Pulsed Current Limitations of High Power Electrochemical Energy Storage Devices

Recently manufacturers of electrochemical energy storage devices have produced cells that are more power dense then previously available. The types of cells include lithium-ion batteries (LIBs), electric-double-layer capacitors (EDLCs), and lithium-ion capacitors (LICs) among others. As a result of the higher power density, the ability to use these devices as the prime power source of compact pulsed power systems is increased. A few pulsed power sources have already been developed which draw their prime power from electrochemical energy storage devices, and the number of systems as well as their capabilities will only increase as the energy storage technologies continue to advance. Though manufacturers often list peak pulsed current capability on the cell 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 some of the newest 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 and the current limitations of many of the cells tested thus far will be presented.