Electroplating Carbon Nano-Onion on Copper for Dendrite-Free and Anode-Free Zinc-Ion Batteries

Zinc-ion batteries (ZIBs) have emerged as a promising and safer alternative to traditional lithium-ion batteries (LIBs) due to their cost-effectiveness, material abundance, and the use of non-flammable aqueous electrolytes; however, the widespread adoption of ZIBs is still hindered by challenges such as dendrite formation, hydrogen evolution, and electrode passivation. Herein, the electroplating of carbon nano-onions (CNOs) and Cu is demonstrated to form a CNO-embedded-Cu coating onto Cu foil for use as Zn anode current collectors, which facilitates high zinc plating/stripping efficiency (99.89%) over 1400 cycles. This CNO-embedded-Cu coating ensures high conductivity of the substrate surface and stabilizes Zn deposition by embedded CNOs. This CNO@Cu film achieves long-term cycling with an 85.5% depth of discharge over 176 h, outperforming traditional Cu (102 h). Further, a ZIB fabricated with a CNO@Cu current collector in an anode-free configuration paired with a zincified NH₄V₄O₁₀ cathode demonstrates a high volumetric energy density of 194.8 Wh L^-1. CNO@Cu offers a low-cost, scalable, and high-performance solution for industrial anode-free ZIBs, and this work sets the foundation for future improvements in ZIBs by utilizing cost-effective, industrial-grade nanomaterials.