Hierarchically Interconnected 3D Catalyst Structure of Porous Multi-Metal Oxide Nanofibers for High-Performance Li-O2 Batteries.

Abstract

Non-aqueous lithium-oxygen batteries (LOBs) have emerged as a promising candidate due to their high theoretical energy density and eco-friendly cathode reaction materials. However, LOBs still suffer from high overpotential and poor cycling stability resulting from difficulties in the decomposition of discharge reaction Li2 O2 products. Here, a 3D open network catalyst structure is proposed based on highly-thin and porous multi-metal oxide nanofibers (MMONFs) developed by a facile electrospinning approach coupled with a heat treatment process. The developed hierarchically interconnected 3D porous MMONFs catalyst structure with high specific surface area and porosity shows the enhanced electrochemical reaction kinetics associated with Li2 O2 formation and decomposition on the cathode surface during the charge and discharge processes. The uniquely assembled cathode materials with MMONFs exhibit excellent electrochemical performance with energy efficiency of 82% at a current density of 50mAg-1 and a long-term cycling stability over 100 cycles at 200mAg-1 with a cut-off capacity of 500 mAhg-1 . Moreover, the optimized cathode materials exhibit a remarkable energy density of 1013Whkg-1 at the 100th discharge and charge cycle, which is nearly four times higher than that of C/NMC721, which has the highest energy density among the cathode materials currently used in electric vehicles.