Current transmission pathways in potassium intercalated graphene

Abstract

Carbon-based conductors are the focus of considerable research investigating the material roles and transport mechanisms which determine current transmission performance. Ab initio analysis of the potassium–graphene system suggests that neither material constituent should be cast in a subordinate current transmission role. When the dopant density is low, the potassium atoms perform a conventional doping function, improving the conductivity of the current carrying carbon substrate via charge transfer. As the doping density increases, the potassium atoms begin to form a second transmission pathway, complimenting the carbon substrate pathway and contributing to the net current transport. At the highest modeled dopant density, corresponding to the well known KC8 structure studied in various experiments, the potassium atoms form a parallel and nominally independent current transmission network, whose contribution to electron transport approximately matches that of the underlying graphene. Consistent with published experimental data on doped nanowires, the modeling results show that conductivity is a sensitive function of potassium concentration. The sensitivity is due to an internal state transition, not subject to direct experimental measurement, which strongly influences nanocomposite conductor performance.