A Polyamide Gel Polymer Electrolyte Hybridizing SiO ₂ Aerogel for High‐Energy‐Density Lithium Metal Batteries

Lithium metal batteries (LMBs) hold immense promise for next-generation high-energy-density storage systems. However, inherent challenges including unstable solid electrolyte interphases (SEIs) and dendrite growth, critically impede its practical deployment in high-energy-density batteries. Herein, a composite poly(N,N'-Methylenebisacrylamide) (PMBA) gel polymer electrolyte hybridizing SiO₂ aerogel (SiO₂/PMBA GPE) is developed through in situ polymerization. The SiO₂ aerogel incorporation accelerates Li⁺ transport by disrupting polymer chain alignment, and simultaneously regulates Li⁺ solvation structures through Lewis acid-base interactions between SiO₂ aerogel and electrolyte components. This synergistic effect facilitates rapid kinetics and uniform Li deposition, as well as promotes a stable Li₃N, LiF-rich interphase that may suppress dendrite growth. The SiO₂/PMBA-based Li||Cu half-cell achieves a high average coulombic efficiency (CE) of 97.7% over 300 cycles after the initial activation stage at 0.1 mA cm^-2, while Li||Li symmetrical cell demonstrates exceptional cycling stability exceeding 4000 h at 0.1 mA cm^-2, indicating superior compatibility with lithium metal anode. The Li||NCM811 cell exhibits high discharge capacity of 171.6 mA g^-1 at 1 C, and outstanding cycling stability with 90.6% capacity retention after 300 cycles. Noteworthy, the pouch cell with practical Li||NCM811 configuration achieves a high energy density of 453.87 Wh kg^-1. The in situ polymerized SiO₂/PMBA GPE design exhibits a promising prospect for the practical application of high energy density LMBs.