Mg-Li-Cu alloy anode for highly reversible lithium metal batteries

Lithium metal is considered as the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential. However, undesirable parasitic reactions, poor cycling stability and safety concerns could be caused by uncontrolled dendrite and high reactivity of Li metal, which hinder the practical application of Li-metal anode in high-energy rechargeable Li metal batteries (LMBs). Here, a facile way is reported to stabilize Li metal anode by building high lithiophilic Mg-Li-Cu alloy. Due to the delocalization of electrons on the deposited lithium enhanced by Cu self-diffusion into Mg-Li alloy, the growth of lithium dendrites could be inhibited by Mg-Li-Cu alloy. Moreover, the parasitic reactions with electrolyte could be avoided by the Mg-Li-Cu alloy anode. It is noteworthy that the symmetric battery life of Mg-Li-Cu alloy electrodes exceeds 9000 h at 1 mA cm−2 and 1 mAh cm−2. The full cell (LiFePO4 || Mg-Li-Cu) exhibits a specific capacity of 148.2 mAh g−1, with a capacity retention of 96.4%, at 1 C after 500 cycles. This work not only pave the way for application of flexible alloy anode in highly stable LMBs, but also provides novel strategies for preparation and optimization of Mg alloy.