Conformal Engineering of Both Electrodes Toward High‐Performance Flexible Quasi‐Solid‐State Zn‐Ion Micro‐Supercapacitors

Abstract

Abstract The severe Zn‐dendrite growth and insufficient carbon‐based cathode performance are two critical issues that hinder the practical applications of flexible Zn‐ion micro‐ssupercapacitors (FZCs). Herein, a self‐adaptive electrode design concept of the synchronous improvement on both the cathode and anode is proposed to enhance the overall performance of FZCs. Polypyrrole doped with anti‐expansion graphene oxide and acrylamide (PPy/GO‐AM) on the cathode side can exhibit remarkable electrochemical performance, including decent capacitance and cycling stability, as well as exceptional mechanical properties. Meanwhile, a robust protective polymeric layer containing reduced graphene oxide and polyacrylamide is self‐assembled onto the Zn surface (rGO/PAM@Zn) at the anode side, by which the “tip effect” of Zn small protuberance can be effectively alleviated, the Zn‐ion distribution homogenized, and dendrite growth restricted. Benefiting from these advantages, the FZCs deliver an excellent specific capacitance of 125 mF cm−2 (125 F cm−3) at 1 mA cm−2, along with a maximum energy density of 44.4 µWh cm−2, and outstanding long‐term durability with 90.3% capacitance remained after 5000 cycles. This conformal electrode design strategy is believed to enlighten the practical design of high‐performance in‐plane flexible Zn‐based electrochemical energy storage devices (EESDs) by simultaneously tackling the challenges faced by Zn anodes and capacitance‐type cathodes.

Keywords

• electrode engineering
• energy storage devices
• flexibility
• patternable electrode
• Zn‐ion micro‐supercapacitors