利用電化學法探討鋰離子電池連續充放電、溫度管理與應力分析

Abstract

近年來行動裝置與電動車發展，使得鋰離子電池在未來扮演著更重要的角色，然而與其相關的議題就更被重視。在本論文當中，探討了四個主題，第一個是電池的充放電行為與升溫情形之預測與驗證，第二個是電池的循環壽命預測，第三個是隔熱膠等級的選擇，第四個是電極微結構之應力分析。 對於循環壽命而言，我們成功建立一套模型，並且可以模擬出電池在常溫及許多種充放電條件下的循環壽命預測，並與實驗數據所建立的模型比較之。再將電池循環充放電行為推廣到變溫下的情形，並基於常溫下的驗證，我們可以預測變溫下電池的循環壽命。 在隔熱膠等級預測上，我們先模擬出三十六安時電池之放電曲線與溫度增長情形，並與工研院所量測之實驗點比較，之後預測其充電曲線，並延伸到兩串兩並及四串兩並電池組之充放電行為與溫升模擬。最後，探討不同熱傳導係數下的隔熱膠對於電池之溫度差異影響。 我們可以得出鋰原子嵌入、出電極下，對於電極所產生之應力，並與理論解析解比較。接著探討不同充電模式對於不同狀態之電池並聯之應力所產生的影響。

As rapid development of mobile devices and electric vehicle, the issue of energy storage becomes important. Lithium-ion batteries have been extensively used as important energy storage devices. On this thesis, we focus on issues related to lithium-ion battery. These are four subjects, namely, continuous charge-discharge cycle and thermal behavior, cycle life prediction, the determination of thermal interface material, and stress analysis on the electrode. The cycle life of batteries are studied. We develop a capacity fade model which is able to predict the battery cycle life at different cycling conditions. We verify the model results with the capacity loss calculated by empirical formula based on experimental data. By using two-way coupling, we extend the results to variable temperature. Our verification indicates that the capacity fade model can predict the battery cycle life with varying temperature. The thermal effect is then investigated by using interface materials with different thermal conductivity. We simulated the discharge curve of ITRI-made cells and compare it with experimental results. We also predict the charge-discharge behavior of the battery pack under varying temperature condition. The stress induced by lithium intercalation processes has destructive effects on the electrode particle, thus minimizing the stress is the solution to prolong the battery cycle life. We develop a porous electrode theory for stress analysis. As a result, we could address the effects of different charge protocols on electrode stresses. The analysis is performed using parallel-connected cells.