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Sustainable functionalized fiber-based structures for application in electronic and electrochemical systems
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Sustainable fiber-based structures for application in electronic and electrochemical systems
Publication . Carvalho, José Tiago Macedo de; Pereira, Luís; Martins, Rodrigo
The main goal of this PhD project was to develop fiber-based energy storage devices, commonly also known as textile-based electrochemical energy storage devices (TEESDs), namely supercapacitors (SCs). By incorporating sustainable processes and materials, two main architectures of fiber-based 1D and 2D, were explored and integrated into textiles.
The developed 1D fiber-shaped supercapacitors (FSCs) combine stretch-broken carbon fiber yarns (SBCFYs) as both current collector and active material, paired with an in-situ regenerated cellu-lose-based ionic hydrogel (RCIHs) as electrolyte. The SBCFYs and cellulose can be recovered for reuse, allowing the fabrication of new 1D FSCs without significant loss in electrochemical performance, even after 2 years and 5 months, owing to the hydrophilic nature of cellulose and stability of the SBCFYs.
The hybridization of SBCFYs was further explored with V2O5, MnO2 and MoS2 as active mate-rials with a particular focus on MoS2. Hydrothermal synthesis using conventional- and microwave-as-sisted heating (CAH, MAH) was conducted. MAH hybridized SBCFYs demonstrate 95.7 % capacitance retention after 3000 cyclic voltammetry (CV) cycles. Moreover, both hybridized SBCFYs displayed capacitive behavior even after 60 days of being synthesized through both approaches.
The 2D architecture was explored by utilizing screen-printing with commercially available inks, including silver, carbon, and PEDOT:PSS, as current collectors and active materials. An impregnated cotton fabric with cornstarch-based electrolyte (CotCSBE) was applied, providing an adhesive and ro-bust interface between the symmetric parts of the device. The influence of the number of PEDOT:PSS printed layers on devices performance was investigated, achieving capacitances of 5.51±0.44 mF·cm-2 at 5 mV·s-1, with 81.93 % retention after 10,000 galvanostatic charge-discharge (GCD) cycles for four layers. The potential of using reduced graphene oxide (rGO) and laser induced graphene (LIG) as both current collectors and active materials in the 2D architecture was also considered.
The fabricated 1D and 2D SCs exhibited versatility on different prototypes. Six woven FSCs connected in series light up three red LEDs. Additionally, five FSCs, hybridized via MAH, connected in series and hand-stitched onto a cotton fabric, demonstrated their ability to power a humidity and temperature sensor for up to 6 minutes. Six printed and textile-based 2D SCs, also connected in series, continually powered a watch for 1 hour.
MoS2 decorated carbon fiber yarn hybrids for the development of freestanding flexible supercapacitors
Publication . Carvalho, José Tiago; Correia, Afonso; Cordeiro, Neusmar J. A.; Coelho, João; Lourenço, Sidney A.; Fortunato, Elvira; Martins, Rodrigo; Pereira, Luís; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Nature Publishing Group
Academic and industrial efforts have focused on developing energy storage devices for wearable and portable electronics using low-cost, scalable, and sustainable materials and approaches. In this work, commercially available stretch-broken carbon fiber yarns (SBCFYs) were hybridized with mixed phases of 1 T and 2H MoS2 nanosheets via conventional and microwave-assisted heating (CAH, MAH) without the use of binders to fabricate symmetric freestanding 1D fiber-shaped supercapacitors (FSCs). Electrochemical characterization performed in a three-electrode configuration showed promising results with specific capacitance values of 184.41 and 180.02 F·g−1, at 1 mV·s−1 for CAH and MAH, respectively. Furthermore, after performing 3000 CV cycles at 100 mV·s−1, the capacitance retention was 79.5% and 95.7%, respectively. Using these results as a reference, symmetric 1D FSCs were fabricated by pairing hybridized SBCFYs with MoS2 by MAH. The devices exhibited specific capacitances of approximately 58.60 ± 3.06 F·g−1 at 1 mV·s−1 and 54.81 ± 7.34 F·g−1 at 0.2 A·g−1 with the highest power density achieved being 15.17 W·g−1 and energy density of 5.06×10–4Wh·g−1. In addition, five 1D FSCs were hand-stitched and connected in series onto a cotton fabric. These supercapacitors could power a temperature and humidity sensor for up to six minutes, demonstrating the practicality and versatility of the prepared 1D FSCs for powering future electronic systems.
Screen-printed, flexible, and eco-friendly thermoelectric touch sensors based on ethyl cellulose and graphite flakes inks
Publication . Figueira, J.; Bonito, R. M.; Carvalho, J. T.; Vieira, E. M. F.; Gaspar, C.; Loureiro, Joana; Correia, J. H.; Fortunato, E.; Martins, R.; Pereira, L.; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; IOP Publishing
Despite the undoubtable interest in energy conversion, thermoelectric (TE) materials can be approached from a temperature-sensitive perspective, as they can detect small thermal stimuli, such as a human touch or contact with cold/hot objects. This feature offers possibilities for different applications one of them being the integration with scalable and cost-effective, biocompatible, flexible, and lightweight thermal sensing solutions, exploring the combination of sustainable Seebeck coefficient-holding materials with printing techniques and flexible substrates. In this work, ethyl cellulose and graphite flakes inks were optimized to be used as functional material for flexible thermal touch sensors produced by screen-printing. Graphite concentrations of 10, 20 and 30 wt% were tested, with 1, 2 and 3 printed layers on four different substrates—office paper, sticker label paper, standard cotton, and organic cotton. The conjugation of these variables was assessed in terms of printability, sheet resistance and TE response. The best electrical-TE output combination is achieved by printing two layers of the ink with 20 wt% of graphite on an office paper substrate. Subsequently, thermal touch sensors with up to 48 TE elements were produced to increase the output voltage response (>4.5 mV) promoted by a gloved finger touch. Fast and repeatable touch recognition were obtained in optimized devices with a signal-to-noise ratio up to 340 and rise times bellow 0.5 s. The results evidence that the screen-printed graphite-based inks are highly suitable for flexible TE sensing applications.
Sustainable electrochemical energy storage devices using natural bast fibres
Publication . Manjakkal, Libu; Jain, Amrita; Nandy, Suman; Goswami, Sumita; Tiago Carvalho, José; Pereira, Luís; See, Chan H.; Pillai, Suresh C.; Hogg, Richard A.; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); Elsevier Science Publisher B.V.
Naturally abundant materials play a crucial role in the development of sustainable electrochemical energy storage (EES) devices including batteries and supercapacitors (SCs). This is due to limited available resources with regards to energy storage materials, and the environmental pollution produced by the toxic materials utilized in conventional EESs. In the current review, development in the field of natural bast fibres (jute, flax, hemp and kenaf) based EES devices performances is highlighted. This review emphasizes methods such as the direct use of modified fibres and activated carbon from biomass for the design of EES devices. Activated fibres were developed using both physical and chemical activation methods. Key challenges including active electrode materials preparation, capacitive retention, and the implementation of the fibre based EES devices are critically discussed. Furthermore, the recent surge in the use of wearables and portable technologies that demand further development of flexible/non-flexible EES devices are also explored. Future trends and perspectives on materials development, power management interface, recycling, biodegradability and circular economy are also addressed. It is concluded that the development of new renewable energy systems using bast fibres has many remarkable advances in device performance. For this, an innovative approach is required to develop high energy density bast fibre based sustainable EES devices which will be potentially implemented for clean energy solutions.
Alkali-Doped Nanopaper Membranes Applied as a Gate Dielectric in FETs and Logic Gates with an Enhanced Dynamic Response
Publication . Gaspar, Diana; Martins, Jorge; Carvalho, José Tiago; Grey, Paul; Simões, Rogério; Fortunato, Elvira; Martins, Rodrigo; Pereira, Luís; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; ACS - American Chemical Society
The market for flexible, hybrid, and printed electronic systems, which can appear in everything from sensors and wearables to displays and lighting, is still uncertain. What is clear is that these systems are appearing every day, enabling devices and systems that can, in the near future, be crumpled up and tucked in our pockets. Within this context, cellulose-based modified nanopapers were developed to serve both as a physical support and a gate dielectric layer in field-effect transistors (FETs) that are fully recyclable. It was found that the impregnation of those nanopapers with sodium (Na+) ions allows for low operating voltage FETs (<3 V), with mobility above 10 cm2 V-1 s-1, current modulation surpassing 105, and an improved dynamic response. Thus, it was possible to implement those transistors into simple circuits such as inverters, reaching a clear discrimination between logic states. Besides the overall improvement in electrical performance, these devices have shown to be an interesting alternative for reliable, sustainable, and flexible electronics, maintaining proper operation even under stress conditions.
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SFRH/BD/139225/2018