The structure and electrochemical properties of La2MgNix (x = 8.7-9.9) hydrogen storage electrode alloys
The structure and electrochemical properties of La2MgNix (x = 8.7-9.9) hydrogen storage electrode alloys
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DOI：
10.1016/j.jallcom.2006.04.032
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发表时间：
2007-02
影响因子：
6.2
通讯作者：
Ying Li;Y. Lei;Linshen Chen;G. Lu;Qiu-lin Wang
中科院分区：
文献类型：
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作者：
Ying Li;Y. Lei;Linshen Chen;G. Lu;Qiu-lin Wang
本文研究了Ni含量对La2MgNix(x=8.7–9.9)合金晶体结构和电化学性能的影响。所有合金均由六方PuNi3型结构的主相和少量杂质相（LaNi5、MgNi2）组成。合金中Ni含量的增加导致晶胞体积和氢化物稳定性下降，并导致氢化时晶胞体积膨胀率（ΔV/V）显着降低。随着Ni含量的增加，合金在50mA/g下的放电容量略有增加，在x=9.0时达到最大值411.5mAh/g，合金电极在800mA/g（HRD800）下的高倍率放电能力从38.8（x=8.7）大幅提高到84.4%（x=9.9）。富镍合金高倍率放电能力的提高归因于合金电极电催化活性的提高和合金本体中氢扩散速率的提高。在x=8.7~9.6的成分范围内，合金的循环稳定性（S100）随着Ni含量的增加而增加，从54.1（x=8.7）增加到63.4%（x=9.6）。循环稳定性的改善主要归因于富镍合金在氢化时较低的电池体积膨胀。
In this paper, the effect of Ni content on the crystal structure and electrochemical properties of the La2MgNix(x=8.7–9.9) alloys was investigated. All the alloys are composed of a main phase with hexagonal PuNi3-type structure and a small quantity of impurity phases (LaNi5, MgNi2). The increase of Ni content in the alloys leads to a decrease in both the cell volume and the hydride stability, and leads to a noticeable decrease in cell volume expansion rate (ΔV/V) on hydriding. As Ni content increases, the discharge capacity of the alloys at 50mA/g increases slightly and passes through a maximum of 411.5mAh/g at x=9.0, the high-rate dischargeability of the alloy electrodes at 800mA/g (HRD800) improves greatly from 38.8 (x=8.7) to 84.4% (x=9.9). The increase of high-rate dischargeability of the Ni-rich alloys is ascribed to the increase of the electrocatalytic activity of the alloy electrode and the higher diffusion rate of hydrogen in the bulk of the alloys. In the composition range of x=8.7–9.6, the cycling stability (S100) of the alloys increases with increasing of Ni content, increasing from 54.1 (x=8.7) to 63.4% (x=9.6). The improvement in cycling stability is mainly attributed to the lower cell volume expansion of the Ni-rich alloys on hydriding.