A General Equivalent Electrical Circuit Model for the characterization of MXene/graphene oxide hybrid-fiber supercapacitors by electrochemical impedance spectroscopy – Impact of fiber length

• A transmission line model with Warburg impedance is needed to fit the spectra. The electrical resistance of fibers governs high frequency 45° line. increases yarn length. Performance engineering electrochemical energy-storage devices such as Supercapacitors (SCs) requires updated modeling capable characterizing their output in unique device geometries. In this work, an Equivalent Electrical Circuit (EEC) developed data pseudo-capacitive and electrostatic fiber-shaped supercapacitors (FSCs). applied for interpretation measured on FSCs made reduced Graphene Oxide (rGO) MXene case pseudo-capacitors pure carbon Double-Layer Capacitors (EDLCs) active electrode materials, polyvinylalcohol (PVA) gel infiltrated sulfuric acid electrolyte separator. FSC charge storage behavior modeled using a Transmission Line Model (TLM) including finite pseudo-capacitance, Constant-Phase Element (CPE) contribution. part Nyquist plots characterized by straight use TLM clearly improves quality compared Randles circuit usually used pseudo-capacitor modeling. difference between two ciruits becomes more visible length SC yarns increases, which consistent observed increase internal fiber evidenced TLM. Furthermore, fitting results indicate that predominantly corresponds fiber, i.e. electron conductive phase electrode, instead ionic usual SCs. Finally, low spectra correctly CPE without any leakage resistance, showing self-discharge not significant issue contribution, at least range tested.