Revisiting the Dielectric Spectrum: Tricks and Treats of Analysis and Interpretation Around the Conductivity Relaxation

The emergence of polymer nanodielectrics as suitable materials in energy storage devices highlights the importance of a deep understanding of their dielectric/electrical properties. When conductive materials are employed as nanofillers, strong interfacial polarisation and free charge carrier transport phenomena occur that both contribute to the imaginary permittivity as a peak and as a power law in the form of σ 0 /( ε 0 ω s ), respectively. To effectively discern and understand the two phenomena, the use of different dielectric formalisms is often preferred, that is, by the complex electric modulus M *( ω ). However, when M *( ω ) is employed, the free charge carrier contribution transforms into a step in M′ ( ω ) and into a peak in M ″( ω ), namely, the conductivity relaxation, that can be difficult to distinguish from interfacial polarisation or dipolar effects. A general relation is proposed here to describe the non‐Debye polarisation component of interfacial polarisation and non‐Ohmic transport of free charge carriers in its electric modulus representation. From this relation, the conductivity relaxation can be isolated into a separate function and is shown to exhibit a symmetrical broadening that cannot be described by the semi‐empirical Havriliak–Negami function when it deviates from Ohmic behaviour.