(1. 蘭州理工大學(xué)材料科學(xué)與工程學(xué)院，蘭州 730050；
2. 蘭州理工大學(xué)省部共建有色金屬先進(jìn)加工與再利用國家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050)
摘 要: 采用真空電弧熔煉和熱處理制備了A5B19型儲氫合金La0.4Y0.6Ni3.52Mn0.18Al0.1，研究了退火溫度(1173~1373 K)對合金La0.4Y0.6Ni3.52Mn0.18Al0.1相結(jié)構(gòu)和電化學(xué)性能的影響規(guī)律。結(jié)果表明，隨退火溫度增加，主相A5B19型(3R-Ce5Co19+2H-Pr5Co19)相豐度逐漸增加至81%(質(zhì)量分?jǐn)?shù))，其中1273 K時3R-Ce5Co19型相豐度最高(57%，質(zhì)量分?jǐn)?shù))，進(jìn)一步提高退火溫度有利于合金形成2H-Pr5Co19型相。主相3R-Ce5Co19和2H-Pr5Co19型相的晶胞參數(shù)a、c及晶胞體積V隨退火溫度增加均呈逐漸增大趨勢，但1373 K退火時其晶胞參數(shù)和體積均有所降低。電化學(xué)分析表明，隨退火溫度升高，合金電化學(xué)PCT曲線的放氫平臺壓有所增加；增加Ce5Co19型相豐度有利于改善合金電極的放電容量、倍率性能和循環(huán)穩(wěn)定性；退火溫度為1273 K時，合金的電化學(xué)性能最佳，其最大放電容量達(dá)到386.6 mA？h/g；放電電流密度為900 mA/g 時的高倍率性能ηHRD,900為76.7%，經(jīng)循環(huán)100周后的容量保持率S100=90.1%。氫原子在合金體相中的擴(kuò)散是影響合金電極高倍率放電性能和動力學(xué)反應(yīng)的控制步驟。
關(guān)鍵字: 鎳氫電池；La-Y-Ni系儲氫合金；熱處理；微觀結(jié)構(gòu)；電化學(xué)性能
（1. School of Materials Science and Engineering, Lanzhou University
of Technology, Lanzhou 730050, China;
2. State Key Laboratory of Advanced Processing and
Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou
730050, China）
Abstract:The effect of annealing temperature (1173-1373 K) on the phase structure and electrochemical performance of new A5B19 type hydrogen storage alloy La0.4Y0.6Ni3.52Mn0.18Al0.1 was systematically investigated. The results show that the content of the main phase A5B19 (3R-Ce5Co19+2H-Pr5Co19)-phase increases with the increase of annealing temperature, of which the 3R-Ce5Co19 phase abundance is the highest (57%, mass fraction) at 1273 K, and further increasing the annealing temperature will help the alloy form2H-Pr5Co19 type phase. The unit cell parameters a, c and unit cell volume V of the 3R-Ce5Co19 and 2H-Pr5Co19 type phases all gradually increase with the increase of annealing temperature, but the unit cell parameters and volume decrease after annealing at 1373 K. With the increase of annealing temperature, the desorption plateau of the electrochemical P-C isotherms increases. The electrochemical analysis show that increasing the abundance of Ce5Co19 type phase is beneficial to improve the discharge capacity, rate performance and cycle stability of the alloy electrodes. When the annealing temperature is 1273 K, the electrochemical properties of the alloy electrode are the best, the maximum discharge capacity reaches 386.6 mA？h/g (60 mA/g), the high-rate discharge ability at current density of 900 mA/g (HRD900) is 76.7%, and the capacity retention after 100 cycles (S100) is 90.1% (300 mA/g). The diffusion of hydrogen atoms in the alloy body is control step that affects the high-rate discharge performance and dynamic reaction of the alloy electrodes.
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