Effects of Porous Separators on Dendrite Growth in Lithium Batteries

Abstract

Dendrite growth on the surface of the anode in lithium batteries can diminish their energy storage capacity and increase safety concerns, i.e. risks of a short circuit. Dendrite growth consists of two stages, nucleation and growth. Favorable sites for the nucleation of dendrites are difficult to avoid and so suppressing dendrites after nucleation is a promising research direction. Previous work has suggested that the local mass transport in the electrolyte is closely related to the structure of dendrites. In this research, a mesoscale diffusion-reaction model is used to study the effects of various porous separator geometries and configurations on dendrite formation. The porous separators act to restrict the local mass transport near the anode surface, which effects dendrite structure and growth rates. The porous separator structures considered in this study highlight the importance of both porosity and tortuosity. These attributes are often simplified when reporting characteristics in experimental tests or ignored in other simulations. In this study, we directly observe the impact of separator characteristics on the local mass transport gradient through the separator and the subsequent dendrite growth. By taking into account the impact of both overall and local porosity and tortuosity on dendrite growth, battery design can be improved.