Vitamin C-Derived Oxygen-Functionalized Carbon Dots as a Novel Modulator for Regulating Zn²⁺ Deposition and...

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 Zn^{2 +} deposition, and their coordination with Zn^{2 +} 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.