Improving lithium deposition in porous electrodes: Phase field simulation

Abstract

The development of structured lithium metal anodes is a key area of focus in the field of lithium battery research, which can significantly improve the energy density, cycle life and safety of lithium metal batteries. In this study, an electrochemical phase field model is used to construct the total free energy of the electrochemical system in conjunction with the effect of the porous electrode scaffold. It investigates the anisotropy of the diffusion coefficient of lithium ions in the electrolyte and the effect of the gradient size of the porous electrode scaffolds on the lithium deposition within the pores. Our numerical results show that increasing the diffusion coefficient of lithium ions in the x-direction cannot improve the lithium deposition within the pores. Instead, it leads to the appearance of lithium dendrites in the top layer of the porous electrode. Appropriately increasing the diffusion coefficient of lithium ions in the y-direction can significantly increase the lithium deposition capacity within the pores. However, excessive increases can lead to a reversal of the lithium deposition capacity within the pores. In addition, adopting the gradient size of the porous electrode scaffold in the y-direction can effectively alleviate the phenomenon that lithium metal is preferentially deposited at the top of the scaffold. These findings provide new ideas for the future design of structured lithium metal anode batteries.