Ultrathin zinc-carbon composite anode enabled with unique three-dimensional interpenetrating structure for high-performance aqueous zinc ion batteries

Zinc (Zn) anodes in aqueous zinc ion batteries (AZIBs) suffer from severe dendritic growth and corrosion reactions, and the resulting Zn loss prevents the batteries from stable cycling during the deep discharging process. Satisfactory performance can be achieved using over-thick Zn foils (>100 μm), but at the expense of full-cell energy density. Here, a facile strategy of co-rolling Zn foil and chemically expanded graphite (CEG) at room temperature is proposed to prepare an ultrathin Zn-carbon composite anode (Zn@CEG) with an adjustable thickness (6–40 μm). In Zn@CEG, Zn is uniformly embedded into the laterally arranged graphite spacing, forming a unique three-dimensional (3D) interpenetrating structure. The hydrophobic microregions of CEG accelerate the desolvation and conduction of Zn2+, promote uniform current density distribution, and suppress dendrites. Moreover, the transverse graphite sheets restrict the deep corrosion caused by electrolyte penetration. Thus, the symmetric cell assembled with ultrathin Zn@CEG stably cycles over 350 h at a discharge depth of 23.3%. When the Zn@CEG is matched with the high-loading MnO2 cathode (16 mg cm−2), the full cells achieve 500 and 800 cycles at low negative/positive capacity ratios of 6.9 and 10.7, respectively. This scalable strategy for constructing ultrathin Zn anodes provides new ideas for commercializing AZIBs.