Highly Stable Garnet Fe2 Mo3 O12 Cathode Boosts the Lithium-Air Battery Performance Featuring a Polyhedral Framework and Cationic Vacancy Concentrated Surface.

Abstract

Lithium-air batteries (LABs), owing to their ultrahigh theoretical energy density, arerecognized as one of the next-generation energy storage techniques. However, it remains a tricky problem to find highly active cathode catalyst operating within ambient air. In this contribution, a highly active Fe2 Mo3 O12 (FeMoO) garnet cathode catalyst for LABs is reported. The experimental and theoretical analysis demonstrate that the highly stable polyhedral framework, composed of FeO octahedrons and MO tetrahedrons, provides a highly effective air catalytic activity and long-term stability, and meanwhile keeps good structural stability. The FeMoO electrode delivers a cycle life of over 1800h by applying a simple half-sealed condition in ambient air. It is found that surface-rich Fe vacancy can act as an O2 pump to accelerate the catalytic reaction. Furthermore,theFeMoOcatalystexhibitsasuperiorcatalyticcapabilityforthedecompositionofLi2 CO3 .H2 O in the air can be regarded as the main contribution to the anode corrosion andthe deterioration of LAB cells could be attributed to the formation of LiOH·H2 O at the end of cycling. The present work provides in-depth insights to understand the catalytic mechanism in air and constitutes a conceptual breakthrough in catalyst design for efficient cell structure in practical LABs.