(Invited) Understanding and Mitigating Calendar Aging Capacity Losses in Zn Metal Anodes

While development of next-generation batteries beyond lithium chemistries has focused on cycling and rate performance, understanding of calendar aging mechanisms has lagged significantly but is equally important for practical deployment. Our work presents the first detailed study on calendar aging in Zn metal batteries, where we discover large capacity losses of 12-37% within just the first 24 hours of aging, an order of magnitude greater than any previous battery chemistry studied. We reveal that Zn calendar aging is distinct from that of lithium, necessitating new approaches for investigation. In particular, we use titration gas chromatography that can quantify contributions of both corrosion and dead Zn formation to calendar aging losses, a departure from previous coulometric approaches widely used for Li chemistries but which could not distinguish between the two. Contrary to known aging mechanisms in Li chemistry, dead Zn (rather than corrosion) accounts for most of the capacity lost during Zn calendar aging . This surprising finding provides important insights for mitigation strategies that can minimize capacity losses during calendar aging.