镁基储氢合金动力学调控及电化学性能

Kinetics Tuning and Electrochemical Performance of Mg-Based Hydrogen Storage Alloys

镁基合金储氢密度高且镁资源丰富,是固态储氢的良好工作介质,同时Mg-RE-TM储氢合金作为NiMH电池负极在电化学储能领域也有重要的应用。但镁基储氢合金存在吸/放氢温度过高、动力学性能缓慢的缺点,在电化学性能方面则面临循环稳定性差、工作温度区间窄等难题。本文结合近年来国内外的重要研究进展和本研究组的工作,总结了镁基储氢材料吸/放氢动力学调控及高性能Ni-MH电池镁基储氢合金负极的主要研究进展。首先阐述了镁基储氢合金吸/放氢反应主要调控方法及相应的机制;随后介绍了通过氢化反应原位生成多尺度多相复合结构调控吸/放氢动力学的方法,以及基于多尺度多相协同所创制的一系列具有良好宽温区电化学性能的A2B7型RE-Mg-Ni负极合金;最后揭示了Mg-Ni基非晶储氢合金负极材料的电化学性能衰减的新机理,并据此建立的电化学改善其性能的方法。

Mg-based alloys are good candidates for solid-state hydrogen storage because of their high hydrogen storage density and abundant resource.Meanwhile,Mg-RE-TM alloys have important applications in electrochemical energy storage as negative electrodes for Ni-MH batteries.However,Mgbased hydrogen storage alloys have some disadvantages,such as high temperature and slow kinetics for hydrogen absorption/desorption,poor cycle stability,and a narrow working temperature as an electrode in a Ni-MH battery.The research progress on Mg-based alloys for hydrogen storage and negative electrode of Ni-MH battery with wide working temperature is summarized in this review,combined with our recent year.s research works.First,the main methods and mechanism for tuning the reaction of hydrogen absorption/desorption of Mg-based hydrogen storage alloys are described,followed by an introduction to the progress on tuning kinetics via in-situ formation of a multiscale and multiphase composite structure through hydrogenation.Second,a series of A2 B7 types of RE-Mg-Ni alloys with excellent electrochemical performance and a wide working temperature has been developed using multiscale and multiphase synergy for application as a negative electrode of Ni-MH battery.Finally,the newly discovered mechanism of electrochemical performance degradation is described for Mg-Ni based amorphous alloy negative electrode for Ni-MH battery,and methods for selecting new electrolyte and surface protection are proposed for promoting the cyclic stability of Mg-Ni.