Frequency Domain Characterization of Batteries for the Design of Energy Storage Subsystems

The Ragone chart is a pictorial representation to express the well-known the trade-off between available energy vs. power of different classes of energy storage devices (ESDs) like batteries or supercapacitors. Ragone charts, however, do not normally provide information about individual devices, which is an essential requirement for the actual design of the energy storage sub-system. This work addresses this issue and proposes a systematic method to build the Ragone-plot for a specific ESD. We specifically focus on batteries, although the proposed methodology could be applied to any ESD that provides the required technical information.The main distinctive feature of our method is that it relies exclusively on data that can be taken from the data-sheet of the target device. Since recent works reveal that power analysis in frequency domain overcomes the limitation in the time domain, the work also proposes a method to convert classic Ragone plot into the frequency domain. We demonstrate our method on a set of batteries with different features and show how even comparable devices in terms of cost and capacity can have quite sensibly different frequency domain characteristics. A practical application example shows how to select optimal ESD based on its frequency characteristics and the frequency information in the workload.