Effect of Adding Ag on Charge-Discharge Characteristics and Interface Analysis of Mg Alloy Anode Materials for Lithium-Ion Rechargeable Batteries

• Main Authors: Tung-HsuanHsiao, 蕭彤宣
• Other Authors: Fei-Yi Hung
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/48891601930010044364

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 101 === Lithium-ion batteries have been widely applied in various electronic devices due to their higher energy density, higher working voltage and relatively lower cost than other secondary systems. However, the current choice of graphite anode for lithium-ion batteries has the disadvantages of low energy density. Thus, there has been a growing interest in developing alternative anode materials. The theoretical specific capacity of magnesium is much higher than that of graphite, but magnesium has several disadvantages, such as high activity, low safety and severe volumetric expansion during lithiation/delithiation processes, which greatly limits the cycle life of the electrodes. In this study, Mg-Zn-Al(ZA) alloy was performed as the anode materials of lithium-ion batteries, Mg-based structure was used as the active materials, and utilizing the second phase Mg32(Al.Zn)49 to inhibit the volumetric changes. Meanwhile, adding nano- scale Ag particles into the powder systems, and then their microstructures and charge-discharge characteristics were investigated. The results indicated that the ZA anode materials had the significant differences in working temperature and current density. It had the highest discharge capacity and the best coulomb efficiency at 55℃ and 80mA/cm2. Furthermore, the effects on adding Ag particles with different ratio into ZA anode materials showed that it was able to rapidly reduce the irreversible capacity and enhance cycle performance. In addition, Ag/ZA electrodes were performed by thermal evaporation, and the results of interface diffusion and oxidation behavior by heat treatment were discussed. It was confirmed that after heat treatment, Ag/ZA electrodes formed good diffusion behavior and anti-oxidation property. Therefore, Ag/ZA had mechanical alloy interface layer by coating Ag particles, and then enhanced the charge-discharge characteristics.