Bi-C monolayer as a promising 2D anode material for Li, Na, and K-ion batteries

Electrode materials with high electrochemical efficiency are required for battery technology that can be used to store renewable energy. Bismuth (Bi) has shown great potential as an electrode material for metal ion batteries due to its large volumetric capacity and reasonable operating potential. However, the cycling performance deteriorates due to the drastic volume changes that occur during alloying and dealloying. Herein, we design a 2D Bi-C metal sheet using density functional theory and investigate the feasibility of this nanosheet for alkali metal ion batteries. The predicted metallic Bi-C monolayer (ML) are highly stable and show sound electrode performance. Moreover, alkali metal atoms exhibit high diffusivities on both sides (Bi and C sides) with low energy barriers of 0.252/0.201, 0.217/0.169, and 0.179/0.136 eV for Li, Na, and K ions, respectively. Furthermore, the Bi-C ML shows high theoretical storage capacities of (485 mA h g^-1) for Li and Na and (364 mA h g^-1) for K and low open-circuit voltage of 0.12, 0.24, and 0.32 V for Li, Na, and K ions, respectively. These exciting findings show that the predicted Bi-C ML can be used as an anode material for Li-, Na- and K-ion batteries.