Ionic Liquid Induced Static and Dynamic Interface Double Shields for Long-Lifespan All-Temperature Zn-Ion Batteries.

Abstract

Aqueous Zn-ion batteries (ZIBs) have experienced substantial advancements recently, while the aqueous electrolytes exhibit limited thermal adaptability. The low-cost Zn(BF₄)₂ salt possesses potential low-temperature application, while brings unsatisfied stability of Zn anodes. To address this challenge, an ionic liquid based eutectic electrolyte (ILEE) utilizing the Zn(BF₄)₂ presenting remarkable stability across a temperature range of ≈-100-150 °C is developed, enabling ZIBs to operate in diverse thermal conditions. The inner Zn²⁺ solvation structure can be modulated to a BF₄ ^--rich state within the ILEE system, forming a static ZnF₂ layer at the electrolyte-Zn anode interface, as evidenced by ab initial molecular dynamic simulations. Moreover, the positively charged EMIM⁺ can accumulate on the Zn anodes to form the secondary electrostatic dynamic shield that mitigates the uncontrollable Zn dendrites growth, enhancing the overall cycling life of Zn anodes to over 10 times compared with the pure Zn(BF₄)₂ system. When utilizing the ILEE as the electrolyte, PANI||Zn full cells demonstrate acceptable performances under the all-temperature environments, especially presenting a long life of over 9500 cycles at a low temperature of -40 °C and 500 cycles at a high temperature of 60 °C. This special ILEE holds significant promise for future aqueous batteries in extreme environment.