(197ap) First-Principles Study on the Role of Oxygen-Functional Groups in Heterogeneous Interface of MoS2/Reduced Graphene Oxide for Sodium Ion Battery Anode

Reduced graphene oxide (rGO) is used to improve the electrochemical performance of anode materials in sodium ion batteries by organizing rGO-based heterogeneous bilayers. However, it still lacks in-depth fundamental understanding of the heterointerface in these heterogeneous bilayers and how this affects their electrochemical performance. In this work, using different computational models (MoS₂/Graphene (Gr), MoS₂/Gr-O, MoS₂/Gr-OH, and MoS₂/Gr-COOH) we study Na affinity in the heterointerface and how the different oxygen-functional groups influence the sodium ion battery anode performance of the heterogeneous bilayers. Our density functional theory (DFT) results show that the major descriptor for the Na affinity in heterogeneous bilayers is unveiled as the non-covalent bonding nature, not charge distribution around Na ion. Furthermore, the Na affinity of each functional group at the MoS₂/rGO heterointerface is consistent with the trend of the activation barrier of Na. To infer the charge capacity, the phase stabilities are evaluated by adsorbing Na on a single layer of rGO, and the results show that Na-adsorbed rGO has more stable phases than graphene. The epoxy functional group enables maintains not only the charge capacity but also reduces the activation barrier of Na. These discoveries on the relationship between oxygen-functional of rGO in heterogeneous bilayer and their electrochemical performance will motivate the design of advanced anode materials for sodium ion batteries.