Integrated Hydrogel-Zn Structure with Modified Interface Realizing Fast Ion Transfer for Long Cycling Zn-ion Battery

Abstract

Fabrication of gel electrolytes are effective strategy to solve the side reactions and dendrite growth of Zn anodes in aqueous rechargeable zinc batteries (ARZBs). However, complicated synthesis and ex-situ assembled processes lead to poor electrode–electrolyte interfacial contact, which hinders ion transfer. Herein, compatible and stable electrode–electrolyte structure is constructed by in-situ polymerization process. The tightly coupled electrode–electrolyte interface reduces the mass transfer impedance, balances electric field distribution, and thus inhibits dendrites. What’s more, the −SO3H groups in gel electrolyte play a significant role which performs as cation transport channels to regulate the deposition behavior of Zn along (002) crystal plane. The intercanected and porous structure of this electrolyte promote the desolvation process of [Zn(H2O)6]2+ and inhibit the side reaction. As a result, the symmetric cell exhibits ultra-long lifespan over 4,530 h (＞188 days), Zn||Cu cell delivers an average coulombic efficiency (CE) of 99.85 % with 1,000 cycles. Zn||MVO cell operates stably for over 2,700 cycles with CE of 99.91 %. This integrated hydrogel-Zn structure provides broad application prospect in wearable devices.