Enhanced ALD Nucleation on Polymeric Separator for Improved Li–S Batteries

Lithium–sulfur (Li–S) batteries, with their superior energy densities, are emerging as promising successors to conventional lithium-ion batteries. However, their widespread adoption is hindered by challenges such as the shuttle effect of polysulfides, which affects discharge capacity and cycling stability. This study explores the transformative potential of atomic layer deposition (ALD) of Al2O3 on commercial PP/PE/PP separators (Celgard), combined with the use of UV ozone exposure to enhance ALD nucleation on the separator surface, to address these challenges. We demonstrate that ALD Al2O3 not only preserves the separator's inherent morphology but also enhances its chemical interactions toward polysulfide, crucial for optimal battery performance. Moreover, batteries with the modified separator exhibit an enhanced specific capacity, reaching up to ∼1150 mAh/g, and a reduced lithium plating overpotential, indicating improved kinetics. Our findings, based on X-ray photoelectron spectroscopy surface characterization and electrochemical evaluations, underscore the significance of ALD-enhanced separators in elevating Li–S battery efficiency by polysulfide adsorption. The research opens up possibilities for high-performance Li–S batteries, suitable for a broad range of applications.