Study on microstructure and electrochemical performance of the MlNi_3.55Co_0.75?xMn_0.4Al_0.3(Cu_0.75P_0.25)_x (x?=?0-0.5) composite alloys

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• 作者：Bo Zhang ; Wenyuan Wu ; ^{WuWY8368@hotmail.com} ; Xue Bian ; Ganfeng Tu
• 关键词：Hydrogen absorbing materials ; Microstructure characteristics ; Electrochemical properties ; Kinetics properties
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：15 August, 2013
• 年：2013
• 卷：236
• 期：Complete
• 页码：80-86
• 全文大小：1281 K

文摘

In order to improve the high-rate discharge capability without diminishing the cycle stability, we investigate the substitution of Cu-P for Co on the microstructure and electrochemical properties of the MlNi_3.55Co_0.75?xMn_0.4Al_0.3(Cu_0.75P_0.25)_x (x?=?0-0.5) composite alloys. The results obtained by XRD, SEM and EDS show that the MlNi_3.55Co_0.75Mn_0.4Al_0.3 alloy consists of a single phase, and the substitutional alloys are composed of multiphase structures. The electrochemical studies reveal that the substitutional alloys can be easily activated within one cycle, but the maximum discharge capacity decreases from 296.8?mA?h?g^?1 (x?=?0) to 275?mA?h?g^?1 (x?=?0.5). With the increase of Cu-P content, the capacity decay rate D₁₀₀ initially decreases from 1.26?mA?h?g^?1?cycle^?1 (x?=?0) to 0.80?mA?h?g^?1?cycle^?1 (x?=?0.3), and then increases to 1.19?mA?h?g^?1?cycle^?1 (x?=?0.5). The overall high-rate discharge capability is significantly improved with increasing Cu-P content, which is in agreement with the monotonous increase of the exchange current density and the hydrogen diffusion coefficient. The best compromise between excellent high-rate discharge capacity and favorable cycle stability of the series alloys is obtained when x?=?0.3.