where F is the Faraday constant, R is the gas constant, T is the temperature at which D s was calculated, and c is the concentration of protons in the system. Calculating c required making some assumptions. We assumed that having one proton on each side of a layer of DSG did not change D s . Adding two protons corresponds to 3.34 × 10 -24 moles of protons. We used a DFT optimized configuration to estimate the height of the graphanol cell. After accounting for non-optimal layer packing by adding 2 Å, we obtained a c axis value of 8.4 Å and a cell volume of 6 × 10 -22 cm 3 . This results in a c value of 0.0057 mol/cm 3 and a σ of 3135 mS/cm, which is about twice the value of SSG.