3D printing zwitter Molecule‐Enhanced Solid Polymer Electrolytes for High‐Energy Lithium Metal Batteries

Abstract Unsatisfying preparation controllability, mechanical properties, ionic conductivities, and working voltage windows limit the practical applications of solid polymer electrolytes (SPEs) in lithium‐metal batteries. Herein, a 3D printing strategy combined with zwitter molecule modification is proposed to efficiently solve the problems of SPEs with a polyvinylidene fluoride‐hexafluoropropylene (PH) matrix. The electron‐donating property resulting from the carboxyl groups of aspartate acid (Asp) induces the cis‐conformation change of polyvinylidene fluoride, which enhances the Li + transport and anion immobilization on polymer chains. In addition, the amphoteric functional groups of Asp simultaneously promote the lithium salt dissociation and Li + desolvation with N,N‐dimethylformamide, thus leading to the formation of stable Li 3 N/LiF‐enriched interphases between electrodes and electrolyte. Moreover, the 3D printing technology increases the continuity and uniformity of the SPE membrane, further increasing the ionic conductivity and mechanical properties. As a result, the SPE exhibits high ionic conductivity (1.20 × 10 −4 S cm −1 ), large transfer number (0.68), wide electrochemical window (4.6 V), and good tensile strength (≈110 MPa), endowing the half cells with good cycling performance over 2000 h with a low overpotential of 40 mV. Furthermore, high‐energy densities (492 Wh kg −1 and 1303 Wh L −1 ) are delivered by a pouch cell with the SPE, indicating good application prospects.