Mosaic rGO layers on lithium metal anodes for the effective mediation of lithium plating and stripping

Abstract

The passivation of lithium metal anodes to mitigate an unstable solid electrolyte interface and parasitic dendrite growth is the key premise for their successful implementation in lithium metal batteries. Herein, aiming to simultaneously reduce the interfacial resistance and to suppress lithium dendrites, we coated lithium metal anodes with two-dimensional (2D) rGO layers prepared via a solvent-evaporation-assisted self-assembly. Upon lithiation/delithiation, the rGO coating cracked into mosaic-like flakes, in between which the interconnected gaps served as the passage for uniform lithium plating/stripping. Half cells composed of a sandwich Cu/Li/rGO electrode vs. Cu foils revealed much improved Li usage and coulombic efficiencies. Through ex situ SEM imaging and XPS depth profiling, a comprehensive view of Li intercalation, deposition, and dendrite suppression on the rGO coating was obtained. As a result of the improved kinetics of Li transportation, excellent electrochemical performances were demonstrated in symmetric gLi‖gLi cells with a stabilized overpotential of only 87.9 mV at 5 mA cm⁻² over 600 cycles, and in Li–S batteries with a stabilized capacity of 1200 mA h g⁻¹ at 1C near 1000 cycles.