Novel high-performance lithium-ion battery separator made of chain-extended-poly(Butylene Adipate-co-terephthalate)/modified-polypropylene using gravure printing

In this work, a novel high-performance lithium-ion battery (LIB) separator based on chain-extended poly(butylene adipate-co-terephthalate) (CE-PBAT)/modified-polypropylene with the combination of the beneficial attributes of synthetic and biodegradable (with a significant biodegradation rate) polymers was proposed. The gravure printing technique joined to a compounding process produced a very thin nano-porous separator with an extraordinary morphology (cavity size = 68 nm and the number density of holes 16 μm−2 with ~ 43% porosity) via applying a wet-manufacturing method. The compatibilizer of polypropylene-grafted-maleic anhydride formed a microstructure with well-dispersed nano-holes by increasing the compatibility of polar PBAT with non-polar polypropylene. Reducing the CE-PBAT amount in the formulation by 50 wt.% increased the cavity size to 208 nm, and decreased the porosity to 34.2%. The surface wettability showed no significant change, while the bulk wettability was reduced by 26% through quantification of the electrolyte absorption amount (decrease from 128.7 to 94.3%). A further increase in the CE-PBAT loading content worsened the microstructural properties and wettability of the separators because of the appearance of phase separation in the polymer media. According to the resultant data, the CE-PBAT content of 75 wt.% was found to be the most optimum level with the best microstructural characteristics and wettability. The achieved ion conductivity of 2.86 mS.cm−1 for the LIB produced with the optimum separator exhibited a 633% increase compared to the neat polypropylene.