Ag–Co Electrocatalysts for Rechargeable Lithium–O2 Batteries: O2 Pressure and Current Density Effects

Abstract

In this study, we evaluated the Ag–Co alloy as a catalyst in the Li–O2 battery electrode aiming to improve the electrochemical performance of the energy system. Ag–Co alloys were obtained by cyclic voltammetry from an electrolytic bath. The influence of O2 pressure (1.5, 2.0, and 2.5 atm) and current density (25, 50, and 75 μA cm−2) on the charge and discharge on the cell were studied. It was observed that a medium value of O2 pressure and current density was favorable to obtain a high capacity. Energy-dispersive X-ray presented that the cyclic voltammetry technique did not favor cobalt deposition. Scanning electron microscopy showed homogeneity of the deposits with the presence of cracks and small crystals. X-ray diffraction evidenced Li2O as well as the Raman spectra for nickel foam electrode. Oxygen evolution reaction was improved with Ag–Co catalyst according to linear sweep voltammetry and cyclic voltammetry analysis. Steel mesh electrode showed higher discharge capacity (336 mAh gc−1) when compared with nickel foam (115 mAh gc−1) which suggests that materials with lower cost can be used as electrodes in Li–O2 batteries.