In Situ Formed Ir₃Li Nanoparticles as Active Cathode Material in Li-Oxygen Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Lithium-oxygen (Li-O₂) batteries offer high energy density but suffer from low efficiency due to high charge overpotentials.
• Controlling lithium superoxide formation is key to improving Li-O₂ battery performance.

Purpose of the Study:

• To investigate subnanometer iridium (Ir) clusters as cathode materials for Li-O₂ batteries.
• To understand how Ir particle size influences lithium superoxide formation and charge potentials.
• To explore the mechanism behind the formation of active cathode structures.

Main Methods:

• Use of size-selected subnanometer Ir clusters as cathode catalysts.
• Electrochemical characterization including DEMS, Raman, and titration.
• High-resolution transmission electron microscopy (HRTEM) for nanoparticle analysis.
• Density functional theory (DFT) calculations for mechanistic insights.

Main Results:

• Ir nanoparticles facilitate lithium superoxide formation as the discharge product.
• Iridium nanoparticles of approximately 1.5 nm exhibited the lowest charge potentials.
• During discharge, 1.5 nm Ir nanoparticles transformed into Ir₃Li core-shell structures.
• These Ir₃Li structures likely template the growth of lithium superoxide.

Conclusions:

• In situ formed Ir₃Li core-shell nanoparticles represent a novel cathode material for Li-O₂ batteries.
• This discovery offers a new pathway to reduce charge overpotentials and enhance energy efficiency.
• The findings provide a new direction for designing advanced cathode materials for next-generation batteries.