Identifying the Role of Lewis‐base Sites for the Chemistry in Lithium‐Oxygen Batteries

Lewis-base sites have been widely applied to regulate the properties of Lewis-acid sites in electrocatalysts for achieving a drastic technological leap of lithium-oxygen batteries (LOBs). Whereas, the direct role and underlying mechanism of Lewis-base in the chemistry for LOBs are still rarely elucidated. Herein, we comprehensively shed light on the pivotal mechanism of Lewis-base sites in promoting the electrocatalytic reaction processes of LOBs by constructing the metal-organic framework containing Lewis-base sites (named as UIO-66-NH₂ ). The density functional theory (DFT) calculations demonstrate the Lewis-base sites can act as electron donors that boost the activation of O₂ /Li₂ O₂ during the discharged-charged process, resulting in the accelerated reaction kinetics of LOBs. More importantly, the in situ Fourier transform infrared spectra and DFT calculations firstly demonstrate the Lewis-base sites can convert Li₂ O₂ growth mechanism from surface-adsorption growth to solvation-mediated growth due to the capture of Li⁺ by Lewis-base sites upon discharged process, which weakens the adsorption energy of UIO-66-NH₂ towards LiO₂ . As a proof of concept, LOB based on UIO-66-NH₂ can achieve a high discharge specific capacity (12 661 mAh g⁻¹ ), low discharged-charged overpotential (0.87 V) and long cycling life (169 cycles). This work reveals the direct role of Lewis-base sites, which can guide the design of electrocatalysts featuring Lewis-acid/base dual centers for LOBs.