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

ABSTRACT 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 SiO ₂ aerogel (SiO ₂ /PMBA GPE) is developed through in situ polymerization. The SiO ₂ aerogel incorporation accelerates Li ⁺ transport by disrupting polymer chain alignment, and simultaneously regulates Li ⁺ solvation structures through Lewis acid‐base interactions between SiO ₂ aerogel and electrolyte components. This synergistic effect facilitates rapid kinetics and uniform Li deposition, as well as promotes a stable Li ₃ N, LiF‐rich interphase that may suppress dendrite growth. The SiO ₂ /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 SiO ₂ /PMBA GPE design exhibits a promising prospect for the practical application of high energy density LMBs.