Highly Conductive and Stable Two-Dimensional WC4 Acting as an Efficient Anode Material for Alkali-Metal Ion Batteries: Insight from DFT

Extensive studies have been carried out on two-dimensional (2D) metal carbides (MCs) as prospective nominees for alkali-metal ion batteries (AMIBs). These materials have attracted interest because of their substantial specific surface area, enabling them to accommodate a large quantity of metal ions along with their excellent diffusivity. However, the high metal content in these materials results in strong Coulomb’s repulsive interactions with Li/Na/K ions, leading to a low storage capacity. To tackle this challenge, we have adjusted the carbon composition in 2D WC4 to enhance its storage capacity and mitigate the repulsive forces between W and Li/Na/K ions. Our computational analysis has revealed that the WC4 monolayer maintains dynamic and thermal stability, with a robust cohesive energy that supports its experimental synthesis. The WC4 monolayer, as an anode material, exhibits high electronic conductivity and diffusivity and rapid ion transfer rate, as verified by low activation energy barriers of 0.55 eV for Li-ion batteries (LIBs), 0.084 eV for Na-ion batteries (SIBs), and 0.081 eV for K-ion batteries (PIBs), which facilitate robust charging and discharging processes. Additionally, the average voltages calculated for Li-, Na-, and K-ion batteries are 0.65, 0.46, and 0.42 V, respectively. Consequently, the WC4 monolayer demonstrates impressive Li, Na, and K storage capacities, reaching 577, 462, and 462 mA h g–1, respectively, for maximum loading. These results demonstrate that 2D WC4 as a promising anode material for alkali-ion batteries.