Mechanism of Effect of Roughness on Dendrite Growth

Abstract

Lithium metal is an ideal anode material for high energy density rechargeable batteries. However, the repeated use of the battery leads to the increase of the roughness of the electrode surface, which aggravates the growth of harmful dendrites. The harmful dendrites will lead to short circuit and cause safety hazard. In this paper, the aspects of overpotential, curvature and pit shape were studied to understand the mechanism of effect of roughness on dendrite growth. The results show that the growth of needle like and dendritic dendrites is mainly due to the local disturbance of surface current density. The disturbance of surface current density is caused by the relative asymmetry of overpotential, curvature and deposition rate. High overpotential and small curvature will aggravate the disturbance of local current density, resulting in asymmetric dendrite formation. We also found lithium deposition in the pit, which is consistent with the published experimental results. However, whether dendrite can grow in the pit depends on the size of the pit. These results provide meaningful information for optimizing battery performance and improving safety.