Improving Capacity and Thermal Degradation Characteristics of Li/(CFx)n Cells using Anion Binding Agent in the Electrolyte

Abstract

At Sandia National Laboratories we are exploring ways to improving capacity and the thermal degradation characteristics of Li/(CFx)n cells. We prepared (CFx)n electrodes with two different thicknesses and tested them in coin cells in conventional organic electrolytes and in Sandia developed electrolyte containing LiF complexed with an anion-binding- agent (ABA) as Li salt. Both the delivered capacity and the thermal characteristics of the thicker electrodes (15 mils thick) that have Teflon as binder are better in ABA containing electrolyte. For example, 2016 coin cells containing ABA and LiF (despite low conductivity) showed ~ 10% higher capacity than those containing the highly conductive electrolyte (HCE). Similar trend was observed for cells aged 4 days at 80oC and tested at 25oC. However, with thinner electrodes (1.5 -2 mil thick) that have PVDF as binder the delivered capacity was similar in the different electrolytes but the thermal behavior is better in ABA containing electrolyte