Degradation mechanisms of zinc-air batteries used in hearing aid

Abstract

Hearing aid devices are powered by the oxidation of oxygen and zinc that occurs within zinc-air batteries. Zinc-air batteries have an average discharge time of 7 days. Therefore, hearing-aid devices need frequent battery replacement. In this paper, degradation mechanisms of zinc-air batteries investigated where a competition mechanism between zinc passivation and dendritic formation dictates the battery life. This research included exposure time from none to 9 days and to document dendritic growth with time. Scanning electron microscope images were taken to quantify the damage growth as well energy dispersive X-ray tests were conducted to comment on the composition changes. The results confirmed an increase in oxygen in exposed batteries from unexposed. These results matched findings from past literature. Exposure time was investigated to optimize battery lifespan. In conclusion, life of zinc-air batteries depends on the competition mechanism of zinc passivation and dendritic formation caused by oxidation and our investigation shows that this occurs within the first 7 days.