Unlocking the Power of Lewis Basicity in Oxide Lattice Oxygens: A Regulating Force for Enhanced Oxygen Evolution Kinetics in Li-O2 Batteries.

Abstract

Lithium-oxygen batteries (LOBs) require fast oxygen conversion kinetics to achieve good cycling performance and high energy efficiency. In the text of catalysts for LOBs, Lewis basicity of lattice oxygens (OL) in common transition metal oxides is often underestimated due to the weak electron donor characteristic of OL. In this work, a new spinel-type high entropy oxide with Lewis basicity (LB-HEO) was synthesized through a Joule-heating method. OL was activated by regulating the tetrahedral site-OL-octahedral site (MTd-OL-MOh) units in the spinel-type HEO, enhancing the Lewis basicity. Used as cathode catalyst for LOBs, LB-HEO could attract Li+ and increase the disorder in discharge product, lithium peroxide (Li2O2), promoting the delithiation process and the interfacial charge transfer at the LB-HEO|Li2O2 interface. The activation energy of interfacial charge transfer was significantly reduced from 63.5 kJ mol-1 to 22.4 kJ mol-1. As a result, low charging overpotential of 0.97 V and long cycling lifespan of 135 cycles at 100 mA g-1 were achieved with capacity limitation of 1000 mAh g-1. The strategy based on the regulation of Li+ behavior through its interaction with Lewis bases provides a promising prospective for the design of non-noble metal catalysts for high-performance LOBs.