Publicação
Development of innovative components for the new generation of batteries
| Resumo: | The growing demand for renewable energy systems and high-energy-density applications has intensified the need for advanced and more efficient energy storage technologies. Lithium-ion batteries, though historically valued for their versatility, efficiency and energy density, are approaching their theoretical limits. Their reliance on liquid electrolytes continues to raise concerns regarding interfacial stability, longevity, and safety. Solid-state electrolytes, particularly solid polymer electrolytes (SPEs), have emerged as safer and more stable alternatives, compatible with alkali metal anodes. Simultaneously, embedded sensors enable in situ operation monitoring and improve battery safety and performance. This dissertation, developed within an FCT-funded project on smart battery components, focused on synthesising SPEs based on sodium carboxymethyl cellulose (NaCMC), doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and plasticised with glycerol. A systematic set of compositions was prepared by varying dopant concentrations to identify optimal formulations for solid-state batteries. Membranes were characterised for optical, chemical, structural, thermal, mechanical, electrochemical, and surface properties using techniques such as ultraviolet-visible spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy (EIS), Xray diffraction, polarised optical microscopy, scanning electron microscopy, thermogravimetric analysis, tensile testing, and contact angle measurements. The highest ionic conductivity (4.40 × 10-4 S/cm) was achieved for the NaCMC-based membrane with 150% LiTFSI and a 1:2 NaCMC-to-glycerol ratio, although mechanical fragility limited applicability. The 1:1 formulation with 50% LiTFSI offered a better compromise, with conductivity of 2.62 × 10-5 S/cm, Fmax = 3.0 ± 1.4 N, and εb = 58 ± 15%. All membranes exhibited thermal stability of at least 160 °C. Additionally, exploratory experiments assessed membrane interactions with loop antenna-based sensors. Electrical characterisation revealed signal shifts upon membrane application, supporting sensor sensitivity and SPE integration. Preliminary lithium-metal halfcells were also assembled and characterised via cyclic voltammetry, galvanostatic charge and discharge, and EIS, establishing protocols for future integration of the synthesised SPEs. Overall, this study provides a comprehensive assessment of biopolymer-based SPEs as multifunctional battery components, co |
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| Autores principais: | Sousa, Sara Alves de |
| Assunto: | Solid polymer electrolytes Solid-state batteries Embedded sensors Eletrólitos sólidos poliméricos Baterias de estado sólido Sensores embebidos Ciências Naturais::Outras Ciências Naturais |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | português |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The growing demand for renewable energy systems and high-energy-density applications has intensified the need for advanced and more efficient energy storage technologies. Lithium-ion batteries, though historically valued for their versatility, efficiency and energy density, are approaching their theoretical limits. Their reliance on liquid electrolytes continues to raise concerns regarding interfacial stability, longevity, and safety. Solid-state electrolytes, particularly solid polymer electrolytes (SPEs), have emerged as safer and more stable alternatives, compatible with alkali metal anodes. Simultaneously, embedded sensors enable in situ operation monitoring and improve battery safety and performance. This dissertation, developed within an FCT-funded project on smart battery components, focused on synthesising SPEs based on sodium carboxymethyl cellulose (NaCMC), doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and plasticised with glycerol. A systematic set of compositions was prepared by varying dopant concentrations to identify optimal formulations for solid-state batteries. Membranes were characterised for optical, chemical, structural, thermal, mechanical, electrochemical, and surface properties using techniques such as ultraviolet-visible spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy (EIS), Xray diffraction, polarised optical microscopy, scanning electron microscopy, thermogravimetric analysis, tensile testing, and contact angle measurements. The highest ionic conductivity (4.40 × 10-4 S/cm) was achieved for the NaCMC-based membrane with 150% LiTFSI and a 1:2 NaCMC-to-glycerol ratio, although mechanical fragility limited applicability. The 1:1 formulation with 50% LiTFSI offered a better compromise, with conductivity of 2.62 × 10-5 S/cm, Fmax = 3.0 ± 1.4 N, and εb = 58 ± 15%. All membranes exhibited thermal stability of at least 160 °C. Additionally, exploratory experiments assessed membrane interactions with loop antenna-based sensors. Electrical characterisation revealed signal shifts upon membrane application, supporting sensor sensitivity and SPE integration. Preliminary lithium-metal halfcells were also assembled and characterised via cyclic voltammetry, galvanostatic charge and discharge, and EIS, establishing protocols for future integration of the synthesised SPEs. Overall, this study provides a comprehensive assessment of biopolymer-based SPEs as multifunctional battery components, co |
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