铸态及退火态La(0.8-x)Nd_xMg_(0.2)Ni_(3.15)Co_(0.2)Al_(0.1)Si_(0.05)(x=0～0.4)合金的电化学贮氢性能(英文)

Electrochemical hydrogen storage characteristics of as-cast and annealed La_(0.8-x)Nd_xMg_(0.2)Ni_(3.15)Co_(0.2)Al_(0.1)Si_(0.05)(x=0-0.4)alloys

通过铸造及退火处理制备La-Mg-Ni基A2B7型La0.8-xNdxMg0.2Ni3.15Co0.2Al0.15(x=0,0.1,0.2,0.3,0.4)电极合金,并研究Nd部分替代La对合金结构及电化学性能的影响。结果表明,所有合金样品的主相均为六方结构的Ce2Ni7型(La,Mg)2Ni7及六方结构的CaCu5型LaNi5,同时还有部分LaNi3和NdNi5残余相。铸态及退火态合金的放电容量及高倍率放电性能随着Nd含量的增加先增加后减小。当x=0.3时,铸态及退火态合金的放电容量达到最大值,分别为380.3mA·h/g和384.3mA·h/g。合金的电化学循环稳定性随着Nd含量的增加而持续增加。当Nd含量从0增加至0.4%时,铸态合金在第100次充放电循环时的容量保持率(S100)从64.98%增加至85.17%,而退火态合金的S100值从76.60%增加至96.84%。

The La-Mg-Ni-based A2B7-type La0.8-xNdxMg0.2Ni3.15Co0.2Al0.15 （x=0, 0.1, 0.2, 0.3, 0.4） electrode alloys were prepared by casting and annealing. The influences of partial substitution of Nd for La on the structure and electrochemical performance of the as-cast and annealed alloys were investigated. It was found that the experimental alloys consist of two major phases, （La, Mg）2Ni7 phase with the hexagonal Ce2Ni7-type structure and LaNi5 phase with the hexagonal CaCu5-type structure, as well as some residual phase LaNi3 and NdNi5. The discharge capacity and high rate discharge ability （HRD） of the as-cast and annealed alloys first increase and then decrease with Nd content growing. The as-cast and annealed alloys （x=0.3） yield the largest discharge capacities of 380.3 and 384.3 mA·h/g, respectively. The electrochemical cycle stability of the as-cast and annealed alloys markedly grows with Nd content rising. As the Nd content increase from 0 to 0.4. The capacity retaining rate （S100） at the 100th charging and discharging cycle increases from 64.98% to 85.17% for the as-cast alloy, and from 76.60% to 96.84% for the as-annealed alloy.