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采用熔铸和快凝技术制备过计量比AB5.6型储氢合金La0.8Ce0.2Ni4.65-xMn0.9Ti0.05(V0.3Fe0.4Al0.3)x(x=0~1.0),研究了(V0.3Fe0.4Al0.3)对铸态和快凝合金相结构和电化学性能的影响。XRD和SEM结果表明:铸态合金组织由基体Ca Cu5型相和少量第二相组成;当x<0.7时,快凝合金组织为计量比是AB5.5的Ca Cu5型单相组织,当x≥0.7后,合金中形成少量富La的La-Ni相;铸态与快凝合金的晶胞参数a,c及晶胞体积V均随x的增加而增加,快凝合金晶胞参数和晶胞体积明显大于铸态组织。室温(298 K)下铸态和快凝合金的放氢平台压随x的增加均依次降低,其中快凝合金放氢平台压降低幅度大。电化学测试结果表明:随x的增加,铸态和快凝合金电极的活化性能和最大放电容量均呈下降趋势,但电极循环稳定性逐渐提高;x=0.3~0.5时,快凝合金电极的最大放电容量为306~316 m Ah·g-1,经100次循环后的容量保持率S100达90%左右,快凝合金电极的循环寿命明显优于铸态合金。
The AB5.6 type hydrogen storage alloy La0.8Ce0.2Ni4.65-xMn0.9Ti0.05 (V0.3Fe0.4Al0.3) x (x = 0 ~ 1.0) was prepared by the method of melt casting and rapid solidification. (V0.3Fe0.4Al0.3) on the structure and electrochemical properties of as-cast and rapidly-coagulating alloys. The results of XRD and SEM show that the as-cast alloy consists of CaCu5 phase and a small amount of second phase. When x <0.7, the rapidly solidified alloy is CaCu5 single phase with AB5.5. ≥0.7, a small amount of La-Ni phase rich in La was formed in the alloy. The unit cell parameters a and c and the unit cell volume V of the as-cast and fast-set alloys both increased with the increase of x. Cell volume was significantly larger than as-cast tissue. Room temperature (298 K) under the as-cast and fast-setting alloy hydrogen desorption platform pressure with the increase of x decreased in turn, including fast-coagulation hydrogen desorption platform pressure drop lower. The results of electrochemical tests show that the activation energy and the maximum discharge capacity of as-cast and fast-solidified alloys decrease with the increase of x, but the cyclic stability of the electrodes gradually increases. When x = 0.3 ~ 0.5, The maximum discharge capacity is 306 ~ 316 m Ah · g-1. After 100 cycles, the capacity retention rate S100 reaches 90%. The cycle life of the fast-solidified alloy electrode is obviously better than that of the as-cast alloy.