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Novel composite materials consisted of elemental Si and rare-earth metal silicides, Sm–Si, Gd–Si, and Dy–Si, were synthesized and were evaluated for the first time as a high-performance anode material of Li-ion battery. Thick-film electrodes of the silicide/Si composites were prepared by an arc melting method and a successive gas-deposition method. Among them, the Gd–Si/Si composite electrode exhibited reversible Li-insertion/extraction reactions and the best cycling performance: the initial Coulombic efficiency was 80% and the discharge capacity at the 1000th cycle was 840 mA h g−1. In addition to this, the composite electrode delivered a superb high-rate performance with the capacity of 2100 mA h g−1 even at the high current rate of 12.0 A g−1 (4.8C). The remarkable performances demonstrated that the gadolinium silicide is favorable to significantly enhance anode properties of Si-based composite electrodes.

For the development of a rechargeable metal-air battery, which is expected to become one of the most widely used batteries in the future, slow kinetics of discharging and charging reactions at the air electrode, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively, are the most critical problems. Here we report that Ruddlesden-Popper-type layered perovskite, RP-LaSr3Fe3O10 (n = 3), functions as a reversible air electrode catalyst for both ORR and OER at an equilibrium potential of 1.23 V with almost no overpotentials. The function of RP-LaSr3Fe3O10 as an ORR catalyst was confirmed by using an alkaline fuel cell composed of Pd/LaSr3Fe3O10-2x(OH)2x·H2O/RP-LaSr3Fe3O10 as an open circuit voltage (OCV) of 1.23 V was obtained. RP-LaSr3Fe3O10 also catalyzed OER at an equilibrium potential of 1.23 V with almost no overpotentials. Reversible ORR and OER are achieved because of the easily removable oxygen present in RP-LaSr3Fe3O10. Thus, RP-LaSr3Fe3O10 minimizes efficiency losses caused by reactions during charging and discharging at the air electrode and can be considered to be the ORR/OER electrocatalyst for rechargeable metal-air batteries.

The electromagnetic (EM) wave absorbers were prepared from the magnetite powders obtained as a byproduct in the recycle process for the sludge powder scraps of NdFeB-type sintered magnets. The resulting EM wave absorbers showed the minimum RL value of −32 dB at 16.5 GHz with 1.2 mm thickness. Reduction of the magnetite powders leads to improve the EM wave absorption properties (RL

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In this work, we developed thin-film anion-conducting NaCo2O4 electrolyte for solid alkaline fuel cell composed. The NaCo2O4 powder was slurried with poly vinylidene difluoride (PVDF) and N-methyl pyrrolidone (NMP). The slurry was once or twice painted on the punched metal base by the doctor blade method, followed by calcination at 600{degree sign}C for 5 h. In addition, wet powder spraying method was applied. In preparing NaCo2O4 film, the density of the NaCo2O4 greatly affected the cell performance. The cell made by twice-casting doctor blade method showed higher performance than other method since its density of NaCo2O4 increased.

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