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Promising metal hydride electrode performance of LaNi4.5Co0.4Al0.1, prepared by induction melting and next hydrogen-induced decrepitation, was proven in the present study. Both the composition and microstructure of the electrode material were found to be responsible for its reliable hydrogen capacity and cycle stability. After prolonged exposure to air, the alloys retain their high hydrogen sorption characteristics, revealing only 10% capacity reduction. The gas phase hydriding of the alloys confirms the hydrogen capacity obtained under electrochemical conditions. Furthermore, the influence of C, Co, and Co3O4 additions to the LaNi5-based alloy on the hydrogen electrode performance was also elucidated. The highest capacity of 300 mAh g−1, remaining constant for 20 cycles, was obtained for LaNi4.5Co0.4Al0.1 + 15 mg Co3O4. This material maintains excellent capacity also at high current densities, making it a suitable electrode material in Ni/MH batteries. [ABSTRACT FROM AUTHOR]

The oxidation of carbon in conventional gas diffusion electrodes is a limiting factor for the life of secondary metal-air batteries. Replacement of carbon with zeolite is a possible solution to avoid its oxidation in the gas-diffusion electrodes (GDE) and thus to increase the battery lifetime. Due to the fact that the technology provides the required number of charge/discharge cycles, it is applicable for solar energy storage. Zeolites are a large group of natural or synthetic porous aluminosilicate minerals. Their porous structure provides good gas permeability. The gas diffusion layer of the electrode must also have good hydrophobicity. To prevent leakage of electrolyte from the battery, the zeolite was mixed with an appropriate amount of polytetrafluoroethylene, and the electrode was subjected to hot pressing according to a specially developed procedure. The experiments were performed in a specially designed test cell. Its construction ensures measurements of the bifunctional gas-diffusion electrode in a half-cell configuration applying a reference hydrogen electrode. The stationary volt-ampere characteristics and impedance tests were performed on the zeolite electrodes at certain operating points. The cell was subjected to cycling at charge/discharge current ± 2 mA/cm2, respectively. The obtained experimental results show that zeolite is a suitable material for carbon substitution in secondary metal air batteries. The zeolite/polytetrafluoroethylene (PTFE) ratio needs to be optimised in order to improve the gas permeability of the gas diffusion layer without compromising hydrophobicity. [ABSTRACT FROM AUTHOR]

Recently, the interest in developing highly safe rechargeable energy storage systems that are environmentally friendly and integrate that a low cost into the electric grid with electric vehicles now included in the agenda of global energy policies, has grown immensely. As a promising technology, rechargeable zinc-air batteries have received a lot of attention in the last few years. In this research work we focus on the improving the performance of the gasdiffusion electrode (GDE) for secondary Zn-air batteries. A new generation of GDE has been developed and tested in a half-cell configuration. The gas-diffusion layer was developed by heat treated at up to 300°C carbon black. A mixture of Ag and Co3O4 has been used for the bi-functional catalyst in the active layer (AL). Preliminary studies of the gas-diffusion layer (GDL) with different carbon blacks and different ratios between the PTFE and carbon blacks showed that the most stable GDL is produced by Vulcan XC-72 carbon black teflonized with 60 % PTFE. The steady state polarization curves and the charge/discharge tests revealed a superior electrochemical performance of the heat treated carbon material employed in the GDL. [ABSTRACT FROM AUTHOR]