Composite particles for electrochemical device positive electrode, method for producing the same, electrochemical device positive electrode, and electrochemical device

Composite particles for an electrochemical device positive electrode, comprising a positive electrode active material, a carbon-based conductive material, and a binder resin,

• wherein a ratio of an amount of carbon atoms of a center region to an amount of carbon atoms of an outer region (amount of carbon atoms of center region/amount of carbon atoms of outer region) in the composite particle as measured in accordance with the following measurement method is 0.3 or more and 1.0 or less:
• [Measurement method]
• (1) In a cross-sectional image of a composite particle, the center of a square whose one side is 15 μm is aligned with the center of a cross-section of the composite particle;
• the square is divided into 9 regions whose one side is 5 μm;
• an amount of carbon atoms in each region is measured;
• and an average value thereof is defined as the amount of carbon atoms in the center region;
• (2) in the cross-sectional image of the composite particle, the center of a square whose one side is 15 μm is aligned with the center of the cross-section of the composite particle;
• the square is moved from the center in each of the four directions of right, up, left and down of the cross-sectional image until the square contacts an outer edge of the cross-section of the composite particle;
• each square is divided into three regions each having a size of 15 μm×5 μm to produce a total of 12 regions;
• an amount of carbon atoms of each region is measured;
• and an average value thereof is defined as the amount of carbon atoms of the outer region;
• and
• (3) the amount of carbon atoms of the center region is divided by the amount of carbon atoms of the outer region.