Quantifying Sacrificial Additive Depletion Kinetics in Commercial Lithium Pouch Cells
Sacrificial additive depletion in commercial pouch cells follows pseudo-first-order kinetics, triggering gas evolution and rapid impedance rise when exhausted.
Interphase Resistance
Meaning
Electrical impedance generated at boundary layers between solid electrode materials and liquid electrolytes hinders ion transfer during charge and discharge operations. Elevated interphase resistance increases cell polarization, reduces energy output, and accelerates thermal losses under high C-rate operation. The total value combines passivation film resistance and charge transfer resistance across the double layer.
This resistance boundary isolates solid-state interfaces without including bulk electrolyte or metallic collector impedance.
Charge Kinetics
Desolvation of solvated lithium ions at the solid electrolyte interphase creates an energy barrier that limits low temperature performance. Higher interphase resistance forces greater overpotential during fast charging, increasing the likelihood of metallic lithium plating on graphite anodes. Cold environments exacerbate charge transfer bottlenecks, severely reducing usable battery capacity.
Optimizing film composition lowers interfacial barriers to maintain rapid lithium transport across electrode surfaces.
Film Evolution
Passivation layer thickening over repeated charge cycles increases total internal cell resistance. Solvent decomposition products build up over time, trapping active lithium ions and reducing energy density.
Diagnostic Method
Electrochemical impedance spectroscopy isolates interfacial resistive components from ohmic and diffusion contributions across frequency spectra. Measuring interphase resistance across varied states of charge identifies specific aging mechanisms in degraded battery packs. Cell manufacturers track interphase impedance changes during environmental aging tests to establish warranty lifespans for commercial applications.