Nested Monolithic Supercapacitor Patch Simultaneously Achieving High Stretchability, Stability, and Facile Integration for Flexible Electronics

Stretchable supercapacitors (SSCs) are pivotal energy storage components for emerging flexible and wearable electronics. However, simultaneously achieving high energy density, exceptional stretchability, integration compatibility, and off‐the‐shelf availability remains challenging. This study reports a self‐adhesive and super SSC fabricated via a nested structural design, wherein two wave‐patterned hydrogel electrodes are printed into an adhesive hydrogel electrolyte matrix. The excellent proton conductivity of the hydrogel electrolyte and the pseudocapacitance of the hydrogel electrode endow the SSC with a remarkable specific capacitance of 4122.0 mF cm −2 and energy density of 366.4 µWh cm −2 . Experimental characterization and finite element simulations elucidate the triple energy dissipation mechanism underpinning the super‐stretchability of the nested SSC. First, the low‐modulus bulk electrolyte matrix preferentially dissipates global stress, reducing fracture of the high‐modulus electrodes. Second, the intrinsic adhesion of the electrolyte matrix significantly enhances interfacial toughness (270.26 J m −2 ) on the electrodes, achieving an interfacial energy dissipation. Third, the wave‐patterned electrode structure contributes to geometric energy dissipation. These synergistic mechanisms enable the SSC to retain 92% capacitance even under 420% strain. Crucially, the nested platform facilitates monolithic integration for high‐voltage output, while the self‐adhesive property allows conformal attachment to deformable substrates for powering flexible electronics.