Lithium-copper alloy embedded in 3D porous copper foam with enhanced electrochemical performance toward lithium metal batteries

Abstract Suppressing dendrite growth and accommodating volume change, among others, are the main challenges for lithium (Li) metal anode to be used in rechargeable Li batteries. The commercial macroporous copper (Cu) foam current collector may only tackle these challenges to a little extent, and it is usually unable to provide sufficient Li nucleation sites, leading to rapidly increased polarization and unstable cycling performance. Herein, we report a three-dimensional composite anode comprising Li–Cu alloy melt-cast on a commercial Cu foam (CF) current collector (Li–Cu/CF), which can be converted to a unique architecture consisting of Li metal supported by an interconnected CuLix alloy nanowire network formed because of the phase separation, when the molten Li–Cu alloy cools down and gets solidified. Compared to the bare Li foil, the Li–Cu/CF anode shows a smaller polarization and better cycle stability in the carbonate electrolyte at various current densities ranging from 1 to 5 mA/cm2 and is free from dendrite growth upon repeated Li plating/stripping. This can be attributed to the low Li nucleation overpotential and high Coulombic efficiency (96%) during Li plating on and stripping from the thus-obtained hierarchically structured CF collector, as well as the higher proportion of Li2O relative to LiF in the solid-electrolyte interphase layer. Moreover, when assembled in a full cell paired with the LiFePO4 cathode, the Li–Cu/CF anode also exhibits much better rate capability and cycle performance than the bare Li foil. Our work provides a new convenient approach to construct a dendrite-free Li metal anode that can be potentially deployed in the next-generation high energy density rechargeable Li batteries.