A Lasagna-Inspired Nanoscale ZnO Anode Design for High-Energy Rechargeable Aqueous Batteries

Rechargeable batteries using aqueous electrolyte have intrinsically low flammability and are promising alternatives to lithium ion batteries for mid- and large-scale energy storages. Among aqueous battery anode materials, zinc metal stands out because of the highest energies (5846 Ah/L volumetric capacity, 3 times the amount of a lithium metal anode) and an operating potential near the lower limit of water stability window. However, the rechargeability of Zn anodes is hindered by passivation and dissolution problems associated with the solid-solute-solid transformation during cycling. Here we solve both problems simultaneously by designing a distinctive nanostructured zinc anode in which 100 nm ZnO nanoparticles are wrapped and segmented by graphene oxide (GO) sheets. The small size of primary ZnO nanoparticles prevents passivation, while the GO wrap and segmentation confine soluble Zn(OH)(4)(2-) intermediates from escaping. This lasagna-like nanostructured Zn anode measured a high volumetric capacity of 2308 Ah/L and achieved a remarkable capacity retention of 86% after 150 cycles. In contrast, the open-structured ZnO nanoparticle anode, without the protection of GO, completely died after 90 cycles.