Spherical metal mechanism toward revolution of Zn growth for ultrafast plating/stripping kinetics

Aqueous zinc batteries have attracted wide attentions due to their high security and theoretical capacity. However, intrinsic hexagon flake stacking mechanism of Zn metal anode raises uncontrollable Zn dendrite growth and poor electrochemistry property. Herein, innovative spherical Zn metal growth mechanism is firstly proposed assisting by graphene quantum dots (GQDs) through electroplating process. The strongest adsorption energy between Zn2+ and GQDs is formed for preferential GQDs-Zn clusters producing, and then the nucleation of Zn surrounding GQDs is ideally happened. After the subsequent remainder Zn2+ plating, the homogeneous composite Zn spheres are prepared on Cu foam skeleton. Remarkably, GQDs cores fixed in the matrix always lead to the recoverable spherical Zn growth procedure during repetitive plating/stripping processes. Combining the preferential Zn (002) crystal texture, the significant spherical Zn metal anode reaches stable thermodynamics to effective suppression of Zn dendrites growth and side reactions occurrence. Under ultrahigh current density of 20 mA cm-2, the stability of 908 cycles is achieved in half-cell. This work provides a new mechanism for designing neotype Zn metal anode to thoroughly avoid the natural drawbacks of traditional hexagon shape Zn, which is significant for the practice application of aqueous zinc batteries.

Automated summary

In this study, a new mechanism for the growth of spherical Zn metal anode was proposed using graphene quantum dots (GQDs) through electroplating process. The GQDs formed strong adsorption energy with Zn2+, leading to the nucleation of Zn around the GQDs and ultimately resulting in the homogeneous composite Zn spheres. This work provides a new approach to overcome the drawbacks of traditional hexagon shape Zn and is significant for the practical application of aqueous zinc batteries.