Method for manufacturing coated active material for use in lithium-ion battery

The purpose of this invention is to provide a method for manufacturing a coated active material for use in a lithium-ion battery, said method being capable of improving the electron conductivity of said active material. This method for manufacturing a coated active material for use in a lithium-ion battery, said coated active material comprising a lithium-ion-battery active material with at least part of the surface thereof coated by a coating agent containing a conductivity-improving agent and a coating resin, is characterized by having a step in which the lithium-ion-battery active material is mechanically coated with the coating resin and the conductivity-improving agent and is also characterized in that the ratio (D 2 /D 1 ) between the mean particle diameter (D 2 , in µm) of the coating resin and the mean particle diameter (D 1 , in µm) of the lithium-ion-battery active material is 1/5 or less and the ratio (D 3 /D 1 ) between the mean particle diameter (D 3 , in µm) of the conductivity-improving agent and the mean particle diameter (D 1 , in µm) of the lithium-ion-battery active material is 1/10 or less.