微量LaNi5合金與機械球磨對Mg3MnNi2合金電化學特性之影響

The study of ball-milling and LaNi5 alloy additive on the electrochemical performances of Mg3MnNi2 alloy

郭峻誠(Chun-Cheng Kuo)

指導教授 ： 李勝隆

國立中央大學/工學院/能源工程研究所/碩士(2011年)

摘要

利用恆溫揮發鑄造法（Isothermal Evaporation Casting Process，IECP）製備Mg3MnNi2合金，藉由機械球磨法與添加微量LaNi5合金，觀察各合金之結構變化與電化學特性之影響。
Mg3MnNi2合金經由機械球磨法減少顆粒及晶粒尺寸，導致比表面積的增加與吸放氫擴散路徑的縮小，進而改善Mg3MnNi2合金放電電容量，球磨30分鐘有最大放電電容量206 mAh/g較鑄態合金提升40 mAh/g，但經球磨過之合金其放電循環壽命則會大幅降低。
此外，將球磨30分鐘Mg3MnNi2合金添加 x wt.% LaNi5 (x=10,20及30)合金藉由球磨法形成複合材料，發現隨著LaNi5合金的含量增加，球磨30分鐘Mg3MnNi2合金放電循環壽命隨之提升，球磨30分鐘Mg3MnNi2-30 wt.% LaNi5合金擁有最佳放電電容量與放電循環壽命。

關鍵字

鎂基合金電極 ； 機械球磨法 ； 恆溫揮發鑄造法

並列摘要

Mg3MnNi2 alloy were prepared by IECP. The Mg3MnNi2 alloy were modified by mechanical ball-milling and LaNi5 alloy additive on the Mg3MnNi2 alloy. The phase structures and electrochemical properties of the ball-milled Mg3MnNi2 alloys and Mg3MnNi2-LaNi5 composites were studied.
The surface modification of the alloys by mechanical ball-milling led to improvement of the discharge capacity, due to increment surface area and decrement diffusion length for the desorption of absorbed hydrogen. The ball-milled 30 min of Mg3MnNi2 alloy had the largest discharge capacity 206 mAh/g that was higher than the as-cast Mg3MnNi2 alloy 40 mAh/g, but the ball-milled alloys cycle life decreased obviously.
The ball-milled 30 min Mg3MnNi2- x wt.% as-cast LaNi5 (x=10,20 and 30) composites were fabricated by mechanical ball-milling. It was found that the ball-milled 30 min 30 min Mg3MnNi2 alloy increased cycle life with increment the LaNi5 alloy content. And the ball-milled 30 min Mg3MnNi2-30 wt.% as-cast LaNi5 alloy was effectively maintained high discharge capacity and cycle life.

並列關鍵字

ball-milling ； Mg-based alloy electrode ； IECP method

參考文獻

[1] K. T. Chau, Y. S. Wong, C. C. Chan, “An overview of energy sources for electric vehicles”, Energy Conversion & Management, Vol.40, pp.1021-1039 (1999)

[2] Gowri S. Nagarajan, J. W. Van Zee, “Characterization of the performance of commercial Ni/MH batteries”, Journal of Power Sources, Vol.70, pp.173-180 (1998)

[3] Daniel Assumpcao Bertuol, Andrea Moura Bernards, Jorge Alberto Soares Tenorio, “Spent NiMH batteries: Characterization and metal recovery through mechanical processing”, Journal of Power Sources, Vol.160, pp.1465-1470 (2006)

[4] G. Sandrock, “A panoramic overview of hydrogen storage alloys from a gas reaction point of view”, Journal of Alloys and Compounds, Vol.293-265, pp.877-888 (1999)

[5] Li Sun, Pei Yao, Huakun Liu, Douglas H. Bradhurst, Shixue Duo, “Mg2Ni hydride electrodes prepared by sintering and subsequent ball milling with Ni powders”, Journal of Alloys and Compounds, Vol.293-295, pp.536-540 (1999)