As an external additive with a core shell structure, the core is made of the same polymer material as the toner, while the shell is coated with silica. During printing, the core material migrates through the silica shell, maximizing fusing efficiency even at low temperatures and significantly contributing to energy savings. The lower fusing temperature also helps extend printer lifespan and improve print speed. The silica-coated shell ensures thermal stability during storage and transportation, preventing caking, while maintaining the electrostatic performance of silica. The surface treated structure minimizes moisture absorption and ensures stable usage amounts.