Cyclic sulfone additives for lithium ion batteries

An electrochemical energy storage device comprising:

• a cathode;
• an anode;
• an electrolyte comprising an aprotic organic solvent system, a metal salt, and at least one cyclic sulfone organic compound additive according to the molecular structure below:
• wherein:
• R3 is an electron withdrawing group, or a C1-C12 linear or branched, alkyl group where at least one hydrogen is substituted with an electron withdrawing group;
• and R1, R2, R4, R5 are each independently hydrogen, C1-C12 linear or branched, substituted or unsubstituted alkyl and fluoroalkyl groups, or C6-C14 aryl groups wherein the hydrogen atoms can be unsubstituted or can be a halogen, alkyl, alkoxy, perfluorinated alkyl, silyl, siloxy, silane, sulfoxide, amide, azo, ether, and thioether group or combinations thereof;
• and
• a separator.