MH-Ni电池低温放电性能的研究

Study on low-temperature discharge characteristics of Ni-MH batteries

研究了贮氢合金中稀土组成和Mo含量、化学计量比、结晶组织、电解液浓度对MH Ni电池低温放电性能的影响。试验发现 ,合金中Nd含量的提高 ,使合金传热较慢 ,不利于MH Ni电池低温放电 ;而Ce含量的提高 ,降低氢化物稳定性 ,改善MH Ni电池低温放电性能 ;La含量的增加 ,提高氢化物稳定性 ,降低了MH Ni电池 - 4 0℃放电能力。贮氢合金化学计量比的提高 ,使合金产生具有催化性的第二相 ,明显地改善了MH Ni电池低温放电性能。贮氢合金冷却速度太快 ,晶粒细化 ,氢在合金中的扩散速度下降 ,降低了MH Ni电池低温放电能力。贮氢合金中加入Mo并不能提高电池低温放电容量 ,少量的Mo反而使MH Ni电池低温放电性能恶化。电解液浓度由 30 %提高到 35% (质量百分数 )可改善MH Ni电池 - 4 0℃放电能力。

Effects of the rare earth compositions and Mo additive in hydrogen storage alloy, the stoichiometric ratio, the crystal structure and the electrolyte concentration on low temperature discharge characteristics of Ni MH batteries were studied.The results show that the heat transfer speed of hydrogen storage alloy is reduced with the increase of Nd content in the alloy, that is disadvantageous to low temperature discharge characteristics of Ni MH batteries.However, the low temperature discharge characteristics can be improved by the increase of Ce content and the stoichiometric ratio in the alloy, though the stability of hydride is decreased. In addition, the discharge capacity of Ni MH batteries at -40 ℃ is reduced by the increase of La content in the alloy, though the stability of hydride is increased.The faster hydrogen storage alloy solidifies, the worse low temperature characteristics of Ni MH batteries is. Small amount of Mo additive in hydrogen storage alloy can reduce low temperature discharge capacity of Ni MH batteries. The increase of electrolyte concentration can improve dischargeability of Ni MH batteries at -40 ℃.