掺镁La-Y-Ni系A_(2)B_(7)型储氢合金结构和电化学性能研究  

Structure and Electrochemical Properties of La-Y-Ni Based A_(2)B_(7)-type Hydrogen Storage Alloys with Magnesium Doping

作　　者：周健飞 袁远 张海民 谢云丁 罗永春[1,2] Zhou Jianfei;Yuan Yuan;Zhang Haimin;Xie Yunding;Luo Yongchun(School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;The State Key Laboratory of Advanced Processing and Reuse of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《中国稀土学报》2024年第4期730-741,I0004,共13页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金项目(51761026)资助。

摘　　要：通过粉末冶金烧结方法制备A2B7型含镁La_(1.9-x)Y_(x)Mg_(0.1)Ni_(6.48)Mn_(0.32)Al_(0.2)(x=0~1.8)和无镁La_(0.8)Y_(1.2)Ni_(6.48)Mn_(0.32)Al_(0.2)合金,研究了掺杂Mg条件下Y元素对合金物相组成、晶体结构和电化学性能的影响规律和协同作用。结果表明,适量增加Y含量有助于含Mg合金形成2H-Ce_(2)Ni_(7)型相单相组织,Mg与Y原子优先占据2H-Ce_(2)Ni_(7)型主相中的[A_(2)B_(4)]结构单元,随Y含量x增加,2H-Ce_(2)Ni_(7)型主相晶胞参数a,c,V_(cell)及[A_(2)B_(4)]与[AB_(5)]单元结构的体积差ΔV_(d)均逐渐减小,但无镁及含镁x=1.8合金的2H-Ce_(2)Ni_(7)型主相具有相对较高的V_(cell)和ΔV_(d)值。合金的放氢PCT曲线特征和电化学性能与掺Mg,Y含量及ΔV_(d)关系密切,含镁合金的电化学性能优于无镁合金,其中含镁x=1.0~1.2合金具有较小的ΔV_(d)和最佳的电化学性能,该电极放电容量达到最大值375 m Ah·g^(-1),经100周充放电循环后的容量保持率S100为91%,放电电流密度为900 mA·g^(-1)时的高倍率放电性能HRD_(900)为80%。通过掺Mg和优化Y含量可明显改善La-Y-Ni系A_(2)B_(7)型合金的电化学性能。Mg-containing La_(1.9-x)Y_(x)Mg_(0.1)Ni_(6.48)Mn_(0.32)Al_(0.2)(x=0~1.8) and Mg-free La_(0.8)Y_(1.2)Ni_(6.48)Mn_(0.32)Al_(0.2)A_(2)B_(7)-type alloys were prepared by powder metallurgy sintering, the effects of Mg doping and Y content on the phase constitutes, crystal structure and electrochemical properties of the alloys were investigated. The results show that an appropriate increase of Y content is beneficial to the formation of single phase with 2H-Ce_(2)Ni_(7) type for the Mgcontaining alloys. Mg and Y atoms preferentially occupy the [A_(2)B_(4)] subunit, the cell parameters a, c, and V_(cell) of the 2H-Ce_(2)Ni_(7)-type main phase and the volume difference ΔV_(d) between the V_([A_(2)B_(4)]) and V_([AB_(5)]) units volume gradually decrease with increasing Y content, however, the V_(cell) and ΔV_(d) of 2H-Ce_(2)Ni_(7) type phase for x=1.8 and Mgfree alloys are relatively high. The reversible hydrogen release performance and electrochemical properties of the alloys are closely related to the Y content and ΔV_(d). The electrochemical properties of the Mg-containing alloys are better than those of the Mg-free alloy with the same Y content, where x=1.0~1.2 Mg-containing alloys have smaller ΔV_(d) and the best electrochemical properties, resulting in the maximum discharge capacity of 375 mAh·g^(-1), with remaining capacity retention rate S_(100) of 91% after 100 charge/discharge cycles, and the high rate discharge performance HRD_(900) is ~80% at a discharge current density of 900 mA·g^(-1). Thus, the electrochemical properties of La-Y-Ni system A_(2)B_(7) type alloys can be significantly improved by doping Mg and optimizing Y content.

关 键 词：镍/金属氢化物电池 La-Y(Mg)-Ni系储氢合金 晶体结构 电化学性能 

分 类 号：TG139.7[一般工业技术—材料科学与工程]