Butler-Volmer Equation

chemistry

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 22, 2026

Quick Summary

The Butler-Volmer equation is a fundamental relationship in electrochemistry that quantitatively describes the rate of an electrochemical reaction. It relates the net current density (i) to the partial current densities of oxidation (i_→) and reduction (i_←), concentrations of reacting species, rate constants, and transfer coefficients.

The equation is expressed as:
[i = i_0 \left( e^{\alpha_a n F \eta / RT} - e^{-\alpha_c n F \eta / RT} \right)]
where i₀ is the exchange current density, (\eta) is the overpotential, (\alpha_a) and (\alpha_c) are transfer coefficients, n is the number of electrons transferred, F is Faraday's constant, R is the ideal gas constant, and T is the absolute temperature.1

This equation helps understand how electrode potential influences reaction rates and is crucial in fields like electrocatalysis.23

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

electrochemical reaction
The Butler-Volmer equation
The reversible electrode potential can be introduced into equation (1) and the potentials taken relative to its value. When so expressed, they are termed overpotentials and can be stated as η = E − E_rev; equation (1) then transforms to equation (3):
Read More
The reversible electrode potential can be introduced into equation (1) and the potentials taken relative to its value. When so expressed, they are termed overpotentials and can be stated as η = E − E_rev; equation (1) then transforms to equation (3):
Read More