Healable Ionic Conductors with Extremely Low‐Hysteresis and High Mechanical Strength Enabled by Hydrophobic Domain‐Locked Reversible Interactions

Abstract Extremely low hysteresis, high mechanical strength, superior toughness, and excellent healability are essential for stretchable ionic conductors to enhance their reliability and meet for cutting‐edge applications. However, the fabrication of stretchable ionic conductors with such mutually exclusive properties remains challenging. Herein, extremely low‐hysteresis and healable ionic conductors with a tensile strength of ≈8.9 MPa and toughness of ≈23.2 MJ m −3 are fabricated through the complexation of 4‐carboxybenzaldehyde (CBA) grafted poly(vinyl alcohol) (PVA) (denoted as PVA‐CBA) and poly (allylamine hydrochloride) (PAH) followed by acidification and ion‐loading steps. The acidification step generates the PVA‐CBA/PAH ionic conductors with in situ formed dynamic hydrophobic domains that lock and stabilize noncovalent interactions. This significantly minimizes the energy dissipation of the ionic conductors during cyclic mechanical loading (≤200% strain), resulting in ionic conductors with extremely low hysteresis (≈5%). The fractured ionic conductors can be healed at 60 °C to restore their original properties. Because of the extremely low hysteresis, the PVA‐CBA/PAH ionic conductors show a highly stable and reproducible electrical response over 5000 uninterrupted loading–unloading cycles at a strain of 200%. The ionic conductor based sensors exhibit a high sensitivity to a wide range of strains (1–500%).