  Zn metal battery has been considered a promising alternative energy storage
technology in renewable energy storage and grid storage. It is well-known that
the surface orientation of a Zn metal anode is vital to the reversibility of a
Zn metal battery. Herein, the (101)-oriented thin Zn metal anode (down to 2
{\mu}m) is electrodeposited on a Cu surface by adding dimethyl sulfoxide (DMSO)
electrolyte additive in ZnSO4 aqueous solution. Scanning electron microscope
(SEM) observation indicates the formation of flat terrace-like compact
(101)-oriented surfaces. Insitu optical observation confirms that the
(101)-oriented surfaces can be reversibly plated and stripped. DFT calculations
reveal two mechanisms for the nucleation and growth of the Zn-(101) surface:
(1) formation of Zn(101)//Cu(001) could lower the interface energy as compared
to Zn(002)//Cu(001); (2) large reconstruction of the Zn (101) surface with DMSO
and H2O absorption. Raman, XPS, and ToF-SIMS characterizations indicate that
adding DMSO in ZnCl2 could facilitate the formation of ZnO-based SEI on Zn
metal surface, while OH- and S-based SEI can be obtained with DMSO in ZnSO4.
The electrochemical testings are performed, which demonstrates a higher
cyclability for the (101)-oriented Zn in the half cell as well as a lower
charge transfer barrier with respect to the (002)-dominated surface of the same
electrode thickness. Zn||V2O5 full cells are further assembled, showing better
capacity retention for the (101)-Zn as compared to the (002)-Zn with the same
thickness (5 {\mu}m, 3 {\mu}m, and 2 {\mu}m). We hope this study to spur
further interest in the control of Zn metal surface crystallographic
orientation towards ultrathin Zn metal anodes.
