Electrolytic deposition of Ni particles on MCMB for Lithium Ion Battery

為了獲得高容量、高電位及高充放電效率的鋰電池陽極材料，在中間相碳微球( mesophase carbon micro bead ，MCMB)上塗佈高導電率的金屬膜是一有效方法，本研究成功地利用電化學沉積方式將鎳金屬鍍在中間相碳微球粉末上形成Ni/MCMB粉體，並應用於鋰離子二次電池之負極材料，藉由極化曲線分析電化學反應，並挑選最佳沉積電位反應區間。Ni/MCMB粉體經由TEM、XRD、SEM/EDS分析，顯示粉體為Ni/C的結構；沉積條件以0.3M和0.5M濃度的氯化鎳溶液在14V及0.7A下進行沉積，可以得到最佳的沉積效果。將碳複合材料製作成鈕扣電池，測試不同C-Rate下材料之克電容量，Ni/MCMB材料在1C放電下相較MCMB克電容量提升71~135%；從交流阻抗儀分析樣品的界面阻抗，發現Ni/MCMB材料之介面阻抗大幅降低65~85%。In order to get anode materials of high capacity, high potential and fast charge and discharge rate, coating high conductivity metals in mesophase carbon micro bead (MCMB) is an efficient way. In this study, the electrochemical deposition of nickel on MCMB, has been successfully carried out to enhance the performance of anode material in lithium ion battery. The electrochemical reaction through was analyzed by polarization curves. Ni/MCMB powders showed the Ni/C structures by TEM, XRD and SEM/EDS analysis. The deposition conditions in 0.3 M and 0.5 M NiCl2 solutions at 14V and 0.7A showed the more uniform dispersion and the finer particles. Coin cells composed of such Ni coated carbon powders revealed 71~135% more coating than the uncoated carbon powders at 1C rate, resulting from the interfacial resistance of Ni/MCMB 65~85% lower than MCMB.誌謝 I 摘要 II Abstract III Contents IV Table contents V Figure contents VI Chapter 1 Introduction 1 Chapter 2 Literature Survey 6 2.1 Electrochemical deposition 6 2.2 Materials for Anode 7 Chapter 3 Experimental 10 3.1 Cathodic polarization and deposition 10 3.2 Transmission Electron Microscopy (TEM) 11 3.3 Scanning electron microscopy (SEM) 11 3.4 X-ray diffraction (XRD) 11 3.5 Thermal gravitational/differential thermal analysis (TGA/DTA) 11 3.6 Fabrication of working electrode 12 3.7 AC impedance 12 3.8 Electrochemical testing 12 Chapter 4 Results and Discussion 16 4.1 Cathodic reactions 16 4.2 Surface morphology 17 4.3 Crystal structures 18 4.4 Discharge and charge performances 19 4.5 AC impedance analysis 19 Chapter 5 Summary and Conclusions 34 References 3