Biobased Polymer Electrolyte with Plant Cell Wall‐Inspired Architecture: Biomimetic Integration of Cellulose‐Lignin for Nonflammable Cryogenic Lithium Batteries

Abstract The pursuit of safe and temperature‐resilient lithium batteries faces a critical dilemma: conventional liquid electrolytes compromise safety with flammable organic solvents, while existing solid‐state alternatives suffer from insufficient ionic conductivity. This study unveils a nonflammable biomimetic electrolyte architecture inspired by plant cell walls, integrating bacterial cellulose (BC) with lignin‐derived flame‐retardant microspheres (LNDP) and lithium‐functionalized hydroxyapatite (HAPLi). The “cellulose−lignin−hemicellulose” biomimetic framework establishes multiple Li + transport channels, and achieves high Li + transfer number (0.75) and exceptional ionic conductivity (4.69 mS cm⁻ 1 at 30 °C; 0.162 mS cm⁻ 1 at −20 °C) through the fluorine/phosphorus‐rich solid electrolyte interphase (SEI). At 0.2 C, the assembled Li||LiFePO 4 battery with BC/Li‐FR exhibits a high initial discharge capacity of 117 mAh g −1 at −20 °C, and stably cycles 800 cycles with a high retention rate of 97.7%. The Li||NCM811 battery maintains a high capacity of 151.4 mAh g⁻ 1 after 130 cycles at −20 °C. This work demonstrates that the BC/Li‐FR architecture enables self‐regulating lithium‐ion deposition behavior, thereby effectively suppressing dendrite formation and growth. The findings lay a groundbreaking foundation for developing inherently safe lithium batteries capable of stable operation across a wide temperature spectrum, including challenging cryogenic environments.