電化學(xué)性能的影響
(蘭州理工大學(xué) 甘肅省有色金屬新材料
省部共建國家重點實驗室, 蘭州 730050)
摘 要: 采用單輥快凝方法制備了過化學(xué)計量比稀土貯氫合金La(NiMn)α-xAlx(5<α<6,x為0~0.5)，研究了Al含量及淬速對合金電極性能及微觀結(jié)構(gòu)的影響。 結(jié)果表明： 快淬過化學(xué)計量比合金相結(jié)構(gòu)均為過飽和CaCu5型單相， 且隨Al含量的增加， 合金晶胞體積呈線性增大；不同淬速條件下合金凝固組織的形貌和晶態(tài)存在明顯差別。 隨Al含量的增加， 合金電極的放電容量有所降低， 但電極循環(huán)壽命得到極大改善。當(dāng)x=0.3和淬速為10~15 m/s時，合金電極的最大放電容量為322和309 mA·h/g， 經(jīng)150次循環(huán)后， 電極容量保持率分別為93.5%和95.5%。 低溫(400 ℃)退火對合金電極活化性能有所改善，但并未影響合金的循環(huán)壽命。
關(guān)鍵字: AB5型無鈷貯氫合金； Al含量； 微觀結(jié)構(gòu)；電化學(xué)性能
hydrogen storage alloys
WANG Da-hui, KANG Long, CHEN Jian-hong
（ 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
