The effect of S-functionalized and vacancies on V2C MXenes as anode materials for Na-ion and Li-ion batteries

The electrochemical properties of V₂C and V₂CT₂ (T = O, S) MXenes with and without vacancy as anode materials for Na-ion and Li-ion batteries, have been studied using first-principles calculation. The present results indicate that the adsorption strength of Li-ion and Na-ion on V₂CS₂ are less than that of O-functionalized, together with a lower diffusion barrier. Simultaneously, V₂CS₂ monolayer exhibits lower open-circuit voltage (OCV) values of 0.72 and 0.49 V for Li- and Na-ion, respectively. Interestingly, the presence of atomic vanadium vacancy on V₂CS₂ monolayer exerts more prominent effects on enhancing adsorption strength than that of carbon vacancy for Li-ion and Na-ion, but with an exception for the diffusion of Li-ion and Na-ion on V₂CS₂ monolayer. The finding suggests that the V₂CS₂ monolayer is expected to be a potential candidate as anode material for Li-ion and Na-ion battery due to its lower open-circuit voltages and diffusion barriers.