Electrolyte Design via Cation–Anion Association Regulation for High-Rate and Dendrite-Free Zinc Metal Batteries at Low Temperature

Low-temperature zinc metal batteries (ZMBs) are highly challenged by Zn dendrite growth, especially at high current density. Here, starting from the intermolecular insights, we report a cation-anion association modulation strategy by matching different dielectric constant solvents and unveil the relationship between cation-anion association strength and Zn plating/stripping performance at low temperatures. The combination of comprehensive characterizations and theoretical calculations indicates that moderate ion association electrolytes with high ionic conductivity (12.09 mS cm^-1 at -40 °C) and a stable anion-derived solid electrolyte interphase (SEI) jointly account for highly reversible and dendrite-free Zn plating/stripping behavior, resulting in high-rate and ultrastable cycle performance at low temperature. As a result, at -40 °C, Zn//Zn cells can stably cycle over 400 h at 5 mA cm^-2 and 10 mAh cm^-2 and Zn//Cu cells exhibit an exceptional average Coulombic efficiency (CE) of 99.91% for 1800 cycles at 1 mA cm^-2 and 1 mAh cm^-2. Benefiting from enhanced low-temperature Zn plating/stripping performance, Zn//PANI full cells stably operate for 12,000 cycles at 0.5A g^-1 and 35,000 cycles at 5 A g^-1. Impressively, at -60 °C, Zn//Cu cells still display a high average CE of 99.68% for 2000 cycles. This work underscores the crucial effect of cation-anion association regulation for high-rate and dendrite-free Zn metal anodes, deepening the understanding of intermolecular interaction insights for low-temperature electrolyte design.