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系统研究了Co替代Ni对LaNi3.8型LaNi3.8-xCox(x=0.0,0.2,0.4,0.6)贮氢合金组织结构和电化学性能的影响。研究表明,所有合金都由LaNi5、Ce5Co19和Pr5Co19相组成。随着Co含量的增加,3个相的相丰度发生变化,而且单胞体积也相应的增加,这使得合金的放氢平台压降低到镍氢电池需要的范围(0.01~0.1 MPa)。与LaNi3.8相比,含Co合金的循环性能得到改善。LaNi3.4Co0.4具有最大的放电容量,这一点与固态放氢量一致。LaNi3.6Co0.2倍率放电性能最好,具有最大的交换电流密度(Io)和最小的电荷转移电阻(Rct)。
The effect of Co substitution Ni on the microstructure and electrochemical properties of LaNi3.8-type LaNi3.8-xCox (x = 0.0,0.2,0.4,0.6) hydrogen storage alloys was studied systematically. Studies have shown that all the alloys consist of LaNi5, Ce5Co19 and Pr5Co19 phases. With the increase of Co content, the phase abundance of three phases changed, and the unit cell volume increased correspondingly, which made the pressure drop of the hydrogen release platform of the alloy down to the required range (0.01 ~ 0.1 MPa). Compared with LaNi3.8, the cycling performance of Co-containing alloys is improved. LaNi3.4Co0.4 has the largest discharge capacity, which is consistent with the amount of hydrogen released in the solid state. LaNi3.6Co0.2 discharge rate of the best performance, with the largest exchange current density (Io) and the smallest charge transfer resistance (Rct).