Enabling a stable and dendrite-suppressed Zn anode via facile surface roughness engineering

Abstract

• Smoother zinc metal anode surface exhibits better hydrophilicity. • Smoother zinc metal anode surface exhibits lower potential barrier and faster reaction kinetics. • Monitoring anode surface electrochemical behaviors during charging. • Computational simulation of the relationship between surface roughness and battery performance. The safety and cycle lifespan of zinc metal-based aqueous batteries are greatly restricted by zinc anode. The poor cycling performance of zinc metal anode is often considered to be impacted by the dendrite growth, surface passivation, zinc metal corrosion and hydrogen evolution reaction, while surface roughness is a matter that has often been ignored in past studies. Herein, a roughness gradient is constructed on the zinc anode surface by a simple grinding and pasting method. It has been found the modified zinc anodes with lower surface roughness exhibit the smaller zinc deposition overpotential and longer cycle life. Further, in situ optical microscopy photographs indicate that the zinc anode with an optimized roughness enables more uniform distribution of zinc precipitation and corrosion sites, which will facilitate a stable cycling performance of aqueous zinc ion batteries. The Zn anode dendrite-suppressing mechanism via surface roughness engineering was revealed through finite element computational simulation. These results emphasize the effectiveness of roughness engineering for tuning the surface physics of Zn anode and provide a facile strategy to develop better and safer aqueous zinc ion batteries.