本實驗將利用恆溫揮發鑄造法(Isothermal Evaporation Casting Process，IECP)製備不同比例之 Mg3MnNi2-Mg2Ni合金系統，觀察Mg3MnNi2相(β相)對Mg2Ni相(γ相)電化學與吸放氫特性之影響。 由ICP成分分析與X光繞射分析顯示IECP製程穩定，可製備不同比例之Mg3MnNi2-Mg2Ni合金系統。藉由放電曲線與PCI曲線分析，發現HCP-Mg2Ni相(γ相)與FCC-Mg3MnNi2相(β相)之充放電過程中氧化還原電位相近，吸放氫反應壓力也相似。由XPS分析得知，添加β相於Mg2Ni(γ相)合金中，可減緩Mg2Ni合金在強鹼電解液環境下Mg(OH)2之生成速度，進而提升Mg2Ni合金放電電容量、放電效率與放電循環壽命。 由放電循環壽命與吸放氫速率測試結果也發現Mg3MnNi2相(β相)較Mg2Ni相(γ相)不易被強鹼電解液所腐蝕且不易氫化，使其添加於Mg2Ni合金時，造成Mg2Ni之電化學特性則獲得改善，但吸放氫速率隨Mg3MnNi2相(β相)添加量增加而遞減。 Mg3MnNi2-Mg2Ni alloy systems with different ratio is produced by an innovative method, isothermal evaporation casting process (IECP) in this work. The effects of Mg3MnNi2(β phase) on the electrochemical and hydrogenation properties of Mg2Ni(γ phase) alloy were investigated. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and X-ray diffraction (XRD) analyses demonstrate that mass production for Mg3MnNi2-Mg2Ni alloy systems with different ratio was successfully fabricated by IECP. It is observed that HCP-Mg2Ni (γ phase) and FCC-Mg3MnNi2 (β phase) have nearly oxidation/reduction potential and their absorption/ desorption pressure plateaus are similar. It is also found by X-ray photoelectron spectroscopy (XPS) that addition Mg3MnNi2 in Mg2Ni alloy reduced the passive Mg(OH)2 layer formation and led to discharge capacity, discharge efficiency and discharge cycle life improving. It is found that it is difficult to corroded in alkaline electrolyte and hydrogenation for Mg3MnNi2 in comparison with Mg2Ni. It is caused Mg3MnNi2 addition in Mg2Ni resulted in an improvement for electrochemical properties and a deceleration for hydriding-dehydriding rate.