High performance materials for artificial muscles and energy storage devices

Abstract

Artificial muscles (i.e., stimuli-responsive materials) are muscle-like materials and devices that mimic muscle's functionality (e.g., contraction, rotation, and bending) in different aspects. Some of the common performance metrics used for evaluating artificial muscles are cycle life, gravimetric/volumetric energy and/or power density, efficiency, cost, and controllability of muscle. Having a good combination of these performance metrics is very desirable and an active field of research. Many of the state-of-the-art designs are made from some exotic materials such as carbon nanotubes and metal nanowires which are not yet commercially available; here, new designs are proposed which their performance favorably compares to those of the rival materials and yet made of readily available materials. In addition to artificial muscles, designs for fast charging micro-supercapacitors are also proposed. Fast charging energy storage devices such as supercapacitors have applications in different industries ranging from automobile to telecommunication. Cellphones, for example, use fast charging micro-supercapacitors in their GSM/GPRS modulus to generate high current pulses for signal transmission purposes. The current technologies, such as tantalum/niobium oxide micro-supercapacitors are evolving around enhancing the energy and power density by increasing the specific capacitance and operating voltage. Yet, increasing the specific capacitance is still a major challenge. In this thesis, aside from discrete component geometry, flexible (e.g., yam-based) supercapacitors have various applications from flexible circuits to wearable devices. Design and fabrication of high performance supercapacitors by utilizing metal nanowires (e.g., niobium nanowires) in both forms (i.e., flexible and solid/rigid devices) are investigated as well.