Rational design of lignin-based materials for high-performance zinc-ion energy storage systems: fundamentals,...

Zinc-ion energy storage systems (ZIESS) are promising, safe, and cost-effective alternatives to lithium-ion batteries but still face challenges such as dendrite growth, sluggish ion transport, and interfacial instability. Lignin, a renewable aromatic biopolymer, is a sustainable platform to mitigate these issues owing to its abundant functional groups and structural tunability. In ZIESS, lignin-based materials play multifunctional roles in electrodes and electrolytes through their tunable chemistry, redox activity, and compatibility with aqueous zinc systems. This review summarizes recent advances in the rational design of lignin-based materials for ZIESS, emphasizing chemical/physical modification and carbonization with heteroatom doping to enhance ionic/electronic transport and interfacial stability. The diverse functions of lignin-based materials in electrodes, electrolytes, binders, separators, and interfacial layers are highlighted, along with key challenges and future directions toward scalable and green fabrication. This work provides integrated insights that couple molecular design with electrochemical function, guiding the sustainable development of lignin-based materials for advanced ZIESS.