Supramolecule combination of fullerene and metalloporphyrin improves zinc-air battery function

Zinc-air batteries are an inexpensive, powerful battery alternative that can be used on the small scale to power electronics or on the large scale for electric vehicles or energy storage. These batteries work when oxygen from the air oxidizes zinc, but the difficulty in oxygen activation which degrades battery performance has prevented their wide commercial adoption.

Information presented in a paper published in Carbon Future on 19 January shows how fullerene- metalloporphyrin derived carbon materials as catalysts can improve the performance and stability of zinc-air batteries.

“The sluggish kinetic characteristics caused by the difficulty in oxygen activation, oxygen to oxygen bond cleavage, and oxide removal of oxygen reduction in zinc-air batteries have limited their application in the commercial field,” said Fang-Fang Li, a professor at the School of Materials Science and Engineering at Huazhong University of Science and Technology in Wuhan, China. “Carbon-based non-noble metallic catalysts have been regarded as promising materials for oxygen reduction reaction due to their large surface areas, high electrical conductivity, outstanding mechanical properties, and excellent stability in electrochemical environments.”

Fullerene is an allotrope of carbon with a closed cage structure in the shape of a soccer ball. Fullerene crystals are created through a process called liquid-liquid interface precipitation. During this process, fullerene and active organic cobalt-metalloporphyrin are dissolved in a good solvent and then precipitate from the mixed solution when a poor solvent is added to the good solvent, thus obtaining the fullerene-metalloporphyrin cocrystal. Researchers created four versions of Co, N co-doped carbons using the cocrystal as the precursor to seek the best performance. Three were heated to different temperatures (700°C, 800°C, and 900°C) and then the final sample was also heated to 800°C, but mixed differently from the other samples without the liquid-liquid interface precipitation method.

Before testing the performance of the fullerene-metalloporphyrin cocrystal and its derived Co, N codoped carbons, researchers studied the structural features of the samples through scanning electron microscopy and X-ray diffraction, Raman spectroscopy, and additional measurements. They found that the liquid-liquid interface precipitation method increased defects, which improved the performance of the oxygen reduction reaction. They also consistently found that the co-crystal heated to 800°C performed better than the others tested throughout the experiment.

To test the performance of the fullerene-metalloporphyrin cocrystal derived Co, N codoped carbons, researchers built a homemade zinc-air battery, using the Co, N codoped carbons as the cathode. “The results highlight the exceptional long-term stability exhibited by Co, N codoped carbons. The optimized zinc-air battery performance of Co, N codoped carbons underscores the robust and enduring electrocatalytic performance. This combination of high power density and extended stability positions fullerene-metalloporphyrin cocrystal derived d Co, N codoped carbons as a highly promising catalyst for practical applications of zinc-air batteries,” said Li. 

Other contributors include Ao Yu, Qi Huang, Shixin Gao, Tingting Xu, and Ping Peng at Huazhong University of Science and Technology and Wei Zhang, Nimanyu Joshi, and Yang Yang at University of Central Florida.

The National Natural Science Foundation of China supported this research.

About Carbon Future

Carbon Future is an open access, peer-reviewed and international interdisciplinary journal that reports carbon-related materials and processes, including catalysis, energy conversion and storage, as well as low carbon emission process and engineering. Carbon Future will publish Research Articles, Reviews, Minireviews, Highlights, Perspectives, and News and Views from all aspects concerned with carbon. Carbon Future will publish articles that focus on, but not limited to, the following areas: carbon-related or -derived materials, carbon-related catalysis and fundamentals, low carbon-related energy conversion and storage, low carbon emission chemical processes.

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