Defect‐Piezo‐Coupled Porous Cubes Boost Stable Electrolytes for All‐Solid‐State Sodium Metal Batteries

Interfacial instability caused by uncontrolled dendrite growth and side reactions restricts the energy density and cycle life of sodium metal batteries. Herein, a composite solid‐state electrolyte PEO‐Porous‐Cube‐ZnO (PPCZO) integrating synergistic piezoelectric‐defect bifunctional modulation is constructed by embedding a ZIF‐8‐derived porous cube ZnO (PC‐ZnO) with oxygen vacancies (OVs) as a multifunctional filler. OVs amplify the piezoelectric response of PC‐ZnO, enabling homogeneous Na + deposition and effectively suppressing Na‐dendrite formation. Meanwhile, OVs establish a local electric field and expose additional Lewis‐acid sites, while the porous‐cube structure strengthens interactions with PEO chains and increases the amorphous fraction, which firmly anchors TFSI − and mitigates interfacial decomposition side reactions. Consequently, PPCZO delivers a wide electrochemical stability window (5.11 V), high Na⁺ transference number (0.41), and outstanding stability (symmetrical Na//Na cells run over 1600 h at 0.1 mA cm −2 and 60 °C). Pouch cells assembled with PPCZO demonstrate practical potential and safety, and 3D printing (3DP) is further leveraged to expand possibilities for specialized applications. This work presents a promising paradigm for the advanced design and fabrication of solid‐state sodium‐metal batteries.