Ab Initio Prediction and Characterization of Mo2C Monolayer as Anodes for Lithium-Ion and Sodium-Ion Batteries.

Identifying suitable electrodes materials with desirable electrochemical properties is urgently needed for the next generation of renewable energy technologies. Here we report an ideal candidate material, Mo2C monolayer, with not only required large capacity but also high stability and mobility by means of first-principles calculations. After ensuring its dynamical and thermal stabilities, various low energy Li and Na adsorption sites are identified, and the electric conductivity of the host material is also maintained. The calculated minor diffusion barriers imply a high mobility and cycling ability of Mo2C. In addition, the Li-adsorbed Mo2C monolayer possesses a high theoretical capacity of 526 mAh·g(-1) and a low average electrode potential of 0.14 eV. Besides, we find that the relatively low capability of Na-adsorbed Mo2C (132 mAh·g(-1)) arises from the proposed competition mechanism. These results highlight the promise of Mo2C monolayer as an appealing anode material for both lithium-ion and sodium-ion batteries.