▎ 摘　　要

NOVELTY - Method for improving water dispersibility of a conductive carbon powder, involves exposing the conductive carbon powder to a plasma jet or reacting with a plasma-treated reaction gas. USE - The method is useful for improving water dispersibility of a conductive carbon powder. ADVANTAGE - The method improves hydrophilicity and water dispersibility of conductive carbon powder, and stably improves water dispersibility of carbon powder without defects in carbon powder. The conductive carbon powder is continuously and stably dispersed in water-based solvent. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing a carbon powder colloidal solution, involving (i) performing above-mentioned steps and (ii) adding the conductive carbon colloidal powder to a water-based solvent and stirring to obtain the product.