A Lithium-Oxygen Battery Exploiting Carbon Nanotubes, Graphene and Gold Catalyst

Abstract

Lithium-oxygen (Li-O₂) battery is considered a high-energy alternative to Li-ion one due its characteristic electrochemical conversion process, with the additional advantage of lower cost and environmental impact. However, this emerging battery still requires an enhancement of stability and lifespan to allow its use as a practical energy storage system. In this work we investigate an electrode material benefitting of multiwalled carbon nanotubes (MWCNTs), few layer graphene (FLG), and gold nano-powder catalyst to improve the Li-O₂ battery performances in terms of energy efficiency, cycle life and stability. Morphological, structural, and electrochemical tests indicate that the composite electrode can actually boost the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and enhance the Li-O₂ process reversibility, with a capacity of 1000 mAh g⁻¹ over 70 cycles. On the other hand, the tests reveal the role of the gold in decreasing the polarization and increasing the cell life. Therefore, the results suggest the combination of carbons with various morphologies as a suitable architecture for hosting the Li-O₂ reaction products and allowing their reversible reaction. On the other hand, the results highlight the necessity for a better tuning the noble metal characteristics to further enhance the cell performances.