3D‐Printed Ultrahigh‐Conductivity Polymer Gel Electrodes with High Mass Loading for Thickness‐Independent Zinc‐Ion Hybrid Micro‐Supercapacitors

Abstract Simultaneously achieving high mass loading and uncompromised capacitance performance represents a critical challenge for advancing zinc‐ion hybrid micro‐supercapacitors (ZHMSCs) toward practical applications. This study addresses this fundamental limitation by developing direct ink writing (DIW) 3D‐printed Zn ²⁺ ‐poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate/MXene (Zn‐PM) gel electrodes for high mass loading ZHMSCs. Synergistic PEDOT:PSS/MXene interactions enable formulation of high‐concentration viscoelastic printable gel inks, yielding thick gel electrodes with ultrahigh mass loading (32.2 mg cm ⁻² ) and high shape fidelity via precise 3D printing. Rationally engineered Zn‐PM gel electrodes undergo phase separation, complete PSS removal, and PEDOT electronic structure transition through MXene doping, Zn ²⁺ coordination, and freeze–thawing processing, thereby constructing 3D continuous conducting networks with ultrahigh conductivity (2326 S cm ⁻¹ ) and hierarchical porous architectures with accelerated rapid ion transport kinetics. The fabricated quasi‐solid‐state ZHMSCs, integrating 3D‐printed Zn‐PM gel cathodes and electrodeposited Zn nanosheet anodes, exhibit a groundbreaking areal capacitance of 2179 mF cm ⁻² and energy density of 333.6 µWh cm ⁻² with thickness‐independent energy storage characteristics, outperforming current state‐of‐the‐art zinc‐ion hybrid capacitors. This work provides a new paradigm for engineering ultrahigh mass‐loading micro‐energy storage devices via synergistic integration of rational electrode architecture engineering and advanced 3D printing fabrication strategies.