Highly thermal stable and robust ceramic-coated separators (CCSs) should be included for large-format lithium-ion batteries (LIBs) to secure their safety even at various abnormal conditions such as automobile accident. However, the ceramic coating layer of a few micrometers needs additional coating and slitting processes, resulting in increasing the separator price. Moreover, the hydrophobicity of polyethylene separators requires non-polar organic solvent-based coating slurry consisting of ceramic particles and polymeric binders. In general, organic solvents started to be excluded in the industry field owing to their environmental pollution and additional recovery facility. That is why aqueous ceramic coating process should be developed while overcoming its wetting problem upon hydrophobic polyethylene separators.

Herein, we newly introduce an anionic surfactant, containing both hydrophobic and hydrophilic groups, to make the aqueous slurry be well-dispersed and easily wetted upon polyethylene separators. Due to the cationic property of Al₂O₃ surface in water, anionic surfactants are appropriate in this application. Among various them, we have chosen disodium laureth sulfosuccinate (DLSS) for this system. We optimized the water-based ceramic coating process using DLSS and investigated the physical properties of Al₂O₃ ceramic-coated separators. We also studied the electrochemical properties of cells containing the CCSs.

Acknowledges
This research was supported by the New Technology Convergency Type Growth Engine Project of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2014M3C1A8074768) and the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977)