Optimization of conductivity for MXene polymer nanocomposites by the number and diameter of contacts among adjacent nanosheets

In this study, a model for the conductivity of MXene-based samples is developed by simultaneously considering the percolation threshold, inter-nanosheet interfacial contacts, contact geometry, and electron tunneling effects. The percolation onset volume fraction and the network portion are demonstrated by interphase dimensions as well as the diameter and thickness of the MXene nanosheets. Accordingly, the proposed model is constructed based on physically meaningful and measurable parameters, providing an efficient framework for estimating the conductivity of MXene system. Parametric analysis and experimental conductivity facts from representative systems are employed to validate the method. The highest conductivity as 5.1 S/m is gained when nearly all MXene nanosheets participate in the conductive network and the interphase thickness is 40 nm. Furthermore, when the number of contact points reaches 40 and the contact circle diameter is 50 nm, the conductivity increases significantly, approaching 6.2 S/m. Overall, larger interphase region, shorter tunneling distance, larger contact area, higher contact number, and a greater fraction of networked nanoparticles lead to improved conductivity.