Controllable and large-area growth of ZnO nanosheet arrays under ambient condition as superior anodes for scalable aqueous batteries

Two-dimensional (2D) oxides have been the focus of substantial research interest recently, owing to their fascinating physico-chemical properties. However, fabrication of large-area 2D oxide materials in a controlled manner under mild conditions still remains a formidable challenge. Herein, we develop a facile and universal strategy based on the sonochemistry approach for controllable and large-area growth of quasi-aligned single-crystalline ZnO nanosheets on a Zn substrate (Zn@SC-ZnO) under ambient conditions. The obtained ZnO nanosheets possess the desired exclusively exposed (00 (1) over bar) facets, which have been confirmed to play a critical role in significantly reducing the activation energy and facilitating the stripping/plating processes of Zn. Accordingly, the constructed Zn@SC-ZnO vertical bar vertical bar Zn@SC-ZnO symmetric cell has very low polarization overpotential down to similar to 20 mV, with limited dendrite growth and side reactions for Zn anodes. The developed Zn@SC-ZnO//MnO2 aqueous Zn-ion batteries (ZIBs) show a voltage efficiency of 88.2% under 500 mA g(-1) at the stage of 50% depth of discharge, which is state of the art for ZIBs reported to date. Furthermore, the as-assembled large-size cell (5 cm x 5 cm) delivers an open circuit potential of 1.648 V, and can be robustly operated under a high current of 20 mA, showing excellent potential for future scalable applications.