Monolayer Mo2C as anodes for magnesium-ion batteries

Bismuthene as a novel anode material of magnesium/zinc ion batteries with high capacity and stability: a DFT calculation

In our research, we utilize density functional theory (DFT) to explore the properties of magnesium and zinc atoms adsorbed on bismuthene. Our findings indicate that the hollow site is the most favorable adsorption site for Mg and Zn atoms on bismuthene. The results indicate that Mg and Zn adsorption on the bismuthene surface results in significantly high conductivity, with notable adsorption energies of -3.38 eV for Mg and -3.91 eV for Zn. The bismuthene structure can adsorb 9 Mg and 18 Zn atoms with negative average adsorption energy. These findings suggest excellent stability of bismuthene during the adsorption of magnesium and zinc. Notably, we propose theoretical storage capacities of 2308 mA h g-1 for magnesium-ion batteries (MgIBs) and 4616 mA h g-1 for zinc-ion batteries (ZnIBs), while maintaining structural stability during the adsorption of these metal ions. The observed average open-circuit voltages for bismuthene are 0.01 V for Mg and 0.03 V for Zn, with the material retaining its metallic properties throughout the adsorption process. Furthermore, the calculated diffusion barriers for Mg and Zn are 0.1 eV and 0.21 eV, respectively. Our findings like storage capacity, diffusion energies, and low OCV surpass those of most studied two-dimensional materials, positioning bismuthene as a promising anode material for metal-ion rechargeable batteries.

Monolayer α-beryllene as an anode material for magnesium ion batteries with high capacity and low diffusion energy barrier

High specific capacity and fast charge/discharge rate are important indicators for the development of next-generation ion batteries. Compared with conventional monovalent ion batteries like lithium-ion batteries and sodium-ion batteries, multivalent ion batteries have attracted extensive attention owing to their high energy densities. Here, we systematically explore the interactions between Mg atoms and α-beryllene monolayers by means of density functional theory calculations. Mg atoms can be adsorbed stably on α-beryllene monolayers with the adsorption energy of -0.24 eV. The low diffusion energy barriers (0.099/0.101 eV) indicate the rapid mobility of Mg during the charge/discharge process. Moreover, the α-beryllene monolayer exhibits an ultra-high theoretical specific capacity of 5956 mA h g^-1 for Mg, a low average open-circuit voltage of 0.24 V, and a tiny volume change of -1.08%. Finally, the constructed h-BN/α-beryllene heterostructure shows that h-BN can serve as a protective cover to preserve pristine α-beryllene in respect of metallicity, Mg adsorption capability, and fast ionic mobility. The above mentioned outstanding results make α-beryllene a promising anode material for magnesium-ion batteries.