Influence of sulfurization treatments on electrochemical performances of spherical-like NiO/Rod-like Co3O4 electrocatalysts on air-cathodes of rechargeable Zn-metal/air energy storage system

Abstract

Background

Renewable energy is an interesting way to decrease the influence of global warming effect but unstable energy output is the key problem that has to be overcome. To develop an energy storage system is thus an important way for industrial application.

Methods

Powders of spherical-like nickel oxide (NiO)/rod-like tri-cobalt tetra-oxide (Co₃O₄) were obtained using co-precipitation method and then elemental sulphur was doping into samples under sulfurization process. These S-doped samples attached onto carbon powders were coated onto Ni-foams as air-cathodes of our homemade Zn-metal/air energy storage systems for further tests.

Significant findings

The samples showed lower XRD peak intensities and uniform S element distribution in S-incorporated NiO/Co₃O₄ electrocatalysts with an increase in S-doping ratio after sulfurization. Sample with S content of 2.09 % on air-cathode in our homemade battery showed the best electrochemical performance, which exhibited the lowest charge/discharge voltage difference value of 0.73–0.76 V and specific energy capacity of around 766.71 mA-h/g-Zn at constant discharge current density of 10 mA/cm². In the electrochemical impedance spectra of samples, high carrier concentration and low charge transfer resistance of the sample with S content of 2.09 % made it have the best electrochemical performance and stability in electrolyte.