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

Why It Matters

By mitigating dendrite formation and electrolyte degradation, VC‑CDs dramatically extend the lifespan of aqueous zinc‑ion batteries, making them a viable, low‑cost alternative to lithium‑ion systems for grid‑scale storage.

Key Takeaways

• VC-CDs guide uniform Zn deposition, suppress dendrites.
• Oxygen groups lower water activity, reducing side reactions.
• Zn||Zn cells achieve 2000 h stable cycling with VC-CDs.
• Coulombic efficiency reaches 99% over 2000 cycles in Zn||Cu.
• Full cells retain 80% capacity after 2000 cycles at 4 A g⁻¹.

Pulse Analysis

Aqueous zinc‑ion batteries (AZIBs) have attracted attention as a safer, cheaper counterpart to lithium‑ion technology, thanks to zinc’s abundance and the non‑flammable nature of water‑based electrolytes. Yet, practical deployment has been hampered by two persistent problems: dendritic zinc growth that can short‑circuit cells, and vigorous side reactions between the electrolyte and the metal surface that consume active material and generate gas. Researchers have therefore been exploring electrolyte additives and surface modifiers that can tame these failure modes without compromising ionic conductivity.

The newly reported vitamin C‑derived carbon dots (VC‑CDs) address both challenges in a single package. Their negative surface charge draws them to the positively charged zinc anode, where they form a thin, uniform coating that smooths the local electric field and directs Zn²⁺ ions to deposit evenly. Simultaneously, oxygen‑containing functional groups on the dots engage water molecules through hydrogen bonding, effectively lowering the water activity at the interface and suppressing hydrogen evolution and zinc corrosion. This dual action also facilitates faster Zn²⁺ migration, translating into higher capacity utilization and lower overpotential during charge‑discharge cycles.

Performance data underscore the commercial relevance of VC‑CDs. Symmetric Zn||Zn cells cycled continuously for 2,000 hours without voltage decay, while Zn||Cu asymmetric cells maintained a Coulombic efficiency of 99 % over the same number of cycles. Full‑cell tests with Zn||VO₂ cathodes retained 80 % of their initial capacity after 2,000 cycles at a demanding 4 A g⁻¹, and a 15 % capacity increase was observed at 1 A g⁻¹. Successful pouch‑cell prototypes demonstrate that the additive can be integrated into scalable manufacturing processes, positioning VC‑CDs as a promising lever for accelerating the adoption of next‑generation, large‑scale energy storage solutions.