Nano-Cu-embedded carbon for dendrite-free lithium metal anodes

Abstract

Lithium metal has been considered as a promising anode material for a long time because of its inherent high capacity and low potential. However, dendrite formation upon cycling hinders its application. Herein, a nano-Cu-embedded porous carbon (Cu@carbon) is synthesized by a simple heat treatment of a Cu–organic framework, and is then applied as a host for Li plating/stripping. It is found that the nano-Cu particles are uniformly embedded in the bulk and surface of the carbon, integrating high conductivity and high surface area. DFT calculations and experimental data indicate that the CuC_x formed at the interface can serve as lithiophilic sites for Li nucleation and growth. As a result, the host material exhibits a dendrite-free Li plating/stripping. The half cell (Li‖Cu@carbon) shows a high coulombic efficiency of 99.3% over 200 cycles even with a high cycling capacity of 4 mA h cm⁻², and the Li@Cu@carbon based symmetric cell can be cycled stably for over 2000 h at 1.0 mA cm⁻². Furthermore, the corresponding Li-metal capacitor (activated carbon‖Li@Cu@carbon) and battery (LiFePO₄‖Li@Cu@carbon) exhibit high cycling stability, with 80.1% capacity retention after 10 000 cycles (capacitor) and 94.7% capacity retention after 1000 cycles (battery). These achievements make our anode among the most stable Li anodes reported so far.