Achieving high capacity by controlling the size of Fe/Co-N-C(t) in the cathode of lithium-oxygen batteries

Considering the energy crisis and environmental pollution caused by fossil fuel combustion, using clean energy resources is essential for the sustainable realization of human society. There is a growing need for energy storage devices that possess a greater energy density than lithium-ion batteries. Lithium-oxygen batteries are suitable for the next generation of rechargeable batteries due to their high theoretical energy density (~۳۵۰۰ Whkg−۱)[۱,۲]. Two samples were synthesized in a bimetallic system of iron and cobalt using a Metal-Organic Framework (MOF). The duration of precursor addition to the reaction vessel was controlled to synthesize Fe/Co-N-C(۱۰h) and Fe/Co-N-C(At once). The structural properties of the samples were analyzed using XRD, Raman, FT-IR, SEM, TEM, BET, and, ICP. Electrochemical tests were performed to evaluate the prepared catalysts’ activity as a lithium-oxygen battery cathode material. The Fe/Co-N-C(At once) sample, with its larger surface, showed a greater discharge capacity (۸۶۷۰ mAhg-۱) than the Fe/Co-N-C(۱۰h) sample (۸۳۳۹ mAhg-۱). However, the Fe/Co-N-C(۱۰h) sample had a larger electrochemical active surface area due to the presence of more metals in the MOF shell, resulting in higher ORR/OER activity in an alkaline environment and more stability (۱۸۰ hours) as a lithium-oxygen battery cathode compared to the Fe/Co-N-C(At once) sample (۹۰ hours).