Miniaturized Supercapacitors: Focused Ion Beam Reduced Graphene Oxide Supercapacitors with Enhanced Performance Metrics

Abstract

Miniaturization of energy storage devices with enhanced performance metrics can reduce the footprint of microdevices being used in our daily life. Micro‐­supercapacitor architectures with planar geometry provides several advantages, such as, the ability to control and reduce the distances ions travel between two electrodes, easy integration to microdevices, and offer the potential of being extended into 3D without compromising the interelectrode distances. Here, focused ion beam (FIB) technology is used to directly write miniaturized planar electrode systems of reduced graphene oxide (FIB‐rGO) on films of graphene oxide. Using optimized ion beam irradiation, interdigitated FIB‐rGO electrode designs with 40 μm long and 3.5 μm wide fingers with ultrasmall interelectrode spacing of 1 μm demonstrate a large capacitance (102 mF cm−2), ultrasmall time response (0.03 ms), low equivalent series resistance (0.35 mΩ cm2), and retain 95% of the capacitance after 1000 cycles at an ultrahigh current density of 45 mA cm−2. These performance metrics show remarkable improvements on several counts of supercapacitor performance over existing reports due to the miniaturized electrode dimensions and minimal damage to the graphene sheets. It is believed that these results can provide avenues for large‐scale fabrication of arrayed, planar, high‐performance micro‐supercapacitors with a small environmental footprint.

Wearable Textile‐Based In‐Plane Microsupercapacitors

“…The areal capacitance of our approach is generally higher than or comparable with that of MSCs fabricated by spray-coating of electrochemically exfoliated graphene/ PEDOT:PSS on paper (5.4 mF cm −2 ) and graphene/multiwalled carbon nanotubes (MWNT) on PET (2.54 mF cm −2 ), [21,22] screen printing of N-doped graphene on PET (3.4 mF cm −2 ), [23] in situ femtolaser-reducing of graphene on paper (4.92 mF cm −2 ), [24] and photolithography patterning of rGO or porous carbonacous materials on Si wafers (0.087-2.1 mF cm −2 ). [17,26] Compared to flat substrates, the wavy textile woven from a lot of microfibers can load more active materials, and therefore achieved high specific capacitance. [17,26] Compared to flat substrates, the wavy textile woven from a lot of microfibers can load more active materials, and therefore achieved high specific capacitance.…”

A Highly Durable, Transferable, and Substrate‐Versatile High‐Performance All‐Polymer Micro‐Supercapacitor with Plug‐and‐Play Function

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The ever-growing demands of portable and wearable electronic devices require continuous development in highly compact and/or flexible energy storage. Therefore, extensive investigation on micro-supercapacitors (μSCs) based on a number of printing, [2,3] lithography, [4][5][6][7][8] and laser (and/or ion) assisted methods [9][10][11][12][13] have been carried out. [1] On the other hand, the microfabrication technology opens up the possibilities for fabrication of microenergy-storage-devices with planar interdigitated structure.

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“…[1] On the other hand, the microfabrication technology opens up the possibilities for fabrication of microenergy-storage-devices with planar interdigitated structure. Therefore, extensive investigation on micro-supercapacitors (μSCs) based on a number of printing, [2,3] lithography, [4][5][6][7][8] and laser (and/or ion) assisted methods [9][10][11][12][13] have been carried out. Although these μSCs show excellent energy-storage performance (e.g., excellent power density and long cycle life) and great feasibility to be integrated to miniaturized devices, the usage scenarios are still limited due to the following disadvantages.…”

The Structural and Compositional Changes of Graphene Oxide Induced by Irradiation With 500 keV Helium and Gallium Ions

“…The ion micro‐ or nano‐beam irradiation, with a very high spatial resolution, is opening new potential routes to applications in micro/nano‐electronics (micro‐supercapacitors, micro‐bots) . Especially, the gallium (Ga) and helium (He) ion beams have become an integral part of modern electron microscopy facilities with focused ion beams (FIB method) and can be used for selective ablation, maskless patterning, and production of integrated circuits . In contrast to more common irradiation with low energy ions, the GO irradiation with medium and high energy ions is rarely mentioned and to our best knowledge, this is the first comparison of medium energy Ga and He ion irradiation influence on the GO structural, compositional, and electrical properties.…”