Hierarchically Porous and Hetero‐Structured Black Phosphorus/Ti₃C₂T_X MXene Aerogel Fiber for Wearable Supercapacitors with Implantable Capability

Abstract Architected fibrous electrodes with hierarchically porous, stable interface coupling, and good biocompatibility that accelerates charge transfer and storage are vital to realize high‐performance fiber‐shaped supercapacitors (FSCs) toward wearable and implantable systems. Here, a hierarchically porous and hetero‐structured black phosphorus/Ti₃C₂T_X MXene aerogel (A‐BP/Ti₃C₂T_X) fiber based on electrostatic self‐assembly and microfluidic spinning methods is reported. The as‐prepared A‐BP/Ti₃C₂T_X fiber with interconnected porous networks, high conductive skeleton, and substantial interfacial building exhibits a low diffusion energy barrier of H⁺, the large adsorption energy of H⁺, fast interfacial electron conduction, and excellent structural stability by density functional theory calculations and in situ/ex situ characteristics. As a result, the A‐BP/Ti₃C₂T_X fiber presents boosted electrolyte ion diffusion kinetic and capacitance of 369 F g⁻¹. Furthermore, the asymmetric FSCs deliver good energy density of 6.39 Wh kg⁻¹ and long cycling stability of 20 000 cycles, thereby successfully powering wearable devices. More importantly, by combining the hydrogel adhesion agent, the implantable FSCs that can firmly adhere to the tissues show significant bending stability (88.52% capacitance retention after 5000 cycles), impressively adhesive capability in tissue fluid or wetted tissue surface, and considerably no cell toxic. The work offers a broad path for designing structural fiber electrodes for implantable energy technology and wearable applications.