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Zhenkun Wu– MSE JPP PKU PhD Defense
Time: June 6th 2015, 7:00 am(Beijing Time)
Location: Room 806, Pacific Development Center, Peking University (52th Haidian Road, Haidian district, Beijing)
The presentation will be broadcast live to Georgia Tech
Coordinate Time in GT: June 5th 2015, 7:00 pm (Atlanta, EST)
Location: IPST, RM 114.
Committee (with advisor & program affiliation)
Dr. Ching-Ping Wong (GT), co-advisor
Dr. Shulin Bai (PKU), co-advisor
Dr. Meilin Liu (GT)
Dr. Zhong Lin Wang (GT)
Dr. Pingchou Han (PKU)
Dr. Anyuan Cao (PKU)
Dr. Ruqiang Zou (PKU)
Title
Engineered Graphene for Supercapacitors, ac Line-Filters and Thermal Interface Materials
ABSTRACT
The conformal reduction and assembly of graphene oxide (GO) by metal makes it suitable for scalable production of solid flexible micro-supercapacitors (MSCs). The as-prepared MSC shows a specific areal capacitance of 0.95 mF/cm2 and maintains 98.3% after 11000 times of charge/discharge cycles. In addition, extremely small relaxation time constant of 4.8 ms is achieved in gelled electrolyte, which indicates high ion transfer mobility within the structure. The device also exhibits great flexibility which retains 93.5% of the capacitance after 5000 times of bending and twisting. The device exhibits a phase of -75.4º at 120 Hz with a specific areal capacitance much larger than that of commercial aluminum electrolytic capacitors (316 µF/cm2). These properties make the as-fabricated MSC promising for energy storage as well as line-filtering in wearable electronics. Based on the metal reduction of GO, a facile approach is designed to improve the performance of rGO-based supercapacitors and investigate the underlying mechanism. The capacitance increase is mainly attributed to the pseudocapacitance of the benzene derivative molecules rather than their spacing effect. Moreover, the para and ortho substituted benzene derivatives contribute much more than the meta substituted ones.
Meanwhile, a 3D graphene/polydimethylsiloxane composite is designed that gives a thermal resistance of as small as 14 mm2K/W. A convenient non-contact transient program is also developed to measure the thermal resistance, which is applicable for the measurement of thermal contact resistance in various situations.
