Interfacial space charge design with desired electron density to enhance sodium storage of MoS2@Nb2O5 anode

Abstract

The interfacial effect is crucial for achieving superior sodium-ion storage performance in MoS2-based anodes. In this study, we constructed an interfacial effect by hydrothermally synthesizing Nb2O5 nanoparticles on MoS2 nanosheets (MoS2@Nb2O5). XPS analysis confirms a significant chemical interaction between MoS2 and Nb2O5 through interfacial covalent bonding (Mo-S/Nb-O) which enhances interatomic electron migration. Electrochemical kinetic analysis indicates an increased pseudocapacitance contribution. The galvanostatic intermittent titration technique (GITT) analysis shows improved charge transfer kinetics. Ex-situ XPS results reveal the reversible intercalation/deintercalation and oxidation/reduction mechanisms of the MoS2@Nb2O5 anode. Density functional theory (DFT) results show that strong interfacial bonding significantly enhances electrochemical reaction kinetics. The discharge capacity of the MoS2@Nb2O5 anode reaches up to 414.5 mA h g−1 at 0.1 A g−1 after 200 cycles, and the capacity retention is approximately 97.5 % at 2.0 A g−1 after 1000 cycles, demonstrating good rate capability and capacity retention. This in-situ interfacial construction strategy presents an effective approach to designing MoS2-based anodes with improved electrochemical performance.