Carbon Nanotube Based Textiles for Energy Storage Applications

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Addressing energy storage system economics, technical performance, and design issues requires advanced materials research and development. Material selection will play an essential role in making storage technologies affordable, efficient, and reliable options for tackling the increasing demand for energy and its generation via renewables-based sources. Current battery technology cannot compete with energy densities associated with existing sources such as petrol. In order to compete in the market with petrol-based vehicles, the energy density of batteries in electric vehicles (EVs) will have to greatly improve to enable long-range distance EVs widely affordable. Moreover, despite portable electronic devices becoming increasingly small and flexible, the energy management components tend to lag behind the other components when it comes to performance at small size and high flexibility. Another application area that requires innovative energy storage technologies is for military applications. Batteries integrated into textiles could turn military uniforms into "smart fabrics" providing uniforms with a single power source to ensure efficiency and effectiveness of military operations. Thus, the research outlined in the proposal will be focused on advancing the science and technology for multifunctional carbon nanotube (CNT) textiles for energy storage applications. Particular focus will be placed on the optimization of the cathode structure of Lithium-air (Li-air) batteries and the development of all-textile flexible electrochemical double layer supercapacitor (SC). The novel two- and three-dimensional (2D and 3D) textiles developed during this project will be based on CNT fibers and yarns made by a wet-spinning process and a dry-spinning process respectively. Fibers will be plied, twisted and textured to form several geometries with a wide range of mechanical outcomes. Twisting fibers into yarns and then knitting or weaving the yarns into a fabric will facilitate the formation of well defined porous structures with versatile porosity and ultra-high specific surface area providing a highly conductive, low density scaffold for energy storage. The gained understanding and resulting improvements in device performance could facilitate diverse applications of CNTs: electronic textiles that store energy and fibres having unrivalled toughness. When coupled with an inexpensive process for CNT synthesis, a practical process for making continuous, high performance CNT fibres is likely to result in important new products for an aging fibre industry. Before Li-air batteries can be realized as high-performance, commercially viable products there are still numerous scientific and technical challenges that must be overcome. Considerable difficulties are faced in preparing structures for the precipitation of lithium peroxide at the cathode in the discharge process. If the cathode air electrode is fully blocked, the O2 from the atmosphere cannot be reduced which will prevent battery operation. One milestone for this proposal is to develop and fabricate new nanostructured air cathodes consisting of hierarchical arrangement of CNT fibers in a textile form so as to optimize transport of all reactants to the active catalyst surfaces and provide appropriate space for solid lithium oxide products. It is also anticipated that the project will substantially enhance the energy/power densities of SCs. Although SCs are already used in many fields, more lightweight, compact and mechanically flexible energy storage devices with greater energy densities are required for a significant number of applications from wearable energy that could be incorporated into garments to space applications.