Model-based Optimization of Battery Energy Storage Systems

A lithium-ion battery model based on the Single Particle Model (SPM) is formulated in MATLAB®. The model consists of a set of first-principle (algebraic and PDEs) and empirical equations that describe the dynamic behaviour of a Li-ion battery system. A sensitivity analysis is performed to identify the most important parameters and variables in the model. To assess the loss of battery capacity through cycling, the reduction of the electrolyte (ethylene carbonate) is considered as a side reaction. The battery is cycled until the end-of-life conditions are met: EODV (end of discharge voltage) below 3 V or capacity fading greater than 20% of the initial capacity of the battery. A gradient-based optimization is performed, identifying the maximum number of cycles within the simulated conditions. The influence of time of discharge, depth-of-discharge and ageing parameters is also assessed.