Graphite oxide paper as a polarizable electrical conductor in the through-thickness direction

Graphite oxide (GO) paper is a polarizable electrical conductor in the through-thickness direction, as shown by alternating-current electrical testing performed with decoupling of the volumetric and interfacial contributions. The solid part (69 vol%) of the dark brown paper (112e358 mm thick) exhibits carbon/oxygen atomic ratio 2.0, and interlayer spacing 8.60 Å. At 50 Hz and 2 MHz respectively, the inplane conductivity is 0.07 and 2.5 S/m, the through-thickness conductivity is 6.7 10 6 and 4.8 10 3 S/ m, the through-thickness relative dielectric constant is 915 and 91, the specific capacitance of the interface with an electrical contact is 18.3 and 1.1 mF/m2, and the areal resistivity of this interface is 1.5 105 and 1.0 102 U cm2. The conductivity is due to slightly incomplete intercalation (but without residual graphite), as shown by a weak X-ray diffraction peak at interlayer spacing 4.33 Å. The interface contributes, but the volumetric capacitance/resistance dominates. The decrease of k with increasing frequency (50e200 Hz) is attributed to the functional-group-related dipole friction. The increase of the through-thickness conductivity with increasing frequency is attributed to the decreasing excursion of the charge carriers and the consequent decrease in the chance of the carriers to encounter interfaces. © 2016 Elsevier Ltd. All rights reserved.