Effects of a nanometrically formed lithiophilic silver@copper current collector on the electrochemical nucleation and growth behaviors of lithium metal anodes

Abstract

Herein, we study the effects of a nanometrically uniform array of Ag nanoparticles (AgNPs) on the electrochemical nucleation and electrodeposition behavior of Li metal anodes (LMAs). The AgNP array is grown directly on the surface of commercial planar Cu current collectors (CCs) using a thermal evaporation system by limiting the growth of Ag thin films to an island stage. When the film is grown to an evaporation thickness of 3 nm, AgNPs with an average diameter of 11.4 nm are uniformly formed on the surface of Cu CCs. On the electrochemical nucleation of Li, the uniformly distributed AgNPs effectively provide nucleation sites for Li deposition and hence increase the nuclei density and spatial uniformity and decrease the size of the nuclei and nucleation overpotential. As a result, a dendrite-free, dense and pebble-like morphology of Li deposits is formed, and a high Coulombic efficiency (CE) of 98.5% is obtained during 100 cycles of the repeated electrodeposition and stripping of Li at a current density of 0.5 mA cm−2 for 1 mAh cm−2. In contrast, the cycle life of pristine Cu is limited to the 83rd cycle in the same testing environment.