Surface Engineering of N-Doped Carbon Derived from Polyaniline for Primary Zinc-Air Batteries

Abstract

Zinc-air batteries (ZABs) with metal-free cathodes are considered environmentally friendly and cost-effective. However, more active and durable catalysts are required for this purpose. Herein, polyaniline (PANI)-derived carbon materials were obtained to boost the oxygen reduction reaction (ORR) and, consequently, the performance of a primary ZAB. The developed porous N-doped carbon (NDC) materials were engineered by varying the polymerization time and calcination temperature (500–900 °C). SEM micrographs and BET surface areas showed that the polymerization of aniline under cold conditions (5 °C) at 6, 8, or 24 h did not have a significant effect on the morphology or surface area. The fibrous structure of PANI was engineered by temperature, resulting in a progressive increase in the surface area until a three-dimensional porous structure was achieved at 900 °C with the highest area of 601.9 m² g⁻¹. The surface doping of nitrogen species shifted from PANI-rich N species to enriched graphitic N from 12.69 % (500 °C) to 24.26 % at 900 °C. The NDC 900 °C presented a voltage of 1.4 V and power density of 56 mW cm⁻² (only 7 mW cm⁻² lower than that of Pt/C). The results demonstrate that this material is an excellent candidate for high-performance primary ZABs.