Effect of Interfacial Activity on the Lithium Storage Behavior in Three-Dimensional Porous Host Electrodes

Abstract

Lithium-metal is considered a promising anode material for rechargeable batteries, owing to its high specific capacity of 3,860 mAh g-1 and low redox potential. However, various technical challenges, such as uneven Li deposition and large volume expansion, need to be addressed for the development of rechargeable Li-metal batteries. In recent years, there has been extensive research on the design and construction of three-dimensional (3D) porous electrodes that can host metallic Li. In practice, inhomogeneous nucleation and dendritic growth of Li still occur on top of the 3D host electrodes due to the kinetic limitation of Li+ in electrolyte-filled pores. In this work, we propose an interfacial activity gradient design to promote the bottom-up growth of Li in the 3D-Cu host electrode while suppressing the top growth. The Li plating behavior of the 3D-Cu host electrode is analyzed using a theoretical model based on a modified transmission line. Based on the theoretical results, a conformal lithiophilic nanolayer is formed via galvanic displacement to activate Li nucleation over the bottom, whereas an inert, non-conductive coating passivates the top surface. The 3D-Cu electrode with the interfacial activity gradient shows considerable improvements in Coulomic efficiency and cycling stability during repeated Li plating-stripping, compared to the conventional electrode with uniform interfacial activity. Our study demonstrates that the interfacial activity gradient design may provide an effective approach to developing highly efficient and robust Li metal electrodes based on 3D porous architectures.