Selenium heteroatom-doped mesoporous carbon as an efficient air-breathing electrode for rechargeable lithium–oxygen batteries

Abstract

Intentionally heteroatom-doped mesoporous carbon was generated from spent disposable paper cups and explored as an air-breathing electrode for a rechargeable lithium–oxygen (Li–O₂) battery. The crystal structures and morphologies of the respective boron, nitrogen and selenium-doped carbons were generated and were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics conducted on a rotating ring disk electrode (RRDE) under Ar and O₂ atmospheres in 0.1 M KOH revealed that the Se heteroatom-doped carbon (SeC900) electrocatalyst achieved inherently high catalytic activity as compared to the boron and nitrogen-doped carbon. The high surface area, effective O₂ adsorption and enhanced active sites provided by the Se heteroatom lead to high ORR and OER catalytic activities for the SeC900 electrocatalyst. A CR2032 coin cell was fabricated to demonstrate the Li–O₂ battery using the SeC900 electrocatalyst as an air-breathing electrode, which showed a stable open circuit voltage (OCV) of 3.14 V and a high discharge capacity of 1618 mA h g⁻¹ at a current density of 50 Ag⁻¹. Thus, a metal-free bifunctional air-cathode has been developed for the Li–O₂ battery. The fabricated air coin cell was applied for practical implementation by lighting three series-connected commercial red LED bulbs continuously for about 5 h on a single charge.