Low Cost FeCo Bimetal Cathode for Li-Air Batteries

Abstract

In spite of the extremely high theoretical specific capacity of lithium oxygen (Li-O2) electrochemistry,1 low energy efficiency makes this system impractical. Among the catalysts, noble metals and their derivatives have shown improved results with low overpotentials during an oxygen evolution reaction (OER).2 Moreover, bimetal noble metal alloys have also exhibited remarkable decreases of charge overpotentials.3 However, use of noble metal based catalysts makes overcoming their inherent high cost impossible. Therefore, low cost catalysts with acceptable performance are essential for practical Li-O2 battery use. In this report, an iron cobalt bimetal-carbon nanotube (FeCo-CNT) composite was synthesized as a catalytic air cathode material for Li-O2 batteries. An Li-O2 battery using FeCo-CNT air electrodes exhibited higher efficiency than that of pristine CNT as well as higher capacity. Spectroscopic and electron microscope analyses showed that the improved cell performances can be attributed to the catalytic effect of FeCo. As a cost-effective non-noble metal catalyst, FeCo-CNT demonstrated performance comparable to noble metal catalysts in Li-O2 systems.