Synergy of Strongly Coordinating Salts and Weakly Coordinating Solvents Enables Stable and Fast-Kinetics Zinc Metal Batteries

The development of Zn metal batteries is hindered by Zn dendrites, notorious side reactions, and performance decay in harsh temperatures. Despite the efficacy of strongly coordinating organic solvents in addressing these issues, challenges persist regarding low ionic conductivity, high viscosity, and high desolvation barrier, particularly at low temperatures. Additionally, the strongly coordinating solvents around Zn²⁺ diminish anions participating in the first solvation shell, leading to the formation of an organic-rich interphase. To achieve balanced physicochemical properties, an electrolyte system combining chaotropic Zn(ClO₄)₂ salts with weakly coordinating solvents (MeOH) and highly coordinating salts (Zn(OAc)₂) is proposed. Experimental and simulation results reveal that this system creates an anion-rich solvation shell with low desolvation barriers, inhibiting water decomposition and promoting the formation of an inorganic-organic-rich solid electrolyte interphase. OAc^- also assists in the dense vertical zinc deposition along the (101) crystal plane. The reconstructed weak hydrogen bonds between MeOH and H₂O break the highly ordered structure of water at low temperatures, enabling a higher ionic conductivity. Consequently, the battery employing the designed system yields superior electrochemical performance across a wide temperature range (-80 °C-40 °C). The proposed strategy facilitates the electrolyte design for wide-temperature Zn metal batteries with fast reaction kinetics.