A Freestanding Porous Polyurethane/PEDOT:PSS/MnO x Sandwich‐Structured Electrode for Flexible Supercapacitors

Flexible supercapacitors (FSCs) are promising power sources for wearable electronics, yet their performance is often limited by the use of rigid metallic current collectors. In this study, we presented a freestanding porous polyurethane/PEDOT:PSS/MnO x sandwich‐structured electrode fabricated through a straightforward solution‐based method. The design employed a flexible porous polyurethane (PC) film as the substrate, while high‐capacitance MnO x and MnO x /PEDOT (PM) composites were encapsulated between highly conductive PEDOT:PSS layers serving as the active materials. Leveraging the exceptional mechanical flexibility of the PC film, the high electrical conductivity of PEDOT:PSS, and the superior capacitance of MnO x and PM, along with their synergistic interactions including strong interfacial adhesion, rapid charge transfer, and efficient ion diffusion, the as‐fabricated PCS‐MPM‐PS electrode delivered a high areal capacitance (Ca) of 408.9 mF cm −2 (~371.2 F g −1 ) at 1 mA cm −2 . Furthermore, a solid‐state symmetric SC was fabricated using two identical PCS‐MPM‐PS electrodes, delivering a high Ca of 152.6 mF cm −2 at 1 mA cm −2 . Notably, this performance remained stable across various bending angles, demonstrating excellent mechanical flexibility and significant potential for use in wearable energy storage devices.