Lignin-Based Electrode Materials with a “Spiderweb–Mucilage” Structure for Dual-Energy Storage

With the rapidly growing demand for flexible energy storage devices in wearable electronics, the development of electrode materials that combine high energy/power density with excellent flexibility has become critical. Inspired by the natural “spiderweb–mucilage” structure, we successfully prepared a lignin-based electrode material via electrospinning, carbonization, and hydrothermal processes. This material achieves efficient dual-mode energy storage by mimicking the synergistic roles of the spider web and mucilage. The material features an rGO-CNFs skeleton with high conductivity (4.02 S·cm–1) and flexibility, serving as a “conductive spider web”, while NiCo-LDHs nanosheets are anchored as “mucilage” for rapid Faradaic reactions. The above components are tightly interconnected by stable M–O–C chemical bonds, endowing the composite structure with excellent mechanical robustness. This design yields exceptional performance: a specific capacitance of 1492.6 F·g–1 at 1 A·g–1, vastly surpassing pure CNFs (161.4 F·g–1) and rGO-CNFs (440.6 F·g–1). Such excellent electrochemical performance originates from the synergistic effect of dual-energy storage and the significantly enhanced electrolyte wettability of the electrode, whose contact angle with the electrolyte is reduced from 133.3° to 34.4°. The assembled flexible symmetric supercapacitor achieves an energy density of 82.67 Wh·kg–1 at 800 W·kg–1 and retains 94.5% capacitance after 2000 cycles, demonstrating excellent stability.