Improved performances of Cr₂N monolayer as electrode of lithium ion battery through surface termination: A first-principles calculation

To improve the performance of the lithium ion batteries (LIBs), one of the hottest topics in this field is searching high-performance electrode candidates. Recently, a new kind of MXene, named Cr2N monolayer attracted our interests, which can be successfully exfoliated from the bulk Cr2GaN structure by removing the layers of Ga. Since the surface of Cr2N monolayer is full of active sites, it is interesting to investigate the possibility of Cr2N monolayer and its derivatives as electrode materials for LIBs. Here, we performed first-principles calculations basing on density functional theory (DFT) to study the adsorption, diffusion and capacity of Li atoms on the Cr2N monolayer and its derivatives. Our results show that Cr2NF2 and Cr2NO2 monolayers are promising candidates of LIBs. The diffusion energy barriers of Li atom on Cr2NF2 and Cr2NO2 monolayer are only 0.18 eV and 0.58 eV, which ensures the excellent charge-discharge rates. More importantly, the theoretical specific capacity of Cr2NF2 monolayer is calculated to be about 583 mA h.g-(1 )and that of Cr2NO2 monolayer is about 556 mA h.g(-1), which are high enough to support commercial applications.