CAJ | 학술논문

利用机械合金化法制备了 La2 Mg17+200%(质量分数)Ni复合储氢合金,并对不同球磨时间时合金的微观结构和电化学性能进行研究。结果发现,在球磨过程中Ni 粉诱导了 La-Mg-Ni 非晶/纳米晶结构的形成。XRD和 HRTEM结果共同表征了球磨80h时,合金中有 Ni 金属的存在,且 XRD 衍射峰强度较低,宽化严重,SAD 为宽化的多环,表明形成非晶结构。电化学及其反应动力学测试结果发现,不同球磨时间的电化学反应的动力学控制机理是不同的。球磨60和80h后合金中不仅存在 La-Mg-Ni 非晶相,同时也有催化剂金属Ni,使合金的表面电荷转移反应电阻较小,氢在合金体相内的扩散系数D 和极限电流密度IL 均最大,最终导致80h 的放电容量为最大值948.3mAh/g。然而,当合金的球磨时间为100和120h时,合金粉化到纳米级,100h 的电荷转移反应电阻R ct 最大,合金表面电化学反应缓慢,且合金体相内的极限电流密度和氢扩散系数均最小,属于合金电解液表面间的电荷转移和氢向体相内扩散联合控制的过程,必然导致其放电比容量较小。
이용궤계합금화법제비료 La2 Mg17+200%(질량분수)Ni복합저경합금,병대불동구마시간시합금적미관결구화전화학성능진행연구。결과발현,재구마과정중Ni 분유도료 La-Mg-Ni 비정/납미정결구적형성。XRD화 HRTEM결과공동표정료구마80h시,합금중유 Ni 금속적존재,차 XRD 연사봉강도교저,관화엄중,SAD 위관화적다배,표명형성비정결구。전화학급기반응동역학측시결과발현,불동구마시간적전화학반응적동역학공제궤리시불동적。구마60화80h후합금중불부존재 La-Mg-Ni 비정상,동시야유최화제금속Ni,사합금적표면전하전이반응전조교소,경재합금체상내적확산계수D 화겁한전류밀도IL 균최대,최종도치80h 적방전용량위최대치948.3mAh/g。연이,당합금적구마시간위100화120h시,합금분화도납미급,100h 적전하전이반응전조R ct 최대,합금표면전화학반응완만,차합금체상내적겁한전류밀도화경확산계수균최소,속우합금전해액표면간적전하전이화경향체상내확산연합공제적과정,필연도치기방전비용량교소。
The microstructure and electrochemical hydrogen storage properties of La2 Mg17 and Ni powders pre-pared by mechanical grinding method have been studied.It was found that Ni powder induced the formation of amorphous/nanocrystalline structure of La-Mg-Ni alloy.XRD and HRTEM results represent that when ball milling 80h,the alloy in the presence of metal Ni,and the intensity of XRD diffraction decreased and the peak-broad aggravation,forming to the amorphous structure.At the same time,transmission electron microscope and electron diffraction diagram (SAD)showing as the widen ring,which was further confirmed the amorphous structure.Electrochemical kinetics results indicated that the dynamic mechanism of electrochemical reaction was different with the different ball milling time.When ball milled 60 and 80h in the alloy not only exist amor-phous La-Mg-Ni alloys,but also catalyst Ni,make the smaller alloy surface charge transfer reaction resistance and higher the diffusion coefficient D and limiting current density IL ,ultimately lead to the discharge capacity for maximum at 948.3mAh/g.However,when the alloy ball milling time increased to 100 and 120h,alloy powders were in nanosized,the charge transfer reaction resistance Rct with 100h was the largest,the electro-chemical reaction of alloy surface was quite slow,and the limiting current density and the hydrogen diffusion coefficient D in the alloy bulk was minimum,which corresponding to charge transfer stage and the diffusion in alloy bulk combination controlling process.It was inevitably lead to the smaller discharge capacity.