Al2O3/TiO2 coated separators: Roll-to-roll processing and implications for improved battery safety and performance

[摘要] Heat generation is one of the major concerns with lithium-ion batteries (LIBs) while charging them at higher currents, which could inadvertently impact the rate performance and battery safety. Polymer separator is one of the least thermal conductive components of a LIB. In addition, commercial separators for LIBs are made from polyolefin membranes that tend to shrink and curl at higher temperatures due to lower melting temperature (similar to 130 degrees C), which increases the risk of internal short circuiting. Developing separators with improved thermal stability and higher electrolyte uptake is essential for enhancing safety as well as performance of LIBs. In this work, thin layer of ceramic coatings (Al2O3 and TiO2) are applied on a propylene membrane to improve thermal stability and electrolyte affinity without compromising rate performance. A slurry with 100% Al2O3 coated on the polypropylene separator exhibited the best improvement in thermal stability (shrinkage of 0.6% vs 6.0% for uncoated membrane) and excellent rate performance with 92% capacity retention at 2C. The Al2O3 coated separator demonstrated excellent electrolyte wettability compared to the uncoated. The cross-plane thermal-conductivity of the ceramic coated separators is analyzed to understand heat transfer behavior. The thermal-conductivity of the separator is improved by similar to 3.2 times with the Al2O3 coating.

[发布日期] 2021-09-30

[关键词] Ceramic coated separators;Thermal conductivity;Thermal stability;Roll-to-roll processing;Al2O3 and TiO2