Aerogel‐Directed Ionic Fibers Overcoming Mechanics–Conductivity Trade‐Off

The simultaneous achievement of high ionic conductivity and mechanical robustness in ionic fibers remains a fundamental challenge for flexible electronics and bioinspired systems. Here, we present a cellulose aerogel‐based ionic fiber (ABIF) that overcomes this trade‐off through a multilevel synergistic energy dissipation strategy. By integrating ionic liquid infiltration with polyurethane encapsulation, the ABIF achieves an exceptional combination of ionic conductivity (≈0.27 S m − 1 ), fracture strength (27.37 MPa), fracture strain (210%), and toughness (39.75 MJ m − 3 ). Mechanistic investigations reveal that the cooperative interplay among elastic deformation of the aerogel scaffold, viscous flow and interfacial sliding of the ionic liquid, and plastic deformation with crack‐arresting of the polyurethane layer enables efficient energy dissipation while preserving continuous ion transport pathways. As a proof‐of‐concept, the ABIFs are configured into capacitive biomimetic neural fibers, which exhibit signal fidelity comparable to commercial transmission lines, broad frequency response, and long‐term operational stability. Integration into a biomimetic robotic hand demonstrates reliable transmission of complex control signals under mechanical loading and impact. This work establishes a new design paradigm for high‐performance ionic conductors, opening avenues for flexible electronics, soft robotics, and bioinspired intelligent systems.