Recharge of electrochemical energy storage devices at pulsed elevated rates

Abstract

It has been shown previously that high power lithium-ion battery cells, such as the Saft VL8V [1] and GAIA 27 Ahr battery [2], are capable of discharging currents at rates much higher than their rated C values for time scales on the order of tens of milliseconds. This ability makes them an attractive prime power source for pulsed power applications. While these cells are capable of elevated rate discharge, recharge at an elevated rate is traditionally thought of as being catastrophic to the cell lifetime. In both defense and automotive applications, there is a high desire to recharge electrochemical energy storage devices at a faster rate. Previous research in this area has applied charge rates to batteries that are a few times the cell's rated C value in a steady state application with findings that recharge time can be significantly reduced [3]. New research in this area is being conducted at the University of Texas at Arlington. The aim of the research is to understand the charge rate limitations of electrochemical energy storage devices, such as lithium-batteries, supercapacitors, and lithium-ion capacitors, when the elevated charge is applied in a pulsed fashion. The effect these types of elevated recharge rates have on the fundamental material properties inside the cells is being researched as well. This paper describes the rationale behind the experiments, the experimental setup developed, and the research progress made thus far.