Spatially Confined Engineering Toward Deep Eutectic Electrolyte in Metal‐Organic Framework Enabling Solid‐State Zinc‐Ion Batteries

Abstract Uncontrollable interfacial side reactions generated from common aqueous electrolytes, just like the hydrogen evolution reaction (HER) and dendrite growth, have severely prevented the practical application of zinc‐ion batteries (ZIBs). Solid‐state ZIBs are considered to be an efficient strategy by adopting high‐quality solid‐state electrolytes (SSEs). Here, by confining deep eutectic electrolyte (DEE) into the nanochannels of metal‐organic framework (MOF)‐PCN‐222, a stable DEE@PCN‐222 SSE with internal Zn 2+ transport channels was obtained. A distinctive ion‐transport network composed of DEE and PCN‐222 in the interior of DEE@PCN‐222 realizes the efficient Zn 2+ conduction, contributing to high ionic conductivity of 3.13×10 −4 S cm −1 at room temperature, low activation energy of 0.12 eV, and a high Zn 2+ transference number of 0.74. Furthermore, experimental and theoretical investigations demonstrate that DEE@PCN‐222 with its unique channel structure could homogeneously regulate the Zn 2+ distribution and effectively alleviate the side reactions. Highly reversible Zn plating/stripping performance of 2476 h can be realized by the SSE. The solid‐state ZIBs show a specific capacity of 306 mAh g −1 and display cycling stability of 517 cycles. This unique design concept provides a new perspective in realizing the high‐safety and high‐performance ZIBs.