电化学性能的影响
(兰州理工大学 甘肃省有色金属新材料
省部共建国家重点实验室, 兰州 730050)
摘 要: 采用单辊快凝方法制备了过化学计量比稀土贮氢合金La(NiMn)α-xAlx(5<α<6,x为0~0.5)，研究了Al含量及淬速对合金电极性能及微观结构的影响。 结果表明： 快淬过化学计量比合金相结构均为过饱和CaCu5型单相， 且随Al含量的增加， 合金晶胞体积呈线性增大；不同淬速条件下合金凝固组织的形貌和晶态存在明显差别。 随Al含量的增加， 合金电极的放电容量有所降低， 但电极循环寿命得到极大改善。当x=0.3和淬速为10~15 m/s时，合金电极的最大放电容量为322和309 mA·h/g， 经150次循环后， 电极容量保持率分别为93.5%和95.5%。 低温(400 ℃)退火对合金电极活化性能有所改善，但并未影响合金的循环寿命。
关键字: AB5型无钴贮氢合金； Al含量； 微观结构；电化学性能
hydrogen storage alloys
（ State Key Laboratory of Gansu Advanced Nonferrous Metal Materials,
Lanzhou University of Technology， Lanzhou 730050, China ）
Abstract: The rare earth based over-stoichiometric AB5 type La(NiMn)α-xAlx (5<α<6, x=0-0.5) hydrogen storage alloys were prepared by rapid quenching. The effects of Al additive on the microstructures and electrochemical properties of the quenched alloys La(NiMn)α-xAlx(x=0-0.5) were investigated comprehensively. The experimental results show that the phase structures of the quenched alloys La(NiMn)α-xAlx(x=0-0.5) are only composed of CaCu5 type phase, both the lattice parameters and the unit cell volume increase with the increase of x. The discharge capacities of the alloys decrease obviously and the cycle stability increases dramatically with the increase of Al content. For alloys with x of 0.3 and at the relative lower quenching rate(10~15 m/s), the maximum discharge capacities of the quenched alloys reach 322 and 309 mA·h/g, respectively, the rates of capacity retention (S150) of the alloys after 150 charge/discharge cycles are about 93.5%~95.5%. After annealing at 400 ℃, the discharge capacities of the quenched alloys are enhanced slightly, but the cycle stabilities are not influenced.
Key words: AB5-type Co-free hydrogen storage alloy; Al content; crystal structure; electrochemical properties
