Functionalized Graphite Nanosheet Interfaces Enable (002)-Oriented Epitaxial Zinc Growth in Aqueous Zinc-Ion Batteries

Graphite nanosheets with highly oriented conductive coatings have been developed to guide uniform zinc deposition in aqueous zinc-ion batteries (ZIBs). By leveraging mechanical ball milling and chemical functionalization, hydroxyl and carboxyl groups are grafted onto graphite nanosheets. The graphite nanosheets’ slurry is coated on copper foil using shear force, ensuring the coating thickness is smaller than the graphite nanosheet diameter to promote horizontal alignment, which contributes to the formation of the (002)-oriented structure of the conductive coating. The resulting Cu@C current collector exhibits enhanced hydrophilicity and abundant zincophilic sites from rich oxygen-containing groups, promoting uniform Zn2+ distribution around the anode and guiding Zn2+ uniform transport along the (002) plane and zinc epitaxial growth. Structural characterization confirms the formation of two-dimensional, highly oriented graphite nanosheets on the copper substrate. Electrochemical tests reveal that Zn||Cu@C asymmetric cells achieve outstanding cycling stability and high Coulombic efficiency over thousands of cycles at various current densities, while Zn||Cu cells suffer from dendrite formation and rapid performance decay. Full cells with MnO2 cathodes further demonstrate improved capacity, rate performance, and charge-transfer kinetics when paired with Cu@C anodes. This work provides a practical strategy for crystal-plane-guided zinc deposition, offering insights into the design of long-life and high-performance zinc-ion batteries.