High Power, Gel Polymer Lithium-Ion Cells with Improved Low Temperature Performance for NASA and DoD Applications

摘要

Both NASA and the U.S. Army have interest in developing secondary energy storage devices that are capable of meeting the demanding performance requirements of aerospace and man-portable applications. In order to meet these demanding requirements, gel polymer electrolyte-based lithium-ion cells are being actively considered, due to their promise of providing high specific energy and enhanced safety. In pursuit of these objectives, high rate, gel-polymer lithium-ion cells from LG Chem/Compact Power are being actively evaluated to determine their applicability to meet ARMY and NASA needs. These cells, consisting of LiMn_2O_4-based cathode material, graphite anode material, and a proprietary gel polymer electrolyte, were primarily developed to target the automotive industry (EV and HEV applications). In addition to evaluating baseline cells, a number of prototype cells were fabricated with the incorporation of a low temperature liquid electrolyte developed at JPL, consisting of 1.0 M LiPF_6 EC+DEC+DMC+EMC (1:1:1:3 v/v), which was impregnated into the polymer matrix. To evaluate the performance of these cells, a number of characterization tests were performed including: determining the rate capacity as a function of temperature (both charge at room temperature and low temperature), the cycle life performance (both 100% DOD and 30% DOD LEO), the pulse capability, and the impedance characteristics at different temperatures.