{\em{Ab initio}} study of layered chromium disulfide (CrS$_2$) toward a new anode material for Li-ion batteries

There has been considerable interest in use of transition-metal disulfides, such as MS$_2$ (M$=$Mo, W), as new anode materials in Li-batteries to improve their battery performance. Since CrS$_2$, if synthesized, would be much lighter than MoS$_2$ or WS$_2$, it would exhibit higher Li capacity. To verify this expectation, we investigate the adsorption and diffusion properties of Li on layered Cr$_2$ and its Li capacity using DFT implemented with van der Waals correction. We thoroughly search for variuos Li adsorption sites, on which the binding energies are higher than Li clustering energy ($\sim1.6$~eV). Based on the these calculations, we identify the diffusion paths and barriers of Li atoms within the layered CrS$_2$ as well as on a free-standing single-layer of CrS$_2$. We find that Li atoms exhibit almost free intra-layer diffusion resulting in an improved mobility of Li at room temperature, while inter-layer diffusion is difficult to occur. We also estimate the Li-capacity of the CrS$_2$ by evaluating the energy gain as well as the average binding energy while intercalating more Li atoms. We find that CrS$_2$ can have larger Li-capacity than graphite, which is being widely used for anode material, implying that CrS$_2$ may be a good candidate for Li-battery electrode.