COVID-19 is a pandemic that has caused serious disruption in almost every day-to-day life around the world, and wearing a mask is essential for human safety from this virus. However, masks are non-recyclable materials, and the accumulation of masks used every day causes serious environmental issues. In this study, we investigate the recycling of mask materials for addressing the environmental problems and transforming as a high value-added material through chemical modification of masks. The recycled mask is applied as a separator for aqueous rechargeable batteries, and shows outstanding safety and electrochemical performance than the existing separator. This approach will lead to an advanced energy technology considering nature after overcoming COVID-19.