Lithium-sulfur (Li-S) batteries are described extensively in the literature, but existing computational models aimed at scientific understanding are too complex for use in applications such as battery management. Computationally simple models are vital for exploitation. This paper proposes a non-linear state-of-charge dependent Li-S equivalent circuit network (ECN) model for a Li-S cell under discharge. Li-S batteries are fundamentally different to Li-ion batteries, and require chemistry-specific models. A new Li-S model is obtained using a ‘behavioural’ interpretation of the ECN model; as Li-S exhibits a ‘steep’ open-circuit voltage (OCV) profile at high states-of-charge, identification methods are designed to take into account OCV changes during current pulses. The prediction-error minimization technique is used. The model is parameterized from laboratory experiments using a mixed-size current pulse profile at four temperatures from 10 °C to 50 °C, giving linearized ECN parameters for a range of states-of-charge, currents and temperatures. These are used to create a nonlinear polynomial-based battery model suitable for use in a battery management system. When the model is used to predict the behaviour of a validation data set representing an automotive NEDC driving cycle, the terminal voltage predictions are judged accurate with a root mean square error of 32 mV

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An isothermal model for an electrochemical capacitor is presented, analyzed and discussed. In essence, the model accounts for the transient conservation of species and charge in the solid and the electrolyte phase; two main length scales are considered: one corresponding to the entire cell (macroscale) and the other for the active material in the porous electrodes (microscale).Based on an electrochemical capacitor with Ruthenium dioxide electrodes, a scaling analysis is carried out after calibration and validation with experiments, for which good agreement is found. The analysis allows us to not only secure the relevant scales and nondimensional numbers characterizing an electrochemical capacitor, but also to identify limits at which the model can be reduced to a one-dimensional counterpart on the macroscale. Furthermore, a quasi-steady state can be achieved under certain conditions at the microscale, which leads to the elimination of the radial coordinate from the system of governing equations. These findings, in turn, lead to reduced model formulations that are computationally efficient and promising for inclusion in detailed stack models. The latter is explored by emulating stacks of ten and hundred cells. Finally, the inclusion of the equation of change for energy and heat generation is discussed.

Rocking disc electrode voltammetry (RoDE) is introduced as an experimentally convenient and versatile alternative to rotating disc voltammetry. A 1.6 mm diameter disc electrode is employed with an overall rocking angle of Θ = 90 degree applied over a frequency range of 0.83 Hz to 25 Hz. For a set of known aqueous redox systems (the oxidation of Fe(CN)6 4in 1 M KCl, the reduction of Ru(NH3)6 3+ in 0.1 M KCl, the oxidation of hydroquinone in 0.1 M pH 7 phosphate buffer, the oxidation of Iin 0.125 M H2SO4, and the reduction of H + in 1 M KCl)