Phosphate-Based Compounds as Additives for 5-Volt Lithium-Ion Electrolytes

Abstract

We have shown in previous work that fluorinated phosphate esters make effective additives to the standard carbonate-based electrolyte used in commercial and experimental Li-ion batteries. New results indicate that the degree of fluorination seems to have an effect on the performance of these additives in helping the full cell retain capacity during cycling tests. Experimental evidence gathered from half cell and full cell data lead us to hypothesize that fluorinated phosphate esters are participating in the formation of a tougher, more redox-resistant solid electrolyte interphase layer on both anode and cathode. Therefore, we propose a network-forming mechanism in which fluorinated phosphate esters function to protect the electrolytes from the electrodes in our tested Li-ion battery systems.