由於近年來對能源的需求日漸劇增，除了發展太陽能、風力、潮汐與地熱等可再生能源，電池儲能技術也漸漸受到重視，其中鋰離子電池具備能量密度高、重量輕、高電容量、環境汙染低等優點，成為最具有潛力的電池系統之一。在鋰離子電池中，層狀正極材料有高電壓、高電容量等的優點，因此為目前普遍商業用的材料，隨著時間的演進，由LiMO2 (M = Ni、Co、Mn)之一元層狀材料逐漸發展為二元層狀材料(M = NixCoy、NixMny、MnxCoy)，甚至是三元層狀材料(M = NixCoyMnz)，其中，三元層狀材料具備較好的熱穩定性、較高的電容量、成本較低等的優點，使其成為相當具競爭力的正極材料。
　　然而，在充放電的過程中仍舊存在電解液在電極表面分解、氣體的產生、過渡金屬離子溶出等的問題，造成電容量衰退、電池壽命減短以及安全的問題，由於在正極材料與電解液介面的反應可能會嚴重影響電池的電化學表現，但目前並未有完整的研究，因此，相對於實驗方法耗費大量金錢、時間與人力成本，本研究使用第一原理計算(Ab initio calculation)的方法，探討已商業化之LiNi1/3Co1/3Mn1/3O2 (NCM)正極與電解液介面之初期反應。
　　第一部分為原子級模型的建立與能量計算，首先建構出NCM的塊材模型，結構優化計算後與實驗結果比較，確認結構的正確性，接著以軟體切面建出表面的模型，經過收斂計算後即可計算表面能，並建立此材料的Wulff shape，模擬實際顆粒的形貌，觀察材料在實驗上較傾向露出的晶面，再者，進一步在表面上吸附電解液分子，計算吸附能判斷可能吸附的位置與方式。
　　第二部分則為電化學性質分析，首先，計算吸附前與吸附後的模型電荷密度差，並分析電荷轉移的現象，再者，針對吸附前後的模型進行態密度分析，並計算分波態密度與局域態密度，分析電解液分子吸附對於材料電子能帶結構的影響，有助於了解電解液分子在材料表面的初期反應。

LiNi1/3Co1/3Mn1/3O2 (NCM) is a promising cathode material with high capacity and high voltage in lithium ion batteries. However, the capacity fading mechanism and long-term cycling behavior remain a significant problem. It has been reported that these problems are related to kinds of irreversible reaction on the electrode/electrolyte interface, such as decomposition of electrolyte and the dissolution of transition metal ions. Unlike anode materials, we have less understanding of the interface between cathode and electrolyte. In this work, ab initio calculations based on density functional theory (DFT) were performed to examine the initial reactions at NCM/electrolyte interface. The atomistic model of NCM was constructed. In addition, the slab models of different facet were also constructed. With these proposed model, the surface energies of each facet were calculated. Then the simulated morphology of NCM which is also called Wulff shape was constructed. Based on the exposed planes on the Wulff shape, the adsorption models were constructed. The adsorption process was investigated according to adsorption energy, charge density difference and density of states. The result gives an insight to understand the initial reaction at NCM/electrolyte interface.

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