A lithiated zeolite-based protective layer to boost the cycle performance of lithium−oxygen batteries via redox mediator sieving

Abstract

Lithium–oxygen (Li–O₂) batteries with ultra-high theoretical specific energy (3500 Wh kg⁻¹) have attracted significant attention, but the sluggish electrochemical processes of discharge product Li₂O₂ lead to poor cycling stability. Redox mediators (RMs) as soluble catalysts are widely used to assist with the electrochemical formation/decomposition of Li₂O₂. However, the shuttle effect of RMs causes severe deterioration of both RMs and Li metal anodes. Herein, for the first time we synthesize a lithiated zeolite-based protective layer on Li anodes to mitigate the shuttle effect of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) in Li–O₂ batteries. The protective layer successfully blocks the migration of TEMPO toward the Li anode owing to the angstrom-level aperture size of lithiated zeolite. Due to the excellent redox-mediator-sieving capability of the protective layer, the cycle life of the Li−O₂ batteries is significantly prolonged more than ten times at a current density of 250 mA g⁻¹ and a limited capacity of 500 mA h g⁻¹. This work demonstrates that the lithiated zeolite-based protective layer capable of molecular sieving is a facile and scalable way to mitigate the shuttle effect of RMs in Li–O₂ batteries.