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Nanostructured Yarn Composites for Structural Energy Storage

Periodic Reporting for period 1 - ENERYARN (Nanostructured Yarn Composites for Structural Energy Storage)

Reporting period: 2018-06-01 to 2020-05-31

The project was based on the multiscale engineering principles, from the CNT yarns-level to unidirectional CNT fabrics and composite structures. At the yarn-level, interactions and infiltration with polymers were exploited in order to develop new yarn stretching strategies in dry and wet state to demonstrate high mechanical properties in CNT fabrics with multiple yarns. Such fabrics were used in hybrid composite laminas, and implemented successfully in multifunctional materials for energy storage applications.
The project was focused on enhancing the cooperative load-bearing ability of CNT bundles within the yarns, and therefore, on maximizing the mechanical performance of macro-scale CNT fabrics and materials on their basis. CNT yarn-based fabrics were developed by comprising more than 200 meters of continuously spun CNT filaments from optimized synthesis conditions reassuring stable and reproducible manufacturing process.
Two strategies of stretching were implemented to maximize the alignment of CNT yarn fabrics: dry and wet with a range of solvents. The alignment of the initial and stretched fabrics was quantified through the orientation distribution function, determined by static WAXS and SAXS X-ray tests using synchrotron radiation source. Furthermore, in situ SAXS and WAXS X-ray analysis and Raman spectroscopy were performed coupled with the micromechanical tensile testing to evaluate the mechanism of stretching and the cooperative loading of CNTs in multiyarn fabrics depending on the degree of alignment.
CNT fabric laminate composites were fabricated using vacuum bag infusion and hybridized with conventional carbon fabrics, and IR and Raman spectroscopy studies were performed to evaluate the degree of polymer infiltration in respect to the observed longitudinal mechanical properties of the laminates. The perspective of application of CNT fabrics in strong and tough light-weight electrodes for novel batteries and supercapacitors has been demonstrated.
The project involved training-through-research for advanced characterization methods, including extensive work at synchrotron facilities, and soft skills training covering the essential topics on the science communication, economics and finances in science, R&D results valorization, and IP management, which strengthened the expertise of the researcher in the field of novel CNT fabrics and their applications in the energy-storing technologies.
The results include also the developed methodologies to enhance alignment of CNT fabrics and their toughness, as well as methodology to evaluate fracture toughness based on the adapted essential work of fracture method and experimental set-up for in situ X-ray and Raman spectroscopy analysis of the stress-transfer within macroscopic CNT ensembles, which were integrated into manufacturing process of CNT materials at IMDEA Materials Institute and can be further scaled up, as well as implemented in training materials and lectures for materials science and engineering students.
The achieved results have been disseminated through publications and presentations at international conferences and outreach activities, and are of interest for academic and industrial entities working on innovative materials engineering, such as producers of high-performance fibres, prepregs, and composite structures.
The achieved results enhance the core competences and innovative capacity of the researcher and IMDEA Materials Institute in synthesis and advanced characterization of novel CNT fabrics through demonstrated structural applications. The developed stretching method to enhance mutual alignment and stress-transfer in multiyarn CNT fabrics is a critical step for scaling up the manufacturing process and further industrial implementation.
The obtained results contribute to the tackling the major European societal challenges, such as to reduce weight of transport systems and energy resources consumption, and are in the frame of European Energy 2020 strategy, Europe 2020 Flagship Initiative, and The Green Paper “A 2030 framework for climate and energy policies”. The project demonstrates the successful implementation of novel CNT fabrics in current collectors and electrodes for batteries and structural elements coupled with superior toughness and outperforming previous literature data with improved mechanical performance that enables further development of light weight flexible and stretchable batteries.
Aligned CNT fabrics with enhanced mechanical properties