Positive electrode material for lithium ion secondary battery, positive electrode for lithium ion secondary battery, lithium ion secondary battery, evaluation method of positive electrode material for lithium ion secondary battery

摘要

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 LiFeMPO(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 (Δbis a difference between a chromaticity bin a Labcolorimetric system after heating the active material particle for a 72-hour under an air atmosphere and at 180°C and the chromaticity bbefore heating the active material particle).SELECTED DRAWING: None