Two-dimensional ZrC2 as a novel anode material with high capacity for sodium ion battery

Rational design of high-performance anode materials is of paramount importance for developing rechargeable lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, a ZrC2 monolayer is predicted by performing the particle swarm optimization (PSO) algorithm. The high energetic, dynamic, and thermal stabilities of the ZrC2 monolayer are confirmed by cohesive energy, phonon dispersion, and molecular dynamics simulations, respectively. Unexpectedly, we find that the theoretical specific capacity for Na on the ZrC2 monolayer reaches as high as 932 mA h g(-1), which is even higher than that of Li. Meanwhile, the diffusion energy barrier of Na on the ZrC2 monolayer is only 0.02 eV, ensuring the ultrafast charge/discharge rate. Additionally, the calculated open-circuit voltage (OCV) suggests that the change of Na intercalation voltage is steady. Therefore, our results consistently demonstrate that the ZrC2 monolayer can be an ideal anode material for SIBs.