Mechanically Robust and Highly Conductive Lignin-Derived Dual-Network Eutectic Electrolytes

Conventional eutectic quasi-solid electrolytes (EQSEs), despite their intrinsic safety and sustainability, are fundamentally limited by the mechanical-conductivity trade-off, severely restricting practical deployment. Here, a lignin-engineered double-cross-linked EQSE is reported that overcomes these challenges through synergistic dual-dynamic networks: (1) an organic polyacrylamide/poly(acrylic acid) (PAM/PAA) framework establishing continuous ion-transport channels and (2) Fe3+-coordinated cross-links coupled with hydrogen bonding resolving the mechanical-conductivity trade-off. The resultant DES–LN–Fe3+ electrolyte simultaneously achieves a high ionic conductivity of 0.031 S cm–1 at 25 °C and exceptional ductility (851% strain). When deployed in flexible supercapacitors, it delivers a high specific capacitance of 310.6 F g–1 (0.1 A g–1) with exceptional low-temperature resilience (45.8% capacity retention at −40 °C) and cycling stability (95.7% after 10,000 cycles). Notably, the electrolyte doubles as a high-sensitivity strain sensor (gauge factor = 3.183), enabling real-time monitoring of biomechanical motions. This work establishes a dynamic dual-cross-linking paradigm to design multifunctional quasi-solid electrolytes for integrated energy storage and sensing platforms in extreme environments.