Morphological control of electrodeposited lithium metal via seeded growth: stepwise spherical to fibrous lithium growth

Abstract

Uncontrolled Li deposition and side reactions on the Li metal surface induce low coulombic efficiency, poor cycle performance, and safety risks. Identification of the Li deposition mechanism governing the morphology evolution is prerequisite for establishing a strategy to control the morphology and resolve these issues. Here, we found that fibrous Li growth follows the initial spherical Li particle formation when the Li sphere size reaches the critical value during Li deposition. Based on the morphology evolution mechanism, a seeded Li deposition strategy of changing the current from low to high (0.2 to 1.8 mA cm⁻²) is proposed to minimize the surface area of Li deposits. Stepwise spherical to fibrous Li growth successfully produced a well-controlled completely fibrous Li morphology. The Li deposits of the seeded growth strategy achieved smaller surface areas, suppressed side reactions, and remarkably improved cycle life compared to that of single current deposition with the same average current density (1 mA cm⁻²).