Atomic structure and electrical property of ionic liquids at the MoS2 electrode with varying interlayer spacing

Understanding the structure and properties at the electrolyte-electrode interface is vital for the rational design of the supercapacitors or other electrochemical devices. In this work, we explored the influence of interlayer spacing of the MoS2 electrode on the interfacial structure and electrical properties of sodium-ionic liquids (ILs) electrolytes via performing the all-atom molecular dynamics simulations. From the number density, charge density, and electrical potential distribution near the surface, the Mo- and S-terminal edges possess positive and negative features when the interlayer spacing is less than 8.5 angstrom. Meanwhile, the strength of the first density layer of ILs increases with the increase of the interlayer spacing of MoS2 for both Mo- and S- terminal surfaces in the neutral or charging state. Furthermore, the coordination number of sodium ion at the electrode surface was analyzed, and it was shown that the S-terminal surface has a larger coordination number than that on the Mo-terminal surface. Interestingly, the coordination number of MoS2 with the interlayer spacing of 8.0 angstrom is the lowest in the ranges of 6.5 similar to 8.5 angstrom. The electrolyte's charge screening factor also reflects the opposite electrical state of Mo- and S-terminal surfaces and weakens with increasing the interlayer spacing and surface charge density. The obtained understanding of ILs at electrode interfaces with different layer spacings in this work will provide insight into the molecular mechanisms of ILs-based sodium supercapacitors or other electrochemical devices in critical chemical engineering processes.

Automated summary

This study investigates the impact of interlayer spacing of the MoS2 electrode on the interfacial structure and electrical properties of sodium-ionic liquids electrolytes through molecular dynamics simulations, revealing the positive and negative features of Mo- and S-terminal edges, differences in coordination numbers of sodium ions at electrode surfaces, and variations in charge screening factors with interlayer spacing and surface charge density.