2012-11-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/709996摘要：可充放電式鋰離子電池在現今可攜式儲電市場被廣泛使用。然而，以離子嵌入化學(intercalation-chemistry)方式運作的鋰電池還無法達成電動車的性能要求，特別是其能量密度還不足以支持長途旅行。為使電動車具市場競爭力，次世代鋰電池包括鋰空電池的成功繫於負極材料能否轉換成鋰金屬。可充放電鋰金屬電池的問題來自於枝晶(dendrite)的生成，並導致充放電性能衰減甚或安全問題。實驗已經發現使用添加物增強電解質中聚合物隔膜(polymer separator)的機械強度可以抑制枝晶生成。因隔膜材料隨著製造技術的演進已有可能兼顧高強度與高離子傳導效能，能合理化分析質傳、反應動力與隔膜強度間交互作用對枝晶生成影響的理論已不可或缺。 本計畫提出併用即時實驗觀測與理論模擬的方式深入研究枝晶生長現象。鋰電池中枝晶生長可視為導因於鋰電極與電解質間介面的不穩定性(interfacial instability)。為合理化分析枝晶生長，嚴謹架構質量守恆、動量守恆與電量守恆的電化學模型十分重要。本計畫先以稀薄溶液理論架構出電化學模型，再對發展出的模型進行線性穩定分析(linear stability analysis)，以擾動法(perturbation method)推算出枝晶起始(onset)與抑制(inhibition)的條件。實驗部分執行鋰電池充放電過程中枝晶生長的即時觀測。我們記錄枝晶起始與生長率，並與理論預測比較，以驗證及修訂理論模型並提出物理解釋。 <br> Abstract: Rechargeable lithium ion batteries have prevailed in the current portable storage market. However, the performance demands of electric vehicles (EVs), especially in the aspect of high energy capacity for long journey range, have not been met by the intercalation-chemistry based lithium batteries. The success of next generation lithium batteries for competitive EVs including lithium air depends on a paradigm shift of anode materials towards lithium metal. The failure of rechargeable lithium metal batteries is generally attributed to dendrite formation, which leads to poor cycling performance and safety issues. Experiments have suggested that using additives to increase the mechanical strength of the polymer domains of electrolytes can inhibit dendrite formation. As separator materials begin to approach the high-modulus and high ionic conductivity requirements using advanced fabrication techniques, a physical theory becomes necessary to rationalize the coupling effects of mass transport, reaction kinetics, and elastic strength of separators on dendrites. We combine in-situ investigation with theoretical modeling to facilitate the understanding of dendrite growth phenomena. Dendrite formation can be viewed to occur between lithium electrodes and the electrolyte due to interfacial instability. To rationalize the process of dendrite formation, an electrochemical model built upon a rigorous framework of material balance, momentum balance, and charge balance is developed. Linear stability analysis based on the developed electrochemical model will be performed via the perturbation method to identify the criteria for the onset and inhibition of dendrites. In-situ experiments are conducted to observe dendrite growth during charge/discharge cycling of lithium batteries. The onset time and growth rate of dendrites will be recorded and compared with model predictions to validate and refine our theory.枝晶聚合物隔膜鋰金屬擾動法dendritelithiumpolymer separatorperturbation method