铸态La0.75Mg0.25Ni3.3Co0.2Six(x=0～0.2)电极合金的电化学与动力学性能

摘要

In order to improve the electrochemical cycle stability of La-Mg-Ni system (A2B7-type) hydrogen storage alloy, the Si is slightly added in the alloy. La0.75Mg0.25Ni3.3Co0.2Six(x=0, 0. 05. 0. 1. 0. 15, 0. 2) hydrogen storage alloys were prepared by casting. The electrochemical performances and microstructures of the alloyswere determined and measure ,at the same time the kinetic performances of the as-cast were measured,inclu-ding the HRD, the EIS and so on. The obtained results show that the alloys are multi-phase structure and are composed of the CaCus-type phase and the Ce2Ni7-!ype phase. The amount of the CaGu5-type phase gradually increases with the increase of Si content, but the amount of the Ce2Ni7-type phase correspondingly decrease. The addition of Si enhances the cycle stability of the alloys, but decreases the discharge capacities and the HRD of the alloys, this is relate to the add of Si change the relative content of the phase in the alloys and make the passivation phenomenon.%为了提高La-Mg-Ni系A2B7型贮氢合金的电化学循环稳定性,添加少量的Si,用铸造工艺制备了La0.75 Mg0.25 Ni3.3 Co0.2 Six(x＝0、0.05、0.1、0.15、0.2)贮氮合金,分析并测试了其微观结构和电化学性能,以及高倍率放电能力,交流阻杭等动力学性能.结果表明,合金具有多相结构,主相由CaCu5型相和Ce2Ni7型相组成.随着Si元素含量的增加,合金中的CaCu5型相逐渐的增加,Ce2Ni7型相则相应地减少.Si元素的添加提高了合金的循环稳定性,但使合金的最大放电容量和高倍率放电能力下降,这与Si添加使合金中各相的相对含量发生改变和使合金表面产生钝化现象有关.