Constructing Copper Substrate Surface Manipulates Zinc Anode Chemistry*

Aqueous zinc-ion batteries (AZBs) have attracted attention due to their safety, low cost, high earth abundance, and high theoretical capacity of 820 mAh g^-1. However, Zinc (Zn) metal anode suffers from uneven Zn plating, which leads to the formation of dendrites and the unusable (“dead”) Zn. In this project we modified copper (Cu) foil surface by fast etching to manipulate the morphology of Zn plating/stripping and improve its reversibility.  The etched Cu surface helps facilitate the even deposition/stripping of Zn with densely packed hexagonal plates rather than random nucleation with dendrite growth, controlling the nucleation process and improving the battery's reversibility. Our Cu//Zn coin cells showed that the etched Cu operates for more than 858 hours compared to bare Cu of only 180 hours, and a significantly lower polarization voltage. Our anode-free coin cell device with lithium manganese oxide (LMO) cathodes showed a 36% longer cyclability with the etched Cu and higher specific capacity. The etched Cu substrate also shows a long cyclability of 100 cycles in a high-capacity 10mAh cm^-2 device with 50% zinc utilization rate (50 % ZUR). Our results indicate that the etched copper substrate regulates compact and dendrite-free Zn plating, resulting in long-term cycling stability, lower polarization, and improved device performance.