Page 9 - Дисертація_Влад_Христина_Ігорівна

The study also presents, for the first time, the use of Ni-C, Co-C, and NiCo-C

nanocomposites, synthesized via pyrolysis, as anode materials for Ni-MH power

sources. Co-based composite showed the highest discharge capacity (up to 330

mAh/g), whereas Ni-based provided better cycling stability.

New multiphase intermetallic compounds of the A B and A B types (A = La,
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7
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Pr, Nd, Y, Mg; B = Ni, Co) were synthesized and studied. It was found that
substitution of Ni with Co and La with Y affects phase composition, hydrogenation,

and electrochemical activity. La–Mg–Ni, La–Mg–Ni–Co, and La–Y–Mg–Ni–Co

alloys showed high discharge capacity (>350 mAh/g), fast activation (≤4 cycles), and

excellent high-rate dischargeability (up to 90% after 50 cycles). Alloys containing Nd

and Pr demonstrated lower capacities but improved cycle stability. Kinetic behavior

was shown to depend on both structural factors and substitution in the metal

sublattice.

Electrochemical charge–discharge properties of “intermetallic – nanostructured

metal additive” composite materials were investigated. The addition of Raney type

powders significantly improved discharge capacity and overall electrochemical

performance compared to the base intermetallics.

Magnesium-based hydride composites with mono- and bicomponent

nanostructured Ni–Co–Fe additives (Raney type) were synthesized for the first time.
The composites were obtained by mechanochemical ball milling in hydrogen at

pressures up to 2 MPa. It was found that Ni–Fe catalysts had comparable activity to
pure metals, while Co–Fe additives significantly enhanced the hydrogenation rate,

particularly at early synthesis stages. Catalytic activity in NaBH hydrolysis was also
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studied for Raney powders based on Ni, Co, Fe. In all cases, the hydrolysis reaction

resulted in full conversion of NaBH and the highest hydrogen generation rate was
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observed for the ternary NiCoFe alloy (344 ml·H /min·g ).
cat.
2
Keywords: hydrogen, hydrogen energy, hydrogenation, hydrolysis, diffusion,

electrochemistry, catalyst, composite, metal hydride, nanomaterials, hydrogen

evolution reaction, sorption/desorption of hydrogen.

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