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Estudo do envelhecimento de baterias de iões de lítio
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Advisor(s)
Abstract(s)
As baterias de iões de lítio desempenham um papel fundamental em diversas
tecnologias, como dispositivos eletrónicos portáteis, veículos elétricos e sistemas de
armazenamento de energia renovável. No entanto, o seu processo de
envelhecimento durante a utilização afeta o desempenho, a capacidade de
armazenamento e a segurança. O envelhecimento pode ser provocado por fatores
como a temperatura, profundidade de descarga, taxa de variação da corrente e
número de ciclos de carga e descarga, que aceleram a degradação interna, resultando
na perda de capacidade e aumento da resistência interna.
Um dos métodos mais utilizados para estimar o seu estado de saúde (SOH) é o
método convencional baseado na degradação da capacidade, capaz de prever o SOH
com precisão, embora seja um processo lento e demorado.
Este trabalho tem como objetivo principal simular o comportamento da bateria para
diferentes estados de carga (SOC). Para isso, foi necessário estimar um modelo de
circuito equivalente e analisar os parâmetros de impedância através de gráficos de
Nyquist. O método de otimização por enxame de partículas foi aplicado para ajustar
os parâmetros do modelo equivalente, com o objetivo de alinhar o modelo estimado
aos dados experimentais. Os dados foram analisados com base em gráficos de
Nyquist com diferentes SOC’s e número de ciclos. Observa-se que, à medida que o
número de ciclos aumenta, a resistência interna tende a aumentar, o que poderá
estar associado a um comportamento transitório da capacidade.
Lithium-ion batteries play a fundamental role in feed various modern technologies, such as portable electronic devices, electric vehicles, and renewable energy storage systems. However, their ageing process during operation affects its performance, storage capacity, and safety. Ageing can be triggered by factors such as temperature, depth of discharge, current variation rate, and the number of charge/discharge cycles, which accelerate internal degradation, resulting in capacity loss and increased internal resistance. One of the most commonly used methods to estimate the State of Health (SOH) is the conventional method based on capacity degradation, which can predict the state of health accurately, although it is a slow and time-consuming process. This study aims to simulate battery behaviour for different States of Charge (SOC). To achieve this, it was necessary to estimate an equivalent circuit model and analyse impedance parameters through Nyquist plots. The Particle Swarm Optimization (PSO) method was applied to adjust the parameters of the equivalent model, with the goal of aligning the estimated model to the experimental data. The data was analysed through Nyquist plots with different SOC’s and numbers of cycles. We observed that as the number of cycles increases, internal resistance tends to decrease, which may be linked to a transient behaviour in capacity.
Lithium-ion batteries play a fundamental role in feed various modern technologies, such as portable electronic devices, electric vehicles, and renewable energy storage systems. However, their ageing process during operation affects its performance, storage capacity, and safety. Ageing can be triggered by factors such as temperature, depth of discharge, current variation rate, and the number of charge/discharge cycles, which accelerate internal degradation, resulting in capacity loss and increased internal resistance. One of the most commonly used methods to estimate the State of Health (SOH) is the conventional method based on capacity degradation, which can predict the state of health accurately, although it is a slow and time-consuming process. This study aims to simulate battery behaviour for different States of Charge (SOC). To achieve this, it was necessary to estimate an equivalent circuit model and analyse impedance parameters through Nyquist plots. The Particle Swarm Optimization (PSO) method was applied to adjust the parameters of the equivalent model, with the goal of aligning the estimated model to the experimental data. The data was analysed through Nyquist plots with different SOC’s and numbers of cycles. We observed that as the number of cycles increases, internal resistance tends to decrease, which may be linked to a transient behaviour in capacity.
Description
Keywords
Algoritmo de Otimização Bateria de Iões de Lítio Espectroscopia de Impedância Eletroquímica Mecanismos de
Degradação Mecanismos de Envelhecimento Modelo de Circuito Equivalente