Alloyed electrode materials are considered as potential
high-performance
anodes for Mg-ion batteries (MIBs). Herein, employing first-principles
calculations, we reveal the feasibility of MgCu2 alloys
as anode materials for MIBs. This work shows that the inherent metallicity,
excellent electrical conductivity, and thermal, dynamic, and mechanical
stability of MgCu2 can contribute to the high-rate performance
and stability in batteries. It is found that the volume expansion
rate from MgCu2 to Mg2Cu is only 107.37%, which
avoids the failure caused by the large volume change. Besides, MgCu2 possesses small Young’s moduli, regulating the volume
change during charging/discharging. Especially, MgCu2 not
only has a low open-circuit voltage (0.221 V) but also a theoretical
capacity as high as 1688 mA h/g when forming Mg2Cu. In
addition, both MgCu2 and the final product Mg2Cu have low diffusion energy barriers of Mg ions (0.318 and 0.307
eV), which implies the high cycle rate potential. The transformation
mechanism investigation during the formation of Mg2Cu from
MgCu2 indicates that Mg ions are first adsorbed on the
(1 0 0) surface of MgCu2 before conversion and then directly
convert to the final Mg2Cu. In conclusion, MgCu2 shows strong suitability as an ideal anode material for MIBs.