An Electrode‐Crosstalk‐Suppressing Smart Polymer Electrolyte for High Safety Lithium‐Ion Batteries

Abstract Electrode crosstalk between anode and cathode at elevated temperatures is identified as a real culprit triggering the thermal runaway of lithium‐ion batteries. Herein, to address this challenge, a novel smart polymer electrolyte is prepared through in situ polymerization of methyl methacrylate and acrylic anhydride monomers within a succinonitrile‐based dual‐anion deep eutectic solvent. Owing to the abundant active unsaturated double bonds on the as‐obtained polymer matrix end, this smart polymer electrolyte can spontaneously form a dense crosslinked polymer network under elevated temperatures, effectively slowing down the crosstalk diffusion kinetics of lithium ions and active gases. Impressively, LiCoO 2 /graphite pouch cells employing this smart polymer electrolyte demonstrate no thermal runaway even at the temperature up to 250 °C via accelerating rate calorimeter testing. Meanwhile, because of its abundance of functional motifs, this smart polymer electrolyte can facilitate the formation of stable and thermally robust electrode/electrolyte interface on both electrodes, ensuring the long cycle life and high safety of LIBs. In specific, this smart polymer electrolyte endows 1.1 Ah LiCoO 2 /graphite pouch cell with a capacity retention of 96% after 398 cycles at 0.2 C.