Silicon-based energy storage devices with electrolyte containing cyanate based compounds
Electrolytes and electrolyte additives for energy storage devices comprising cyanate based compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte comprising at least two electrolyte co-solvents, wherein at least one electrolyte co-solvent comprises a cyanate based compound.
1. An energy storage device comprising:
a first electrode;
a second electrode;
a separator between the first electrode and the second electrode; and
an electrolyte system comprising:
a cyanate based compound;
a linear carbonate;
a cyclic carbonate; and
a Li-containing salt; wherein said cyanate based compound is any one of formulae (VI), (VII) and (VIII):
wherein R 6 , R 7 and R 8 are each independently selected from the group consisting of a C 1 -C 8 alkylene, C 2 -C 8 alkenylene, a C 2 -C 8 alkynylene, a cycloalkylene, an arylene, —O—,
and
wherein R 6 , R 7 and R 8 may be optionally substituted by —F, alkyl, alkenyl, cycloalkyl, aryl, —CN, —N + C − , fluoro-alkyl, fluoro-ether, —N(CH 3 ) 2 ,
and
wherein R L , R M , R N and R O are each independently selected from the group consisting of a bond, a C 1 -C 8 alkylene, a cycloalkylene, an arylene and —Si—, wherein R L , R M , R N and R O may be optionally substituted by —F, alkyl, alkenyl, alkynyl and aryl.
2. The energy storage device of claim 1 , wherein the linear carbonate is selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC).
3. The energy storage device of claim 1 , wherein the electrolyte system further comprises a co-solvent selected from the group consisting of methyl acetate (MA), ethyl acetate (EA), methyl propanoate, and gamma butyrolactone (GBL).
4. The energy storage device of claim 1 , wherein the cyclic carbonate is selected from the group consisting of fluoroethylene carbonate (FEC), di-fluoroethylene carbonate (DiFEC), Trifluoropropylene carbonate (TFPC), ethylene carbonate (EC), vinyl carbonate (VC), propylene carbonate (PC), -fluoromethyl-5-methyl-1,3-dioxolan-2-one (F-t-BC), 3,3-difluoropropylene carbonate (DFPC), and 3,3,4,4,5,5,6,6,6-Nonafluorohexyl-1-ene carbonate.
5. The energy storage device of claim 1 , wherein the cyclic carbonate is a fluorine containing cyclic carbonate.
6. The energy storage device of claim 5 , wherein the fluorine containing cyclic carbonate is FEC at a concentration of about 5% or more.
7. The energy storage device of claim 1 , wherein the electrolyte is substantially free of non-fluorine containing cyclic carbonate.
8. The energy storage device of claim 1 , wherein the Li-containing salt is a fluorinated Li salt.
9. The energy storage device of claim 1 , wherein the Li-containing salt has a concentration of about 1 M or more.
10. The energy storage device of claim 1 , wherein at least one of the first electrode and the second electrode is a Si-base electrode.
11. The energy storage device of claim 10 , wherein the Si-based electrode is an anode.
12. The energy storage device of claim 11 , wherein the anode is a Si-dominant anode.
13. The energy storage device of claim 11 , wherein the anode comprises:
greater than 0% and less than about 99% by weight of Si particles, and
greater than 0% and less than about 90% by weight of one or more types of carbon phases, wherein at least one of the one or more types of carbon phases is a substantially continuous phase that holds the composite material film together such that the silicon particles are distributed throughout the composite material film.
14. The energy storage device of claim 13 , wherein the anode comprises greater than 50% and less than about 97% by weight of Si particles.