High Quality Content by WIKIPEDIA articles! The Tafel equation relates the rate of an electrochemical reaction to the overpotential.The Tafel equation was first deduced experimentally and was later shown to have a theoretical justification. The equation is named after German chemist Julius Tafel (1862-1918).On a single electrode the Tafel equation can be stated as Delta V=Atimes lnleft(frac{i}{i_0}right) where V is the overpotential, V; A is the so called "Tafel slope", V; i is the current density, A/m2 and; i0 is the so called "exchange current density", A/m2.