A Mechanically Durable Hybrid Hydrogel Electrolyte Developed by Controllable Accelerated Polymerization Mechanism Towards Reliable Aqueous Zinc-Ion Battery

Abstract

Increasing boom of bendable, safe and economical aqueous energy storage devices puts forward more demands on the tolerance of hydrogel electrolytes. However, the development of such robust hydrogel electrolytes still remains a challenging risk due to the vulnerability of mechanical deformation and complex preparation process. Herein, we present a controllable accelerated polymerization (CAP) mechanism to fabricate the poly acrylamide ( PAM)-based hybrid hydrogel electrolytes by one-step process within one minute at room temperature. The rapid free-radical reaction of acrylamide monomer is triggered by the high concentration of electrolyte salt ( ZnSO 4 ) benefiting from the collaboration of Zn 2+ and SO 4 2− which is proved by both a serious of experimental characterizations and theoretical calculations. A rigid and hydrophilic Na-montmorillonite lamella and ZnSO 4 salt plasticized PAM-based (MMT-PAM) hybrid hydrogel electrolyte is prepared with a short gelation time (~1 min). The MMT-PAM hydrogel electrolyte presents significantly enhanced mechanical properties (a tensile strength of 0.25 MPa, a compressive strength of 0.39 MPa, an elongation rate of 1075%, high storage modulus, and loss modulus) and high Zn 2+ conductivity of 20.7 mS cm −1 , which conduce to suppress the random growth of Zn dendrite. Consequently, the fabricated Zn//NaV 3 O 8 ·1.5H 2 O batteries with MMT-PAM hydrogel achieve significantly boosted cycle stability and rate capability.

Keywords: polymerization mechanism, hydrogel electrolyte, Aqueous Zn-ion battery, interface stability