Meaning
Electrochemical potential deviation from equilibrium at a negative electrode surface occurs during current passage. Anode polarization governs charge transfer kinetics and mass transport limitations inside a lithium-ion cell during high-rate cycling. The boundary condition determining applicability sits at the threshold where parasitic side reactions like lithium plating begin alongside intercalation.
Kinetic Resistance
Charge transfer resistance dominates this shift at low current densities. Butler-Volmer kinetics describe how the overpotential scales with applied current density. Slow electron transfer rates at the graphite or silicon solid electrolyte interphase boundary force a larger activation overpotential.
Activation polarization rises sharply when temperature drops because desolvation kinetics at the electrode interface slow down.
Transport Impedance
Concentration gradients within the electrolyte and solid matrix drive mass transfer overpotential during sustained high-rate discharge. Lithium-ion diffusion coefficients through the active material dictate how fast ions reach the reaction sites. Concentration polarization grows nonlinearly as active material utilization approaches depletion limits.
Tortuosity of the separator and electrode pores restricts ionic mobility, compounding concentration gradients across the cell stack.
Thermal Feedback
Ohmic heating generated by the overpotential alters internal resistance and accelerates subsequent polarization rates. Joule heating raises the cell temperature, which lowers overall impedance while simultaneously accelerating degradation mechanisms. Elevated temperatures mitigate charge transfer resistance temporarily at the expense of accelerated electrolyte decomposition.
Cell pack management systems must monitor this voltage deflection to prevent irreversible lithium deposition on the negative terminal during rapid charging regimes.
