Fundamental problems of hydrogen and renewable energy and fuel all technologies

MH composite materials for photoelectrochemical hydrogen generation and accumulation and storage under stationary conditions

The project is aimed to solve the problem of getting to the needs of the hydrogen energetics highly efficient hydrogen energy storage materials, namely hydrides of magnesium alloys that decompose at low temperatures and thus possess a combination of properties such as high hydrogen storage capacity and cyclic stability during rapid kinetics of sorption-desorption of hydrogen. Therefore, the aim of one of the project tasks is lowering thermal stability of hydride phases of Mg-based mechanical alloys by choice and optimization of the composition and conditions of their deriving as well as by their dispersion and mechanical alloying.

Fields of application

The hydrogen energetics is the main field of application of hydrogen-sorption materials developed during the project fulfillment. It is also expected using the developed hydrogen-sorption materials based on magnesium and its alloys in laboratory installations for thermal hydrogen desorption researches, in high-power modules of energy convertors and hydride heat pumps, etc.

Brief description

In the project part devoted to developing methods of deriving and improving the properties of hydrogen-sorption materials for hydrogen storage alloys based on magnesium, it is planned to carry out researches aimed at obtaining complex characteristics of these materials necessary for their practical application as hydrogen batteries and in the first place, fast kinetics and low temperature of full hydrogen release at a pressure 1 bar. To achieve the specified improving performance of the obtained materials, we plan to use new synthesis methods (mechanical and reactive mechanical alloying) as well as to involve processes of mechanical alloying and dispersion, which allow to change and generate needed hydrogen-sorption properties, required chemical state of their surfaces through effects on electronic and thermodynamic properties. Mechanical synthesis was carried out of magnesium-based alloys with different composition of alloying elements, in particularly Mg-Si-Ti-Fe alloys. The optimal composition of alloys and their synthesis conditions providing improved complex of specified essential characteristics was determined.

Expected properties

Results of the project studies of the effect of different alloying elements and different synthesis conditions on hydrogen-sorption properties, thermal stability and kinetics of hydrogen desorption process of mechanical alloy composites based on Mg enable improved mechanical-chemical methods used to obtain materials for hydrogen storage and to optimize conditions of their synthesis. The results will improve a number of characteristics of practice needs (hydrogen capacity and cyclic stability, kinetics of hydrogen sorption-desorption, thermal stability and decomposition temperature of the hydride phase).

Advantages

It has been established that mechanical alloying of Mg by Al-Fe, Al- Ti gives best hydrogen-sorption characteristics and kinetics of hydrogen desorption from MgH₂ hydride phase in comparison with that alloying by Fe. As a result of reactive milling 10 hours the mixtures Mg + 10 wt%. Al + 10 wt.% Ti ; Mg + 10 wt%. Al +10 wt.% Ni, we have achieved bigger value of hydrogen capacity (6.57 wt.% H2, 5.57 wt.% H₂). Temperature of the beginning of 1-st H₂ desorption from MgH₂ was found to be 285°C. Temperature of the beginning of H2 desorption from the hydride phase of the alloy obtained by grinding the mixture Mg + 10 wt%. Al +21 wt.% Ni in Ar after the 1st hydrogenation was found to be 250°C at a pressure of hydrogen in the reactor 1 bar. After reactive milling 20 hours we have achieved of hydrogen capacity 5.58 wt.% H₂. Temperature of the beginning of 1-st H₂ desorption was 260°C (PH2 = 1 bar). It has been established that the addition of Si, Ti, Fe to magnesium leads to significant 6 times improvement in kinetics of hydrogen desorption from the hydride phase MgH₂ .

Competitors

Department Mater.Scien.&Engineer.ZhejiangUniversity,China
Department Mater.Univer London, UK
Course in Materials Science &Chemistry, Tokai University, Numazu, Japan
Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller, Norway.

Stage of development

Transition metals compounds, cause interest as efficient catalysts, due to the high affinity of transition metal cations to hydrogen. The most promising in this respect is titanium. We have determined the effect of lowering the temperature and improving the kinetics of H₂ desorption from MgH₂ hydride phase of the alloy obtained by reactive milling through mechanical alloying of Al and Ti, Al and Fe, Al and Ni of magnesium in the process of milling in a hydrogen atmosphere. We have also studied contribution to reducing thermal stability and decomposition temperature of MgH₂ hydride phase of the mechanical alloys Mg +5% (10%) wt.Si +5% (2%) wt. Ti+ Fe 2% (5%) wt. that was synthesized under different conditions of hydrogenation. The above results indicate that our studies allow choosing the composition of alloying elements and conditions of synthesis of mechanical alloys that provide maximum heat resistance and low decomposition temperature of MgH₂ hydride phase while improving the kinetics of hydrogen sorption-desorption. With the use of thermal hydrogen desorption at hydrogen pressure of 0.1 MPa hydrogen-sorption characteristics, thermal stability and kinetics of hydrogen desorption from the obtained mechanical alloys have been investigated and activation energy of H₂ desorption from the alloys has been defined.

Intellectual property

Publications on results carried out within the project:

Ershova O.G., Dobrovolsky V.D., SoloninY. M., Khyzhun O.Yu, Koval A.Yu. The effect of Al on thermal stability and kinetics of decomposition of MgH₂ prepared by mechanochemical reaction at different conditions // Materials Chemistry and Physics. – 2015. – 162. – p.408 – 416.

Dobrovolsky V.D., Ershova O.G., Solonin Yu. M., Khyzhun O.Y. Influence of titanium and iron additives to magnesium upon hydrogen-sorption properties, thermal stability and kinetics of hydrogen desorption from MgH₂ phase of mechanical alloy // Powder Metallurgy & Metal Ceramics, 2016, No. 7-8, P. 124-137.

Dobrovolsky V.D., Ershova O.G., Solonin Yu. M. Thermal Resistance and the Kinetics of Hydrogen Desorption from Hydrides of the Mg–Al–Ni–Ti Mechanical Alloy //Materials Science. – 2016. - 51(4), 457-464, DOI 10.1007/s11003-016-9862-z

V.D. Dobrovolsky, O.Y. Khyzhun, A.K. Sinelnichenko, O.G. Ershova,Y.M. Solonin. XPS study of influence of exposure to air on thermal stability and kinetics of hydrogen decomposition of MgH₂ films obtained by direct hydrogenation from gaseous phase of metallic // Journal of Electron Spectroscopy and Related Phenomena.- 2017.- 215, p. 28-35.

Valentin Davidovich Dobrovolsky, Olga Georgievna Ershova, Yuriy Michailovich Solonin. Alloying effect of Ti, Fe, Ni and Al on hydrogen desorption behavior of MgH₂ synthesized by reactive mechanical alloying. // Innovations in Corrosion and Materials Science. -2017. – v. 7. – p. 1-15.

Ershova O.G., Dobrovolsky V.D., Solonin Y.M. Mechanical alloys Mg-Me (Me: Ti, Fe, Ni, Al) & Mg -Me1-Me2 (Ме1: Al; Me2: Ti, Fe, Ni) with low resistance and improved kinetics of hydrogenation /dehydrogenation for hydrogen storage applications // French-Ukrainia Journal of Chemistry. 2018. –v. 6. – isse 1. – p. 31-55.

Dobrovolsky V.D., Ershova O.G., Solonin Yu. M. Magnesium-based composites obtained by reactive mechanical alloying for hydrogen storage systems // Materials Science: Achievements and Prospects. In 2 tons. T1.- Kiev: Academperiodika. - 2018. – p. 174-194

Contact information

Executing : Frantsevich Institute for Problems of Materials Science of National Academy of Sciences of Ukraine

Project 15 «MH composite materials for photoelectrochemical hydrogen generation and accumulation and storage under stationary conditions».

Project leader:

Ershova Olga G.

Dr. of Sc.,

Tel. +38 044 424-03-91

Е-mail: dobersh@ipms.kiev.ua