LITHIUM ION ELECTROLYTES WITH LIFSI FOR IMPROVED WIDE OPERATING TEMPERATURE RANGE

1 . A lithium ion battery cell, comprising:

a housing;

a cathode disposed within the housing, wherein the cathode comprises a cathode active material;

an anode disposed within the housing, wherein the anode comprises an anode active material; and

an electrolyte disposed within the housing and in contact with the cathode and anode, wherein the electrolyte includes a solvent mixture and a lithium salt serving as a primary lithium ion conductor in the electrolyte to allow for lithium ion intercalation and deintercalation processes at the cathode and the anode during charging and discharging of the lithium ion battery cell; and

wherein the solvent mixture includes a cyclic carbonate and one or more non-cyclic carbonates, wherein the lithium salt is lithium bis(fluorosulfonyl)imide (LiFSI), and wherein the solvent mixture and LiFSI are configured to enhance the low temperature performance of the lithium ion battery cell at operating temperatures below 0° C.

2 . The lithium ion battery cell of claim 1 , wherein LiFSI is the only lithium salt used to produce the electrolyte.

3 . The lithium ion battery cell of claim 1 , wherein the lithium ion battery cell has a lower area specific impedance at −30° C. than if the electrolyte used LiPF 6 as the lithium salt.

4 . The lithium ion battery cell of claim 1 , wherein the lithium ion battery cell has a lower area specific impedance at −30° C. than if the electrolyte used LiPF 6 as the lithium salt and LiFSI as an additive.

5 . The lithium ion battery cell of claim 1 , wherein the solvent mixture includes a non-cyclic ester.

6 . The lithium ion battery cell of claim 1 , wherein the electrolyte includes a carbonate-based additive but does not include a borate-based additive.

7 . The lithium ion battery cell of claim 1 , wherein LiFSI is the only lithium salt used to produce the electrolyte, and wherein the solvent mixture consists essentially of the cyclic carbonate, the one or more non-cyclic carbonates, and a non-cyclic ester.

8 . The lithium ion battery cell of claim 1 , wherein LiFSI is the only lithium salt used to produce the electrolyte, and wherein the solvent mixture consists essentially of:

the cyclic carbonate in an amount between 5 vol % and 30 vol % based on the total volume of the solvent mixture;

the one or more non-cyclic carbonates, present as a first non-cyclic carbonate and a second non-cyclic carbonate, wherein the first and second non-cyclic carbonates together represent between 50 vol % and 80 vol % of the total volume of the solvent mixture; and

a non-cyclic ester in an amount between 5 vol % and 20 vol %, based on the total volume of the solvent mixture.

9 . The lithium ion battery cell of claim 8 , wherein the cyclic carbonate is propylene carbonate (PC), the first non-cyclic carbonate is ethyl methyl carbonate (EMC), the second non-cyclic carbonate is dimethyl carbonate (DMC), the non-cyclic ester is methyl butyrate (MB), and wherein the electrolyte includes vinylene carbonate (VC) as an additive but does not include a borate-based additive or LiPF 6 .

10 . The lithium ion battery cell of claim 9 , wherein the solvent mixture is PC/EMC/DMC/MB (20:30:40:10 vol %), VC is present in an amount of 1 wt % based on the weight of the electrolyte, and LiFSI is present in a concentration between 1.0 M and 1.6 M.

11 . The lithium ion battery cell of claim 1 , wherein the anode active material includes a titanate-based material or a graphite-based material.

12 . The lithium ion battery cell of claim 1 , wherein the cathode active material includes a lithium nickel manganese cobalt oxide (NMC) active material, a lithium cobalt oxide (LCO) active material, a lithium cobalt aluminum oxide (NCA) active material, a lithium metal oxide spinel (LMO-spinel) active material, or any combination thereof.

13 . A lithium ion battery cell, comprising:

a housing;

a cathode disposed within the housing, wherein the cathode comprises a cathode active material;

an anode disposed within the housing, wherein the anode comprises an anode active material; and

an electrolyte disposed within the housing and in contact with the cathode and anode, wherein the electrolyte includes a solvent mixture, a lithium salt serving as a primary lithium ion conductor in the electrolyte to allow for lithium ion intercalation and deintercalation processes at the cathode and the anode during charging and discharging of the lithium ion battery cell, and lithium bis(fluorosulfonyl)imide (LiFSI) as an additive; and

wherein the solvent mixture includes a cyclic carbonate, a first non-cyclic carbonate and a second non-cyclic carbonate, and wherein the solvent mixture and the LiFSI additive are configured to enhance the low temperature performance of the lithium ion battery cell at operating temperatures below 0° C.

14 . The lithium ion battery cell of claim 13 , wherein LiFSI is present in an amount between 0.1 wt % and 1.0 wt %, based on the weight of the electrolyte.

15 . The lithium ion battery cell of claim 13 , wherein LiFSI is present in an amount of 0.5 wt %, based on the weight of the electrolyte.

16 . The lithium ion battery cell of claim 13 , wherein the electrolyte includes one or more additives, and LiFSI is the only lithium salt used as an additive in the electrolyte.

17 . The lithium ion battery cell of claim 16 , wherein the one or more additives include a carbonate-based additive.

18 . The lithium ion battery cell of claim 17 , wherein the carbonate-based additive is vinylene carbonate, and is present in an amount between 1.0 wt % and 2.0 wt %, based on the weight of the electrolyte.

19 . The lithium ion battery cell of claim 13 , wherein the solvent mixture includes a linear ester.

20 . The lithium ion battery cell of claim 13 , wherein the solvent mixture consists essentially of the cyclic carbonate, the first non-cyclic carbonate, the second non-cyclic carbonate, and a non-cyclic ester.

21 . A lithium ion battery cell, comprising:

a housing;

a cathode disposed within the housing, wherein the cathode comprises a cathode active material;

an anode disposed within the housing, wherein the anode comprises a titanate-based active material; and

an electrolyte disposed within the housing and in contact with the cathode and anode, wherein the electrolyte includes a solvent mixture, a lithium salt, and one or more additives; and

wherein the one or more additives include a vinyl trialkoxysilane, or a partially fluorinated ester, or a combination thereof.

22 . The lithium ion battery cell of claim 21 , wherein the one or more additives include the vinyl trialkoxysilane, and the vinyl trialkoxysilane is represented by the formula (X 1 )(X 2 )(X 3 )(X 4 )Si, wherein:

X 1 , X 2 , X 3 , and X 4 are each covalently bonded directly to the Si atom;

X 1 , X 2 , and X 3 are independently (OR) groups;

R is an alkyl chain having between 1 and 4 carbons; and

X 4 is a vinyl group.

23 . The lithium ion battery cell of claim 22 , the vinyl trialkoxysilane is vinyl trimethoxysilane (VTMS) and vinyl triethoxysilane (VTES).

24 . The lithium ion battery cell of claim 21 , wherein the one or more additives include the partially fluorinated ester.

25 . The lithium ion battery cell of claim 24 , wherein the partially fluorinated ester is a condensation product of a fluorinated or partially fluorinated alcohol with a non-fluorinated carboxylic acid.

26 . a condensation product of a fluorinated or partially fluorinated carboxylic acid with a non-fluorinated alcohol.

27 . The lithium ion battery cell of claim 24 , wherein the partially fluorinated ester is 2,2-trifluoroethyl butyrate (TFEB) or ethyl trifluoroacetate (ETFA).