Effect of surface roughness after pulse arc plasma treatment on current test of metal anodes

Abstract One of the ways to improve the performance of metal-air batteries (MAB) is to increase the specific surface area of the anodes. Significant progress in MAB technology has been achieved with metal anodes made of zinc and aluminum. The specific surface area of metals can be increased by treating the surface with an intense plasma flow, which melts the surface and creates micron-scale roughness. In this work, the authors used pulsed arc plasma to treat the surface of metallic materials. Experiments on zinc and aluminum samples demonstrated that roughness parameters increased for both materials after plasma treatment. Testing of plasma-treated aluminum and zinc electrodes in an MAB cell demonstrated a clear correlation between increased roughness and the expected increase in output current: (1.1–1.5) A for zinc and (0.75–1.1) A for aluminum. Model calculations of the specific surface area showed that its value increases significantly in the presence of high and sharp protrusions. However, this effect is more pronounced for aluminum than zinc. Observations revealed that due to the pinching effect of the pulsed current and plasma contraction, deep cracks formed in the central part of the zinc electrode surface. Nevertheless, this effect inherent to arc plasma is not critical when processing non-magnetic materials with a higher melting point than zinc. Thus, pulsed arc plasma treatment is one effective method for increasing the specific surface area of anodes for metal-air batteries made of metallic materials.