High-performance dual-ion Zn batteries enabled by a polyzwitterionic hydrogel electrolyte with regulated anion/cation transport and suppressed Zn dendrite growth

Abstract

The rechargeable aqueous Zn battery is promising for next-generation wearable energy storage devices, due to its outstanding safety and low cost. Herein, we report a high-performance dual-ion Zn battery with both cations and anions hosted in the polyaniline (PANI) cathode. Of special interest is that a polyzwitterionic hydrogel electrolyte is specifically designed to regulate both the anion and cation transport, which originates from the strong electrostatic interaction between polyzwitterions with counter free ions. The ion-conducting and mechanical properties are then optimized by adjusting the polyzwitterionic content in the hydrogel networks. The intrinsic regulated anion/cation transport channels result in stable and uniform plating/stripping behaviors of the Zn metal anode, and meanwhile promote the cation/anion hosting reaction in the PANI cathode. These synergistic effects provide the Zn/PANI battery with excellent electrochemical performances, achieving a capacity of 102.5 mA h g⁻¹ and a high retention rate of 87.5% after 600 cycles at 5 A g⁻¹. Furthermore, a solid-state pouch cell is prepared for wearable devices with demonstrated excellent electrochemical performances, high flexibility and safety.