Powder cohesion and flow engineering as key enablers of high-performance ceramic-coated separators for lithium-ion batteries

• Ceramic-coated separators are widely used in Li-ion batteries. • Their performance is determined by the characteristics of the ceramic powders used. • In this study, the impact of ceramic powders on separator performance was analyzed. • Precise control of powder cohesion and flow properties proved to be a key strategy. • It contributes to the growth of high-stability and high-durability Li-ion batteries. Powder-flow engineering of ceramic powders offers a new handle to optimize ceramic-coated separators beyond conventional control of particle size and morphology. Ceramic-coated separators are widely used in lithium-ion batteries owing to their excellent thermal stability and electrolyte wettability. The performance of these separators is determined primarily by the characteristics of the ceramic powders used. In this study, both the fundamental properties of ceramic powders and their cohesion and flow properties are quantitatively analyzed to investigate their impact on separator performance. Three types of boehmite powders—that is, high-cohesion (BH-HC), medium-cohesion (BH-MC), and low-cohesion (BH-LC) powders—with varying levels of cohesion are synthesized using a hydrothermal method, and their physical characteristics are systematically compared. The low-cohesion BH-LC powder exhibits superior flow properties, enabling uniform slurry dispersion and consistent coating layer formation. The fabricated separators exhibit low thermal shrinkage, improved electrolyte wettability, and excellent ionic conductivity and electrochemical performance. This study confirms that precise control of powder cohesion and flow properties is a key strategy for enhancing the performance of ceramic-coated separators and contributes to the development of high-stability and high-durability lithium-ion batteries. These results demonstrate that engineering powder cohesion and flow behavior provides an effective strategy for designing high-performance ceramic-coated separators and high-safety lithium-ion batteries. This effect cannot be achieved by controlling particle size or shape alone.