Carbonized polymer dots with intelligent recognition and dynamic protection for highly stable Zn-ion batteries

Electrolyte additives play a critical role in enhancing the performance and extending the lifespan of zinc-ion (Zn²⁺) batteries (ZIBs). However, it remains a great challenge to design intelligent additives that can autonomously regulate the electrolyte structure and realize dynamical protection for the zinc (Zn) anodes. In this study, a novel kind of smart fluorinated and nitrogen-doped carbonized polymer dots (FNCPDs) is synthesized as multifunctional additives for ZIBs. FNCPDs interact with Zn²⁺ and water molecules through coordination and hydrogen bonding, thereby effectively modifying the Zn²⁺ solvation structure and suppressing water activity. Especially, the co-deposited FNCPDs form a dynamic protective layer, mitigating water-induced side reactions and inducing Zn plating along the (002) plane during Zn plating. Notably, FNCPDs can detach from the Zn anode during stripping, continuing to regulate solvate Zn²⁺ and limit water activity. In addition, FNCPDs promote a thin solid electrolyte interphase (SEI) formation and suppress dendrite growth during cycling. The Zn||MnO₂ full cell with FNCPDs electrolyte maintains a high discharge capacity of 164.12 mAh g^-1 after 1200 cycles, with a capacity retention of approximately 85.65 %. This strategy highlights the significant potential of environmentally friendly, low-cost carbon dots for application in the field of energy storage.