An air secondary battery has a gas diffusion electrode as the positive electrode, so that the battery has no need to store the active mass in the electrode and the capacity of the positive electrode is not limited. This also means that the weight of the air electrode can be reduced and is independent of the battery capacity. For this purpose, we have been developing the air electrode’s material which consists of nickel-based film co-deposited with pyrochlore-type oxide on resin by electroless nickel plating [1]. In this work, we present a novel preparation method to obtain the nickel-based film which contains Bi_2-xRu₂O_7-z nano-particles in the outermost surface on resin and the results of the polarization measurements for oxygen reduction and evolution in KOH solutions.

The precipitate obtained from the metal salt solution containing Bi(III) and Ru(III) after adding NaOH solution was calcined to obtain Bi_2-xRu₂O_7-z nano-particles, which were added into the electroless nickel plating solution. The oxide particles on the outermost surface of the nickel-based film formed on ABS resin were obtained by electroless nickel plating with using the rotating disk electrode (RDE). The obtained sample was analyzed by SEM and EDX and used as the rotating disk electrode in a three-electrode cell to measure the polarization behaviors for oxygen reduction and evolution in 0.1 mol/L KOH solutions.

The SEM and EDX results revealed that more Bi_2-xRu₂O_7-z particles were deposited on the outermost surface of the nickel-based film formed on ABS resin than those in our previous work [1], although the oxide particles seemed to be aggregated. This surface modified resin electrode was set as the RDE in KOH solution, and cyclic voltammetry was carried out for ORR and OER, in which the measurement for oxygen reduction was performed with the solutions under O₂ or N₂ atmosphere and the net current was obtained by subtracting the current in N₂ from that in O₂. The results indicated that the oxygen reduction and evolution on the electrode were observed and the current density for both reactions was higher than that obtained in our previous work [1], because more oxide catalysts were contained in the nickel-based film and were seen on the outermost surface, resulting in the increase in surface area. The results also indicated a possibility of a light air electrode based on 3D-structured resin of which the surface is modified with a conductive nickel-based film containing a bi-functional oxide catalyst such as bismuth ruthenium oxide. More detailed results will be shown in this paper.

Reference

[1]Y. Tamura, M. Morimitsu, PRiME 2016, Abs#0787, Honolulu (2016).