Dual‐Scale Al2O3 Particles Coating for High‐Performance Separator and Lithium Metal Anode

Herein, the polyethylene (PE) separators are coated by micro/nanoalumina particles. The alumina particles with different sizes play different roles. The microalumina mainly enhances the thermal stability of the polyolefin separator and provides large channels for lithium‐ion diffusion. The nanoalumina particles are helpful in improving the lithium‐ion transference number by increasing the contact interface area of electrolyte/alumina. The lithium‐ion transference number of the separators with different coatings increases from 0.32 to 0.40, mainly due to the ratio of micro/nanoalumina particles. Meanwhile, ion conductivity increases from 0.30 to 0.40 mS cm −1 . As a result, the cycling stability of the lithium metal anode is greatly improved by the synergetic effect of microsized alumina particles and nanosized alumina particles.