Co-solvent and additive joint engineering enable long-life and wide-temperature Zn metal battery

The dendrite growth and interfacial side reactions pose significant threaten to the practical applications of aqueous zinc metal batteries (AZMBs), especially at subzero temperature environments. To this end, co-solvent and additive joint engineering is proposed to design hybrid electrolyte, which consists of a mixture of 1,2-propanediol (1,2-PG) solvent and H2O with trace amounts of 18-crown-6 molecules, for constructing stable wide-temperature AZMBs. Notably, the 18-crown-6 and 1,2-PG molecules can both disturb the original hydrogen-bond network of H2O molecules. Interestingly, the 18-crown-6 molecules predominantly tends to absorb on the Zn anode surface and form favorable organic-inorganic hybrid SEI layer to regulate Zn deposition behaviors. The 1,2-PG molecules are responsible for reconstructing the solvation structure of Zn2+ and lowering the solid-liquid transition temperature of aqueous electrolyte, suppressing the H2O-induced side reactions and improving the antifreezing capability of electrolyte. Furthermore, the hybrid electrolyte induces the preferential Zn(002) plane deposition under the low temperature environments due to the synergistic effect of 18-crown-6 and 1,2-PG molecules, enhancing the Zn2+ transport and deposition kinetics. Consequently, the hybrid electrolyte endows the assembled cells with enhanced cycling lifespan and reversibility within the wide temperature range from -50 to 25 °C, expanding the application range of AZMBs.