Development of 3D printed flexible supercapacitors: design, manufacturing, and testing

Abstract

The development of energy storage devices has represented a significant technological challenge for the past few years. Electrochemical double-layer capacitors (EDLCs), also named as supercapacitors, are a likely competitor for alternative energy storage because of their low-cost, high power density, and high fast charge/discharge rate. The recent development of EDLCs requires them to be lightweight and flexible. There are many fabrication techniques used to manufacture flexible EDLCs, and these methods can include pre-treatment to ensure more efficient penetration of activated carbon (AC) patterns onto the substrate, or those that utilise masks for the definitions of patterns on substrates. However, these methods are inconvenient for building cost-effective devices. Therefore, it was necessary to find a suitable process to reduce the steps of manufacture and to be able to print multiple materials uniformly. This research work describes the first use of a 3D printing technology to produce flexible EDLCs for energy storage. In this research work, the four essential elements for the EDLCs substrate, current collector, activated electrode, and gel electrolyte were investigated. The AC powder was milled by ball milling to optimise the paste deposition and the electrochemical performance. A flexible composite EDLC was designed and manufactured by 3D printing. The electrochemical performance of the flexible composite EDLCs was then examined. Being highly flexible is one of the critical demands for the recent development of EDLCs. Therefore, highly flexible EDLCs were designed and manufactured by only one single extrusion process. The 3D highly flexible EDLC maintains significant electrochemical performance under a mechanical bending test. To meet the power and energy requirements, the EDLCs were connected and tested in series and parallel circuits. A supercapacitor based on printed AC material displays an area specific capacitance of 1.48 F/cm2 at the scan rate of 20 mV/s. The coulombic efficiency for the flexible EDLC was found to be 59.91%, and the cycling stability was achieved to be 56% after 500 cycles. These findings indicate that 3D printing technology may be increasingly used to develop more sophisticated flexible wearable electronic devices.