Elastic Hairy Nanoparticle Separator Coating for Enhanced Interfacial Stability in Lithium–Metal Batteries

Hairy nanoparticles (HNPs) provide excellent protection against dendrite formation when applied as an artificial solid electrolyte interface (aSEI) in lithium-metal batteries. ASEIs can be applied to the lithium anode in three different ways: by drop casting, electrospinning, and dip coating. However, each of these application techniques require a significant amount of handling time for the highly reactive lithium. Safer conditions during cell assembly would greatly improve the commercial applicability of lithium metal batteries. Hence, alternative processing of the HNPs in the cells was explored. HNPs with high elasticity were spray-coated on the anode side of the separator, resulting in no additional lithium handling time other than during cell assembly. This improved the common downfall of separator coatings with limited contact between the protective layer and the anode. Due to the more uniform HNP deposition, the separator coating showed a capacity retention of ∼86% after 500 cycles.