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

Bioinspired by plant cell walls' cellulose-lignin-hemicellulose hierarchy, BC synergizes with LNDP/HAPLi as multifunctional linkers to establish a nonflammable BC/Li-FR electrolyte with biomimetic Li⁺ transport highways to boost Li⁺ conductivity (4.69 mS cm⁻¹). The biomimetic BC/Li-FR illustrates the ultra-wide temperature adaptability (−20 to 30 °C) and self-optimizing SEI enables dendrite-free Li deposition (1600 h) for cryogenic LIBs.

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||LiFePO₄ 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.