Limitations of Cyclic Voltammetry on Interdigitated Electrodes for Evaluating Polymer Conductivity

The reliability of extracting the electrical conductivity of electroactive polymer films from cyclic voltammetry (CV) on interdigitated electrodes (IDEs) is assessed using a data-driven, physics-based modeling framework. Pseudo-two-dimensional simulations replicate the IDE geometry and timing of the CV protocols. A porous-layer model that couples Butler–Volmer interfacial kinetics, radial diffusion of dopant anions within polymer globules, and lateral current flow in the IDE reproduces the salient voltammetric features. However, at typical scan rates, conductivity inferred from IDE current differences departs from the equilibrium value: pronounced hysteresis emerges, twin peaks develop, and occasional unphysical negative values appear. Analysis attributes the discrepancies to overpotential, spatially nonuniform doping across the film thickness, and uncompensated transient faradaic contributions to the current difference. Two accuracy-oriented protocols are evaluated: slowing the scan toward a quasi-equilibrium regime and employing staircase voltammetry with step holds until current stabilization. Both approaches recover conductivities consistent with the equilibrium relation and substantially reduce hysteresis. The workflow provides actionable guidance for obtaining reliable conductivity parameters for modeling and designing potentioresistive protective layers in lithium-ion cells and is transferable to other electrochemical systems that require an accurate description of conducting polymers.