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

An electrode material for a lithium-ion secondary battery which is secondary particles including:

• inorganic particles represented by General Formula LiFexMn1-x-yMyPO4, wherein M represents at least one element selected from Mg, Ca, Co, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, Ge, and rare earth elements, 0.05≤x≤1.0, 0≤y≤0.14, and 0≤1−x−y;
• and a carbonaceous film that coats surfaces of the inorganic particles,
• wherein an amount of carbon is 0.5% by mass to 2.5% by mass,
• a specific surface area is 10 m2/g to 20 m2/g,
• a first particle diameter (D90(a)) at which a cumulative volume percentage of a particle size distribution of secondary particles is 90% before an ultrasonic treatment is 20 μm to 40 μm,
• a second particle diameter (D90(b)) at which the cumulative volume percentage of the particle size distribution of the secondary particles is 90% after the ultrasonic treatment is 10 μm to 15 μm,
• a ratio (D90(b)/D90(a)) of the second particle diameter (D90(b)) to the first particle diameter (D90(a)) is 0.3 to 0.5 and
• the ultrasonic treatment is carried out by a following method under a condition of the ultrasonic treatment shown below:
• the ultrasonic treatment is carried out in an ultrasonic dispersion step in a circulation system of a laser diffraction and scattering particle size distribution analyzer LA-950V2 manufactured by Horiba Ltd;
• wherein an ultrasonic intensity in the step is controlled using a software, the ultrasonic treatment is carried out with an intensity, wherein an intensity of the analyzer is capable of setting in a range of 0 to 7, set to 7, a power is set to 30 W, a frequency is set to 20 kHz, and a ultrasonic treatment time is set to 20 seconds excluding a time for a particle size distribution measurement:
• and the particle size distribution is measured with 50 g of water and the 1 mg of secondary particles injected into a sample injection opening.