Plasma-Driven Instantaneous Polymerization: A Pathway to Superior Initiator-Free Organic Gel Polymer Electrolytes for Lithium Metal Batteries

The polymerization methodologies hold critical importance in fabricating high-quality gel polymer electrolytes (GPEs) for solid-state batteries. This work introduces a plasma-activated instantaneous polymerization strategy for the synthesis of initiator-free poly(ethylene glycol) diacrylate (PEGDA)-based GPEs within seconds. The N radicals produced by N 2 plasma can efficiently initiate the polymerization of PEGDA monomers without requiring chemical initiators. Notably, the plasma-derived GPEs (N-GPEs) exhibit superior ionic conductivity (0.69 × 10 –3 S cm –1 ) compared to thermally polymerized counterparts (0.42 × 10 –3 S cm –1 ), due to the formation of optimized ion-conduction pathways. Remarkably, this initiator-free synthetic protocol demonstrates dual interfacial advantages, not only on suppression of initiator-induced side reactions at lithium metal anodes but also formation of a Li 3 N-enriched solid electrolyte interphase (SEI) through reactive nitrogen species, collectively enhancing the interfacial stability and ion transport kinetics. Electrochemical evaluations demonstrate that symmetric Li||Li cells with N-GPEs show stable cycling over 1600 h with minimal polarization (21 mV at 0.1 mA cm –2 ). When integrated into Li||LiFePO 4 full cells, the system achieves 96.3% capacity retention after 200 cycles at 0.5 C, which is much better than the counterpart. This plasma-enabled polymerization technology establishes a paradigm shift in fabrication of polymer electrolyte, offering a rapid and energy-efficient route to high-performance GPEs for energy storage.