臺灣博碩士論文加值系統

鋰離子電池商業化多年，目前廣範應用於手機、筆電……等電子產品上，其正極材料多為LiCoO2，LiCoO2電化學性能穩定、製程成熟，為現今鋰離子電池正極之主流，但是鈷價格昂貴、對環境衝擊大，因此許多研究人員都期待用其他材料取代LiCoO2。LiFePO4正極材料電化學性能優良，且其價格低廉、安全性高，是極受矚目的正極材料。不過LiFePO4鋰離子擴散速率低落及導電性不佳的缺點，使其應用上多有限制。
本實驗嘗試使用貼覆銀片的磷酸鋰鐵靶及射頻磁控濺鍍製造LiFePO4-Ag複合薄膜，並以場發射掃描式電子顯微鏡、X光繞射儀、四點探針對不同銀含量的LiFePO4-Ag複合薄膜做表面形貌、結構、導電性分析，藉由上述分析可觀察到添加銀可使LiFePO4薄膜導電性大幅上升，並於電化學分析中看到LiFePO4-Ag複合薄膜可於10 C高速率下放電，可見添加銀能增加LiFePO4薄膜的快速充放電能力。

Lithium ion batteries has been commercialized successfully. They are widely used in mobile phones and notebooks. LiCoO2 is the most commonly used cathode materials for the lithium ion batteries, due to its stable electrochemical performance and well established process. However, because cobalt is expensive and non-friendly to environment, many researcheres have be trying other materials to replace LiCoO2. LiFePO4 is a popular cathode materials for lithium ion batteries due to good electrochemical performances, low cost, high safety. Unfortunately, LiFePO4 has some drawbacks, such as low Li+ diffusion coefficient and poor electron conductivity, which limited its applications.
Recently, it has been demonstrated that improvement of LiFePO4 electronic conductivity can be achieved by carbon coating and transition metal doping. In this study, LiFePO4-Ag composite thin film were prepared by radio frequency magnetron sputtering. A composite targets, consisted of small Ag sheets attached on LiFePO4 target surface, were used. The surface morphology and microstructures of the as-deposited thin films were observed by scanning electron microscope (SEM). The film crystallography and electronic conductivity was characterized by grazing angle X-ray diffraction (XRD) and four point probe.
It was shown that the conductivity of LiFePO4-Ag composite thin films was greatly enhanced due to Ag mixing. The electrochemical analysis showed that LiFePO4-Ag composite thin films can be discharge at a high rate of 10 C. It can be concluded mixing Ag can improve the high rate performance of LiFePO4 thin film.

誌謝 i
中文摘要 iii
Abstract iv
總目錄 v
圖目錄 vii
表目錄 ix
第一章 緒論及研究動機 1
1.1 薄膜電池概論 1
1.2 研究動機 4
第二章 理論基礎與文獻回顧 7
2.1 鋰離子電池簡介 7
2.1.1 電池的演進歷史 7
2.1.2 鋰離子電池的工作原理 14
2.1.3 薄膜鋰離子電池介紹 16
2.2 磷酸鋰鐵正極材料 19
2.2.1 磷酸鋰鐵簡介 19
2.2.2 磷酸鋰鐵電化學特性 22
2.2.3 磷酸鋰鐵之研究現況 24
2.2.4 磷酸鋰鐵薄膜之相關研究 33
2.2.5 磷酸鋰鐵快速充放電相關之研究 39
第三章 實驗方法與步驟 54
3.1 實驗流程 54
3.2 靶材製備 55
3.3 薄膜試片製備 56
3.3.1 射頻磁控濺鍍法製備混銀磷酸鋰鐵薄膜 56
3.3.2 退火處理 57
3.3.3 基材位置與銀含量分佈量測 58
3.4 材料鑑定與分析 58
3.4.1 低掠角X光繞射儀（Glazing Angle X-Ray Diffractometer） 58
3.4.2 薄膜電性量測 59
3.4.3 冷場發射掃描式電子顯微鏡及能量散佈光譜儀(Cold Field Emission Scanning Electron Microscope and Energy Dispersive Spectrometer ) 60
3.3.4 X-ray光電子能譜儀 ( XPS ) 61
3.5 薄膜電化學特性分析 62
3.5.1 半電池元件製作 62
3.5.2 鈕扣型電池之組裝 63
3.5.3 電池充放電性能測試 63
3.5.4 循環伏安測試 64
第四章 結果與討論 73
4.1 基材位置與銀含量及厚度分佈量測 73
4.2 晶體結構 74
4.3 表面型態及組成成分之鑑定 77
4.4 X光光電子能譜分析 ( X-ray Photoelectron Spectrum，XPS) 81
4.5 電性量測 83
4.6 電化學測試評估 83
4.6.1 循環伏安法(Cyclic Voltammetry) 83
4.6.2 半電池充放電測試 85
第五章 結論 110
第六章 未來研究方向 111
參考文獻 112

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