A Bicontinuous Viscoelastic Network Solid‐State Electrolyte with Integrated Dual‐Electrode Stabilization and Low‐Pressure Adaptability for Zinc‐Ion Batteries

ABSTRACT Solid‐state electrolytes (SSEs) offer a promising route to stabilize both cathodes/anodes in zinc‐ion batteries, yet existing SSEs often fail to simultaneously combine high ionic conductivity, dual‐electrode stability, and low‐pressure processability—a critical requirement for practical deployment. Here, we present a bicontinuous viscoelastic network SSE (BVN‐SSE) engineered from a rationally optimized composite of filler and oligomer phases, along with zinc trifluoromethanesulfonate and bound water. By tuning the filler‐to‐oligomer ratio, we create interpenetrating elastic and viscous networks that combine solid‐like mechanical strength (𝐺′ = 40 kPa) with liquid‐like shear‐thinning rheology (𝐺′′ = 8 kPa). This architecture affords abundant interfacial pathways for fast Zn 2 + diffusion and a large free volume of 187.2 Å 3 , enabling a high ionic conductivity of 2.26 × 10 − 3 S cm − 1 at 25°C. Simultaneously, the solid‐state structure ensures a wide electrochemical window of 2.75 V, contributing to robust interfacial stability at both electrodes. Consequently, the Zn|BVN‐SSE|Zn symmetric cell operates stably for over 4700 h, while the Zn|BVN‐SSE|I 2 full cell achieves near‐unity Coulombic efficiency. Furthermore, the intrinsic viscoelasticity enables conformal electrode contact under low external pressures (0.09–0.2 MPa), maintaining excellent rate capability and cycling stability. This work establishes bicontinuous viscoelastic networks as a versatile materials platform for addressing multi‐faceted interfacial challenges in solid‐state batteries.