POSITIVE ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, POSITIVE ELECTRODE FOR LITHIUM ION S

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PROBLEM TO BE SOLVED : To provide a positive electrode material for a lithium ion secondary battery, which has optimal coatability of a carbonaceous coating film. SOLUTION : The positive electrode material for a lithium ion secondary battery is an active material particle including : a center particle expressed by a general formula of LixFeyMzPO4 (0.95≤x≤1.1, 0.8≤y≤1.1, 0≤z≤0.2, and M is at least one kind selected from a group of Mg, Ca, Co, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, Ge, and a rare earth element); and a carbonaceous coating film that coats a surface of the center particle. A specific surface ratio Δb*/BET is 0.25 or more and 0.35 or less (Δb* is a difference between a chromaticity b* in a L*a*b* colorimetric system after heating the active material particle for a 72-hour under an air atmosphere and at 180°C and the chromaticity b* before heating the active material particle). SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT