退火处理对稀土镁镍系合金电极充放电性能的影响

Effects of Annealing Treatment on the Charge/Discharge Performance of RE-Mg-Ni-based Alloy Electrode

研究了铸态合金及退火合金La0.75Mg0.25Ni3.44Co0.2Al0.03Ti0.03的充放电性能。结果表明,随着退火温度的提高,活化过程合金电极的充放电电位差先减小后增大,放电效率先增大后减小;退火合金的放电比容量均明显高于铸态合金,且1 223K退火合金的放电比容量明显大于其他退火合金;随着充放电电流密度的增加,铸态合金及退火合金的最大放电比容量均降低;退火合金的充放电循环性能得到改善。分析指出,退火合金充放电性能的改善,主要在于合金相结构的改变、组织均匀性的提高和颗粒表面吸氢元素含量的增加。

Charge/discharge performance of La0.75 Mg0. 25 Ni3.44 Co0. 2 Al0.03 Ti0.03 cast alloy or annealed alloys was investigated. The results show that with annealing temperature rising, the alloy charge/discharge potential difference decreases at first and then increases during electrode activation,contrary to the discharge efficiency. All the annealed alloys have higher specific discharge capacity than the cast alloy, and the alloy annealed at 1 223 K has obvious advantage. The maximum specific discharge capacity of the cast alloy or annealed alloys decreases with charge/discharge current density increasing. The cycling performance of annealed alloys is improved,attributed to phase composition change of the alloy,microstructure homogeneity improvement and content increase of hydrogen-absorbing element on particle surface.