Highly Reversible Aqueous Zinc Batteries enabled by Zincophilic-Zincophobic Interfacial Layers and Interrupted Hydrogen-Bond Electrolytes

Aqueous Zn batteries promise high energy density but suffer from Zn dendritic growth and poor low-temperature performance. Here, we overcome both challenges by using an eutectic 7.6 m ZnCl2 aqueous electrolyte with 0.05 m SnCl2 additive, which in situ forms a zincophilic/zincophobic Sn/Zn-5(OH)(8)Cl-2 center dot H2O bilayer interphase and enables low temperature operation. Zincophilic Sn decreases Zn plating/stripping overpotential and promotes uniform Zn plating, while zincophobic Zn-5(OH)(8)Cl-2 center dot H2O top-layer suppresses Zn dendrite growth. The eutectic electrolyte has a high ionic conductivity of approximate to 0.8 mS cm(-1) even at -70 degrees C due to the distortion of hydrogen bond network by solvated Zn2+ and Cl-. The eutectic electrolyte enables Zn parallel to Ti half-cell a high Coulombic efficiency (CE) of >99.7 % for 200 cycles and Zn parallel to Zn cell steady charge/discharge for 500 h with a low overpotential of 8 mV at 3 mA cm(-2). Practically, Zn parallel to VOPO4 batteries maintain >95 % capacity with a CE of >99.9 % for 200 cycles at -50 degrees C, and retain approximate to 30 % capacity at -70 degrees C of that at 20 degrees C.