Mechanically Stable Honeycomb‐Like Gel Polymer Electrolyte Enabling Fast Li + Transport for High‐Performance Lithium Metal Batteries

ABSTRACT Lithium metal batteries (LMBs) are promising high‐energy‐density devices, but their practicality is limited by lithium dendrite growth and interphase instability. Here, we propose a gel polymer electrolyte (GPE) derived from a honeycomb‐like polyurethane/urea foam (PUF) in which the cross‐linking density is increased within a certain range to enhance its mechanical strength and electrolyte retention. The ether (O─) and carbonyl (C═O) groups along the PUF polymer backbone participate in regulating the Li + solvation structure, with the secondary amine groups (─NH─) effectively anchoring anions. This synergistic functionality promotes lithium salt dissociation, enables rapid Li + transport, and yields a high Li + transference number (tLi + ). As a result, the Li || Cu cell achieves uniform Li plating/stripping, achieving an average Coulombic efficiency of 99.2% over 500 cycles at 0.5 mA cm −2 . The battery assembled with LiFePO 4 (LFP) retains 96.9% capacity after 500 cycles at 1 C. The LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) based cell maintains 83.4% capacity at a charging cut‐off voltage of 4.5 V after 200 cycles at 0.5 C. This work introduces a viable strategy for designing high‐performance GPEs applied in LMBs.