Publicação
Development of optical fiber sensors to evaluate the performance and safety of lithium-ion batteries
| Resumo: | Society’s dependency on fossil fuels is becoming a critical obstacle regarding environmental sustainability. The concentrated political power on institutions related to the fossil fuel market represents a worldwide energy dependence. Alternative energy sources could be explored to supply the energetic needs of human activity and better distribute the energy supply around the world. However, to be able to make use of these alternative energies is mandatory to consume them right away or to store them as potential energy, otherwise, they would be wasted. Multiple initiatives are investing and aiming to reduce the usage of fossil fuels by stimulating the research and development of alternative energy sources, together with energy storage development is crucial to potentialize the utilization and adoption of such alternative energies. Nowadays, rechargeable Li-ion batteries are the most adopted, scalable, and demanded energy storage devices in the world. The scarcity of information regarding the interior of the LiBs currently hinders the improvement of the accuracy and predicting capabilities of current battery management algorithms and models, while equally limiting attempts to refine the battery thermal design due to the absence of heat-transfer information. This has led to increasing interest in spatiotemporal imaging of the thermal flows within a cell using temperature sensors. The tracking of gas production and/or pressure variations are also very recent topics of sensing inside the LIBs. However, due to the difficulty and complexity of sensing, the integration of the sensors inside the battery cells being necessary, they were not yet so explored. In this work, hybrid optical fiber sensors based on Fabry-Perot Interferometers (FPIs) and Fiber Bragg Grating (FBG) sensors were successfully developed and characterized to discriminate two impactful parameters (pressure and temperature) internally and externally simultaneously on cylindrical lithium-ion batteries (LiB) in order to improve their operation in safety conditions. The proposed hybrid sensors consist of a photosensitive single-mode fiber (SMF), where the FBGs were inscribed and spliced to a small section of a hollow-core fiber (HCF). To create the FPI, the HCF’s tip was submerged in a UV-photosensitive polymer, creating three cavities and two observable light beam interferences in the optical spectrum, resulting in two Fabry-Perot responses. Out of four created sensors with different HCF and liquid polymer cavity’s lengths, three of them were calibrated to temperature and pressure. By tracking the FP fringes and the resulting envelope shifts of the spectral responses, it achieved higher sensitivities for the hybrid sensor with 175.86 μm and 26.38 μm of cavities’ lengths for the envelope analysis, with 31.65 nm/bar and 1.53 nm/°C, with the pressure sensitivity being the highest recorded value for this type of configuration. After calibrating steps, the hybrid sensor D was selected and embedded inside a commercial LG 18650 LiB to internally dual-parameter sensing. The placement of the FBGs and the Fabry-Perot cavity allow the detection of pressure in all battery and temperature changes near the negative and positive terminals, and in the middle of the battery during several galvanostatic cycles. Externally, were also placed one optical fiber with four FBGs to acquire external temperature variations in the outer case, being one of them outside of the case to ambient temperature control. Galvanostatic cyclic tests were performed through different temperatures, 25.0 and 40.0 °C. The online detection of the FP fringes and FBGs peaks allows, through a matrixial method discrimination, obtain the temperature and pressure variations. It resulted in successful temperature and pressure readings, resembling some occurrences presented in the available literature and other findings which concerns to pressure and temperature behaviours in different battery locations can be highlighted, like some of the thermal events were undetected by the external FBG sensors. Although some key factors need to be further studied to understand the potential of this sensor, like the long-term stability, however this hybrid sensor design has enormous potential to perform simultaneous measurements of internal pressure and temperature shifts during normal and abnormal working conditions of an 18650 LiB. |
|---|---|
| Autores principais: | Freitas, Fábio Henrique Baptista de |
| Assunto: | Optical fiber sensors Lithium-ion batteries Pressure Temperature Simultaneous tracking |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | Society’s dependency on fossil fuels is becoming a critical obstacle regarding environmental sustainability. The concentrated political power on institutions related to the fossil fuel market represents a worldwide energy dependence. Alternative energy sources could be explored to supply the energetic needs of human activity and better distribute the energy supply around the world. However, to be able to make use of these alternative energies is mandatory to consume them right away or to store them as potential energy, otherwise, they would be wasted. Multiple initiatives are investing and aiming to reduce the usage of fossil fuels by stimulating the research and development of alternative energy sources, together with energy storage development is crucial to potentialize the utilization and adoption of such alternative energies. Nowadays, rechargeable Li-ion batteries are the most adopted, scalable, and demanded energy storage devices in the world. The scarcity of information regarding the interior of the LiBs currently hinders the improvement of the accuracy and predicting capabilities of current battery management algorithms and models, while equally limiting attempts to refine the battery thermal design due to the absence of heat-transfer information. This has led to increasing interest in spatiotemporal imaging of the thermal flows within a cell using temperature sensors. The tracking of gas production and/or pressure variations are also very recent topics of sensing inside the LIBs. However, due to the difficulty and complexity of sensing, the integration of the sensors inside the battery cells being necessary, they were not yet so explored. In this work, hybrid optical fiber sensors based on Fabry-Perot Interferometers (FPIs) and Fiber Bragg Grating (FBG) sensors were successfully developed and characterized to discriminate two impactful parameters (pressure and temperature) internally and externally simultaneously on cylindrical lithium-ion batteries (LiB) in order to improve their operation in safety conditions. The proposed hybrid sensors consist of a photosensitive single-mode fiber (SMF), where the FBGs were inscribed and spliced to a small section of a hollow-core fiber (HCF). To create the FPI, the HCF’s tip was submerged in a UV-photosensitive polymer, creating three cavities and two observable light beam interferences in the optical spectrum, resulting in two Fabry-Perot responses. Out of four created sensors with different HCF and liquid polymer cavity’s lengths, three of them were calibrated to temperature and pressure. By tracking the FP fringes and the resulting envelope shifts of the spectral responses, it achieved higher sensitivities for the hybrid sensor with 175.86 μm and 26.38 μm of cavities’ lengths for the envelope analysis, with 31.65 nm/bar and 1.53 nm/°C, with the pressure sensitivity being the highest recorded value for this type of configuration. After calibrating steps, the hybrid sensor D was selected and embedded inside a commercial LG 18650 LiB to internally dual-parameter sensing. The placement of the FBGs and the Fabry-Perot cavity allow the detection of pressure in all battery and temperature changes near the negative and positive terminals, and in the middle of the battery during several galvanostatic cycles. Externally, were also placed one optical fiber with four FBGs to acquire external temperature variations in the outer case, being one of them outside of the case to ambient temperature control. Galvanostatic cyclic tests were performed through different temperatures, 25.0 and 40.0 °C. The online detection of the FP fringes and FBGs peaks allows, through a matrixial method discrimination, obtain the temperature and pressure variations. It resulted in successful temperature and pressure readings, resembling some occurrences presented in the available literature and other findings which concerns to pressure and temperature behaviours in different battery locations can be highlighted, like some of the thermal events were undetected by the external FBG sensors. Although some key factors need to be further studied to understand the potential of this sensor, like the long-term stability, however this hybrid sensor design has enormous potential to perform simultaneous measurements of internal pressure and temperature shifts during normal and abnormal working conditions of an 18650 LiB. |
|---|