Bioinspired Synaptic Branched Network within Quasi‐Solid Polymer Electrolyte for High‐Performance Microsupercapacitors

Abstract The branched network‐driven ion solvating quasi‐solid polymer electrolytes (QSPEs) are prepared via one‐step photochemical reaction. A poly(ethylene glycol diacrylate) (PEGDA) is combined with an ion‐conducting solvate ionic liquid (SIL), where tetraglyme (TEGDME), which acts like interneuron in the human brain and creates branching network points, is mixed with EMIM‐NTf₂and Li‐NTf₂. The QSPE exhibits a unique gyrified morphology, inspired by the cortical surface of human brain, and features well‐refined nano‐scale ion channels. This human‐mimicking method offers excellent ion transport capabilities through a synaptic branched network with high ionic conductivity (σ_DC≈ 1.8 mS cm⁻¹at 298 K), high dielectric constant (ε_s≈ 125 at 298 K), and strong ion solvation ability, in addition to superior mechanical flexibility. Furthermore, the interdigitated microsupercapacitors (MSCs) based on the QSPE present excellent electrochemical performance of high energy (E = 5.37 µWh cm⁻²) and power density (P = 2.2 mW cm⁻²), long‐term cycle stability (≈94% retention after 48 000 cycles), and mechanical stability (>94% retention after continuous bending and compressing deformation). Moreover, these MSC devices have flame‐retarding properties and operate effectively in air and water across a wide temperature range (275 to 370 K), offering a promising foundation for high‐performance, stable next‐generation all‐solid‐state energy storage devices.