A carregar...
Projeto de investigação
Multi-sensing SMART battery Electrodes concept for in-situ operation monitoring
Financiador
Autores
Publicações
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.
Cellulose-based encapsulation for all-printed flexible thermoelectric touch detectors
Publication . Figueira, Joana; Peixoto, Mariana; Gaspar, Cristina; Loureiro, Joana; Martins, Rodrigo; Carlos, Emanuel; Pereira, Luís; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; DCM - Departamento de Ciência dos Materiais; Springer
Printed and flexible electronics have gained considerable scientific attention in recent years, driving the demand for low-energy production techniques, eco-friendly materials and flexible substrates. However, effective encapsulation is essential to protect these devices in harsh environmental conditions. Thus, sustainable encapsulant materials are critical for advancing flexible electronics. In this work, we studied three encapsulant materials—commercial plastic, polyvinyl alcohol and ethyl cellulose—applied to thermoelectric touch sensors printed on paper and fabric substrates. Ethyl cellulose demonstrated promising properties in terms of flexibility, water resistance and transparency, along with a low carbon footprint. Encapsulated substrates with ethyl cellulose exhibited high contact angles (121° on fabric and 116° on paper), indicating robust water repellency. Thermal stability tests showed minimal mass loss (10%) at 315 °C, confirming its temperature resilience. Furthermore, sensors encapsulated with ethyl cellulose retained their electric performance after water submersion for 1 min and withstood 100 bending cycles, maintaining response times below 1 s and signal output around 100 µV. These findings highlight ethyl cellulose as a viable green encapsulant material compatible with large-scale sustainable electronics manufacturing.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de Projetos de I&D em Todos os Domínios Científicos - 2022
Número da atribuição
2022.04012.PTDC