Meaning
Kinetic energy barriers at the electrode interface create a voltage offset during electrochemical reactions. The potential displacement known as charge transfer overpotential represents the driving force required to push ions across the double layer. This potential loss directly reflects electron transfer resistance at active particle surfaces.
The boundary isolates interface kinetics from bulk electrolyte migration and diffusion gradients.
Reaction Kinetics
Activation energy determines the magnitude of potential offset at a given current density. Increased current demand forces charge transfer overpotential to rise according to Butler-Volmer kinetics. Catalyst coatings and active materials with high surface area lower this voltage penalty.
Temperature increases accelerate charge transfer rate and reduce overpotential magnitude. High interfacial resistance exacerbates potential drops at low thermal states.
Cell Degradation
Elevated potential offsets during fast charging shift the negative electrode potential below zero volts versus lithium. Excess charge transfer overpotential triggers metallic lithium plating on graphite anodes. Plated metal increases short circuit risks and permanently reduces active cell capacity.
Heat generation accelerates during high overpotential operation.
Measurement Technique
Electrochemical impedance spectroscopy isolates charge transfer resistance from total cell impedance. Nyquist plot arc analysis quantifies charge transfer overpotential during diagnostic sweeps. Testing under varying temperature regimes reveals interfacial reaction parameters.
