Nonaqueous electrolyte compositions comprising silyl oxalates

An electrolyte composition comprising:

• a) a fluorinated solvent;
• and
• b) a lithium oxalato phosphate salt represented by Formula III:
• LiPF(6-2q)(C2O4)q (III)
• wherein q is 1, 2 or 3;
• wherein the oxalato phosphate salt comprises at least a portion that is derived from at least one silyl oxalate represented by Formula I:
• RR′Si(C2O4) (I),
• wherein R and R′ are each the same or different from each other and independently selected from C1-C5 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, or C6-C10 aryl radical, optionally comprising at least one substituent selected from halogen, hydroxyl, alkoxy, carbonyl, and carboxyl groups.

A method comprising:

• a step of combining:
• a) a fluorinated solvent;
• b) at least one silyl oxalate represented by Formula I:
• RR′Si(C2O4) (I),
• wherein R and R′ are each the same or different from each other and independently selected from C1-C8 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, or C6-C10 aryl radical, optionally comprising at least one substituent selected from halogen, hydroxyl, alkoxy, carbonyl, and carboxyl groups;
• and
• c) LiPF6;
• to form an electrolyte composition.