Silver Nanoparticles on Vertical Graphene As a Stable Lithium Host for Lithium-Metal Batteries

Abstract

The direct use of lithium metal in batteries is jeopardized by the challenging issues related to lithium dendrites or nonuniform lithium deposition, especially in liquid electrolyte and under high current density. Engineering a lithium host that can promote uniform lithium stripping/plating process has attracted tremendous interest to address the challenges. In this study, we design a hierarchical 3D structure, in which edge-oriented graphene (EOG) nanosheets modified carbon nanofiber (CNF) film is used as a scaffold, decorated with Ag nanoparticles (Ag@EOG-CNF), as the lithium host and current collector. Ag nanoparticles not only render the EOG-CNF lithiophilic but also serve as the seeding sites for lithium nucleation to regulate lithium deposition process. In comparison with the previously reported carbon nanofibers or graphene-based lithium hosts, EOG and Ag modification can significantly increase the available surfaces for lithium deposition with reduced local current density. As a result, the Li/Ag@EOG-CNF electrode showed very stable lithium plating/stripping in both symmetric (~25 mV of overpotential within 1000 h of cycling time at the current density of 2 mA cm-2 and capacity of 2 mAh) and asymmetric (Coulombic efficiency maintains above 98.5% within 200 h of cycling time at the current density of 1 mA cm-2 and capacity of 2 mAh) cells.