Capacity fade of a high power battery when evaluated for use within a prime power supply

There is considerable need for a mobile, reliable, efficient, and compact prime power supply for a host of directed energy applications. Recent improvements in the energy and power density of electrochemical lithium-ion batteries have made them a very viable option for this type of application where fast and rep-rate operation is of interest. Despite the proven ability of lithium-ion batteries to source high currents, it is still unclear how they age when they are used to repeatedly source high rate currents in a pulse width modulated manner, as they must if used in a prime power supply. Similarly it is unclear how elevated rate recharge affects the life of the battery. Research has been performed at UTA in which a high power 3 Ah lithium-nickel-cobalt-aluminum-oxide (NCA) cell has been repeatedly discharged at an 85 C rate and 10 kHz frequency while recharged at a 1C rate. A second identical type of cell has been repeatedly discharged at a 1C rate but recharged using a 33C rate (100A) and a switching frequency of 0.11 Hz with a 33% duty cycle. Finally, a third identical type of cell has been cycled using a 1C charge and 1C discharge procedure for comparison of the aging through rated operation. A discussion concerning a wide variety of cells which are of interest for these applications will be presented. Additionally, a discussion of prime power source topologies along with the experimental setup used here and the results collected thus far will also be presented.