【摘要】 研究了快淬和退火态La15Fe77B8型储氢合金的组织结构和电化学性能。应用中频感应熔炼-快淬方法制备了La15Fe77B8型储氢合金,其组成为La15Fe2Ni72Mn7B2Al2。结构分析表明:快淬La15Fe2Ni72Mn7B2Al2合金为多相结构,包括LaNi5相、La3Ni13B2相和(Fe,Ni)相,快淬合金经1223 K保温3 h,然后在873 K保温3 h退火处理后,LaNi5相增加,La3Ni13B2相几乎消失,(Fe,Ni)相增加且形态变大。电化学测试表明,退火合金的最大容量(307 mAh.g-1)略小于快淬合金(309 mAh.g-1),而循环稳定性有所改善。退火合金电极的倍率放电能力(HRD)低于快淬合金,原因在于交换电流密度(I0)及氢在合金中的扩散系数(D)降低。快淬和退火合金电极在低温233 K时均能放出55%的容量。更多还原

【Abstract】 The microstructure and electrochemical performances of the quenched and annealed La15Fe77B8-type hydrogen storage alloy were studied.The La15Fe77B8-type alloy with chemical composition of La15Fe2Ni72Mn7B2Al2 was prepared using a vacuum induction-quenching furnace.Structure analyses showed that the quenched La15Fe2Ni72Mn7B2Al2 alloy was composed of LaNi5 phase,La3Ni13B2 phase and(Fe,Ni) phase.The LaNi5 phase increased,the La3Ni13B2 phase nearly disappeared,and the(Fe,Ni) phase got large in size after the quenched alloy was annealed at 1223 K for 3 h and then at 873 K for 3 h.The electrochemical testing showed that the maximum discharge capacity(307 mAh · g-1) of the annealed alloy electrode was appreciably less than that(309 mAh · g-1) of the quenched alloy electrode,but the cyclic stability of the annealed alloy electrode was improved a little.The annealed alloy,as compared with the quenched alloy,showed lower high rate dischargeability(HRD).It was found that the decrease of both exchange current density(I0) and diffusion coefficient(D) of hydrogen in alloy bulk was the main reason for the degraded HRD of the annealed alloy.The discharge capacity of both the quenched and annealed alloy electrodes at 233 K could reach 55% of the maximum discharge capacity at 298 K.更多还原