Seamlessly connected cathode–gel electrolyte interfaces enable highly stable aqueous zinc batteries

Abstract

Gel electrolytes are widely adopted in aqueous Zn batteries to mitigate water-induced side reactions and cathode dissolution. However, conventional designs with physically isolated cathodes and gel electrolytes create high-resistance solid–quasi-solid interfaces that limit performance. Here, we propose a seamlessly connected cathode–gel electrolyte interface design by constructing an integrated cathode–gel electrolyte configuration, which is achieved by in situ generation of a polymer network within the cathode and its further crosslinking with the polymer matrix of the in situ grown gel electrolyte. As a result, the cathode active material is tightly encapsulated by the polymer network and the outwardly growing gel electrolyte, which not only effectively shortens the ionic transport pathway and enhances the diffusion kinetics, but also suppresses the dissolution of the cathode active material. Consequently, the assembled Zn||Mg_0.1V₂O₅ batteries with this novel design possess significantly improved performance with a high capacity of 200 mAh g⁻¹ at 0.5 A g⁻¹ after 900 cycles. However, the battery with a conventional design suffers from capacity decay and battery failure within 600 cycles under the same conditions. This work provides a general strategy to greatly enhance the electrochemical performance of Zn batteries by constructing seamlessly connected electrode–electrolyte interfaces and might be applied to many other aqueous battery systems.