Battery knowledge · Electrochemistry fundamentals
Exchange current density
The equal and opposite current flowing each way across an electrode interface at equilibrium. A high value means fast kinetics and a small overpotential; it falls steeply with temperature, which is part of why cold cells are sluggish. [1]
- Abbreviation
- i₀
- Unit
- A/m²
Example
Overpotential drives reaction current
At equilibrium net current is zero. At +50 mV, current density is 2.268 A/m².
Fixed concentrations, symmetric transfer coefficients and no transport limitation.
Explore the graph
At equilibrium, forward and reverse reaction currents cancel.
At equilibrium net current is zero. At +50 mV, current density is 2.268 A/m².
i = 2i₀ sinh(Fη / 2RT)
Illustrative model. Fixed concentrations, symmetric transfer coefficients and no transport limitation.
Use in Lemonergy
Connect reaction sites and transport paths.
This is a reference concept. No executable Lemonergy block has been verified for this term.
References & further reading
Technical references
- Quantities, Units and Symbols in Physical Chemistry, 3rd edition, 2nd printing
IUPAC · 2011
Technical reference · Physical-chemistry notation, thermodynamics, electrochemistry and transport quantities.