Fast and Scalable Hydrodynamic Synthesis of MnO2/Defect-Free Graphene Nanocomposites with High Rate Capability and Long Cycle Life.
The integration of metal oxides and carbon materials provides a great potential for enhancing the high energy and power densities of supercapacitors, but the rational design and scalable fabrication of such composite materials still remain a challenge. Herein, we report a fast, scalable, and one-pot hydrodynamic synthesis for preparing ion conductive and defect-free graphene from graphite and MnO2/graphene nanocomposites. The use of this hydrodynamic method using Taylor-Couette flow allows us to efficiently fast shear-exfoliate graphite into large quantities of high-quality graphene sheets. Deposition of MnO2 on graphene is subsequently performed in a fluidic reactor within 10 min. The prepared MnO2/graphene nanocomposite shows outstanding electrochemical performances, such as a high specific capacitance of 679 F/g at 25 mV/s, a high rate capability of 74.7% retention at an extremely high rate of 1000 mV/s, and an excellent cycling characteristic (∼94.7% retention over 20 000 cycles). An asymmetric supercapacitor device is fabricated by assembling an anode of graphene and a cathode of MnO2/graphene, which resulted in high energy (35.2 W h/kg) and power (7.4 kW/kg) densities (accounting for the mass of both electrodes and the electrolyte) with a high rate capability and long cycle life.
['Hong|Seok Bok|SB|', 'Jeong|Jae-Min|JM|', 'Kang|Heon Gyu|HG|', 'Seo|Donghyuk|D|', 'Cha|Younghyun|Y|', 'Jeon|Hyeonyeol|H|http://orcid.org/0000-0001-9176-2913', 'Lee|Geun Young|GY|', 'Irshad|Mobina|M|', 'Kim|Do Hyun|DH|', 'Hwang|Sung Yeon|SY|http://orcid.org/0000-0002-4618-2132', 'Kim|Jung Won|JW|', 'Choi|Bong Gill|BG|http://orcid.org/0000-0002-5452-4091']
hydrodynamics MnO2 graphene nanocomposite supercapacitor