Study On Hydrogen Absorption/desorption Properties Of Mixed Solidified LaNi₅ Alloy

Lanthanum-nickel(LaNi5)alloy has become a popular research object of solid-state hydrogen storage materials because of its good hydrogen storage conditions.Its shortcomings are mainly defects such as poor kinetic performance and easy pulverization.In this paper,a low-pressure mixed solidification adsorption hydrogen storage experiment platform was built.Li5 was used as the adsorbent matrix to construct a lanthanum nickel alloy-expanded graphite mixed system by mechanical ball milling.The mixed system was prepared by adding different contents of expanded graphite(EG)and tableting Hybrid curing material(MHC),nano-constraint modification research on the doping system,thereby improving the hydrogen absorption/desorption characteristics of LaNi5.Using the hydrogen absorption and desorption performance test system,thermal conductivity meter,etc.,the effects of different mass fractions of EG and tablet density on the heat transfer and hydrogen storage performance of the doped system were explored.The main research results are as follows:(1)The influence of thermal conductivity parameters on the mixed curing adsorption system was explored.The LaNi5-x EG(x=2.5,5,7.5wt.%)powder mixing system can be prepared by mechanical ball milling.With the increasing amount of EG,the density of the LaNi5+x wt.%EG mixing powder system gradually decreases.The measurement results of thermophysical parameters show that,within a certain range,the thermal conductivity of bulk mixed materials increases with the increase of EG addition,but they are all lower than pure LaNi5 alloy.Compared with pure LaNi5 alloy powder,the thermal conductivity of EG with mass fractions of 2.5 wt.% and 7.5 wt.% is reduced by 46% and 51.96%,respectively,and the pressure of 100 MPa and 200 MPa is increased by 16.47 times and 17.35 times,respectively.(2)The influence of the mechanical ball milling mixing system is investigated.When the LaNi5-xwt.%EG mixed material is mechanically ball milled at the same speed and ball milling ratio,the system shows better hydrogen storage performance than pure LaNi5 alloy powder.The hydrogen absorption of the bulk LaNi5+x wt.%EG(x=2.5,5,7.5)mixed system increased by 15.68%,29.69%,and 5.3%,respectively,and the reaction efficiency to reach the maximum hydrogen absorption of 50% increased by 41.56%,53.24 % And 33.77%.(3)The effect of curing on the hydrogen absorption/desorption kinetics and the amount of hydrogen absorption/desorption of the LaNi5-xwt.%EG mixed system was investigated.The maximum temperature of the MHC bed cured by adding 5 wt.% of EG under 100 MPa pressure increased by 25 K,the hydrogen absorption increased by 35.85%,and the hydrogen desorption increased by 3.2L.The comprehensive mass and heat transfer performance achieved the absorption/release Hydrogen works best.