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为了改善 La-Mg-Ni 系 A2B7型电极合金的电化学循环稳定性,用 Pr 部分替代合金中的 La,并用熔体快淬工艺制备了La0.75-xPrxMg0.25Ni3.2Co0.2Al0.1(x = 0, 0.1, 0.2, 0.3, 0.4)电极合金。用 XRD、SEM、TEM 分析了铸态及快淬态合金的微观结构。结果表明,铸态及快淬态合金均具有多相结构,包括 2 个主相(La,Mg)Ni3及 LaNi5和 1 个残余相 LaNi2。熔体快淬导致 LaNi5相增加而(La,Mg)Ni3相减少。电化学测试结果表明,熔体快淬显著地提高合金的电化学循环稳定性。当淬速从 0 m/s (铸态被定义为淬速 0 m/s)增加到 20 m/s 时,x=0 合金 100 次充放循环后的容量保持率从 65.32%增加到 73.97%,x=0.4 合金的容量保持率从 79.36%增加到 93.08%。
In order to improve the electrochemical cycling stability of La-Mg-Ni based A2B7 electrode alloy, La was replaced by Pr partially and La0.75-xPrxMg0.25Ni3.2Co0.2Al0.1 x = 0, 0.1, 0.2, 0.3, 0.4) electrode alloy. The microstructures of as-cast and quenched alloys were characterized by XRD, SEM and TEM. The results show that the as-cast and quenched alloys all have multi-phase structure, including two main phases (La, Mg) Ni3 and LaNi5 and one residual phase LaNi2. Rapid quenching of the melt led to an increase of LaNi5 phase and a decrease of (La, Mg) Ni3 phase. Electrochemical test results show that the melt quenching significantly improve the electrochemical stability of the alloy. When the quenching speed increased from 0 m / s (the as-cast state was defined as quenching rate 0 m / s) to 20 m / s, the capacity retention of x = 0 alloy after 100 cycles was increased from 65.32% to 73.97% , the capacity retention of x = 0.4 alloy increased from 79.36% to 93.08%.