Preparation And Properties Of LaNi₅ Based Composite Hydrogen Storage Materials

Hydrogen energy is the best alternative to human needs.However,the backwardness of hydrogen storage technology has seriously restricted the development of hydrogen energy.In the 1960s,LaNi₅ alloys were found to have good reversible hydrogen storage properties,and it has attracted much attention due to it's high safety and objective hydrogen storage energy density.However,the low hydrogen storage capacity and hydrogen absorption rate generally restrict its practical application.In this paper,LaNi₅ is used as the base material,and carbon nanotubes and Mg are added as materials respectively.The two materials are composited by mechanical ball milling under a hydrogen atmosphere.In order to obtain a composite hydrogen storage material with high hydrogen absorption and desorption and rapid hydrogen absorption and desorption rate;Study on the raw material composition and morphology of the ball milling process the composite hydrogen storage material,the influence of phase composition and the hydrogen absorption properties,explore its inner mechanism.The main research results are:?1?With the increase of the amount of CNTs added,the hydrogen absorption rate of LaNi₅-CNTs composite hydrogen storage material first accelerated and then weakened.The reason is that the addition of CNTs provides a channel for hydrogen to enter the surface of the alloy,which accelerates its diffusion rate,but if Too many CNTs,which are intertwined and intertwined,and block the passage of hydrogen into the alloy to cause performance degradation;As the ball milling time increases,the hydrogen absorption performance of the material also increases first and then decreases.This is because the increase of the ball milling time leads to the full opening of the CNTs,so that hydrogen can diffuse into the alloy more quickly,but If the ball milling time is too long,the CNTs will lose the tubular structure,which will adversely affect the hydrogen absorption properties of the composite.When the amount of CNTs added was 10 wt%and the milling time was 20 min,the hydrogen absorption rate of LaNi₅-CNTs composites was the fastest.?2?By mechanically milling the LaNi₅ and Mg,nano-sized hydrides such as Mg H₂ and Mg₂Ni H₄ can be formed,The hydrogen absorption and hydrogen absorption rate of the LaNi₅-Mg composites are improved.With the increase of Mg content,the hydrogen absorption rate and hydrogen absorption of the composites first increase and then decrease.The appropriate Mg element can improve the dynamic properties of the composites.With the increase of ball milling time,the hydrogen kinetics of LaNi5-Mg composites is improved,but the ball milling time is too long,which will make the grain of the material too fine and agglomerate,which will adversely affect the hydrogen kinetics of the material.When the ball milling time is 60 h and the Mg addition amount is 30 wt%,the hydrogen absorption of the LaNi₅-Mg composite can reach up to 4.0 wt%.