Physical interpretations of Nyquist plots
Interpretations of electrochemical measurements like EIS and cyclic voltammetry vary widely and often lead to misinterpretation. Using physics-based models for ion transport and electric double-layer formation, our group demonstrated how specific Nyquist plot features correspond to electrode, electrolyte, and diffuse layer resistances, as well as equilibrium differential capacitance. These quantities can now be retrieved directly from measurements, yielding an internal resistance that closely agrees with the galvanostatic “IR drop.” We have extended this foundational analysis to interpret EIS for hybrid supercapacitors and batteries, as well as cyclic voltammograms for electrochemical capacitors.
1,800+ citations: this method has been used to characterize novel supercapacitor electrode materials (e.g., new carbons, MOFs, MXenes) and other applications including electrocatalysis, photocatalysis, biosensors, and membranes.
