A groundbreaking discovery in battery technology has emerged from the research team led by Professor Jong-Beom Baek and his colleagues at the School of Energy and Chemical Engineering at UNIST. They have pioneered an innovative method for synthesizing fluorinated carbon materials (FCMs) using polytetrafluoroethylene (PTFE) and graphite, revolutionizing the field.
Fluorinated carbon materials have been a topic of immense interest due to their remarkable stability, thanks to the robust C-F bonding, which is the strongest among carbon single bonds. However, conventional fluorination methods relied on hazardous reagents like hydrofluoric acid (HF), rendering them impractical for widespread use.
In this study, the research team introduced a simple and relatively safe approach to produce FCMs on a large scale through mechanochemical depolymerization of PTFE, a common compound found in everyday objects, combined with graphite fragmentation. By employing ball-milling techniques that trigger both mechanical and chemical reactions, they successfully manufactured FCMs with vastly improved performance compared to conventional graphite.
The use of perilous compounds such as fluorine gas or HF in traditional carbon fluoride production not only raises safety concerns but also escalates manufacturing costs due to stringent safety measures. To tackle these issues, Professor Baek’s team devised a solid-phase fluorination method using PTFE, a chemically inert polymer known for its stability in atmospheric conditions and its non-toxic nature when ingested.
Experimental results revealed that subjecting PTFE to energies beyond its threshold led to the breakdown of molecular chains and the formation of radicals. This initiated a reaction resulting in the creation of carbon fluoride complexes, which adhered to the surfaces and edges of graphite particles during subsequent processes.
The resulting FCMs displayed unparalleled storage capacity and electrochemical stability compared to traditional graphite anodes. At a low charging rate of 50 mA/g, the FCMs exhibited storage capacities 2.5 times greater (951.6 mAh/g) than graphite. At a high charging rate of 10,000 mA/g, their storage capacity soared to tenfold higher (329 mAh/g). Impressively, even after undergoing more than 1,000 charge/discharge cycles at a rate of 2,000 mA/g, the FCMs retained 76.6% of their initial capacity, in stark contrast to graphite’s meager 43.8%.
“This study not only unveils safe fluorination methods but also unveils the broader potential of solid-phase reactions,” remarked Boo-Jae Jang, a researcher at the School of Energy and Chemical Engineering at UNIST.
Professor Baek further emphasized the importance of understanding solid-phase reactions, noting how they pave the way for exploring novel materials that were previously uncharted territory.
The study’s remarkable findings have been published in the prestigious journal, Advanced Functional Materials.