Electrode material for lithium-ion secondary battery and method for manufacturing same

An electrode material for a lithium-ion secondary battery comprising:

• particles which are made of LiFexMn1-w-x-y-zMgyCazAwPO4 (here, A represents at least one element selected from the group consisting of Co, Ni, Zn, Al, and Ga, 0.05≦x≦0.35, 0.01≦y≦0.10, 0.0001≦z≦0.001, and 0≦w≦0.02), have an orthorhombic crystal structure, and have a space group of Pmna,
• wherein a mis-fit value [(1−(b2×c2)/(b1×c1))×100] of a be plane which is computed from lattice constants b1 and c1 of the LiFexMn1-w-x-y-zMgyCazAwPO4 and lattice constants b2 and c2 of FexMn1-w-x-y-zMgyCazAwPO4 obtained by deintercalating Li from LiFexMn1-w-x-y-zMgyCazAwPO4 by means of an oxidation treatment using nitrosonium tetrafluoroborate in acetonitrile is 1.32% or more and 1.85% or less.