World's First Development of Innovative Material Doubling Lithium-Ion Battery Performance

Professor Jo Chaeyong's Team at Pusan National University Successfully Extracts Pure Fullerene Crystalline Nanoparticles
Energy Storage Capacity Doubled, Potential to Replace Graphite Anode Materials

[Photo by Getty Images Bank]

[Asia Economy Reporter Kim Bong-su] A material that replaces graphite used in lithium-ion secondary batteries and has more than twice the storage capacity has been developed.

The National Research Foundation of Korea announced on the 31st that Professor Cho Chae-yong's research team at Pusan National University succeeded in obtaining uniform and pure fullerene crystalline nanoparticles of several hundred nanometers in size by developing a new thermal evaporation-cooling method.

Fullerene (C60) is a substance composed of 60 carbon atoms arranged in a soccer ball shape and is one of the very stable carbon allotropes. It is being studied as a material that can replace graphite, the anode material of lithium-ion secondary batteries. However, with existing synthesis methods, only amorphous and size-uneven fullerene could be obtained, which posed limitations.

(Figure 1) Electrochemical Performance and Morphology/Microstructure of C60 Nanoparticles
- Capacity and Coulombic efficiency during charge-discharge cycles of synthesized C60 nanoparticles compared to reference samples (raw C60 and HGC60 powders)
- Electron microscopy images of pure C60 nanoparticles: surface morphology (left inset) and microstructure morphology with Li insertion (applied 0.25 V) (right inset)

The pure fullerene nanoparticles with a face-centered cubic (fcc) structure synthesized for the first time by the research team can theoretically store much more lithium ions (up to 21) than the predicted number (12). Although there have been attempts to increase capacity by combining various functional groups with fullerene or modifying its structure, this research result is differentiated by crystallizing pure fullerene.

The research team expects that applying fullerene as the anode instead of graphite will maintain high energy density and long-term stability in lithium-ion secondary batteries. Structural changes due to the increase and decrease of lithium ions in the fullerene crystal during charge-discharge processes were confirmed through in-situ X-ray diffraction analysis (in-situ XRD) and ex-situ transmission electron microscopy (ex-situ TEM). As a result, the capacity was more than twice that of graphite, the conventional anode material for lithium-ion secondary batteries, and it showed excellent stability after more than 1,000 charge-discharge cycles.

The research team plans to continue theoretical simulations of the changes in fullerene crystal structure according to the increase of lithium ions.

This research result was published on the 28th in the international materials science journal Advanced Materials (featured on the back cover).

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