Multifunctional Polyfluoride Ionogel‐Encapsulated Lithium Anodes for Durable and Safe Pouch Cells under Harsh Conditions

Lithium metal is environmentally sensitive and highly reactive, especially when coupled with flammable organic electrolytes, which pose critical safety challenges for lithium metal batteries under harsh operational conditions. This study tackles this challenge by constructing an integrated strategy for encapsulating lithium metal with a multifunctional polyfluoride ionogel (PFIGE) through in situ thermal polymerization. Based on the cross-linking network design of hexafluorobutyl methacrylate monomer and 1-butyl-3-lithium bis(trifluoromethylsulfonyl)imide ionic liquid plasticizer, C−F group and TFSI− anion cooperate to confer excellent water/oxygen barrier properties of the PFIGE. Meanwhile, the fluorinated skeleton optimizes the Li+ flux by regulating anion migration, thereby promoting the formation of stable inorganic-rich interphases and achieving homogeneous lithium deposition. Additionally, the C−F group forms ion−dipole interactions with imidazole cations to achieve dynamic self-healing capabilities, while the condensed-phase physical barrier and gas-phase radical scavenging effect of the pyrolyzed PFIGE synergistically contribute to the battery safety. ... mehrAs a proof-of-concept, PFIGE-integrated Li||LiNi0.5Co0.2Mn0.3O2 cells demonstrate extended cycling stability at high voltage (4.6 V) and high temperature (80 °C), and a 0.4 Ah-level pouch cell exhibits exceptional resistance to thermal runaway under mechanical/electrical/thermal abuse conditions. This design philosophy presents a paradigm-shifting electrolyte system that significantly enhances the cycle life and safety of lithium metal batteries.