FeTi基储氢材料的研究及进展

Research and Progress in FeTi Based Hydrogen Storage Materials

氢能具有资源丰富,能量高,清洁环保等优点,被视为21世纪最具发展潜力的清洁能源。很多国家和地区都对它进行了大量的研究,使其充分利用并发挥氢的性能。而对于氢能储运是氢能充分利用的关键。现今有很多的学者研究优异的储氢材料来提高氢能的储存效率。而其中FeTi系合金便是一种良好的储氢材料。FeTi系合金中的元素在自然中含量丰富价格便宜,并且FeTi系合金作为储氢材料具有吸放氢温度低等优点,因此它被认为是有很大应用前景的储氢材料。但FeTi基储氢材料也存在一些问题如:活化困难、容易与合金中的很多杂质元素及空气作用中毒而使活性失效等,这些问题都会制约FeTi基储氢材料的发展。本文就目前一些学者通过掺入合金元素(如Zr,V,Mn等)、机械变形和热处理等手段改善FeTi基合金的储氢性能的研究工作进行了总结,并针对FeTi基合金存在的这些问题,提出了防止其与一些杂质元素作用而活性失效以及改善其储氢材料性能措施的建议,为储氢材料领域的研究提供参考。

As a clean and high density energy,hydrogen energy was widely used in fuel cell vehicles,hydrogen power generation,hydrogen heating and many other fields. The key to make full use of hydrogen energy was to improve the storage and transportation of hydrogen energy. In order to make full use of the properties of hydrogen volatilization,many researchers had done a lot of researches on hydrogen storage alloys. Among them,FeTi based alloy was a good hydrogen storage material. The elements in the FeTi based alloy were rich in content and cheap in price in nature,and the FeTi based alloy had the advantage of low hydrogen absorption and desorption temperature in the preparation of hydrogen storage materials,so it was considered to be a hydrogen storage material with great application prospects. However,there were many problems in FeTi based hydrogen storage materials,such as the difficulty of activation,the possibility of poisoning due to interaction with impurities in the alloy and air,etc. These problems restrict the development of FeTi based hydrogen storage materials. The methods to improve the hydrogen storage properties of FeTi based alloys by adding alloying elements(such as Zr,V,Mn,etc.),mechanical deformation and heat treatment,and to inhibit the activity failure by controlling its own impurity elements and adding Zr were summarized. In order to improve the activation property of FeTi based alloy,several strategies were adopted.(1)The hydrogen storage properties of FeTi based alloy were improved by adding alloying elements(Zr,V,Ce,Mn,Ni).(2)The hydrogen storage properties of FeTi based alloy were improved by ball milling,cold rolling,mechanical milling,forging,equal channel angular pressing and high pressure torsion.(3)By controlling the cooling rate,the microstructure of FeTi based alloy was changed,and the hydrogen absorption kinetics of FeTi based alloy was improved.(4)The hydrogen storage properties of the oxidized FeTi based alloys were restored by heat treatment. The content of impurity elements(such as C,Si,Al,O,etc.)should be strictly controlled during the preparation of FeTi based alloy to prevent the active failure of FeTi based alloy. The introduction of high content of Zr into FeTi based alloy can effectively reduce the interaction between the alloy and air,thus weakening the adverse effects.The results were listed as follows:(1)The dissociation energy of hydrogen molecule could be degraded by adding alloy elements,such as easily oxidized element(Mn),because it would be preferentially oxidized and form segregation layer on the alloy surface. In addition,the oxide formed by these elements was embedded on the surface of the alloy,which reduced the compactness of the dense layer of TiO2 layer and improves its activation performance. In addition,if the elements(Zr,Si)forming the second phase were added,the second phase was easily formed in the alloy,and the distribution was uniform,which became the channel for hydrogen atoms to enter the main TiFe phase in the process of hydrogen absorption. In addition,these elements were also easy to form Ti rich phase,which would absorb hydrogen prior to TiFe phase,leading to the formation of microcracks and nucleation sites,promoting hydrogen absorption and improving activation properties.(2)Through ball milling,cold rolling,mechanical milling,forging,equal channel angular pressing,high pressure torsion and other mechanical deformation methods,the grain size could be quickly and effectively reduced,the material defects could be induced,and the activation time could be shortened,so as to improve the hydrogen storage performance of FeTi based alloy.(3)By controlling the cooling rate,the microstructure of FeTi based alloy was changed and the contact between the secondary phase and the main phase was increased. The interface between the secondary phase and the main phase became larger,which led to the decrease of the diffusion distance of hydrogen between the secondary phase and the main phase of TiFe and improved the hydrogen absorption kinetics of FeTi based alloy.(4)The hydrogen storage properties of the oxidized FeTi based alloy were restored by heat treatment.(5)The introduction of high content of Zr into FeTi based alloy could effectively reduce the interaction with air,thus improving the adverse effects. The content of impurity elements(such as C,Si,Al,O,etc.)in FeTi based alloy should be strictly controlled to prevent the active failure of FeTi based alloy. FeTi based alloys had great prospects in the development of hydrogen storage materials. However,its application was limited due to its harsh activation conditions and easy poisoning. The activation properties could be improved by alloying,mechanical deformation and heat treatment. In addition,alloy elements could be added and the content of impurity elements could be strictly controlled to prevent its activity failure.