Robust eutectic gel polymer electrolytes for high-performance zinc-ion batteries by solvent-exchange strategy

Abstract

Conventional hydrogel electrolytes for aqueous zinc-ion batteries suffer from excessive free water and hydrated Zn2+ species, which induce parasitic side reactions and nonuniform Zn deposition, leading to dendrite growth and poor cycling stability. Replacing water with deep eutectic solvents is an effective strategy to reduce water activity and improve electrochemical stability. However, eutectic gel polymer electrolytes (EGPEs) often face challenges in simultaneously achieving structural uniformity and sufficient mechanical robustness. Herein, we developed a deep eutectic solvent-based solvent-exchange strategy to fabricate robust EGPEs with uniform polymer network structures. The prepared electrolytes exhibit tough mechanical properties with a high tensile strength up to 8.1 MPa, and wide temperature adaptability from -20 to 60 °C. In symmetric Zn cells, the EGPE enabled stable Zn plating/stripping for over 3400 h at 0.5 mA cm -2 and maintained good reversibility even under a high depth of discharge of 85.5%, indicating the enhanced Zn anode stability by suppressing zinc dendrite growth and parasitic reactions. The Zn//PANI batteries with EGPEs cycle stably for over 10000 cycles at 3 A g -1 with a high capacity retention of 79.4%. This work provides a facile and effective strategy for developing robust gel polymer electrolytes for zinc batteries operating under harsh conditions.