Simultaneously Stabilizing Both Electrodes and Electrolytes by a Self‐Separating Organometallics Interface for High‐Performance Zinc‐Ion Batteries at Wide Temperatures

Rechargeable aqueous zinc-ion batteries are of great potential as one of the next-generation energy-storage devices due to their low cost and high safety. However, the development of long-term stable electrodes and electrolytes still suffers from great challenges. Herein, a self-separation strategy is developed for an interface layer design to optimize both electrodes and electrolytes simultaneously. Specifically, the coating with an organometallics (sodium tricyanomethanide) evolves into an electrically responsive shield layer composed of nitrogen, carbon-enriched polymer network, and sodium ions, which not only modulates the zinc-ion migration pathways to inhibit interface side reactions but also adsorbs onto Zn perturbations to induce planar zinc deposition. Additionally, the separated ions from the coating can diffuse to the electrolyte to affect the Zn²⁺ solvation structure and maintain the cathode structural stability by forming a stable cathode-electrolyte interface and sodium ions' equilibrium, confirmed by in situ spectroscopy and electrochemical analysis. Due to these unique advantages, the symmetric zinc batteries exhibit an extralong cycling lifespan of 3000 h and rate performance at 20 mA cm^-2 at wide temperatures. The efficiency of the self-separation strategy is further demonstrated in practical full batteries with an ultralong lifespan over 10 000 cycles from -35 to 60 °C.