Ionic conductivity and cycling stability-enhanced composite separator using hollow halloysite nanotubes constructed on PP nonwoven through polydopamine-induced water-based coating method

Ceramic-coating separator can meet the safety requirements of high-power battery through its good thermal tolerance, thus raising more attention recently. During preparation, aqueous coating has been considered as an environmentally friendly method. However, there are some drawbacks for direct coating to be tackled including weak bonding strength and too dense structures of coating layer. In this study, porous sodium alginate/halloysite nanotubes coating was constructed on PP nonwoven by polydopamine-induced water-based coating method to give PHS composite separators. Porous structures were produced by the delayed evaporation of nonsolvent N -methyl pyrrolidone (NMP) in coating slurry. These structures together with hollow structures of halloysite nanotubes (HNTs) were confirmed to boost porosity, wettability and ionic conductivity , thus PHS-4 separator with more HNTs introduced endowing battery with superior discharge performance (159.2 mAh g −1 ) at 0.2 C. Because of more space to store electrolyte, when wetted PHS-4 separator was ignited, it could also give self-extinguishing phenomenon at a shorter time. In addition, the pretreatment of polydopamine before aqueous coating and the overlap among HNTs with high aspect ratio were investigated to increase interfacial peeling strength, therefore PHS-4 separator displayed the best cycling stability with discharge capacity retention achieving 99.1%. Clearly, PHS-4 separator will bring prospect for LIB to pursue high performance and environmentally friendliness.