Hydrogen Storage Properties And Forming Treatment Of RE-Mg-Ni Based Alloy Prepared By Thermal Diffusion Method

Hydrogen energy is considered an important secondary energy source because of its abundant storage capacity,high calorific value of combustion and clean and non-polluting combustion products.Hydrogen storage technology is the key to the effective utilization of hydrogen energy.RE-Mg-Ni based alloys with large hydrogen storage capacity,good reversibility and high safety are very promising solid state hydrogen storage materials.However,the Mg element volatilizes seriously during the induction melting preparation process and the sample consistency is poor,which makes it difficult to further improve the cycle stability and so on.To solve this problem,this paper adopts the thermal diffusion method to prepare RE-Mg-Ni based alloy to accurately regulate the Mg element and hydrogen storage performance,and we select the alloy with good comprehensive hydrogen storage performance to further study the effect of polymer addition on the performance and cyclic stability of RE-Mg-Ni based hydrogen storage alloy.The A₂B₇ type(La_0.34Ce_0.11Sm_0.34Y_0.15)_0.92Mg_0.14Ni_3.42Co_0.11 alloy containing Ce₂Ni₇,Gd₂Co₇ phases was prepared by thermal diffusion method using La_0.34Ce_0.11Sm_0.34Y_0.15-Mg_0.06Ni_3.42Co_0.11 as precursor.The content of Mg element in the alloy was accurately controlled.The study showed that the hydrogen storage capacity of the allo y increased from 1.03wt%to 1.51wt%at 298 K.The kinetic performance increased from 1.23wt%to1.43wt%of maximum hydrogen storage in 17.3 min to 4.4 min.The capacity retention rate of the alloy was increased from 69.6%to 81.1%after 20 cycles of reaction.The study showed that the performance of the RE-Mg-Ni based hydrogen storage alloy could be effectively enhanced by controlling the magnesium content and adjusting the RE/Mg ratio through thermal diffusion method.In order to suppress the pulverization of the hydrogen storage alloy during the process of hydrogen absorption and discharge,the alloy-epoxy resin complex was obtained by adding epoxy resin to(La_0.34Ce_0.11Sm_0.34Y_0.15)_0.92Mg_0.14Ni_3.42Co_0.11 alloy and cold press molding treatment,and the effects of adding epoxy resin on the cyclic stability and hydrogen storage performance of the alloy were investigated.The results showed that the phase structure of the alloy with epoxy resin addition did not change and the hydrogen storage capacity was slightly reduced,but the hysteresis coefficient of hydrogen absorption and discharge of the complex was reduced and the cyclic stability was significantly improved.When the epoxy resin was added at 5.3wt%,the hydrogen storage capacity decreased from 1.51wt%to 1.37wt%at 298 K.The capacity retention rate increased from 81.1%to 86.3%at 20 cycles,and still reached 84.7%at 100 cycles,and there was no obvious chalking phenomenon in the complex.It was indicated that the addition of epoxy resin could improve the cyclic stability of hydrogen storage alloy.