Pulsed evaluation of high power electrochemical energy storage devices

Researchers and manufacturers of lithium-ion batteries (LIBs), electric-double-layer capacitors (EDLCs), and lithium-ion capacitors (LICs) have been able to produce devices with power densities previously thought to be impossible. As a result of their higher power density, these devices are able to source high currents to compact pulsed power loads. Though many pulsed power sources already exist which draw their prime power from electrochemical energy storage devices, the number of systems and their capabilities will increase substantially as energy storage technologies continue to advance. Though manufacturers often list the peak pulsed current capability on the electrochemical cell´s datasheet, sometimes the value listed can be limited by the hardware used to test the cells and not always the cells themselves. In order to experimentally validate the pulsed current limitations of newer electrochemical cells, a low impedance test stand, capable of extracting high pulsed current from individual cells has been developed. The impedance of the stand, roughly equal to or less than 1 milli-Ohm, is such that in most cases, the impedance of the cell dominates the discharge current. A description of the test stand, the 100 ms pulsed current limitations of many different cells, and experiments representative of how these devices can function in a pulsed power system will be presented.