Rational Design of 3-Dimensional Carbon Architectures with Controlled Interfacial Activity for Reversible Li Metal Storage

Abstract

Three-dimensional (3D) host architectures for Li metal storage have emerged as promising strategies for resolving the critical issues of Li metal anodes: severe volume changes and dendritic growth of Li during charge–discharge processes. However, the ionic resistance of electrolyte-filled pores causes the preferential deposition of Li on top of the 3D architecture (i.e., top plating), resulting in early cell failure. To realize Li metal anodes with high capacity and cyclability, herein, we report 3D-architectured electrodes with controlled interfacial activity based on metal–organic framework (MOF)-derived carbon hosts. Electrochemical simulations of Li plating processes in the 3D-architectured electrode suggest that the top plating can be effectively suppressed by increasing the interfacial activity across the thickness toward bottom of the electrode. MOF nanoparticles are pyrolyzed to form highly porous carbon hosts, and then, atomic Ag clusters are incorporated into the host by a galvanic displacement reaction to enhance the interfacial activity. A bi-layered carbon electrode with controlled interfacial activity is fabricated via sequential electrophoretic deposition of the host materials: i.e., as-pyrolyzed carbon on top and Ag-incorporated carbon on bottom. In comparison with the conventional electrode with uniform interfacial activity, the bi-layered electrode exhibits reduced overpotentials for Li plating and enhanced cyclability during galvanostatic Li plating–stripping. The combined computational and experimental studies further demonstrate that the bottom layer with atomic Ag clusters acts as a preferential site for Li nucleation even in the presence of kinetic limitations of ionic transport. As a result, Li deposits are confined in the bi-layered carbon electrode, thereby enhancing the reversibility of Li metal storage. This work provides an effective strategy to develop long-cycling, high-capacity Li metal anodes by controlling the interfacial activity of 3D carbon architectures.