Microwave-assisted synthesis of titania coating onto polymeric separators for improved lithium-ion battery performance

This study adopts an efficient microwave-assisted method to deposit TiO₂ into tri-layered polymeric membranes, forming composite separators for Li-ion batteries (LIBs) consisted of Li₄Ti₅O₁₂ (LTO) anode/Li cathode. The microwave deposition is capable of growing TiO₂ crystals into the porous membranes at 40 °C in a short period of ∼8 min. Both improved thermal and dimensional stability are achieved by the deposition of TiO₂ in the separators. The improvement can be attributed to the formation of robust skeleton to stabilize the separators, imparting a superior insulation and mass transport barrier against volatile compounds formed during the thermal decomposition process. After depositing an appropriate amount of TiO₂, the TiO₂-coated separator still features well-developed porous structure, allowing favorable liquid wettability and high mass uptake of electrolyte. The amount of TiO₂ deposits plays as a crucial role in facilitating the cell performance, including high ionic conductivity, low inner resistance, high operation temperature, high energy density, and excellent cycleability. Accordingly, this low-temperature deposition method of modifying polymeric separators is attractive for application in high-performance LIBs.