電化學(xué)性能的影響
(1. 青島大學(xué) 化學(xué)化工與環(huán)境學(xué)院，青島 266071；
2. 浙江大學(xué) 材料科學(xué)與工程學(xué)院，杭州 310027)
摘 要: 采用熔體快淬法制備(Mg70.6Ni29.4)92La8貯氫合金帶，研究快淬速率對(duì)合金的微觀組織結(jié)構(gòu)及其電化學(xué)性能的影響。結(jié)果表明：隨著快淬速率的加快，合金由納米晶向非晶過(guò)渡，合金的非晶化程度增強(qiáng)，合金帶的最大放電容量增加。冷卻輥線速度為21.8 m/s制備的合金的循環(huán)最大放電容量可達(dá)568.5 mA∙h/g，經(jīng)過(guò)20次循環(huán)后，其最高容量保持率達(dá)79.3%；合金樣品充電完成后形成的氫化物主要是Mg2NiH4，同時(shí)還保留大量的非晶結(jié)構(gòu)。循環(huán)伏安測(cè)試結(jié)果顯示較明顯的氧化峰和還原峰，且峰電位差較小，反映電極合金具有較好的吸放氫反應(yīng)的可 逆性。
關(guān)鍵字: Mg-Ni-La系貯氫合金；微觀結(jié)構(gòu)；電化學(xué)性能；熔體快淬
（1. College of Chemistry, Chemical and Environmental Engineering, Qingdao University, Qingdao 266071, China;
2. College of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China）
Abstract:Hydrogen-storage (Mg70.6Ni29.4)92La8 alloys were prepared by melt-spinning. The effects of velocities of cooling roll on the microstructures and electrochemical properties for the as-quenched ribbons were investigated. The results show that the microstructure is transformed from nanocrystallization to amorphous phase, the degree of short-range order and the discharge-capacity increases with increasing the velocity of cooling roll for (Mg70.6Ni29.4)92La8 alloys. The highest discharge capacity reaches 568.5 mA·h/g for (Mg70.6Ni29.4)92La8 sample at the velocity of 21.8 m/s. The capacity conservation rate of the alloy is 79.3% after 20 cycles. It is obvious that Mg2NiH4 phase is major product with many amorphous phases during the charging process. Cyclic voltammetry results indicate significant peaks responding to oxidation and reduction reactions, and the difference between peak potentials is small, which means good reversibility of the electrode during the charge/discharge reaction.
Key words: Mg-Ni-La hydrogen-storage alloy; microstructure; electrochemical property; melt-spinning
