Fig. 6: Universal effect of different anionic salts.

a Long-term cycle performance of Zn//Zn symmetric cells in ULCE (Zn(OTf)2) at a current density of 0.2 mA cm–2 with a capacity of 0.1 mAh cm–2 at −60 °C. b Long-term cycle performance of single piece of pouch cell with ULCE (Zn(OTf)2) at various temperatures and c corresponding charge and discharge curves.