Controlled Synthesis of Ultrathin 2H-Phase RhPd Alloy Nanostructures for High-Performance Lithium-Oxygen Batteries.

Developing high-efficiency cathode catalysts to address the challenges posed by insulating discharge products represents a key strategy for enhancing the performance of rechargeable lithium-oxygen batteries (LOBs). Herein we report the controlled synthesis of RhPd alloy nanoflowers with an unconventional hexagonal close-packed (hcp, 2H type) phase for high-performance LOBs. As a cathode catalyst, 2H RhPd nanoflowers enable LOBs to achieve an electrochemical stability of 244 cycles and a specific capacity of 22252 mAh g-1, significantly surpassing the performance of common face-centered cubic (fcc) RhPd nanoflowers. Ex/in situ characterizations and theoretical calculations have revealed that unconventional 2H phase RhPd nanoflowers can finely tune the adsorption of discharge products and accelerate the reaction kinetics of Li+-mediated oxygen reduction and evolution, thereby reducing the overpotential and alleviating catalyst degradation. The successful demonstration of high-performance LOBs with unconventional phase alloy nanoflowers highlights the substantial application potential of phase engineering for advancing electrochemical energy storage systems.