# How to calculate the thickness of the double layer at an electrode

I need help calculating a double layer thickness. In this situation two insulated planar electrodes are placed in an electrolyte (in this case drinking water) and a voltage is applied to them of 10V across a 10mm gap (field strength 1V/mm) the field is quickly cancelled out by the electrical double layer, where the ions within the water have been attracted to the insulated surface of the electrode and block out the field.

The equations I have seen such as the Debye length equation don't seem to factor in an electrode potential, can anybody point me in the right direction or better yet show me an equation for calculating what the thickness would be? (apologies if I have missed something obvious)

• Could you use the energy storage of the "capacitor" to determine the thickness? Given dielectric constant, voltage and measured capacitance, thickness could be calculated. – DrMoishe Pippik Jan 4 '16 at 22:05
• Why do you expect that the potential would be a factor? The concentration of the ions is the biggest factor in how long the Debye length will be. The applied potential will change the amount of charge stored, but the length of the double layer should be independent of potential. – Burak Ulgut Jun 3 '16 at 14:31