UNIST Develops High-Efficiency Graphite Anode Material with Jeokrin and Carbon Coating

A research team led by Professor Hyunwook Lee from the Department of Energy Chemical Engineering at UNIST has developed a porous graphite anode material coated with red phosphorus and carbon, called the ‘graphite-phosphorus composite,’ using a vaporization-condensation method.

The developed composite utilizes the advantages of the red phosphorus and carbon coating layers to enhance the conductivity of electrons and lithium ions generated on the graphite surface. The improved conductivity diffuses lithium ions, which were previously concentrated only on the electrode surface during fast charging, making the charging process more uniform.

Additionally, it suppresses dendrite formation that causes battery issues, thereby improving battery stability.

Professor Hyunwook Lee of the Department of Energy Chemical Engineering explained, “To alleviate non-uniformity, it is important to induce a uniform concentration of lithium ions during the electrode charging process.”

The research team utilized the low boiling point (280°C) of red phosphorus (red-colored phosphorus) to uniformly deposit phosphorus components on the graphite surface via vapor deposition.

By sealing graphite and red phosphorus in a quartz tube and heating it above the boiling point, red phosphorus vaporizes. The vaporized red phosphorus uniformly coats the graphite, and deposition occurs as the temperature is lowered.

In particular, by additionally coating with ‘petroleum pitch,’ a residue generated during crude oil separation, a graphite-phosphorus composite with controlled side reactions of red phosphorus was completed.

The research team observed the developed composite in real-time using an optical microscope and analyzed it through image processing. The color of graphite changes according to charging, and it was confirmed that the color distribution of the developed graphite-phosphorus composite became uniform by depth during charging.

Furthermore, due to improved uniformity, stable charging without dendrite formation during fast charging was confirmed through optical microscopy images. In long-term fast charge-discharge tests exceeding 1000 cycles, the composite maintained 94.4% capacity and showed a Coulombic efficiency of 99.8%, confirming its durability.

A comparison of charge and discharge between graphite anode material and graphite-phosphorus composite.

Professor Hyunwook Lee stated, “Graphite-based anode materials will lead the lithium-ion battery market for the next 10 years,” adding, “Research on the energy density of graphite and fast charging is a key factor in the graphite-based anode material market.”

He continued, “The development of graphite anode materials coated with inexpensive red phosphorus and carbon will meet the demands of the battery market.”

This research was conducted with support from the UNIST Future Leading Specialized Project, the Ministry of Science and ICT, and the National Research Foundation’s Early Career Research Program. It was published online on August 29 in the world-renowned international journal in the energy materials field, ‘ACS Energy Letters.’

This content was produced with the assistance of AI translation services.