POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM-ION SECONDARY CELL, AND LITHIUM-ION SECONDARY CELL

The present invention provides a positive electrode active material for a lithium-ion secondary cell having exceptional lithium ion conductivity, the positive electrode active material being such that the absorption of moisture from the atmosphere can be suppressed. This positive electrode active material for a lithium-ion secondary cell has powder particles that include a specific composite oxide, and an organic silicon compound affixed to the surface of the powder particles, the organic functional groups of the organic silicon compound including at least one selected from the group consisting of C2-10 alkyl groups and C6-14 aryl groups. 本发明提供锂离子传导性优良、并且还能够抑制大气中的水分吸附的锂离子二次电池用正极活性物质。所述锂离子二次电池用正极活性物质具有包含特定的复合氧化物的粉末粒子和附着于所述粉末粒子的表面的有机硅化合物，所述有机硅化合物的有机官能团包含选自由碳原子数2～10的烷基和碳原子数6～14的芳基组成的组中的至少一种。