Prediction of TMCCs@MoS2 heterostructures with homogeneous surface terminations as promising anodes for sodium and potassium ion batteries

The construction of the novel van der Waals TMCC//MoS₂ and surface anchored TMCC⊥MoS₂ heterostructures for their potential applications as anodes in alkaline metal ion batteries is investigated employing the first-principles calculations. We predict that the parallel (Nb₂S₂C//MoS₂ and Ta₂S₂C//MoS₂) and anchored (Nb₂S₂C⊥MoS₂ and Ta₂S₂C⊥MoS₂) heterostructures are thermodynamically and thermally stable, and all heterostructures show metallic like electronic band dispersions at Fermi level. The electrochemical energy storage performance of those heterostructures is characterized by calculating the theoretical capacities, open circuit voltages and ion diffusion barrier heights for Li, Na and K absorbates. The predicted total capacities of parallel and anchored TMCC@MoS₂ for LIB, SIB and PIB are in a range from 134 mAh/g to 334 mAh/g, while the obtained mean OCVs are situated between 0.40 V and 0.60 V. For those favorable migration pathways, the diffusion energy barrier heights are found to be in a range from 0.10 eV to 0.60 eV for alkaline metal ions. Notably, TMCC@MoS₂ heterostructures show promising electrochemical performance in terms of their relatively high theoretical capacities for the use as anodes in SIB (130 mAh/g–270 mAh/g) and PIB (134 mAh/g–198 mAh/g).