All-Solid-State Printed Graphene Aerosol Gel - Polymer Energy Storage Devices for Flexible and Twistable Electronics

The continual evolution and rapid implementation of smart electronic appliances and many microelectromechanical systems have led to growing interest in developing micro or nanoscale power sources [1]. With exceptional electrochemical performances such as rapid charge-discharge rate, prolonged cycle life, and ultrahigh power density, supercapacitors (SCs) possess substantial potential as an effective energy storage device, as an alternate storage framework, besides batteries. However, conventional SCs are too bulky to combine with micro-scale electronic devices. Therefore, the design and manufacture of high-end micro-scale SCs, known as micro-supercapacitors (MSCs), with desired device dimensions (of the order of few centimeters/millimeters) and high-performance metrics are needed [2]. During last few years, considerable efforts have been dedicated to fabricating 2D planar interdigitated configuration patterns for MSCs using inkjet printing techniques due to their geometric flexibility and wearable applications [3]. Herein we designed the inkjet-printed graphene aerosol interdigitated electrodes based on flexible all-solid-state MSCs with highly stable and reliable energy storage performance. The fabricated graphene aerosol-based solid-state MSC obtained a high volumetric specific capacitance of 376.63 mF cm^-3 (areal specific capacitance of 76.23 µF cm^-2) at the applied current of 0.25 µA with excellent cyclic stability (∼99 % of capacitance retention over 10000 cycles). Further, MSCs with modular connections in series and parallel were made to achieve tunable operating voltage and capacitance output. To elucidate the mechanical flexibility of the as-fabricated MSC, the electrochemical performances of the graphene aerosol-based solid-state MSC under different bending and twisting states and results in outstanding mechanical flexibility. The electrochemical performance of as-fabricated graphene aerosol-based all-solid-state MSC creates a promising way to develop highly scalable and reliable future miniaturized energy storage devices for integrated wearable electronics.<br/>Keywords: Graphene aerosol, Micro-supercapacitors, Volumetric specific capacitance, Wearable devices.<br/>Acknowledgement: S.R.D. acknowledges support from the U.S. National Science Foundation (NSF), Grant No. NSF CBET No. 1935676, for supporting the present research. S.R.D. also acknowledges HydroGraph Power Inc., Jeffrey and Joy Lessman, and Carl and Mary Ice Keystone Research scholarship for partial support of this work.<br/><u>References:</u> [1] L. Yu, Z. Fan, Y. Shao, Z. Tian, J. Sun, and Z. Liu; Adv. Energy Mater. 2019, 1901839; [2] B. Liu, Q. Zhang, L. Zhang, C. Xu, Z. Pan, Q. Zhou, W. Zhou, J. Wang, L. Gu and H. Liu; Adv. Mater. 2022, 34, 2106309; [3] A. P. S. Gaur, W. Xiang, A. Nepal, J. P. Wright, P. Chen, T. Nagaraja, S. Sigdel, B. LaCroix, C. M. Sorensen, and S. R. Das; ACS Appl. Energy Mater. 2021, 4, 7632−764.