Multiple hydrogen-bond networks enable bio-nanocomposite gel electrolytes with low water activity and anti-freezing ability for ultra-stable aqueous zinc-ion batteries

The inherent safety, cost efficiency, and sustainability of aqueous zinc-ion batteries (AZIBs) position them as an increasingly attractive option for large-scale energy storage systems. However, conventional liquid electrolytes often suffer from the strong hydrogen bonds (HBs) between highly active H₂O molecules, which lead to critical issues such as sluggish desolvation kinetics and poor low-temperature performance. Herein, we introduce a multiple HB network strategy by incorporating a lignin-derived carbon quantum dots (CQDs)-cellulose nanofibrils (CNFs) composite into a polyacrylamide (PAM) matrix to create a bio-nanocomposite gel electrolyte. The CQD-CNF composite, rich in polar groups, disrupts strong H₂O-H₂O HBs, enhancing the weak HBs ratio (50.76%). The resulting gel electrolyte exhibits a room temperature ionic conductivity of 59.32 mS cm^-1, exceptional mechanical flexibility with a 1170% tensile strain, low desolvation energy of 21.38 kJ mol^-1, and excellent anti-freezing capability down to -41 °C. These properties enable over 4000 h of stable operation in Zn||Zn symmetric batteries and an impressive 84.9% capacity retention after 15,000 cycles in Zn||PANI full batteries at -30 °C. The electrolyte's low self-discharge and stability under bending conditions make it ideal for flexible, wearable devices, offering a green, cost-effective and scalable solution for high-performance flexible and wide-temperature AZIBs.