Tunable copolymer eutectogel electrolytes for high-safety lithium-ion batteries

Safe and high-performance electrolytes are essential for the practical development of lithium-ion batteries (LIBs). Here, we report a eutectogel electrolyte constructed by integrating a deep eutectic solvent (DES), polyacrylamide (PAAM), and the zwitterionic polymer poly[2-(methacryloyloxy)ethyl]diethyl-(3-sulfonopropyl) (PMAEDS). The synergistic interplay of these components imparts the optimized PAAM 1 - co -PMAEDS 2 eutectogel with a wide electrochemical stability window (4.0 V), intrinsic non-flammability, and efficient ion transport—arising from the rich intermolecular interactions of the DES, the structural stability of PAAM, and the enhanced LiTFSI dissociation promoted by PMAEDS. When applied in Li 4 Ti 5 O 12 ||LiMn 2 O 4 full cells, the electrolyte enables a high specific capacity of 120.5 mAh g −1 with stable cycling over 260 cycles at 2C, while maintaining reliable operation at −10 °C. Moreover, the designed pouch cell demonstrates scalability and excellent safety under severe mechanical and thermal abuse. This work presents a simple and cost-effective eutectogel electrolyte strategy, offering a promising pathway toward next-generation high-safety LIBs.