Morphosynthesis of 3D Macroporous Garnet Frameworks and Perfusion of Polymer‐Stabilized Lithium Salts for Flexible Solid‐State Hybrid Electrolytes

Abstract Solid‐state lithium‐ion‐conducting membranes are emerging as a promising electrolyte for rechargeable lithium batteries. However, their reliable and scalable preparation still remain challenges, due to low room‐temperature ionic conductivity of solid polymer electrolytes and inherent brittleness of ceramic inorganic electrolytes. Herein, a simple and cost‐effective morphogenetic route is developed for fabricating hierarchically nanostructured 3D garnet‐type Li 7 La 3 Zr 2 O 12 monoliths by using degreasing cotton as a template. Nanostructuring of 3D Li + ‐conducting frameworks offers interconnected and continuous Li + ‐transport pathways in a poly(ethylene oxide)‐based composite electrolyte. The as‐fabricated solid‐state composite electrolyte is flexible and exhibits an enhanced Li‐ion conductivity of 0.89 × 10 −4 S cm −1 as well as a large stable electrochemical window up to 5.5 V versus Li/Li + . The symmetric lithium cell using the 3D‐architectured electrolyte shows good cycling stability at different current densities. Furthermore, the LiFePO 4 (+) | hybrid electrolyte | Li (−) battery working at 30 °C exhibits outstanding rate capability and cyclability and delivers a high coulombic efficiency of nearly 100% at a current density of 0.2 C (1 C = 170 mA g −1 ). The present fabrication route is easy and effective and holds promise for scaled‐up production.