphate. The positive electrode active material comprises an olivine-type phosphate represented by the following formula (I), wherein the maximum peak in an X-ray diffraction pattern obtained using a CuK&#x3b1; ray is the peak of the (031) plane of the olivine-type phosphate and the half-value width of the peak is 1.5&#xb0; or less: AMPO(I), wherein A represents one or more elements selected from among alkali metals; M represents one or more elements selected from among transition metals; a is from 0.5 to 1.5; and b is from 0.5 to 1.5. The method for producing an olivine-type phosphate comprises preparing a raw material comprising element A, element M, and phosphorus (P) so that a A:M:P molar ratio may be a:b:1, preliminary calcining the raw material, and mainly calcining the preliminary calcined raw material.

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Tsukuba, Japan

Maiko Sakai