Graphene network nested Cu foam for reducing size of lithium metal towards stable metallic lithium anode

Abstract

Metallic lithium anode has attracted immense attention for high energy density rechargeable batteries. However, the infinity volume change and safety issues caused by the uncontrollable growth of lithium dendrites during long-term cycling hinder its practical applications. Herein, we explore an effective strategy to solve these problems by building a secondary conductive graphene network inside the macropores of copper foam as a three-dimensional host to fabricate metallic lithium (CuFG@Li) anode. The graphene network, nested in the Cu foam, can further split the large pores of Cu foam to form micron-sized cages. After the molten lithium being infused inside the host, this graphene conductive network can be used as a deposition matrix for lithium metal in the pores and minimize the local size of lithium metal to enhance the reversibility of plating/stripping of lithium and maintain the constant volume of anode during the long cycles. The CuFG@Li anode displays stable cycling for more than 1300 h at a current density of 1 mA/cm2, and exhibits high Coulombic efficiency of 98% over 200 cycles at 1 mA/cm2, which is much better than bare Li foil anode. The CuFG@Li/LiFePO4 full cell is also fabricated and displays excellent rate performance. This strategy presents a general approach to suppress the growth of lithium dendrites and regulate the volume changes for long-lifespan lithium metal batteries.