Carbonized Polymer Dots with Intelligent Recognition and Dynamic Protection for Highly Stable Zn-Ion Batteries

Abstract

Electrolyte additives play a critical role in enhancing the performance and extending the lifespan of zinc-ion batteries (ZIBs). However, it remains a great challenge to design intelligent additives that can autonomously regulate the electrolyte structure and realize dynamically protect 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.

Keywords: Zn ion batteries, Carbonized polymer dots, Multifunctional additives, Zincophilic groups, Dendrite-free anode