Multiferroic Two-Dimensional Cu(CrX₂)₂ (X = S, Se, and Te) as Anode Materials for Lithium-Ion Batteries: A First-Principles Study

Identifying two-dimensional (2D) materials with the desired electrochemical performance for lithium-ion batteries is of great interest in developing next-generation energy devices. Motivated by the successful synthesis of multiferroic 2D materials, Cu(CrX2)2 (X = S, Se, and Te), which exhibit simultaneous ferroelectricity and ferromagnetism, we performed first-principles calculations to investigate their potential as anodes for lithium-ion batteries. It is first demonstrated that the multiferroic Cu(CrX2)2 2D nanosheets exhibit metallic characteristics with a large density of states (DOS) at the Fermi level, making them promising candidates for achieving good electrical conductivity. Next, we comprehensively investigate the electrochemical properties of the predicted systems and demonstrate that lithium exhibits sufficient mobility on their surface, with appreciable stability. For instance, the binding energy (Eb) of the lithium adatom on Cu(CrS2)2 is −4.034 eV, with a diffusion barrier as low as 0.212 eV. As a consequence, the maximum theoretical specific capacity for lithium adatoms reaches as high as 1089 and 666 mAh g–1 respectively, for Cu(CrS2)2 and Cu(CrSe2)2, which can be attributed to a much higher storage capacity of lithium adatoms compared to previously identified 2D anode materials. All of these remarkable properties, including high binding energy (Eb), low diffusion barrier, high specific capacity, and good electrical conductivity, suggest that the proposed multiferroic Cu(CrX2)2 2D materials could be promising electrode materials for lithium-ion batteries.