STUDY ON NONSTOICHIOMETRIC Mm-Ni SYSTEM HYDROGEN STORAGE ALLOYS
CHEN Weixiang;TANG Zhiguan;GUO Hetong;CHEN Changpin (Department of Materials Science and Engineering; Zhejiang University; Hangzhou 310027)(Department of Applied Chemistry; Tianjin University; Tianjin 300072)
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CHEN Weixiang;TANG Zhiguan;GUO Hetong;CHEN Changpin (Department of Materials Science and Engineering; Zhejiang University; Hangzhou 310027)(Department of Applied Chemistry; Tianjin University; Tianjin 300072). STUDY ON NONSTOICHIOMETRIC Mm-Ni SYSTEM HYDROGEN STORAGE ALLOYS. Acta Metall Sin, 1998, 34(2): 184-188.
Abstract The effects of nonstoichiometric ratio x on the structure, thermodynamic properties for the alloys MmBx (Mm=mischmetal, B=Ni0.72Mn0.08Co0.14Al0.06, x=4.2 - 5.5) and the charge-discharge performances of metal hydride electrodes were investigated. With x value decreasing, the unite cell volumes and the enthalpy (-ΔAH) of hydride formation increased. The relationship of plateau pressure and x of the alloys can be expressed as Inpeq= 1. 99 2x - 11. 131. Asx<5.0, the second phase Ce2Ni7 with high electrocatalytic activity segregated in small numbers in the alloys. The electrodes of nonstoichiometric alloys (x<5.0) had more capacity and superior activation than those of MmB5 and MmB5.5. At x=4.8, the nonstoichiometric alloy electrode had the maximum capacity of 274.7 mA.h/g.
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