Prominent Electrode Material for Na-, K-, and Mg-ion Batteries: 2D beta-Sb Monolayer

The applicability of a two-dimensional beta-antimonene (beta-Sb) monolayer as a negative electrode material for Na-, K-, and Mg-ion batteries has been conducted through first-principles calculations based on density functional theory (DFT). Our findings propose that the hollow and top sites are the energetically most stable adsorption sites for Na, Mg, and K atoms. The chronological adsorption energy, charge transfer, open-circuit voltage, theoretical storage capacity, and metal-ion diffusion barrier energy are investigated. The semiconducting beta-Sb monolayer can provide inherent benefits for transportation of electrons through it, which can deliver tremendous mobility with lower barrier energies of 0.10 eV for Na, 0.09 eV for K, and 0.15 eV for Mg for the diffusion process. The double layers of beta-Sb can adsorb ions on both sides, which leads, at high concentrations (Na2Sb, K2Sb, and Mg2Sb), to theoretical storage capacities of 440.22, 440.22, and 880.45 mAh/gm for Na, K, and Mg ions, respectively. Besides, the electronic formation of beta-Sb changed the nature from semiconducting to metallic under metal-ion adsorption, which significantly enhanced the performance of metal-ion batteries. With the given advantages, we propose that the beta-Sb monolayer can be viewed as a potential material for negative electrodes in Na-, K-, and Mg-ion batteries.