Elaborate Control of Inkjet Printer for Fabrication of Chip-based Supercapacitors

Summary

This paper provides a technique for manufacturing chip-based supercapacitors using an inkjet printer. Methodologies are described in detail to synthesize inks, adjust software parameters, and analyze the electrochemical results of the manufactured supercapacitor.

Abstract

There are tremendous efforts in various fields to apply the inkjet printing method for the fabrication of wearable devices, displays, and energy storage devices. To get high-quality products, however, sophisticated operation skills are required depending on the physical properties of the ink materials. In this regard, optimizing the inkjet printing parameters is as important as developing the physical properties of the ink materials. In this study, optimization of the inkjet printing software parameters is presented for fabricating a supercapacitor. Supercapacitors are attractive energy storage systems because of their high power density, long lifespan, and various applications as power sources. Supercapacitors can be used in the Internet of Things (IoT), smartphones, wearable devices, electrical vehicles (EVs), large energy storage systems, etc. The wide range of applications demands a new method that can fabricate devices in various scales. The inkjet printing method can break through the conventional fixed-size fabrication method.

Introduction

In the past decades, multiple printing methods have been developed for various applications, including wearable devices¹, pharmaceuticals², and aerospace components³. The printing can be easily adapted for various devices by simply changing the materials to be used. Moreover, it prevents the wastage of raw materials. To manufacture electronic devices, several printing methods such as screen printing⁴, push-coating⁵, and lithography⁶ have been developed. Compared to these printing technologies, the inkjet printing method has multiple advantages, including reduced material waste, compatibility with multiple substrates⁷, low cost⁸, flexibility⁹, low-temperature processing¹⁰, and ease of mass production¹¹. However, the application of the inkjet printing method has hardly been suggested for certain sophisticated devices. Here, we present a protocol establishing detailed guidelines to use the inkjet printing method for printing a supercapacitor device.

Supercapacitors, including pseudocapacitors and electrochemical double-layer capacitors (EDLCs), are emerging as energy storage devices that can complement conventional lithium-ion batteries^12,13. Especially, EDLC is a promising energy storage device because of its low cost, high power density, and long cycle life¹⁴. Activated carbon (AC), having high specific surface area and conductivity, is used as electrode material in commercial EDLCs¹⁵. These properties of AC allow EDLCs to have a high electrochemical capacitance¹⁶. EDLCs have the passive volume in devices when the conventional fixed-size fabrication method is used. With inkjet printing, the EDLCs can be fully integrated into the product design. Therefore, the device fabricated using the inkjet printing method is functionally better than that fabricated by existing fixed-size methodologies¹⁷. The fabrication of EDLCs using the efficient inkjet printing method maximizes the stability and longevity of EDLCs and provides a free-form factor¹⁸. The printing patterns were designed by using a PCB CAD program and converted to Gerber files. The designed patterns were printed using an inkjet printer because it has precise software-enabled control, high material throughput, and printing stability.

Protocol

1. Design of pattern using PCB CAD program Run the CAD program. Click on the File button atop the program window. To form a new project file, click on the New and Project buttons. To generate the board file, click on the File, New, and Board buttons in order. Set the grid size, multiple, and alt values by clicking on the mesh-shaped Grid button at the top left of th…

Representative Results

The ink was synthesized according to step 2, and the characteristics of the ink could be confirmed according to reference18. Figure 8 shows the structural properties of conductive ink and EDLC ink, as well as the rheological properties of EDLC ink reported in the previous research18. The conductive ink is well sintered to form continuous conducting paths, and the nanoscale roughness is expected to increase the contact area with the EDLC ink (<s…

Discussion

The critical steps in this protocol are involved in the software parameter setup to print the designed pattern by finely adjusting the parameter values. Customized printing can lead to structural optimization and obtaining new mechanical properties¹⁹. The inkjet printing method with software parameter control can be used for sophisticated printing in various industries by selecting the optimized material for the printing process.

In the fabrication of supercapacitors us…

Materials

2” x 3” FR­4 board	Voltera	SKU: 1000066	PCB substrate
Activated carbon	MTI	Np-Ag-0530HT
Eagle CAD	Autodesk		PCB CAD program
Ethyl cellulose	Sigma Aldrich	46070	48.0-49.5% (w/w) ethoxyl basis
Flex 2 conductive ink	Voltera	SKU: 1000333	Flexible Ag ink
Lithium perchlorate	Sigma Aldrich	634565
Propylene carbonate	Sigma Aldrich	310328
PVDF	Sigma Aldrich	182702	average Mw ~534,000 by GPC
Smart Manager	ZIVE LAB	ver : 6. 6. 8. 9	Electrochemical analysis program
Super-P	Hyundai
Terpineol	Sigma Aldrich	432628
Thinky mixer	Thinky	ARE-310	Planetary mixer
Triton-X	Sigma Aldrich	X100
V-One printer	Voltera	SKU: 1000329	PCB printer
ZIVE SP1	Wonatech		Potentiostat device