Subscriber access provided by TULANE UNIVERSITY
Article
Scalable Micro-fabrication of Flexible, Solid-state, Inexpensive and HighPerformance Planar Micro-supercapacitors through Inkjet Printing Method Poonam Sundriyal, and Shantanu Bhattacharya ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.8b02006 • Publication Date (Web): 30 Jan 2019 Downloaded from http://pubs.acs.org on January 31, 2019
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Energy Materials
3
Scalable Micro-fabrication of Flexible, Solid-state, Inexpensive and High-Performance Planar Micro-supercapacitors through Inkjet Printing Method
4 5 6 7
Poonam Sundriyala,b, and Shantanu Bhattacharyaa,b,* a. Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, India, 208016 b. Microsystems Fabrication Laboratory, Indian Institute of Technology, Kanpur, India, 208016 *Corresponding author’s Email Id:
[email protected] 1 2
8 9
Abstract
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
Inkjet printing is becoming one of the most efficient micro-manufacturing tools to fabricate thin film devices for flexible electronics applications. The energy storage unit is one of the critical parts of the electronic devices, and the planar micro-supercapacitors (PµSCs) are the emerging energy storage architecture in miniaturized electronic devices. However, the lack of the high-performance energy storage units with the required flexibility; selection of the costeffective processes, scalability issues related to inexpensive high volume manufacturing; and proper design of the device structure are still some of the major challenges for the flexible supercapacitors (SCs). To address these issues, we report fully printed, solid-state, and flexible PµSCs fabricated on cellulose paper substrates. The digitally designed interdigitated electrode patterns are first printed on paper with rGO ink to construct a conducting matrix. Further, the negative electrode is printed using the AC-Bi2O3 ink, and the positive electrode is printed with rGO-MnO2 ink over each half side of the pre-printed conducting patterns to form an asymmetric design using different nozzles of the same printer. The PVA- KOH electrolyte ink has been printed over the electrode patterns and solidified to get the complete device. Notably, the geometric parameters such as the width of the electrode finger and the width of the interspaces between the adjacent fingers were also optimized to get the optimum electrochemical performance of the device. Interestingly, the as-prepared PµSC device display excellent electrochemical performance; including high energy and power density (energy density of 13.28 mWh/cm3 at a power density of 4.5 W/cm3), excellent rate capability (80 % of the capacitance retention as the current density increases by 32 times), excellent frequency response (a time constant of 0.09 ms), and high cycle stability (92.2 % of the capacitance retention after 20,000 cycles). In addition, the presented method is highly scalable with control over the device thickness, dimensions, size, shape, and implementation through one printing step defined through the computer-aided design (CAD) layout. The devices also show outstanding flexibility, reproducibility, and repeatability. Therefore, the proposed strategy is beneficial to improve the next generation of printable and flexible energy storage systems.
37 38
Keywords: planar micro-supercapacitors, inkjet printing, AC-Bi2O3 ink, rGO-MnO2 ink, cellulose paper.
1 ACS Paragon Plus Environment
ACS Applied Energy Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
1
1. Introduction
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
With the rapidly growing demand of the smart electronic systems such as flexible/wearable devices, self-powered devices, and the Internet of Things, much research focus is required towards the easy design and manufacturing of miniaturized, light-weight, portable, low-cost, eco-friendly, highly flexible, and high-performance energy storage units. 1-3 Such electronic devices necessitate the use of highly flexible and miniaturized power sources which may easily and precisely mount on a variety of surfaces without affecting the device performance. Traditional energy storage systems, including batteries and supercapacitors (SCs), assembled in a sandwich structure, with rigid substrates, and large overall volume are incompatible to meet the versatile form factor and mechanical flexibility requirements that the advanced electronic devices have to offer. Recently, some flexible batteries and SCs have been reported with bendable, stretchable and foldable features, which have provided a foundation for the fundamental understanding and further improvement in this area is definitely desirable.3-7 The performance of the developed devices is still questionable from a practical standpoint due to the excessive use of aqueous electrolytes, the conventional sandwich-like structures, the overall high cost, complex processing methods, and improper design of device components. Therefore, significant attention is required for the development and further advancement of the flexible energy storage devices which can then show high levels of compatibility with the industrial roadmap.
20 21 22 23 24 25 26 27 28 29 30 31 32 33
The thin film and PµSCs are one of the best alternatives for flexible energy storage devices due to their excellent power density, good cyclic stability, excellent rate capability, and good integration compatibility with a variety of shapes and sizes within versatile electronics systems. 8-13 The superior properties of these μSCs as compared to the conventional SCs are because of the following reasons: Firstly, the planar architecture design can increase the contact area between the electrode and the electrolyte, which provides an excellent power density and the rate capability performance of the device. Secondly, due to the elimination of the separators (required in conventional sandwich structure), electrolyte ion-transfer resistance can be reduced, and high-frequency response can be obtained. 14 Thirdly, the planar design is suitable for integration into complex-shaped electronic devices.9, 15, 16 Although much attention has been focused on the improvement of PµSCs, this field remains at a fledgling stage of development mostly due to the lack of exploration in the processing aspects of such devices and also limitations imposed in terms of energy density etc. which distances them from real-world applications.17
34 35 36 37 38 39 40 41
The reported techniques for the PµSCs fabrication are inkjet printing, screen printing, lithography, laser scribing, stamping, and electrochemical deposition.4, 11, 13, 18-21 The most of the methods have several problems like; complex procedures, poor scalability, timeconsuming nature, expensive, and high waste residue. Among the different techniques developed in this area the inkjet printing is one of the smart technologies that eliminate some key scalability problems.22 It uses direct deposition of digitally pre-designed patterns that provides full control over the localization, shape, size, thickness, and architecture of the printed electrodes on different substrate surfaces.23 The advantages of this method as 2 ACS Paragon Plus Environment
Page 2 of 46
Page 3 of 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Energy Materials
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
compared to the other methods are its simplicity, low-cost, non-contact deposition, no material wastage, rapidity, and environment friendliness. In the recent years, the application of the commercially available desktop printers for development of SCs and batteries has significantly reduced the cost of the printed energy storage devices, and subsequently, their production process has also been greatly simplified.24-26 Despite the several advantages that they may possess, the major limitations of this method for its broad application are the development of the printable ink with rigid physical properties which will not clog the printing nozzle and print continuously. 27-29 According to the literature27, the printable ink for the drop-on-demand printer should have a specific range of the viscosity, surface tension, and density and the inverse Ohnesorge number (Z) must be in the range of 4< Z
