Solid-state redox mediator engineering of Ag clusters/CoMoO4 heterostructure for accelerated LiOx conversion kinetics

Abstract

Facing growing energy demands, lithium-oxygen batteries (LOBs) offer a promising high-energy-density alternative but suffer from sluggish oxygen electrocatalysis at the cathode. This work innovatively demonstrates that rational modulation of the metal-support interaction (MSI) between Ag and vacancy-rich CoMoO4 serves as an effective strategy for designing high-performance catalysts. By precisely controlling the Ag incorporation ratio, a unique heterostructured Ag/CoMoO4-2 catalyst was successfully constructed, wherein Ag nanoclusters form an intimate heterointerface with the CoMoO4 substrate. The optimized catalyst exhibits superior bifunctional activity for both the oxygen reduction and evolution reactions (ORR/OER). The Ag/CoMoO4-2 enhanced battery delivers a high discharge capacity of 13886 mAh g-1 and significantly reduced overpotentials of 70 mV. More importantly, it enables an extended cycle life, doubling that of pristine CoMoO4. The introduction of the Ag nanoclusters promote the formation of disk-like Li2O2 during discharge and ensure its complete decomposition upon charging via a solid-state redox mediator mechanism. These findings highlight the critical role of the Ag/CoMoO4 heterostructure in modulating the electronic structure, optimizing interfacial properties, promoting the adsorption of key reaction intermediates, and enhancing the reaction kinetics, thus providing a viable strategy for developing high-performance LOBs.