Scalable, Self‐Aligned Printing of Flexible Graphene Micro‐Supercapacitors

Abstract

Graphene micro‐supercapacitors (MSCs) are an attractive energy storage technology for powering miniaturized portable electronics. Despite considerable advances in recent years, device fabrication typically requires conventional microfabrication techniques, limiting the translation to cost‐effective and high‐throughput production. To address this issue, we report here a self‐aligned printing process utilizing capillary action of liquid inks in microfluidic channels to realize scalable, high‐fidelity manufacturing of graphene MSCs. Microstructured ink receivers and capillary channels are imprinted on plastic substrates and filled by inkjet printing of functional materials into the receivers. The liquid inks move under capillary flow into the adjoining channels, allowing reliable patterning of electronic materials in complex structures with greatly relaxed printing tolerance. Leveraging this process with pristine graphene and ion gel inks, miniaturized all‐solid‐state graphene MSCs are demonstrated to concurrently achieve outstanding resolution (active footprint: <1 mm2, minimum feature size: 20 µm) and yield (44/44 devices), while maintaining a high specific capacitance (268 µF cm–2) and robust stability to extended cycling and bending, establishing an effective route to scale down device size while scaling up production throughput.

3D‐Printed Stretchable Micro‐Supercapacitor with Remarkable Areal Performance

“…The interpenetration between the highly conductive AgNW network and the scaffold of electrochemically active materials may enable rapid, stable, and homogenous charge transfer throughout the entire depth of the electrode, which increases the areal power density of the assembled MSC device . Thanks to the introduction of AgNW networks, the conductivity of the MXene‐AgNW‐MnONW‐C60 nanocomposite films was measured to be as high as 10 970 S cm −1 (Figure S4, Supporting Information), approximately three times higher than that of the pure MXene film, and also higher than that of any previously reported printable electrode inks for MSCs . This high conductivity enables the printed 3D structure to function simultaneously as an electrode and a 3D current collector in MSCs.…”

Graphene‐Based Planar Microsupercapacitors: Recent Advances and Future Challenges

“…Hard‐printing/stamping and gravure, typically roll‐to‐roll, have been also pursued as a method for graphene‐based electrode preparation. Hyun et al combined the stamping method with a Xenon lamp reduction technique to obtain the patterned graphene‐based MSCs as shown in Figure a–e . The polydimethylsiloxane (PDMS) stamp was first fabricated onto a pretreated Si wafer: a mixture of PDMS monomer and its curing agent was poured onto the master mold and cured in an oven.…”

“…e) Electrolyte ink was inkjet‐printed onto the electrolyte receivers. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

Advances on three‐dimensional electrodes for micro‐supercapacitors: A mini‐review

“…Particularly, the in‐plane electrodes configuration not only eliminates the separator and thus significantly reducing the size of MSC unit, but also narrows interspace between positive and negative electrodes to shorten the ionic diffusion distance . Moreover, its intriguing features of straightforward integratability, outstanding mechanical flexibility, good scalability, and ingenious deployments as well as precise tunability of electrodes pattern enable it to gain much popularity recently …”

“…Particularly, the in-plane electrodes configuration not only eliminates the separator and thus significantly reducing the size of MSC unit, but also narrows interspace between positive and negative electrodes to shorten the ionic diffusion distance. 9,10 Moreover, its intriguing features of straightforward integratability, [11][12][13][14] outstanding mechanical flexibility, [14][15][16][17][18] good scalability, [19][20][21][22] and ingenious deployments 23 as well as precise tunability of electrodes pattern enable it to gain much popularity recently. [24][25][26][27] Alternative to gravimetric normalization of performance, [28][29][30] the large areal/volumetric capacities are long-term scientific pursuits for MSCs, although high volumetric energy and power densities are readily achieved for the in-plane MSCs with thin films at present, 31-33 they still suffer from severely low areal energy density compared with the sandwich counterparts.…”