Vitamin C-Derived Oxygen-Functionalized Carbon Dots as a Novel Modulator for Regulating Zn2+ Deposition and Stabilizing Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) are promising alternatives to lithium-ion batteries due to the natural abundance of zinc and inherent safety, but dendrite growth on Zn anode and parasitic side reactions impair their lifespan and large-scale applications. Herein, we introduce vitamin C-derived, oxygen functionalized carbon dots (VC-CDs) as a novel modulator to aqueous electrolyte. Negatively charged VC-CDs preferentially adsorb on Zn anode, homogenizing electric fields and enabling uniform Zn2 + deposition, and their coordination with Zn2 + promotes ion migration, boosting full-cell capacity by 15% at 1 A g- 1. Accordingly, the Zn||Zn symmetric cells deliver a long-term stable cycling lifespan of 2000 h, whereas the Zn||Cu asymmetric cells attain an exceptional Coulombic efficiency of 99% across 2000 cycles. Furthermore, the Zn||VO2 full cells exhibit remarkable cycling stability, retaining 80% of their initial capacity after 2000 cycles at a current density of 4 A g- 1. Notably, the practical feasibility of VC-CDs is further corroborated in both Zn||VO2 and Zn||I2 pouch cells, which highlights their great potential for advancing next-generation aqueous zinc-ion battery technologies.