Z. Yu, S. Dobbs, K. Anderson, P. Sun, B. Zhu, A. Nair, S. Wu
California State Polytechnic University, Pomona,
Keywords: 3D printing, graphene, supercapacitor, laser, UAV
Summary:Unmanned aerial vehicles, or UAVs, have played a dominant role in modern day society. Although UAVs have a variety of routines and are manufactured in different shapes, one aspect remains constant: every UAV must possess a viable, affordable, and efficient power management system that will allow the vehicle to maintain functionality. Since supercapacitors are capable of quickly charging and discharging while possessing a high power storage to weight ratio than traditional lithium ion batteries, applying them to the power management system will greatly improve overall functionality of the system and of the UAV [1-5]. Currently, students and faculty from Electrical & Computer Engineering and Chemistry & Biochemistry departments are collaborating to 3D print lightweight power storage devices-supercapacitors, using graphene electrodes and a gel electrolyte [6-7]. Graphene is under intensive study for energy storage devices, such as batteries and supercapacitors, due to its energy density and ability to recharge. These properties make graphene well suited for electric powered UAVs with the advantage of reducing weight and volume of the device. However, conventional manufacturing, which depends on the lithography process, has limitations in terms of efficiency, operational costs and scalability. We are optimizing a novel approach for mass production of graphene, using an easily applied graphene oxide film and laser-scribed graphene (LSG), which acts as both electrical insulator and a good ionic conductor . The use of a liquid electrolyte also limits the recharging speed and operating temperature. Switching to a solid electrolyte graphene supercapacitor yields enhanced environmental safety and higher energy density, thus a smaller volume needed for UAV aircraft. The current research focuses on the ease of production of such super-capacitor through the development of a superior solid electrolyte, and the robustness of 3D printing and robotic assembly. Taking advantage of the technology allows printing of a supercapacitor which can take any shape programmable in a computer model. Thus, it can be fabricated automatically in one touch, and integrated with any device with a specific structure, and enhance energy storage capacities, voltage range, and cycling properties. Most of all, our approach will ensure that, with the use of lasers in the 3D printing process, all material properties, of pure graphene will be maintained. For this research project the solid electrolyte was fabricated using PVA/LiCl-H2O system. The electrodes were made using the graphene reduced from graphene oxide (GO) via laser-scribed graphene (LSG). Figure 1 shows the schematics of the 3D printing all-solid-state graphene supercapacitor for use in the power storage system. In conclusion, new electric storage devices with two to five times improvement in power storage device power-to-weight ratios could enable electric UAVs to compete with internal combustion and jet engine-powered UAVs for long endurance fights.