Theoretical investigations of TiNbC MXenes as anode materials for Li-ion batteries

The electronic properties and electrochemical performance of double-metal MXenes: TiNbC and TiNbCT₂ (T = O, F and OH) as anode materials for Li-ion batteries (LIBs) have been studied to understand the effects of Nb(Ti)-layer inserting in Ti₂C (Nb₂C) monolayer and terminated functional-group (T = O, F, and OH) on the electrochemical performance. The results demonstrate that all the TiNbC and TiNbCT₂ monolayers are metallic conductivity, while the adsorption of lithium-ion on TiNbC(OH)₂ is unstable, and TiNbCF₂ is unfavorable as anode material for LIBs due to the F-groups and Li-ions forming ring structure. Specifically, TiNbC and TiNbCO₂ nanosheets exhibit such distinctive features as moderate adsorption energies and quite low diffusion barriers of lithium, theoretical storage capacities comparable to Ti₂C monolayer, which manifest the double-metal TiNbC and TiNbCO₂ monolayers as excellent anode materials for LIBs.