Cu Foam-Loaded Cu₂Mg Alloy with High Electrochemical Stability to Regulate the Nucleation of Lithium for Dendrite-Free Lithium Metal Batteries

Abstract

Constructing a lithiophilic layer-modified three-dimensional framework is an effective approach to solve the problems of dendrite growth and volume expansion during Li plating/stripping. Herein, a Cu2Mg alloy layer is constructed on copper foam (CF@Cu2Mg) using a facile thermal evaporation and in situ alloying process for the first time to obtain a highly lithiophilic and dendrite-free lithium metal anode. Density functional theory calculations show that Cu2Mg possesses a more negative adsorption energy (−1.96 eV) than pure Cu (−1.45 eV), implying a better lithiophilicity of Cu2Mg. Moreover, different from other Mg0-containing lithiophilic compounds, the Cu2Mg alloy possesses splendid chemical and electrochemical stability. The Li alloying reaction will not occur in the process of discharge, avoiding the failure of the modification layer. Therefore, a long cycling lifespan of 3500 h with an ultra-low deposition overpotential (∼9 mV) is achieved for the half-cell. The full cell with LiFePO4 as the cathode exhibits good cycling performance at 1 C with a capacity retention rate of 90% after 400 cycles. The construction of Cu2Mg coating in this work points to a new direction for the design of highly lithiophilic and electrochemically stable Mg-containing 3D hosts for dendrite-free lithium metal anodes.