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.