Non-aqueous solvent electrolyte formulations for energy storage devices
Provided herein are improved electrolyte formulations. The improved performance may be realized as improved discharge rate cycling, improved capacity, improved Coulombic efficiency, or improved capacity upon cycling.
1 . An energy storage device, comprising:
a cathode comprising a cathode active material;
an anode comprising an anode active material and a binder, wherein the anode active material comprises surface modified artificial graphite, wherein the surface modified artificial graphite is surface modified with amorphous carbon, wherein the binder comprises a fibrillized binder, and wherein at least one of the cathode and the anode are free from solvent residue;
a separator between the cathode and the anode; and
an electrolyte comprising a lithium salt and a non-aqueous electrolyte solvent formulation comprising ethylene carbonate (EC) and ethyl methyl carbonate (EMC), wherein the volume ratio of EC to EMC is about 1:2.4 to about 1:4;
wherein the energy storage device has a capacity retention after 500 cycles of at least about 80%.
2 . The energy storage device of claim 1 , wherein the non-aqueous electrolyte solvent further comprises dimethylcarbonate (DMC), and comprises EC/DMC in a volume ratio of 1:3.
3 . The energy storage device of claim 1 , wherein the non-aqueous electrolyte solvent comprises EC/EMC in a volume ratio of 1:2.4.
4 . The energy storage device of claim 1 , wherein the non-aqueous electrolyte solvent comprises EC/EMC in a volume ratio of 1:4.
5 . The energy storage device of claim 1 , wherein the non-aqueous electrolyte solvent further comprises dimethylcarbonate (DMC), and comprises EC/DMC in a volume ratio of 1:4.
6 . The energy storage device of claim 1 , wherein the anode active material further comprises natural graphite.
7 . The energy storage device of claim 1 , wherein the anode active material further comprises flake-shaped artificial graphite.
8 . The energy storage device of claim 1 , wherein the cathode active material comprises layered lithium nickel manganese cobalt oxide (NMC).
9 . The energy storage device of claim 1 , wherein the cathode active material comprises sulfur or a material including sulfur.
10 . The energy storage device of claim 1 , wherein the lithium salt is LiPF 6 .
11 . The energy storage device of claim 1 , wherein the energy storage device has a first charge capacity of at least about 150 mAh/g.
12 . The energy storage device of claim 1 , wherein the energy storage device has a first discharge capacity of at least about 100 mAh/g.
13 . The energy storage device of claim 1 , wherein the energy storage device has an efficiency of at least about 70%.
14 . The energy storage device of claim 1 , wherein the energy storage device has a charge capacity retention at 1C of at least about 94%.
15 . The energy storage device of claim 1 , wherein the energy storage device has a discharge capacity retention at 1C of at least about 65%.
16 . A method of forming an energy storage device of claim 1 , comprising:
providing a housing,
placing into the housing the cathode, the anode and the separator between the cathode and the anode; and
placing into the housing the electrolyte to form the energy storage device.
17 . The energy storage device of claim 1 , wherein the non-aqueous electrolyte solvent consists essentially of EC and EMC.
18 . The energy storage device of claim 1 , the cathode comprises a fibrillized binder.
19 . The energy storage device of claim 1 , wherein the fibrillized binder comprises PTFE.
20 . The energy storage device of claim 1 , wherein at least one of the anode active material and the cathode active material comprise spherical-shaped particles.
21 . The energy storage device of claim 1 , wherein the volume ratio of EC to EMC is about 1:3 to about 1:4.
22 . The energy storage device of claim 1 , wherein the binder further comprises an additional binder.
23 . The energy storage device of claim 22 , wherein the additional binder is selected from a carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), co-polymers thereof, and combinations thereof.
24 . The energy storage device of claim 23 , wherein the binder consists essentially of the fibrillizable binder and the additional binder.
25 . The energy storage device of claim 1 , wherein the binder consists essentially of the fibrillizable binder.