Interfacial engineering of 2H-MoS2/N-doped carbon composite for fast potassium interfacial storage

The 2H-MoS2 incorporated with N-doped carbon (2H-MoS2/NC) with high discharge capacity has attracted more research focus as an anode material for K-ion batteries (PIBs). However, large longitudinal lattice deformation at 2H-MoS2/NC heterointerfaces caused by interfacial intercalation of K ions negatively impacts the structural stability, which limits its cycling performance. In this paper, interfacial engineering has been applied to optimize the structural stability of 2H-MoS2/NC. By using first-principle simulation, the evolutions of longitudinal lattice deformation, K adsorption/diffusion performance/behaviour, interfacial strength, and electronic property with the interfacial interlayer spacing have been systematically explored. The results show that with the increase of interlayer spacing from 5.0 to 7.0 & Aring;, the lattice deformation, interfacial strength, and K adsorption kinetics first decrease sharply with interlayer spacing in the range of 5.0-6.5 & Aring;, and then they drop minorly at 6.5-7.0 & Aring;. The K interfacial diffusion capability can be improved due to the decreased charge accumulation at interface that leads to weakened K-S bonding with a rising interlayer spacing. Based on variation of structural stability and K storage performance, an optimal interlayer spacing of 6.75 & Aring; is confirmed. These findings can provide a solid theoretical basis and guidance for the experimental preparation of high-performance 2H-MoS2/NC electrode materials and further cultivate new concepts for the optimal design of two-dimensional composite electrode materials.