A joint research team comprising Professor Hong John (Department of Electronic Chemical Materials, Kookmin University), Professor Lee Jae Hyun (Sungkyunkwan University), Dr Hwang Jun Yeon (Korea Institute of Science and Technology, KIST), and Professor Hong Jin Pyo (Hanyang University) has successfully grown large-area graphene at room temperature and under ambient air conditions using an ultrasonic synthesis method. This achievement has significantly mitigated the production cost and process time issues, which are the biggest obstacles to the commercialisation of graphene. Furthermore, by applying it to aqueous zinc secondary batteries, it has demonstrated its potential as a next-generation secondary battery material.

Graphene is known as a ‘dream material’, being approximately one hundred thousandth the thickness of a human hair yet possessing outstanding mechanical strength and electrical conductivity. Nevertheless, conventional synthesis methods required temperatures exceeding 1,000°C, necessitating expensive equipment capable of meeting these conditions. Low productivity further hindered commercialisation. Crucially, synthesis was inherently limited on metal substrates with low melting points, such as lithium (180°C), tin (232°C), and zinc (420°C).

The joint research team proposed a novel process that directly grows graphene onto zinc substrates with low melting points. This is achieved by inducing ‘cavitation’ – a phenomenon where high-energy ultrasound generates extreme temperatures (over 5,000°C) and pressures (over 1,000 atmospheres) instantaneously on the material's local surface. This novel synthesis method enables large-area graphene synthesis in a short time without requiring separate high-temperature or vacuum equipment.

The research team coated graphene produced via the ultrasonic process onto the zinc cathode surface of aqueous zinc secondary batteries, which are gaining attention as energy storage systems (ESS) for renewable energy power plants. As a result, dendrite growth (sharp, tree-like crystals) and corrosion, long problematic issues on zinc cathodes, were effectively suppressed. Furthermore, the team plans to extend this process to lithium metal cathodes, broadening its application scope into next-generation lithium secondary battery fields.

This research was published online in October 2025 in the internationally renowned academic journal ‘Carbon Energy (Impact Factor=24.2, top 3% in JCR)’ in the field of energy, materials, and chemistry, under the title “Direct Growth of Leopard-Patterned Graphene on Zinc Anodes via Sonochemistry for High-Performance Aqueous Zinc-Ion Batteries”.

(Left) Schematic of the ultrasonic graphene synthesis method, (Right) Synthesis principle of the ultrasonic graphene synthesis method

Professor Hong John stated, “By presenting a large-area graphene growth process that can be performed under normal conditions without special heating or vacuum, we have lowered the practical barriers to graphene commercialisation.” He added, “We will develop it as a core thin-film material for next-generation secondary batteries, including aqueous zinc secondary batteries and next-generation lithium metal batteries.”