All-3D-Printed Flexible Zn-Ion Hybrid Micro-Supercapacitors Enabled by Hierarchical Conductive Networks for Ultrahigh Areal Capacitance

3D-printed flexible zinc-ion hybrid microsupercapacitors (ZHMSCs) show immense promise as emerging energy storage units for flexible microelectronic systems, delivering intrinsic safety, high theoretical capacity, and designable architectures. However, the low intrinsic conductivity of electrode materials and the significant interfacial contact resistance hinder the development of all-printed devices with superior areal capacitance and power density. In this study, a hierarchical conductive optimization strategy is proposed to construct a high-performance flexible ZHMSC via a fully 3D-printing process. At the microscale, highly conductive PEDOT:PSS (PH1000) is introduced as an intercalation agent into the Ti3C2 MXene cathode, effectively suppressing the restacking of MXene layers and constructing efficient ion transport channels. At the macro scale, the interface contact resistance is effectively reduced by in situ printing of the silver current collector. The device exhibits excellent electrochemical performance enabled by a directly printable, high-mass-loading zinc-based composite anode and a water-retentive ZnSO4/hyaluronic acid gel electrolyte. The fabricated flexible ZHMSC delivers a remarkable areal capacitance of 1199.5 mF cm–2 and an energy density of 326.5 μWh cm–2. Moreover, the device demonstrates excellent cycling stability with 82% retention of the initial capacitance after 9000 cycles. This work confirms the effectiveness of a hierarchical conductive network design in enhancing all-printed energy storage and provides an efficient, scalable manufacturing paradigm for the next generation of integrated flexible micropower systems.