Colossal Piezoionic Effect from Hierarchical Asymmetries in Soft Ionotronics

Soft energy harvesters capable of matching the intrinsic compliance of biological tissues are essential for the realization of imperceptible electronics. While piezoionic transduction in soft electrolyte networks offers ideal bio-integration, it produces voltage outputs that are much lower than those of rigid piezoelectrics due to thermodynamic constraints that limit charge separation and transport. Here, we address these challenges through a multiscale synergistic strategy that co-optimizes macroscopic, microstructural, and molecular asymmetries. Specifically, asymmetric electrodes with dissimilar work functions establish a built-in field that actively biases interfacial ionic charge separation. Acting in concert, a microcone array of soft ionic conductors concentrates mechanical stress to drive stress-induced ion dissociation and directional migration, while cation-π interactions within the polymer network function as a molecular kinetic trap to favor anion-dominated transport. This hierarchical coupling in soft ionotronic materials unlocks a colossal four-order-of-magnitude enhancement in voltage sensitivity (>104 mV kPa-1, 0.03-0.07 kPa) and delivers a peak power density of 135.1 µW cm-2. The strategy proves universal as it operates in both ionogels and hydrogels to offer complementary advantages in stability and ionic conductivity. Demonstrations including breathing-driven LED illumination, confirm the scalability. These results establish a generalizable materials framework for high-performance piezoionic energy harvesting and autonomous bio-interfaces.