低Co长寿命储氢合金MlNi_(4.57)Co_(0.17)Mn_(0.25)Al_(0.41)Y_(0.02)退火工艺的研究

Study on Annealing Process of MlNi_(4.57)Co_(0.17)Mn_(0.25)Al_(0.41)Y_(0.02) Low Co and Long Life Hydrogen Storage Alloy

采用真空感应熔炼法制备低Co长寿命储氢合金MlNi_(4.57)Co_(0.17)Mn_(0.25)Al_(0.41)Y_(0.02),进行不同的退火温度(1040、1060、1080℃)和保温5、7、10 h的退火处理,研究了不同退火工艺对合金结构和电化学性能的影响。结果表明,退火有利于合金组分均匀,消除晶格应力;随着退火温度的升高和保温时间的增加,合金的吸放氢等温平衡压PCT逐渐升高,循环稳定性明显增强,合金的最大放电容量和高倍率放电性能有所下降,且退火温度对合金电化学性能的影响高于保温时间的影响。其中,经过1060℃、保温10 h退火的合金,其最大放电容量为332.8 mA·h/g,容量保持率80%的循环次数可达到349次,综合性能最优。

The low-Co MlNi_(4.57)Co_(0.17)Mn_(0.25)Al_(0.41)Y_(0.02)hydrogen storage alloys with long life were prepared using vacuum induction melting method.Annealing was carried at different temperatures(1040℃,1060℃,1080℃)and insulation for 5 h,7 h and 10 h,respectively.The effects of different annealing processes on the microstructure and electrochemical properties of the alloys were studied.The results show that annealing is beneficial to the uniformity of the alloy composition and the elimination of lattice stress.With the increase of annealing temperature and holding time,the isothermal equilibrium pressure of PCT curves for hydrogen absorption and desorption increases gradually,and the cycling stability of the alloys increases significantly.The maximum discharge capacity and high rate discharge performance of the alloys decrease,and the effect of annealing temperature on the electrochemical performance of the alloy is stronger than that of holding time.After annealing at 1060℃for 10 h,the maximum discharge capacity of the alloy is 332.8 mA·h/g,and the cycles of 80%capacity retention rate can reach 349 times.The alloy has the best overall electrochemical performance.