3D‐Printed Ultra‐Thin Solid Polymer Electrolytes with Superior Dielectric Properties for Wide Temperature Range All‐Solid‐State Batteries

ABSTRACT The development of all‐solid‐state batteries (ASSBs) is critical for overcoming the safety and performance limitations of conventional lithium‐ion batteries with liquid electrolytes. Solid polymer electrolytes (SPEs) offer promising processability and interfacial contact but suffer from low room‐temperature ionic conductivity. Liquid crystal electrolytes (LCEs) have emerged as a solution, leveraging their self‐assembling mesophases to create ordered ion transport channels that enhance conductivity. However, translating the molecular advantages of LCEs into high‐performance devices requires advanced manufacturing techniques capable of precise structural control. This work introduces a novel 3D‐printed, ultra‐thin (20 µm) composite LCE membrane engineered for high dielectric constant ( ε r ′ ∼ 40) and ionic conductivity (~10 −3 S cm −1 ). The membrane is composed of a polymer matrix (PVDF), a polymer network formed by the reaction of liquid crystal (LC) monomer RM257 and thiol monomers, and the high‐dielectric small molecule LC 4‐cyano‐4′‐pentylbiphenyl (5CB). When integrated into ASSBs with a lithium metal anode and LiCoO 2 cathode, the printed LCE membrane enables outstanding long‐term cycling stability (retaining a capacity of 76.6% over 3000 cycles). This study demonstrates that combining molecular design with additive manufacturing provides a powerful strategy for developing high‐performance, durable, and safe ASSBs.