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Micro-Supercapacitors Based on Interdigital Electrodes of Reduced Graphene Oxide and Carbon Nanotube Composites with Ultrahigh Power Handling Performance

Authors

  • Majid Beidaghi,

    1. Department of Mechanical and Materials Engineering, Florida International University, 10555 W. Flagler St., EC 3463, FL 33174, USA
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  • Chunlei Wang

    Corresponding author
    1. Department of Mechanical and Materials Engineering, Florida International University, 10555 W. Flagler St., EC 3463, FL 33174, USA
    • Department of Mechanical and Materials Engineering, Florida International University, 10555 W. Flagler St., EC 3463, FL 33174, USA.
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Abstract

A novel method for fabricating micro-patterned interdigitated electrodes based on reduced graphene oxide (rGO) and carbon nanotube (CNT) composites for ultra-high power handling micro-supercapacitor application is reported. The binder-free microelectrodes were developed by combining electrostatic spray deposition (ESD) and photolithography lift-off methods. Without typically used thermal or chemical reduction, GO sheets are readily reduced to rGO during the ESD deposition. Electrochemical measurements show that the in-plane interdigital design of the microelectrodes is effective in increasing accessibility of electrolyte ions in-between stacked rGO sheets through an electro-activation process. Addition of CNTs results in reduced restacking of rGO sheets and improved energy and power density. Cyclic voltammetry (CV) measurements show that the specific capacitance of the micro-supercapacitor based on rGO–CNT composites is 6.1 mF cm−2 at 0.01 V s−1. At a very high scan rate of 50 V s−1, a specific capacitance of 2.8 mF cm−2 (stack capacitance of 3.1 F cm−3) is recorded, which is an unprecedented performance for supercapacitors. The addition of CNT, electrolyte-accessible and binder-free microelectrodes, as well as an interdigitated in-plane design result in a high-frequency response of the micro-supercapacitors with resistive-capacitive time constants as low as 4.8 ms. These characteristics suggest that interdigitated rGO–CNT composite electrodes are promising for on-chip energy storage application with high power demands.

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