Conghui You

Low-Temperature Exfoliated Graphenes: Vacuum-Promoted Exfoliation and Electrochemical Energy Storage

A preheated high-temperature environment is believed to be critical for a chemical-exfoliation-based production of graphenes starting from graphite oxide, a belief that is based on not only experimental but also theoretical viewpoints. A novel exfoliation approach is reported in this study, and the exfoliation process is realized at a very low temperature, which is far below the proposed critical exfoliation temperature, by introducing a high vacuum to the exfoliation process. Owing to unique surface chemistry, low-temperature exfoliated graphenes demonstrate an excellent energy storage performance, and the electrochemical capacitance is much higher than that of the high-temperature exfoliated ones. The low-temperature exfoliation approach presents us with a possibility for a mass production of graphenes at low cost and great potentials in energy storage applications of graphene-based materials.

Flexible and planar graphene conductive additives for lithium-ion batteries

Graphene is introduced into a lithium-ion battery (LIB) as a type of novel but powerful planar conductive additive and the flexible graphene-based conducting network is characterized by a novel “plane-to-point” conducting mode with exceptional electron transport properties and unique geometrical nature (a soft and ultrathin planar structure). With a much lower fraction of graphene additives than those of commercial carbon based additives, the graphene-introduced LiFePO4 cathode shows better charge/discharge performance than commercial cases. Graphene also shows a better performance compared to carbon nanotubes, another type of novel conductive additive with similar fractions. These results present us an indication that graphene will possibly find early application as a flexible and planar conductive additive in high performance LIBs, as our further efforts have shown that a graphene-introduced battery is of better performance as compared to real commercial batteries with conventional additives.