Tailoring MgH_(2) for hydrogen storage through nanoengineering and catalysis

Hydrogen energy has been recognized as “Ultimate Power Source” in the 21st century, which could be the best solution to the looming energy crisis and climate degeneration in the near future. Due to its high safety, low price, abundant resources and decent hydrogen storage density, magnesium based solid-state hydrogen storage materials are becoming the leading candidate for onboard hydrogen storage. However,the high operation temperature and slow reaction rate of MgH_(2), as a result of the large formation enthalpy and high reaction activation energy,respectively, are the first and most difficult problems we need to face and overcome to realize its industrialization. Herein, a state-of-the-art review on tailoring the stable thermodynamics and sluggish kinetics of hydrogen storage in MgH_(2), particularly through nanoengnieering and catalysis is presented, aiming to provide references and solutions for its promotion and application. Promising methods to overcome the challenges faced by MgH_(2)/Mg, such as bidirectional catalysts and nanoconfinement with in-situ catalysis are compared and the required improvements are discussed to stimulate further discussions and ideas in the rational design of MgH_(2)/Mg systems with ability for hydrogen release/uptake at lower temperatures and cycle stability in the near future.

纳米粉球磨机的电力驱动方式及机械结构优化研究

指出纳米化的储氢材料将会被广泛用于燃料电池的汽车之中,介绍了纳米粉的其它典型应用领域。分别论述了实验室中物理与化学方法制备纳米粉的基本原理,分析了物理法制备纳米粉中的机械球磨方法的基本原理、系统组成。重点对实验室中制备微纳米粉的强力球磨机的驱动电动机不同类型、搅拌主轴转动一周内的瞬时变角速度方式,以及其机械结构中的搅拌齿的曲面形状、搅拌主轴上紧固的径向搅拌杆的层数、每层杆的个数、搅拌主轴的断面形状、横向搅拌杆断面形状等优化问题进行了探讨。获得了交流伺服电动机驱动方式以及球磨机的不同机械结构形式对钢球的动力学特性和流场特性、以及物料研磨效果的影响规律,优化出了相应的驱动方式及机械结构方案。

Recent advances in kinetic and thermodynamic regulation of magnesium hydride for hydrogen storage

Developing safer and more efficient hydrogen storage technology is a pivotal step to realizing the hydrogen economy. Owing to the lightweight, high hydrogen storage density and abundant reserves, MgH_(2) has been widely studied as one of the most promising solidstate hydrogen storage materials. However, defects such as stable thermodynamics, sluggish kinetics and rapid capacity decay have seriously hindered its practical application. This article reviews recent advances in catalyst doping and nanostructures for improved kinetic performance of MgH_(2)/Mg systems for hydrogen release/absorption, the tuning of their thermodynamic stability properties by alloying and reactant destabilization, and the dual thermodynamic and kinetic optimization of the MgH_(2)/Mg system achieved by nanoconfinement with in situ catalysis and ball milling with in situ aerosol spraying, aiming to open new perspectives for the scale-up of MgH_(2) for hydrogen storage applications.

Key Technologies for Preparing Nanoparticles of Hydrogen Storage Material by Combining Ball Milling with Aerosol Generation

The developing trend of vehicle is electrical vehicle in future, and fuel cell will become the one of the main batteries of electrical vehicle because of its the prominent properties. The one of current obstacle for fuel cell in popularization and applications is lacking of excellent performance hydrogen storage materials and advanced technologies of preparing nanoparticles for hydrogen storage materials. The principles, typical classifications and characteristics of chemically and physically preparing nanoparticles for hydrogen storage materials are briefly introduced. And it predicts that physical method is going to be the major developing direction for nanoparticles for hydrogen storage material fabrication. The principle, the system composition ＆ characteristics of method by means of combining ball milling with aerosol generation preparing nanoparticles for hydrogen storage materials are expounded. The ball milling process for hydrogen storage material is needed to conduct effective cooling process, and the lower cooling temperature has better milling results. The cooling media for ball milling include room temperature water, ice water, pure ethanol with dry ice and liquid nitrogen. The proper level of vacuum in canister is significant for injecting aerosol particles during the ball milling. In order to maximize the friction force, it is better to design multi-level stirring rod and the profile of stirring rod with large contact area, therefor stirring rod with cylinder has less grinding effect than with ring profile. The more stirring rod with more layers will obtain higher stirring efficiency. The distance between each layer of branches is 2.5 times larger than diameter of the ball. The simulation results show that the average speed has 120% increases from 400 rpm to 800 rpm. Based on the kinetic energy equation, it is obtained that there is 350% increase in energy from 400 r/min to 800 r/min. The higher stirring speed will generate the finer material. And the discussion of this article provides a favorable basis of preparing nanoparticles for hydrogen storage materials in fuel cell vehicle.