Three-dimensional monolithic corrugated graphene/Ni foam for highly stable and efficient Li metal electrode

Abstract

To expedite the commercialization of Li metal anodes by combining them with Li transition metal oxides to achieve a high operating voltage, a carbonate-based electrolyte should be used, which is unstable at low potentials. Therefore, hybrid engineering to prevent dendritic Li growth and increase the coulombic efficiency in highly reactive electrolytes is essential. Here, three-dimensional monolithic corrugated graphene on nickel foam electrode as a Li metal storage framework in carbonate electrolytes is reported. The electrode is fabricated using a simple acid-catalyzed hydrothermal method. This involves separation of few-layer graphene sheets and formation of corrugated graphene sheets on porous Ni foam. During the initial Li deposition, Li ions are inserted into the vertical edge plane boundaries between graphene sheets. Li metal deposits then nucleate and grow further underneath the graphene sheets. The corrugated graphene sheets unfold and function as an artificial solid electrolyte interphase layer that separates the Li deposits from the reactive electrolyte. Consequently, the dendritic Li growth is effectively prevented, and the coulombic efficiency is significantly improved. Electrochemical tests demonstrate the effectiveness of this material design concept, which provides a new route to the development of a Li metal electrode for use in highly reactive electrolytes.